[123doc.vn] - Luan Van Nghien Cuu Anh Huong Cua Lieu Luong Phan Bon Den Sinh Truong Phat Trien Va Nang Suat Cua Giong Lua Th3 3 Va Giong p6 Tai Gia Lam Ha Noi

B GIO DC V O TO TRNG I HC NNG NGHIP H NI

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MAI TH TUN

NGHIN CU NH HNG CA LIU LNG PHN BN TI SINH TRNG, PHT TRIN V NNG SUT CA GING LA TH3-3 V GING P6 TI GIA LM-H NI

LUN VN THC S NNG NGHIP

Chuyn ngnh: TRNG TRT

M s: 60.62.01

Ngi hng dn khoa hc: TS. PHM VN CNG

H NI - 2008

Trng i hc Nng nghip H Ni Lun vn thc s khoa hc Nng nghip i

LI CAM OAN

- Ti xin cam oan rng, s liu v kt qu nghin cu trong lun vn l trung thc v cha tng c ai cng b

- Ti xin cam oan rng, mi s gip cho vic thc hin lun vn ny c cm n v cc thng tin trch dn trong lun vn ny c ch r ngun gc

H Ni, ngy 16 thng 9 nm 2008

Tc gi lun vn

MAI TH TUN

Trng i hc Nng nghip H Ni Lun vn thc s khoa hc Nng nghip ii

LI CM N

Ti xin by t lng bit n su sc ti TS. Phm Vn Cng tn tnh hng dn v to mi iu kin ti hon thnh cng trnh nghin cu ny.

Ti xin cm n Khoa Nng hc, Khoa Sau i hc, c bit l B mn Cy lng thc - Trng HNN H Ni gip rt nhiu cho vic

hon thnh bo co ny. Ti xin cm n Ban lnh o Trung tm Kho kim nghim ging, sn

phm cy trng v phn bn Quc gia, cc cn b phng Kho nghim v kim nh ging cy trng v phn bn to iu kin cho ti hon thnh lun vn.

Ti xin chn thnh cm n tt c nhng bn b ng nghip, ngi thn v gia nh to iu kin thun li cho ti trong qu trnh hon thin lun vn ny.

Lun vn ny kh trnh khi cn c nhng thiu st, ti rt mong nhn c nhng kin ng gp ca ng nghip, bn c v xin trn trng cm n.

H Ni, ngy 16 thng 9 nm 2008

Tc gi lun vn

MAI TH TUN

Trng i hc Nng nghip H Ni Lun vn thc s khoa hc Nng nghip iii

MC LC Trang

Li cam oan i

Li cm n ii

Mc lc iii-vi

Danh mc cc ch vit tt vii Danh mc cc bng viii-ix Danh mc th x

PHN I: M U.........................................................................................1

1.1. t vn ...............................................................................................1

1.2. Mc tiu nghin cu ................................................................................2

1.3. C s khoa hc v thc tin ca ti .................................................2 1.3.1. C s khoa hc .....................................................................................2 1.3.2. C s thc tin......................................................................................2 PHN II: TNG QUAN TI LIU...............................................................3 2.1 Tnh hnh sn xut la trn th gii v Vit Nam...................................3

2.1.1 Tnh hnh sn xut la trn th gii .......................................................3 2.1.2 Tnh hnh sn xut la Vit Nam.........................................................3 2.2 Tnh hnh sn xut la lai trn th gii v Vit Nam..............................5 2.2.1 Tnh hnh sn xut la lai trn th gii ..................................................5 2.2.2 Tnh hnh sn xut la lai Vit Nam....................................................7 2.3 c im sinh l cc ging la thun v la lai ......................................10 2.3.1 c im sinh trng v pht trin ca cy la...................................10 2.3.2 c im h r ca cy la ............................................................................11 2.3.3 Yu cu dinh dng chnh ca cy la v la lai ................................12 2.3.3.1 Yu cu dinh dng m ca cy la v la lai ................................12

Trng i hc Nng nghip H Ni Lun vn thc s khoa hc Nng nghip iv

2.3.3.2 Yu cu dinh dng ln ca cy la v la lai ..................................14 2.3.3.3 Yu cu dinh dng kali ca cy la v la lai .................................15 2.4 Tnh hnh s dng phn bn cho sn xut la .........................................16 2.4.1 C s l lun ca vic bn phn cho cy la .......................................16 2.4.2 Tnh hnh s dng phn bn cho la trn th gii v Vit nam .........18 2.4.3 Phng php bn phn cho la ...........................................................19 2.4.3.1 Cc loi v dng phn bn s dng cho la ......................................19 2.4.3.2 Lng phn bn cho la cc vng trng la chnh.........................20 2.4.3.3 Phng php bn phn cho la .........................................................21 2.4.4 Vn bn phn cn i cho cy la ..................................................24 2.5 Nhng kt qu nghin cu phn bn i vi cy la ..........................25 2.5.1 Kt qu nghin cu v phn m i vi cy la .................................25 2.5.2 Kt qu nghin cu v phn ln i vi cy la...................................30 2.5.3 Kt qu nghin cu v phn kali i vi cy la..................................32 PHN III: VT LIU, NI DUNG V PHNG PHP NGHIN CU.36 3.1. Vt liu nghin cu................................................................................36 3.1.1 Phn bn .............................................................................................36 3.1.2 Ging...................................................................................................36 3.2 Ni dung nghin cu .............................................................................36 3.3 Phng php nghin cu ........................................................................37 3.4 Cc ch tiu theo di v phng php theo di .......................................37 3.4.1. Thi k rung cy: ............................................................................37 3.4.2. Thi k chn: ......................................................................................38 3.5. Bin php k thut p dng ...................................................................40 3.6. Phng php phn tch s liu ...............................................................40 PHN IV: KT QU NGHIN CU V THO LUN ...........................41

Trng i hc Nng nghip H Ni Lun vn thc s khoa hc Nng nghip v

4.1 nh hng ca liu lng phn bn n mt s ch tiu nng ho trong t ................................................................................................................41

4.2. nh hng ca liu lng phn bn n thi gian sinh trng ca ging la TH3-3 v P6 qua cc giai on sinh trng ............................................42 4.3. nh hng ca liu lng phn bn n chiu cao cy ca ging TH3-3 v P6 cc giai on sinh trng.................................................................43 4.4. nh hng ca liu lng phn bn n tc tng trng chiu cao cy ca ging TH3-3 v P6.................................................................................46 4.5. nh hng ca liu lng phn bn n tng trng s nhnh ca ging TH3-3 v P6 qua cc giai on sinh trng ..................................................48 4.6. nh hng ca liu lng phn bn n tc tng trng s nhnh ca ging TH3-3 v P6 qua cc giai on sinh trng ............................................50 4.7. nh hng ca liu lng phn bn n ch s SPAD ca ging TH3-3 v P6 qua cc giai on sinh trng .............................................................52 4.8. nh hng ca liu lng phn bn n ch s dy l (SLA) ca cc ging la th nghim qua cc giai on sinh trng......................................53 4.9. nh hng ca liu lng phn bn n hm lng m tng s ca cc ging la th nghim.....................................................................................55 4.10. nh hng ca liu lng phn bn n ch s din tch l (LAI) ca ging TH3-3 v P6 qua cc giai on sinh trng ........................................56 4.11. nh hng ca liu lng phn bn n khi lng cht kh tch lu ca ging TH3-3 v P6 qua cc giai on sinh trng..................................58 4.12. nh hng ca liu lng phn bn n tc tch lu cht kh (CGR) ca ging TH3-3 v P6 qua cc giai on sinh trng.................................60 4.13. nh hng ca liu lng phn bn n hiu sut quang hp thun ca cc ging la th nghim qua cc giai on sinh trng................................62

Trng i hc Nng nghip H Ni Lun vn thc s khoa hc Nng nghip vi

4.14. nh hng ca liu lng phn bn n nng sut v cc yu t cu thnh nng sut ca cc ging la th nghim...............................................64 4.15. nh hng ca liu lng phn bn n nng sut sinh vt hc v h s kinh t ca cc ging la th nghim.............................................................67 4.16. Tng quan gia nng sut ht v mt s yu t lin quan cc giai on sinh trng...........................................................................................69 4.16.1 Tng quan gia nng sut ht v hm lng Cholorophyll (SPAD) 69 4.16.2 Tng quan gia nng sut ht v ch s din tch l ........................70 4.16.3 Tng quan gia nng sut ht v kh nng tch lu cht kh ..........70 4.16.4 Tng quan gia nng sut v cc yu t cu thnh nng sut .........73 PHN V: KT LUN V NGH ..........................................................75 5.1 Kt lun ..................................................................................................75 5.2 ngh ...................................................................................................75

Trng i hc Nng nghip H Ni Lun vn thc s khoa hc Nng nghip vii

DANH MC CC CH VIT TT

KTN: Kt thc nhnh KTT: Kt thc tr TGST: Thi gian sinh trng TSC: Tun sau cy NXB: Nh xut bn Ha: Hec ta

HSKT: H s kinh t NSSVH: Nng sut sinh vt hc NSLT: Nng sut l thuyt NSTT: Nng sut thc thu

Trng i hc Nng nghip H Ni Lun vn thc s khoa hc Nng nghip viii

DANH MC CC BNG Trang

Bng 2.1: Nhu cu v cn i phn bn Vit Nam n nm 2020 .............18 Bng 2.2: Lng phn bn cho la ...............................................................21 Bng 2.3: Chun on nhu cu dinh dng qua l ca cy la .....................23 Bng 4.1: Kt qu phn tch mt s ch tiu nng ho trong t cc th nghim .........................................................................................................41

Bng 4.2: nh hng ca liu lng phn bn n thi gian sinh trng ca ging la TH3-3 v P6 qua cc giai on sinh trng (ngy) .......................................42 Bng 4.3: nh hng ca liu lng phn bn n tng trng chiu cao cy ca ging TH3-3 v P6................................................................................44 Bng 4.4: nh hng ca liu lng phn bn n tc tng trng chiu cao cy ca ging TH3-3 v P6 (cm/tun) ...................................................47 Bng 4.5: nh hng ca liu lng phn bn n tng trng s nhnh ca ging TH3-3 v P6 .......................................................................................49 Bng 4.6: nh hng ca liu lng phn bn n tc tng trng s nhnh ca ging TH3-3 v P6 (nhnh/khm/tun)........................................51 Bng 4.7: nh hng ca liu lng phn bn n ch s SPAD ca ging TH3-3 v P6 trong v Xun 2008.................................................................53 Bng 4.8: nh hng ca liu lng phn bn n ch s dy l (SLA) ca cc ging la th nghim qua cc giai on sinh trng ..........................................54 Bng 4.9 : nh hng ca liu lng phn bn n hm lng m trong l ca cc ging la th nghim trong v Ma ..................................................55 Bng 4.10: nh hng ca liu lng phn bn n ch s din tch l (LAI) ca ging TH3-3 v P6.........................................................................................57

Trng i hc Nng nghip H Ni Lun vn thc s khoa hc Nng nghip ix

Bng 4.11: nh hng ca liu lng phn bn n khi lng cht kh tch lu ca ging TH3-3 v P6...........................................................................59 Bng 4.12: nh hng ca liu lng phn bn n tc tch lu cht kh (CGR) ca cc ging la th nghim ...........................................................................61 Bng 4.13: nh hng ca cc liu lng phn bn n hiu sut quang hp thun ca cc ging la th nghim qua cc giai on sinh trng...............62 Bng 4.14: nh hng ca cc liu lng phn bn n nng sut v cc yu t cu thnh nng sut ca cc ging la th nghim.....................................64 Bng 4.15:. nh hng ca cc liu lng phn bn n nng sut sinh vt hc v h s kinh t ca cc ging la th nghim ........................................68

Trng i hc Nng nghip H Ni Lun vn thc s khoa hc Nng nghip x

DANH MC CC TH

Trang

th 1: Tng quan gia nng sut thc thu (NSTT) vi Ch s SPAD ca ging TH3-3 v ging P6 cc mc phn bn khc nhau ...........................69 th 2: Tng quan gia nng sut thc thu (NSTT) vi ch s din tch l (LAI) ca ging TH3-3 v ging P6 cc mc phn bn ti cc giai on sinh trng...........................................................................................................71

th 3: Tng quan gia nng sut thc thu (NSTT) vi khi lng cht kh tch lu (DM) ca ging TH3-3 v ging P6 cc mc phn bn khc nhau..............................................................................................................72

th 4: Tng quan gia nng sut thc thu (NSTT) v cc yu t cu thnh nng sut ca ging TH3-3 v ging P6 cc mc phn bn khc nhau trong v Ma 2007 ................................................................................................74 th 5: Tng quan gia nng sut thc thu (NSTT) v cc yu t cu thnh nng sut ca ging TH3-3 v ging P6 cc mc phn bn khc nhau trong v Xun 2008 ...............................................................................................74

Trng i hc Nng nghip H Ni Lun vn thc s khoa hc Nng nghip 1

PHN I

M U 1.1. t vn

Cy la (Oryza Sativa L) l mt trong nhng cy trng cung cp ngun lng thc quan trng nht ca loi ngi, vi 40% dn s th gii s dng la go lm thc n chnh v c nh hng n i sng ca t nht 65% dn s th gii.

Vit Nam, vic p dng thnh tu v la lai c kt qu to ln. Nng sut la lai so vi la thng tng t 20% tr ln v din tch la lai ngy cng tng. Trc y 10 nm, Vit Nam xut khu c mt lng la go ln ng th hai trn th gii (FAO, 2006). Sn xut la lai hin nay Vit Nam c nhiu cng ngh v ging mi c to ra.

gp phn nng cao hn na hiu qu ca vic trng la nhm tng thu nhp cho nhng nng dn trng la v bo v mi trng, tin ti xy dng nn nng nghip bn vng. B NN v PTNT quyt nh thnh lp v xy dng chng trnh ba gim ba tng p dng cho canh tc la.

Trong thi gian gn y cng vi s pht trin ca cc ngnh kinh t, ngnh nng nghip nc ta tng nhanh v nng sut v sn lng la l nh c s ng gp ca cng ngh u th lai v phn bn, trong mc phn bn c vai tr quyt nh ln n nng sut v hiu qu kinh t ca rung la. V vy vic xc nh nh hng ca liu lng phn bn n ch s din tch l v trng lng tch ly cht kh ca la lai v la thun tng giai on sinh trng khc nhau v mi quan h ca chng i vi nng sut ht cc ma v l vic lm ht sc cn thit nhm t nng sut v hiu qu kinh t cao. Chnh v th chng ti tin hnh nghin cu ti: Nghin cu nh hng ca liu lng phn bn ti sinh trng, pht trin v nng sut ca ging la TH3-3 v ging P6 ti Gia Lm - H Ni.


1.2. Mc tiu nghin cu - nh gi nh hng ca liu lng phn bn n cc ch tiu sinh

trng t tm ra yu t no l quyt nh n nng sut ht ca ging la TH3-3, P6.

- Xc nh nh hng ca liu lng phn bn khc nhau n cc yu t cu thnh nng sut.

- Xc nh c liu lng phn bn thch hp vi ging TH3-3, P6 trn vng t ng bng sng Hng - Gia Lm - H Ni nhm t c nng sut cao nht 1.3. C s khoa hc v thc tin ca ti 1.3.1. C s khoa hc

Mc d cc nghin cu cp n nhiu vn nh: Chn to ging, tnh thch ng, su bnh, phn bn v nhiu nghin cu khc lin quan n la. Nhiu ging la mi ca Vit Nam khng nh v tr ca mnh trong sn xut v c ngi nng dn nh gi cao. Tuy nhin v nh hng ca dinh dng cho la, cc nghin cu cha cp n nhiu v liu lng, t l v k thut s dng phn bn a lng cho tng vng, tng cht t v tng ging c th. Vic bn phn khng cn i, k thut bn cha hp l hn ch nng sut, khng pht huy ht tim nng ca ging. Do vy ti ny s ng gp thm vo kt qu nghin cu v vai tr ca cc nguyn t a lng v bin php k thut s dng phn bn hp l cho la. m bo tnh bn vng trong sn xut nng nghip vng ng bng sng Hng v cng l c s cho a phng ch o v nh hng cho sn xut ca vng. 1.3.2. C s thc tin

Xc nh c liu lng, t l N, P, K hp l cho vic thm canh sn xut la nhm: Tng nng sut cy trng, tng sn lng trn n v din tch canh tc. Tng thu nhp v ng thi gp phn n nh ph nhiu ca t. m bo cho vic sn xut c bn vng trn t trng la vng ng bng sng Hng.


PHN II

TNG QUAN TI LIU 2.1 Tnh hnh sn xut la trn th gii v Vit Nam

2.1.1 Tnh hnh sn xut la trn th gii Cy la c ngun gc nhit i, d trng, cho nng sut cao. Hin nay trn th gii c khong trn 100 nc trng la. Vng trng la tng i rng: c th trng cc vng c v cao nh Hc Long Giang (Trung Quc) 530B; Tip 490B, Nht, Italia, Nga (Krasnodar) 450B n nam bn cu, New South Wales (c): 350N. Vng phn b ch yu chu t 300B n 100N. Sn xut la go trong nhng thp k gn y c mc tng ng k, nhng do dn s tng nhanh, nht l cc nc ang pht trin (Chu , Chu Phi, Chu M La Tinh) nn vn lng thc vn l yu cu cp bch phi quan tm trong nhng nm trc mt v lu di. Theo thng k ca Vin Nghin cu la quc t, cho n nay la vn l cy lng thc c con ngi sn xut v tiu th nhiu nht. Chnh v vy, tng sn lng la trong vng 30 nm qua tng ln gp hn 2 ln: t 257 triu tn nm 1965 ln ti 535 triu tn nm 1994. Cng vi n, din tch trng la cng tng ln ng k, nm 1970 din tch trng la ton th gii l 134.390 triu ha, n nm 1994 con s ny ln ti 146.452 triu ha. Trong , cc nc Chu vn gi vai tr ch o trong sn xut v tiu th la go[58], [68]. 2.1.2 Tnh hnh sn xut la Vit Nam Vi iu kin kh hu nhit i, Vit Nam c th coi l ci ni hnh thnh cy la nc. t lu, cy la tr thnh cy lng thc ch yu, c ngha ng k trong nn kinh t v x hi nc ta. Vi a bn tri di trn 15 v Bc bn cu, t Bc vo Nam hnh thnh nhng ng bng chu th trng la ph nhiu.


Vit Nam l mt nc nng nghip, c ti 75% dn s sn xut nng nghip v t lu cy la n su vo tim thc ngi dn, n c vai tr rt quan trng trong i sng con ngi. La go khng ch gi vai tr trong vic cung cp lng thc nui sng mi ngi m cn l mt hng xut khu ng gp khng nh vo nn kinh t quc dn. Mt khc, do c iu kin t nhin thun li ph hp cho cy la pht trin nn la c trng khp mi min ca t nc. Trong qu trnh sn xut la hnh thnh nn 2 vng sn xut rng ln l vng ng bng chu th Sng Hng v ng bng sng Cu Long [33], [44]. Trc nm 1945, din tch t trng la ca nc ta l 4,5 triu ha, nng sut trung bnh t 1,3 tn/ha, sn lng 5,4 triu tn. Hin nay, vi nhng tin b k thut vt bc trong nng nghip, ngi dn c tip cn vi nhng phng thc sn xut tin tin nn h dm mnh dn p dng khoa hc k thut vo sn xut, dng cc ging la mi, cc ging la u th lai, cc ging la cao sn, cc ging la thch nghi vi iu kin c bit ca tng vng, cc ging la cht lng t tiu chun xut khu, kt hp u t thm canh cao, hp l. Nh vy, ngnh trng la nc ta c bc nhy vt v nng sut, sn lng v gi tr kinh t. Nm 1996, nc ta xut khu c 3,2 triu tn lng thc, nm 1999, nc ta vn ln ng hng th 2 trn th gii v xut khu go. Nm 2002, tng sn lng lng thc t 36,4 tru tn, trong la chim 70%. Tuy nhin, con s ny b trng li vo nm 2003 gim xung cn 34,5 triu tn. iu ny ang t ra nhng yu cu mi trong nng nghip. Trong iu kin hin nay, xu hng th ho, cng nghip ho ang din ra mnh, dn s lin tc tng lm din tch t nng nghip ni chung v din tch t trng la ni ring ngy cng b thu hp. V vy, vn cp thit t ra y l cn phi nng cao hn na nng sut v cht lng la, nhm p ng c nhu cu lng thc cho ngi dn v cho xut khu [44] .


2.2 Tnh hnh sn xut la lai trn th gii v Vit Nam 2.2.1 Tnh hnh sn xut la lai trn th gii

Hin tng u th lai la c nghin cu t na u th k 19 do Jones J.W (1926) l ngi u tin cng b v u th lai la trn cc tnh trng nng sut v mt s tnh trng s lng. T n nay, c nhiu nh khoa hc khc tp trung nghin cu c im ny la. Cc cng trnh nghin cu tp trung vo cc vn nh: bn cht di truyn s biu hin u th lai v cc phng php khai thc u th lai.

Cc nh khoa hc n , Nht Bn l nhng ngi u tin xut m rng sn xut la lai thng phm. Ti Vin la quc t - IRRI, cc nh khoa hc xy dng chng trnh nghin cu v la lai lm c s cho pht trin sn xut la lai thng phm. Song tt c h u cha thnh cng v

cha tm ra phng php thch hp sn xut ht lai [1]. Nm 1964, cc nh khoa hc Trung Quc tm ra mt dng la di

bt dc, sau h thnh cng trong vic chuyn gen bt dc c t bo cht vo la trng to ra cc dng la bt dc c (CMS) m ng cho cng tc khai thc u th lai thng phm sau ny [7], [20], [74] .

Nm 1973, Trung Quc sn xut c ht lai F1 h 3 dng nh s dng 3 loi dng b m l: dng bt dc t bo cht, dng duy tr bt dc v dng phc hi hu dc. Nm 1974, Trung Quc gii thiu mt s t hp lai thuc h 3 dng vi u th lai rt cao nh: Shan u 2, Shan u 6, Shan u 63.... Nm 1975, quy trnh k thut sn xut ht lai h 3 dng c hon thin v a ra sn xut [20], [74].

Nm 1976, Trung Quc sn xut c ht lai F1 v gieo cy 140.000 ha la lai, t din tch la lai tng ln lin tc ko theo nng sut la ca c nc tng vi tc cao. Vo nhng nm 1990, Trung Quc trng c 15 triu ha la lai, chim 46% tng din tch la, nng sut vt


20% so vi ging la thun tt nht (Yuan L.P, 1993). Qui trnh k thut nhn dng b m v sn xut ht lai ngy cng hon thin. Nng sut ht ging F1 tng ln tng i vng chc. Vi nhng thnh cng v la lai ca Trung Quc m ra trin vng to ln trong pht trin la lai nhiu nc trn th gii.

Nm 1973, Shiming Song pht hin ra c dng bt dc mn cm nh sng ngy ngn (PGMS) t ging Nongken 58 [20]. Nhiu kt qu nghin cu khc v la lai hai dng cng c cng b. Nm 1991, cc nh khoa hc Nht Bn p dng phng php gy t bin nhn to to ra dng bt dc c mn cm vi nhit [14]. Chng trnh pht trin la lai gia cc loi ph (indica/japonica) c bt u t nm 1987 nh s pht hin v s dng gen tng hp rng, m ra tim nng v nng sut cao cho cc ging la lai hai dng [14]. Nhng t hp gia cc loi ph nh: Chen 232/26 Zhazao; 3037/02428 v 6154S/vaylava a ra Trung Quc nhng khng c s dng trong sn xut i tr, v cy F1 qu to, bng qu ln, s dnh t, dng l qu rng. Bi th, Yang v cng s nm 1997 xut mt l thuyt chn ging nng sut siu cao thng qua vic kt hp dng hnh l tng v u th lai thch hp [59]. Nm 1992, din tch gieo trng la lai hai dng Trung Quc l 15.000 ha vi nng sut 9-10 tn/ha, nng sut cao nht t c l 17,0 tn/ha. Nm 1997, c 640.000 ha nng sut trung bnh cao hn la lai ba dng 5-15%. n nm 2001, din tch la lai hai dng t 2,5 triu ha. Mt s t hp lai hai dng in hnh c nng sut t hn 10,5 tn/ha im trnh din v nng sut trung bnh trn din rng l 9,1 tn/ha. c nhng t hp la lai hai dng mi t 12 n 14 tn/ha trong th nghim. Hu ht cc t hp lai hai dng u cho nng sut cao v phm cht tt hn so vi cc t hp lai ba dng [20]. Gn y hng nghin cu pht trin la lai mt dng l mc tiu cui cng rt quan trng ca cng tc chn ging la lai Trung Quc. tng ca Yuan L. P l c nh u th lai v sn xut la


lai thun tr thnh nhng ti ln, quan trng trong cc chng trnh quc gia v pht trin khoa hc v cng ngh cao.

Nh vy, xu th pht trin tt yu ca la lai, theo Yuan L.P khi xng l pht trin t h thng ba dng n h thng hai dng v sau l la lai h mt dng hay c nh u th lai F1 thnh la lai thun [20] .

S pht trin thnh cng ca cng ngh sn xut la lai Trung Quc c ng dng rng ri nhiu nc trn th gii. Hin nay, c 17 nc nghin cu v sn xut la lai a tng din tch la lai ca th gii ln khong 10% tng din tch trng la v chim 20% tng sn lng la go ton th gii, song pht trin mnh nht vn l Vit Nam v n . La lai thc s m ra hng pht trin mi nng cao nng sut v sn lng la cho x hi loi ngi [7] . 2.2.2 Tnh hnh sn xut la lai Vit Nam

Vit Nam bt u nghin cu la lai t nm 1985, nhng thc s c xc tin mnh t nhng nm 1990. Mt s dng bt dc c t bo cht, dng phc hi v t hp la lai ba dng c nhp ni t Trung Quc v IRRI c nh gi. Nhng kt qu bc u xc nh c mt s dng b m v ging la lai thch ng vi iu kin sinh thi v sn xut ca Vit Nam, em li nng sut v hiu qu kinh t cao (Quch Ngc n, 2002).

Cng tc nghin cu v chn to cc ging la lai Vit Nam cng c thc y mnh m, tp trung vo vic thu thp, nh gi cc dng bt dc c nhp ni, s dng cc phng php chn ging truyn thng nh lai hu tnh, t bin to cc dng b m mi. Cc kt qu nghin cu xc nh c cc vt liu b m tt, thch ng vi iu kin sinh thi min Bc v c kh nng cho u th lai cao nh cc dng m: BoA-B, IR58025A-B, VN-01, 11S, TGMS7, TGMS11, TGMSVN1, T1S-96, 103S, TGMS6; cc dng b: R3, R20, R24, RTQ5... Hong Tuyt Minh, 2002 [36], Nguyn Tr


Hon, Nguyn Th Gm, 2003 [28], Phm Ngc Lng, 2000 [34], H Vn Nhn, 2002 [37], Nguyn Th Trm, 2005 [49].

T nm 1997 n nm 2005, c khong 68 ging la lai trong nc c kho nghim, trong c 3 ging c cng nhn chnh thc: Vit Lai 20, HYT83, TH3-3, mt s ging c cng nhn tm thi HYT57, TM4, HYT100, HYT92, TH3-4, HC1, TH5-1 v Vit Lai 24 v mt s ging trin vng khc [9] .

Ngoi ra, chng ta cng tch cc nhp ni cc ging la lai nc ngoi,

chn lc cc t hp lai tt, thch ng vi iu kin Vit Nam phc v sn xut. Cho n nay, Vit Nam c c mt c cu ging la lai kh a dng, ngoi cc ging ang c s dng ph bin trong sn xut nh: Nh u 838, Nh u 63, D.u 527, Bi tp sn thanh, Bc u 903, nhiu ging mi c m rng trong sn xut c nng sut, cht lng kh nh: Khi phong 1, Q.u s 1, CNR36, Nghi hng 2308, VQ14, Ph u s 1 v mt s ging la lai ca Vit Nam nh HYT83, HYT100, TH3-3, Vit lai 20, TH3-4...Trn Vn Khi, 2006 [30], Phm ng Qung, 2006 [39].

Quy trnh nhn dng b m v sn xut ht lai F1 ca mt s t hp c hon thin v nng sut ht lai tng ln r rt (Nguyn Tr Hon, 2002). Nhiu t hp c sn xut ht lai F1 Vit Nam nh Bc u 903, Bc u 64, Bc u 253, Nh u 838, Nh u 63, D u 527, VL20, TH3-3, HYT83, HYT92, HYT100, HC1, nng sut trung bnh t 1,5-2,5 tn.

Ngoi ra, mt s nghin cu v sinh l ca cy la lai cho thy: u th lai v nng sut ht ca mt s t hp lai c to bi u th lai v din tch l giai on nhnh v tr, mt s khc do u th lai v cng quang hp. Cc nghin cu v phn bn cho thy, khi tng lng phn bn th ch s din tch l (LAI), khi lng cht kh trn ton cy (DM), tc tch ly cht kh (CGR) ca la lai tng vt so vi la thun, c bit giai


on sau cy 4 tun; nng sut ca la lai tng nhiu hn nng sut la thun v c tng quan thun mc c ngha vi LAI v CGR giai on u ca qu trnh sinh trng [9], [10].

Cng tc nghin cu, chn to la lai hai dng cng c xc tin mnh m Vit Nam. Cc nghin cu hin nay tp trung vo mt s lnh vc nh chn to, nh gi cc c tnh nng sinh hc ca cc dng TGMS; tin hnh lai th tm t hp lai cho u th lai cao; xy dng quy trnh nhn dng bt dc v sn xut ht lai F1. Mt s tc gi c cc nghin cu ban u v bn cht di truyn v kh nng phi hp ca mt s vt liu hin c.

c hn 20 dng TGMS mi c chn to ti Vit Nam [43], tuy nhin ch mt s dng nh 103S, T1S-96 c s dng rng ri trong vic chn to cc t hp la lai hai dng mi pht trin vo sn xut. Cc dng ny cho con lai ngn ngy, cht lng go kh tt, c bit d sn xut ht lai nn nng sut ht lai cao, gi thnh h (Phm ng Qung, 2005).

Cc nh chn ging la lai trong nc cng tin hnh chn to cc dng PGMS mi, c tnh cm quang, ph hp vi iu kin Vit Nam. Phng php tin hnh l lai chuyn cc gen cm ng vi di ngy vi ging la c ngun gc xut x xa vi vng pht sinh ca ging khi u tm kiu phn ng vi pha sng ngn hn. C s ca phng php ny l tnh cm ng vi quang chu k c th bin i khi tn ti cc mi trng khc nhau, tc l khi chuyn gen pms t mt ging c mc cm ng nht nh sang

mt ging khc th gen pms c th biu hin phn ng khc. Trong mi trng mi ny, di pha sng nh hng n chc nng hot ng ca gen c th thay i theo. Thc t Vit Nam, cc nh chn ging la lai chn lc thnh cng dng PGMS mi P5S bng phng php lai dng T1S-96 v Peiai64S. Dng ny c phn hu dc khi di ngy ngn hn hoc bng 12h20', bt dc hon ton khi di ngy t 12gi30' tr ln. Thi k cm


ng vo bc 5 ca phn ha ng. Dng P5S c th s dng lm m sn xut ht lai nu tr vo u n trung tun thng 5 min Bc. Nhn dng trong v Xun, cho tr trc 12/4 (Nguyn Th Trm, Trn Vn Quang, 2003) [48].

Nh vy, s lng dng TGMS thc s c ng dng pht trin cc t hp la lai hai dng phc v sn xut nc ta cn rt t, mt s dng cn c hn ch v kh nng kt hp, kh nng cho con lai c u th lai cao v nng sut, kh nng chng chu su bnh v iu kin ngoi cnh bt thun.

Ngoi ra, ngun vt liu dng phc hi phc v cho cng tc chn to la lai hai dng cng cha thc s a dng, phong ph. Chng ta cng cha c cc dng phc hi c kh nng kt hp cao, chng chu su bnh tt, c th s dng chn to nhiu t hp lai c u th lai cao v nng sut.

cng tc chn to la lai hai dng Vit Nam t c hiu qu tt, cn phi tp trung nghin cu chn to ngun vt liu b m mi c c tnh nng sinh hc tt, thch ng rng, kh nng kt hp cao, n nh v d sn xut ht lai. Trn c s chn to v a vo s dng cc t hp lai mi c thng hiu ring, cho nng sut cao v n nh, cht lng go tt, thch ng vi iu kin sinh thi nc ta (Nguyn Tr Hon, 2003).

2.3 c im sinh l cc ging la thun v la lai 2.3.1 c im sinh trng v pht trin ca cy la

Trong ton b i sng ca cy la c th chia ra hai thi k sinh trng ch yu l sinh trng dinh dng v sinh trng sinh thc.

Thi k sinh trng dinh dng c tnh t lc gieo n lc lm ng, l thi k cy la hnh thnh v pht trin l, r, nhnh. la cy thi k ny c th chia ra cc giai on: m rung m v nhnh rung cy. Trong giai on m ko di khong 20 ngy t khi gieo m n khi cy c khong 4-5 l; giai on nhnh ko di khong 40 ngy t khi cy n khi cy la bt u c ng; trong 10-13 ngy u l giai on bn r hi


xanh, giai on nhnh hu hiu ch khong 20 ngy tip theo. Thi k sinh trng dinh dng c nh hng trc tip n vic hnh thnh s bng, l yu t cu thnh nng sut c ngha quyt nh i vi cy la.

Thi k sinh trng sinh thc, bt u t lc lm ng cho n khi thu hoch, bao gm cc qu trnh lm ng, tr bng v hnh thnh ht. Thi k ny quyt nh cc yu t cu thnh nng sut: s ht trn bng, t l ht chc v trng lng 1000 ht, l thi k c nh hng trc tip nht n nng sut thu hoch.

Lin quan ti TGST ca cy la, cc ging la c chia ra: ging cc ngn ngy, ging ngn ngy v ging di ngy. Trong bn phn cho la cn ch : cc ging cc ngn ngy (chn sm) c giai on sinh trng dinh dng ngn, v vy c th bt u phn ha ng trc giai on nhnh ti a. Cc ging di ngy (chn mun) c giai on sinh trng dinh dng di v t s dnh ti a trc khi bt u phn ha ng, thi k t nhnh ti a n u phn ha ng c lc b ko di. Cc ging ngn ngy c di ca giai on sinh trng dinh dng va phi, cy bt u phn ha ng ngay sau giai on nhnh ti a.

2.3.2 c im h r ca cy la La l cy trng c b r chm vi s lng c th t ti 500-800 ci,

tng chiu di r thi k tr bng c th t n 168 m. B r la tng dn v s lng v chiu di qua cc thi k nhnh, lm ng v thng t ti a vo thi k tr bng, sau li gim i. Thi k nhnh lm ng b r pht trin c hnh bu dc nm ngang, cn thi k tr bng, b r la pht trin xung su c hnh qu trng ngc.

B r la phn b lp t 0-20 cm, trong phn ln lp t mt 0-10 cm. La l cy trng c b r n nng v c thi gian t cui nhnh n u lm ng r n ni trn mt t. i vi la gieo thng, b r thng pht trin


mnh lp t mt, phn nhnh nhiu. Cc bin php lm t, bn phn, ti nc, lm c c nh hng n s pht trin ca b r. La thp cy, c kh nng thm canh cao cn cy dy t c mt ti thch. Khi cy dy, tng s r la tng nn m rng c din tch ht cht dinh dng ca qun th rung la, nhng din tch dinh dng ca c th cng b thu hp, trng lng trung bnh ca b r cy la gim. Mun cho c th sinh trng v pht trin tt, cn tng lng phn bn tng ng vi mc cy dy, nh vy mi c th pht huy hn na hiu qu ca vic cy dy v lm tng nng sut. Mt cao, bn phn nhiu l hai bin php b sung cho nhau lm cho qun th pht trin mnh. Khc vi la thng, b r ca la lai pht trin rt mnh, nhanh. R n su v to rng khong 22-23 cm, r ra t cc t v tr thp c xu th su,

hng t, cng trn cao cng pht trin ngang dn. Lp r gn mt t nhiu, r to khong 2mm v c th ra 4-5 ln r nhnh, to ra mt lp r an dy c lp st mt t, lng ht ca la lai nhiu v di (0,1-0,25mm) hn la thung (0,01-0,013mm). R la lai c kh nng ht oxi trong khng kh.

2.3.3 Yu cu dinh dng chnh ca cy la v la lai

2.3.3.1 Yu cu dinh dng m ca cy la v la lai m l mt yu t dinh dng quan trng, quyt nh s sinh trng

v pht trin ca cy trng. m l mt trong nhng nguyn t c bn ca

cy trng, l thnh phn c bn ca axit amin, axit nucleotit v dip lc.

Trong thnh phn cht kh ca cy c cha t 0,5 6% m tng s. Hm

lng m trong l lin quan cht ch vi cng quang hp v sn sinh

lng sinh khi. i vi cy la th m li cng quan trng hn, n c tc

dng trong vic hnh thnh b r; thc y nhanh qu trnh nhnh v s

pht trin thn l ca la dn n lm tng nng sut la. Do vy, m thc


y cy sinh trng nhanh (chiu cao, s dnh) v tng kch thc l, s ht, t l ht chc, hm lng protein trong ht. m nh hng n tt c cc ch

tiu sinh trng, pht trin, cc yu t cu thnh nng sut v nng sut la.

m nh hng ln n vic hnh thnh ng v bng la sau ny, s

hnh thnh s ht trn bng, t l ht chc, trng lng nghn ht

La l cy trng rt mn cm vi vic bn m. Nu giai on

nhnh m thiu m s lm nng sut la gim do nhnh t, dn n s

bng t. Nu bn khng m s lm thp cy, nhnh km, phin l nh,

l c th bin thnh mu vng, bng ng nh, t lm cho nng sut gim.

Nhng nu bn tha m li lm cho cy la c l to, di, phin l mng, d

b su bnh, d lp ; ngoi ra chiu cao pht trin mnh, nhnh v hiu

nhiu, tr mun, nng sut gim. Khi cy la c bn m th nhu cu tt

c cc cht dinh dng khc nh ln v kali u tng [45], [46]. Theo Bi Huy p [18], m l yu t ch yu nh hng n nng sut la, cy c m th cc yu t khc mi pht huy ht c tc dng.

La lai c c tnh nhnh sm, nhiu v tp trung hn la

thun. Do yu cu dinh dng m ca la lai nhiu hn la thun. Kh

nng ht m ca la lai cc giai on khc nhau l khc nhau. Theo Phm

Vn Cng v cs, 2003, 2005 [10], [60], trong giai on t nhnh n nhnh r, hm lng m trong thn l lun cao, sau gim dn. Nh vy,

cn bn tp chung m mnh vo giai on ny. Tuy nhin, thi k ht m

mnh nht ca la lai l t nhnh r n lm ng. Mi ngy la lai ht

3,52 kgN/ha chim 34,69% tng lng ht. Tip n l giai on t bt u

nhnh n nhnh r, mi ngy cy ht 2,74 kgN/ha chim 26,82% tng

lng ht. Do bn lt v tp chung l rt cn thit.


2.3.3.2 Yu cu dinh dng ln ca cy la v la lai Sau m th ln l yu t dinh dng rt quan trng i vi sinh trng

v pht trin ca cy trng, v ln l thnh phn ch yu ca axit nucleic, l

thnh phn ch yu ca nhn t bo. Tc dng ch yu ca ln c th hin

trn mt s mt sau:

- Xc tin s pht trin ca b r la, c bit l r bn v lng ht.

- Lm tng s nhnh v tc nhnh la, sm t s nhnh cc i,

to thun li cho vic tng s nhnh hu hiu, dn n lm tng nng sut la.

- Thc y vic ra hoa, hnh thnh qu, tng nhanh qu trnh tr, chn

ca la v nh hng tch cc n cht lng ht.

- Tng kh nng chng chu vi cc iu kin bt thun v su bnh hi

- Thc y phn chia t bo, to thnh cc hp cht bo v protein.

- Ngoi ra, ln cn c mi quan h cht ch vi s hnh thnh dip lc,

protit v s vn chuyn tinh bt.

Khi thiu ln, l la c mu xanh m, bn l nh hp v mm yu,

mp l c mu vng ta, nhnh km, ko di thi k ch chn. Nu thiu

ln thi k lm ng s nh hng rt r n nng sut la, c th l lm

gim nng sut la.

Khi cy la c cung cp ln tho ng s to iu kin cho b r pht

trin tt, tng kh nng chng hn, to iu kin cho sinh trng, pht trin,

thc y s chn ca ht v cui cng l tng nng sut la [47]. o Th Tun, 1963 [50] cho bit: bn phn c nh hng n phm

cht ht ging r rt, lm tng trng lng nghn ht, tng t l ln trong ht,

tng s ht trn bng v cui cng l cho nng sut la cao hn.

Bi Huy p, 1980 [18] cho rng: ln c vai tr quan trng i vi qu trnh tng hp ng, tinh bt trong cy la v c nh hng r rt n nng sut.


Theo V Hu Ym, 1995 [57], cy non rt mn cm vi vic thiu ln. Thiu ln trong thi k cy non cho hiu qu rt xu, sau ny d c bn nhiu ln th cy cng tr khng u hoc khng thot. Do vy, cn bn ln ngay t giai on u v bn lt phn ln l rt c hiu qu.

Dinh dng ln c lin quan mt thit vi dinh dng m. Nu bn ln s lm tng kh nng ht m v cc cht dinh dng khc. Cy c bn cn i N, P s xanh tt, pht trin mnh, chn sm, cho nng sut cao v phm cht tt.

Nh vy, mun cho cy la sinh trng, pht trin v cho nng sut cao th khng nhng cn cung cp y m m cn cn cung cp y c ln cho cy la [53], [56], [57].

Hu ht cc th nghim trong chu v ngoi ng u cho thy hiu

sut s dng ln la lai l 10-12 kg thc/kg P2O5, cao hn so vi la thun ch t 6-8 kg thc/kg P2O5. 2.3.3.3 Yu cu dinh dng kali ca cy la v la lai

Kali c vai tr khng km phn quan trng i vi s sinh trng ca la v kali c tc dng xc tin s di chuyn ca cc cht ng ho trong cy. Ngoi ra kali cn lm cho s di ng st trong cy c tt do nh hng gin tip n qu trnh h hp. Kali cng rt cn cho s tng hp protit, quan h mt thit vi s phn chia t bo [3], [33], [44], [70]. Vai tr ca kali i vi sinh trng, cc yu t cu thnh nng sut v

nng sut la c nhiu tc gi trong v ngoi nc nghin cu. Ni chung, khi thiu kali th dn n s quang hp ca cy b gim st r rt, ko theo cng h hp tng ln, lm cho sn phm ca qu trnh quang hp trong cy b gim, trng hp ny c th hin rt r trong iu kin thiu nh sng. c bit, vai tr ca kali c th hin r nht trong thi k u lm ng. Trong thi k ny, nu thiu kali s lm cho gi bng thoi ho


nhiu, s bng t, trng lng nghn ht gim, ht xanh, lp lng v bc bng nhiu, phm cht go b gim st.

Kt qu nghin cu t nm 1994 n nm 1996 ca Nguyn Nh H [22] cho thy, khng bn phn kali nh hng xu n cc yu t cu thnh nng sut la (s bng c to thnh gim 6,5-10%, s ht to thnh thp hn, ng thi lm tng t l ht lp lng), nng sut la gim r rt so vi bn kali, Phm Vn Cng v cs, 2007 [11] Khng bn kali lm gim tch lu kali v m trong sn phm thu hoch, m tch lu nhiu trong rm r khng c vn chuyn v ht l nguyn nhn lm gim nng sut v cht lng go [22], [53]. Thiu kali, l la b xm nu, cy pht trin chm v ci cc, thn yu v d b , ht teo qut. Thiu kali lm cy la d b nm bnh, vi khun Theo Nguyn Vi, vi cc ging la hin nay, t l ht chc tng t 30-57% do bn kali v trng lng ht cng tng t 12-30% [56]. i vi la lai t giai on nhnh n tr, cng ht kali tng t la thun. Tuy nhin, t sau khi la tr th la thun ht rt t kali, trong khi la lai vn duy tr sc ht kali mnh, mi ngy ht 670g/ha, chim 8,7% tng lng ht. Nh vy trong sut qu trnh sinh trng, cng ht kali ca la lai lun cao. y l c im dinh dng rt c trng v ht cc cht dinh dng ca la lai. V vy c nng sut cao cn coi trng bn kali cho la lai

2.4 Tnh hnh s dng phn bn cho sn xut la

2.4.1 C s l lun ca vic bn phn cho cy la i vi sn xut nng nghip, phn bn ng mt vai tr quan trng

trong vic tng nng sut. T nhng nm 60 ca th k XX, Vit Nam s

dng phn bn v c trong nng nghip v ngy cng tin b. c bit trong

nhng nm gn y, c rt nhiu ging la lai c a vo s dng, c kh


nng chu phn rt tt, l tin cho vic thm canh cao, nhm khng ngng

tng nng sut la. i vi cy la, m l yu t dinh dng quan trng

nht, n gi vai tr quyt nh trong vic tng nng sut. Vi la lai, vai tr

ca phn bn kali cng c vai tr quan trng tng ng vi m.

Theo Nguyn Nh H, 2005 [23], nhu cu v m ca cy la c tnh cht lin tc trong sut thi gian sinh trng ca cy. Theo V Hu Ym,

1995 [57], hm lng m trong cy v s tch lu m qua cc giai on pht trin ca cy la cng tng r rt khi tng liu lng m bn. Nhng

nu qu lm dng m th cy trng pht trin mnh, l to, di, phin l

mng, tng s nhnh v hiu, tr mun, ng thi d b lp v nhim

su bnh, lm gim nng sut. Ngc li, thiu m cy la ci cc, nhnh

km, phin l nh, tr sm. Hiu lc ca m cn ph thuc vo cc yu t

dinh dng khc. Thng thng cc ging la c tim nng nng sut cao bao

gi cng cn lng m cao; dinh dng cng y th cng pht huy c

tim nng nng sut [57]. Theo De Datta S.K [64] cho rng, m l yu t hn ch nng sut la c ti. Nh vy, tng nng sut la nc, cn to iu kin cho cy la

ht c nhiu m. S ht m ca cy la khng ph thuc vo nng

m xung quanh r m c quyt nh bi nhu cu m ca cy.

nng cao hiu qu bn m th phng php bn cng rt quan

trng. Theo nhiu nh nghin cu th khi bn m vi trn mt rung s gy

mt m ti 50% do nhiu con ng khc nhau nh ra tri, bay hi, ngm

su hay do phn m ho [21], [24], [45]. Theo Bi Huy p, 1980 [18], khi bn vi m trn mt rung la t nh, sau 15 ngy lm mt 50% lng m; cn t tht sau 1 thng mt

40% lng m.


Theo o Th Tun, 1970 [51] li cho rng khi bn vi m trn mt rung la c th gy mt ti 60 70% lng m bn. Chnh v vy, khi bn m cn bn sm, bn tp trung v bn di su xung tng t ni c b r la tp trung nhiu. Theo Nguyn Nh H, 1999 [22], khi bn m ta nn bn sm, bn tp trung ton b hoc 5/6 tng lng m cn bn, bn lt su va c tc dng trnh mt m, li va tng tnh chng lp cho la do b r cy pht trin mnh. Cng theo Nguyn Nh H, nn bn kt hp gia phn v c v phn hu c m c th l phn chung [22], [23]. 2.4.2 Tnh hnh s dng phn bn cho la trn th gii v Vit nam Hin nay, Vit Nam l nc s dng phn bn tng i cao so vi nhng nm trc y do ngi dn p dng c rt nhiu bin php k thut trong thm canh. Theo V Hu Ym, 1995 [57], Vit Nam hin ang l mt trong 20 quc gia s dng phn bn cao nht th gii.

Bng 2.1: Nhu cu v cn i phn bn Vit Nam n nm 2020 Nm

Cc loi phn bn 2005 2010 2015 2020

Tng s 1.900 2.100 2.100 2.100 Sn xut trong nc 750 1.600 1.800 2.100 Ur Nhp khu 1150 500 300 0.0 Tng s 500 500 500 500 Sn xut trong nc 0 0 0 0 KCL Nhp khu 500 500 500 500

Ngun: Phng QL t v phn bn, Cc Trng trt, B NN& PTNT, 5/2007 Theo Nguyn Vn B, 2003 [5], mi nm nc ta s dng 1.202.140

tn m, 456.000 tn ln v 402.000 tn kali, trong sn xut la chim 62%. Song do iu kin kh hu cn gp nhiu bt li cho nn k thut bn


phn mi ch pht huy c 30% hiu qu i vi m v 50% hiu qu i vi ln v kali. Nhng hiu qu bn phn i vi cy trng li tng i cao, do vy m ngi dn ngy cng mnh dn p dng khoa hc k thut vo sn xut. Trong tng lai, vn ha hn s dng mt lng phn bn rt ln trong sn xut nng nghip, mc d nc ta ch yu vn phi nhp khu phn bn [5].

2.4.3 Phng php bn phn cho la

2.4.3.1 Cc loi v dng phn bn s dng cho la La l cy trng c phn ng tt vi phn ho hc nn bn phn ho

hc cho la c hiu qu cao. Trong thm canh la, bn phn hu c ch yu nhm n nh hm lng mn cho t, to nn thm canh nn c th s dng cc loi phn hu c khc nhau, k c rm r la sau khi thu hoch.

Cc loi phn m thch hp cho la l phn m amn, ur. Ur ang tr

thnh dng phn m ph bin i vi la nc v c t l m cao, li rt thch hp bn trn cc loi t la thoi ho. Phn m nitrat c th dng bn thc thi k ng, c bit hiu qu khi bn trn t chua mn.

t chua trng la, bn phn ln nung chy thng cho kt qu ngang phn supe ln hay c th cao hn do trong iu kin ngp nc cng d cung cp cho la m li t b ra tri v cn cung cp c Silic, l yu t dinh dng c nhu cu cao cy la. Tuy nhin nu cn bn thc ln v trng la trn t ngho lu hunh (t bc mu bn t phn hu c) th phi dng phn ln supe.

Loi phn kali thch hp bn cho la l kali clorua. Ngoi ra, cn thng s dng cc loi phn NPK, c bit tt l cc

loi phn chuyn dng cho la, ph hp vi iu kin ca tng vng t trng Kh nng chu chua ca cy la kh, nhng t qu chua, cy la

sinh trng km, c th do nhm ho tan gy ra v hin tng ng c nhm t thy trn cc loi t c pH trn 5,5. Mt khc, sau khi a nc vo rung, t c th b chua hn, nn bn vi l bin php quan trng t la nc


qu chua v vic bn vi phi c kt hp vi mt ch bn phn hp l th mi thu c kt qu mong mun nht.

2.4.3.2 Lng phn bn cho la cc vng trng la chnh Liu lng phn chung thng bn 7-10 tn/ha, v ma nn bn

nhiu hn. Liu lng phn khong bn cho la ph thuc vo nng sut k hoch (c im ca ging, loi hnh cy), ph ca t, cc iu kin kh hu (ma v) v kh nng cn i vi cc loi phn khc. Ging nng sut cao cn bn nhiu hn so vi cc ging la thng, la a phng, la v xun thng bn nhiu hn la v ma, trng la trn t c ph cao cn gim lng phn bn.

Do h s s dng phn m ca cy la khng cao nn lng m cn bn phi cao hn nhiu so vi nhu cu. Lng m bn dao ng t 60-160 kg/ha. Vi trnh thm canh hin ti, t nng sut 5 tn/ha thng bn 80-120 kg/ha. Tuy nhin, trn t c ph trung bnh, t nng sut 6 tn thc/ha cn bn 160 kg N/ha. Trn t ph sa sng Hng, t nng sut trn 7 tn/ha cn bn 180-200 kg N/ha. Cc nc c nng sut la bnh qun cao trn th gii (5-7 tn thc/ha) thng bn 150-200 kg N/ha.

Lng phn ln bn cho la dao ng t 30-100 kg P2O5, thng bn 60 kg P2O5/ha. i vi t xm bc mu c th bn 80 - 90 kg P2O5/ha, t phn c th bn 90 - 150 kg P2O5/ha.

Lng phn kali bn cho la ph thuc ch yu vo mc nng sut v kh nng cung cp kali ca t. Cc mc bn trong thm canh la trung bnh l 30-90 kg K2O/ha, v mc bn trong thm canh la cao l 100-150 kg K2O/ha, trong kali ca phn chung v rm r c hiu sut khng km kali trong phn ha hc. Trn t ph sa sng Hng khi bn 8-10 tn phn chung/ha th ch nn bn 30-90 kg/ha phn kali khong, ngay c trong iu kin thm canh la cao (Nguyn Nh H, 1999).


Bng 2.2: Lng phn bn cho la Lng bn (kg/ha) Vng V Ging N P2O5 K2O

Thun 90-120 60-80 40-60 ng xun La lai 140-160 80-100 60-100

Thun 80-100 40-60 30-50 La lai 120-140 60-80 60-100

Cc tnh Pha Bc Ma

a phng 60-80 30-50 30-50 Thun 100-120 40-60 40-60

ng xun La lai 140-160 80-100 80-100 Thun 80-100 50-70 40-60

Cc tnh Min Trung H thu La lai 120-140 80-100 80-100

ng xun Thun 100-120 40-60 30-40 Xun h Thun 100-120 50-70 30-40 H thu Thun 90-110 60-80 30-40

Thun 80-100 40-60 30-50 Cc tnh

Pha Nam Ma

a phng 60-80 40-60 30-40 Ngun: Nguyn Xun Trng, 2000

2.4.3.3 Phng php bn phn cho la Thi k bn m nh hng ln n sinh trng v nng sut la. Thi

k bn m ph thuc vo c im ging la, ma v, thnh phn c gii t v trnh thm canh. Khng th c mt hng dn chung v thi k bn m cho tt c cc ging, ma v v t trng. Bn m sm to nhiu bng, bn m mun tng ht l ch yu, bn m vo giai on ng lm tng t l protein trong ht. Thi k bn phn m cho la thng gm: bn lt v bn thc nhnh, thc ng, ngoi ra c th c bn nui ht. * Bn phn lt cho la

Trong bn phn cho la thng bn lt ton b phn chung v phn ln, mt phn phn m v kali. Thng bn lt phn chung trong qu trnh lm t, phn ln, phn kali cng vi phn m bn trc khi cy ba ln cui.

Cy la ht kh nhiu ln trong cc giai on sinh trng u v giai on cy con, la b khng hong ln, do vy phn ln cn c bn lt ton


b hoc bn lt v thc sm. Phn ln nn bn ri u trn mt rung trc khi cy ba ln cui gieo cy.

Nn bn lt nhiu phn kali trong cc trng hp sau: trng ging nhnh nhiu hay ngn ngy, la c hin tng b ng c st, t c kh nng hp thu cao hay thiu kali, ma nhiu, ngp nc su, kh hu lnh. Trong thc tin cn chia tng lng phn kali ra bn thc lm nhiu ln, do la l cy c yu cu cung cp kali vo giai on r la n ni trn b mt t-cui nhnh n u lm ng, kali cung cp t t v nc ti thng gim i giai on nhnh ca cy la.

Thng dnh 1/3-2/3 tng lng N bn lt cho cy la, t l phn dng bn lt tu thuc vo tnh cht t, su cy ba, iu kin kh hu, thi gian sinh trng ca la. Cn bn lt nhiu m hn khi cy bng m gi, cc ging la ngn ngy, la cht (la mc li t gc r). * Phn bn thc nhnh

Bn thc nhnh cho la thng bn bng phn m hay phi hp thm vi mt phn phn ln (nu cn cha bn lt ht). Thi gian bn thc nhnh vo khong 18-20 ngy sau gieo hoc sau khi la bn r v hi xanh, vo khong 10-20 ngy sau cy (tu thuc ma v) khi cy la bt u nhnh.

Trn t phn v t qu chua, kh nng c nh ln ca t rt mnh th bn thc ln cho la l cn thit v va nhm h phn v c t trong t, va cung cp dinh dng ln cho la. Vic kt hp bn lt v thc mt phn phn ln ho tan trong nc cho la lm tng hiu qu s dng phn bn. Khi bn thc nn dng cc dng ln ht trnh bm dnh gy chy l.

Thng dnh 1/2-2/3 lng N cn li bn thc nhnh nhm lm cho la nhnh nhanh, tp trung v cng gim lng phn lt, trnh mt m. Cn bn thc nhnh nhiu m cho la trong cc trng hp: cy ging di ngy hay nhnh nhiu, mt gieo hoc cy cao, nhit khi gieo cy cao.


i vi nhng ging la cc ngn, la ma cn phi bn thc nhnh sm hn, cn i vi ging di ngy, la xun c th bn thc mun hn, do thi k sinh trng u ca cy la b ko di.

Bn thc m cho la tt nht l bn sau khi rt nc rung do c th lm tng gp i hiu lc ca phn bn so vi rung c nhiu nc. Khng nn rt nc qu 1 ngy trc khi bn thc v vic rt nc trong mt thi gian di thc y c di pht trin v lm mt m, ng thi rung sau khi bn phn phi c a nc vo ngay sau mt ngy bn m. Dng my tr c c trc quay trn ln phn m vo t cng tng c hiu lc ca phn m, c bit l khi bn thc sm v cy su. * Phn bn thc ng

Bn thc ng cho la thng s dng phi hp phn phn m v kali cn li nhm tip tc cung cp m cho la to c bng la to, c nhiu ht chc, nng cao h s kinh t cho cy la, t nng sut cao. Bn ng tt nht l bn sau khi phn ho ng vo khong 40-45 ngy sau khi gieo, cy.

Bng 2.3: Chun on nhu cu dinh dng qua l ca cy la Hm lng dinh dng (% cht kh)

La lai La a phng Loi dinh

dng

B phn v thi gian ly

mu phn tch Thiu Thiu N


Khi bn t m, th bn thc ng l mt k thut quan trng nng cao hiu sut phn m v l thi k bn m c hiu qu nht. Nhng ging nhnh t, bng to, nng sut da vo s ht trn bng th cn phi ch trng vo t bn n ng v nui ht to c bng to, nhiu ht chc, t nng sut cao.

Bn lt cng nhiu, la sinh trng tt, th thi gian bn ng cng mun v t. i vi cc ging la ma c thi gian sinh trng di (150 - 180 ngy), cn bn thc ng mun hn. Cn dng mt nh gi tnh hnh sinh trng v mu l trong thi k r phn on nhu cu bn thc ng. Khi bn lt c nhiu cng c th khng cn bn thc , m ch cn bn thi k ng. Bn phn lt v thc nhnh c th khng bn phn n ng. Hin nay trong chin lc ba gim ba tng ngi ta cn c vo mu l la quyt nh vic bn thc phn m cho la. Ngoi ra cng c th da vo vic chun on l xc nh nhu cu bn phn cho la.

Nn dng phn kali bn thc ng cho la trong cc trng hp: ging nhnh t trung bnh n t hay ging di ngy, gieo cy tha; t c in th oxy ho kh rt cao, thnh phn c gii rt nh, hay trn t phn (thiu ln v ng c st), t kim (thiu km), ln b t c nh hay ma nhiu [72]. * Phn bn nui ht

Sau khi la tr hon ton c th bn nui ht bng cch phun phn bn l 1-2 ln nhm lm tng s ht chc, tng nng sut. y l thi k bn phn c hiu qu r khi trng la trn t thnh phn c gii nh, c kh nng cung cp dinh dng v gi phn km.

2.4.4 Vn bn phn cn i cho cy la Bn phn cn i cho la l tu theo yu cu ca cy la v cc cht dinh

dng v kh nng p ng tng loi cht dinh dng cho cy la ca t trng la c th m bn phn. Cn c nh lng phn bn cn i cho la:


V ma, h thu (ma ma) lng m cn bn t hn so vi v ng xun. V h cc tnh pha Nam do nng nng, t chua nhiu, phn bc mnh nn cn bn nhiu ln hn so vi v ng xun v v thu ng.

Khi hm lng kali trong nc ti cao (chng hn ph sa nhiu) th bn kali vi lng thp v ngc li. t nh cn bn nhiu kali hn t nng, t ph sa bn t kali hn t xm. t ct, t xm, t bc mu do hm lng kali thp nn cn bn nhiu kali hn so vi cc loi t khc. Trn t ny do hm lng hu c v st thp nn phi chia phn ra lm nhiu ln bn hn gim tht thot phn bn.

t phn, t trng ngho ln li c nhiu st nhm di ng gy c, do cn phi bn nhiu phn ln hn cc loi t khc, nhm gim c ca st, nhm v cung cp ln cho cy la.

Trong rt nhiu trng hp, hin tng l mt nhn t khng cho php c bn cho la n lng m ti a. Nu cy la trc khi tr, nng sut c th gim 50-60%. Ging la mi thp cy c kh nng chng tt, lng m bn ti thch cao hn nhiu.

Nu va thu hoch ht thc, va ly rm r khi ng rung th bn phn nhiu hn, c bit l phn kali, do kh nhiu kali b ly i khi ng rung theo rm r, nhng nu khng ly rm r khi ng rung th ch

khong 5% lng kali b ly i theo sn phm thu hoch qua ht. Khong trong t, r v nc ti l ngun kali cung cp cho cy.

t nh nhiu ct cy cn kali hn, ng thi cc ging nng sut cao cn nhiu kali hn.

2.5 Nhng kt qu nghin cu phn bn i vi cy la

2.5.1 Kt qu nghin cu v phn m i vi cy la Nhu cu m ca cy la c nhiu nh khoa hc trn th gii i

su nghin cu v c nhn xt chung l: nhu cu m ca cy la c tnh cht


lin tc t u thi k sinh trng cho n lc thu hoch. Trong sut qu

trnh sinh trng, pht trin ca cy la, c hai thi k m nhu cu dinh

dng m cao nht l thi k nhnh r v thi k lm ng. thi k

nhnh r cy ht nhiu m nht [8], [31]. Theo Yoshida (1985), lng m cy ht thi k nhnh quyt nh ti 74% nng sut. Bn nhiu m lm cy la nhnh kho v tp trung,

tng s bng /m2; s ht/ bng, nhng trng lng nghn ht (P1000) t thay i [71]. Theo cc tc gi inh Vn L (1978); Bi Huy p (1980); o Th Tun (1980) v Nguyn Hu T (1997): thng thng cy la ht 70% tng lng m l trong giai on nhnh, y l thi k ht m c nh hng

ln n nng sut, 10 15% l ht giai on lm ng, lng cn li l t

giai on sau lm ng n chn.

Qua nhiu nm nghin cu, o Th Tun i n nhn xt: cy la c bn m tho ng vo thi k nhnh r thc y cy la nhnh

kho v hn ch s nhnh b li i. thi k nhnh ca cy la, m c

vai tr thc y tc ra l, tng t l m trong l, tng hm lng dip lc,

tch lu cht kh v cui cng l tng s nhnh [52]. Theo tc gi Bi nh Dinh [16], cy la cng cn nhiu m trong thi k phn ho ng v pht trin ng thnh bng, to ra cc b phn sinh

sn. Thi k ny quyt nh c cu sn lng: s ht/bng, trng lng nghn

ht (P1000) [23]. Yoshida (1985) cho rng: cc nc nhit i lng cc cht dinh dng (N, P, K) cn to ra mt tn thc trung bnh l: 20,5 kg N; 5,1 kg P2O5 v 44 kg K2O. Trn nn phi hp 90 P2O5 60 K2O hiu sut phn m

v nng sut la tng nhanh cc mc bn t 40 120 kgN/ha.


Kt qu nghin cu ca inh Vn C, ti x Gia Xuyn T Lc Hi Dng cho thy: lng m cn bn t 1 tn thc phi t 26 28 kg N. Kt qu ny cao hn nhiu so vi d tnh ca o Th Tun nm 1969, mun t c mt tn thc cn 22,3 kg N trong v chim v 22,6 kg N trong v ma [46].

Theo kt qu tng kt ca Mai Vn Quyn (2002), trn 60 th nghim thc tin khc nhau 40 nc c kh hu khc nhau cho thy: nu t nng sut la 3 tn thc/ha, th la ly i ht 50 kg N, 260 kg P2O5, 80 kg K2O, 10 kg Ca, 6 kg Mg, 5 kg S v nu rung la t nng sut n 6 tn/ha th lng dinh dng cy la ly i l 100 kg N, 50 kg P2O5, 160 kg K2O, 19 kg Ca, 12 kg Mg, 10 kg S [22]. Nh vy, trung bnh c to 1 tn thc, cy la ly i ht 17 kg N, 8 kg P2O5, 27 kg K2O, 3 kg CaO, 2 kg Mg v 1,7 kg S. Theo S. Yoshida (1985), m l nguyn t dinh dng quan trng nht i vi cy la trong cc giai on sinh trng v pht trin. Sau khi tng lng m th cng quang hp, cng h hp v hm lng dip lc ca cy la tng ln, nhp quang hp, h hp khng khc nhau nhiu nhng cng quang hp tng mnh hn cng h hp gp 10 ln cho nn vai tr ca m lm tng tch lu cht kh (Nguyn Th Lm, 1994). Nu bn m vi liu lng cao th hiu sut cao nht l bn vo la nhnh v sau gim dn. Vi liu lng bn m thp th bn vo lc la v trc tr 10 ngy c hiu qu cao (Yoshida, 1985). Nm 1973, Xiniura v Chiba c kt qu th nghim bn m theo 9 cch tng ng vi cc giai on sinh trng, pht trin. Mi ln bn vi 7 mc m khc nhau, 2 tc gi trn c nhng kt lun sau: + Hiu sut ca m (k c rm, r v thc) cao khi lng m bn mc thp.

+ C 2 nh v hiu sut, nh u tin l xut hin thi k nhnh,


nh th 2 xut hin 19 n 9 ngy trc tr, nu lng m nhiu th khng c nh th 2. Nu bn liu lng m thp th bn vo lc 20 ngy trc tr, nu bn liu lng m cao th bn vo lc cy la nhnh [21], [32]. Vin Nng ho - Th nhng tin hnh nghin cu nh hng ca t, ma v v liu lng phn m bn n t l m cy la ht. Khng phi do bn nhiu m th t l m ca la s dng nhiu. mc phn m 80 kg N/ha, t l s dng m l 46,6%, so vi mc m ny c phi hp vi phn chung t l m ht c l 47,4%. Nu tip tc tng liu lng m

n 160N v 240N c bn phn chung th t l m m cy la s dng cng gim xung. Trn t bc mu so vi t ph sa sng Hng th hiu sut s dng m ca cy la thp hn. Khi bn liu lng m t 40N- 120N th hiu sut s dng phn gim xung, tuy lng m tuyt i do la s dng c tng ln [32]. Kt qu nghin cu s dng phn bn m trn t ph sa sng Hng ca Vin Khoa hc Nng Nghip Vit Nam tng kt cc th nghim 4 mc m t nm 1992 n 1994, kt qu cho thy: phn ng ca phn m i vi la ph thuc vo thi v, loi t v ging la [32]. Vin nghin cu la ng bng sng Cu Long c nhiu th nghim v nh hng ca liu lng m khc nhau n nng sut la v ng xun v H thu trn t ph sa ng bng sng Cu Long . Kt qu nghin cu trung bnh nhiu nm, t nm 1985- 1994 ca Vin la ng bng sng Cu Long, chng minh rng: trn t ph sa c bi hng nm c bn 60Kg P2O5 v 30Kg K2O lm nn th khi c bn m lm tng nng sut la t 15- 48,5% trong v ng Xun v v H Thu tng t 8,5- 35,6%. Hng chung ca 2 v u bn n mc 90Kg N c hiu qu cao hn c, bn trn mc 90Kg N ny nng sut la tng khng khng ng k [32].

Theo Nguyn Th Lm (1994), khi nghin cu v bn phn m cho


la cn kt lun: liu lng m bn thch hp cho cc ging c ngun gc a phng l 60Kg N/ha. i vi nhng ging thm canh cao nh CK136 th lng m thch hp t 90Kg 120Kg N/ha. Theo Nguyn Nh H [22], nh hng ca mt cy v nh hng ca liu lng m ti sinh trng ca ging la ngn ngy thm canh cho thy: tng liu lng m bn mt cy dy c tc dng tng t l nhnh hu hiu.

Phn m i vi la lai l rt quan trng. La lai c b r kh pht trin, kh nng huy ng t t rt ln nn ngay trng hp khng bn phn, nng sut la lai vn cao hn la thun. Cc nh nghin cu Trung Quc kt lun: cng mt mc nng sut, la lai hp thu lng m v ln thp hn la thun, mc nng sut 75 t/ha, la lai hp thu m thp hn la thun 4,8%, hp thu P2O5 cao hn 18,2% nhng hp thu kali cao hn 30%. Vi rung la cao sn th la lai hp thu m cao hn la thun 10%, hp thu K2O cao hn 45% cn hp thu P2O5 th bng la thun [10]. Kt qu th nghim trong chu cho thy: trn t ph sa sng Hng, bn m n c lm tng nng sut la lai 48,7%, trong khi nng sut ging la CR203 ch tng 23,1%. Vi th nghim ng rung, bn m, ln cho la lai c kt qu r rt. Nhiu th nghim trong phng cng nh ngoi ng rung cho thy, 1 kgN bn cho la lai lm tng nng sut 9- 18 kg thc, so vi la thun th tng 2- 13 kg thc. Nh vy, trn cc loi t c vn

nh t bc mu, t gley, khi cc yu t khc cha c khc phc v chua, ln, kali, th vai tr ca phn m khng pht huy c, nn nng sut la lai tng c 17,7% trn t bc mu v 11,5% trn t gley [10]. Vi t ph sa sng Hng, bn m vi mc 180 kgN/ha trong v Xun v 150 kgN/ha trong v Ma cho la lai vn khng lm gim nng sut la. Tuy nhin, mc bn 120 kgN/ha lm cho hiu qu cao hn cc mc khc [32].


Thi k bn m l thi k rt quan trng trong vic nng cao hiu lc ca phn lm tng nng sut la. Vi phng php bn m (bn tp trung vo giai on u v bn nh vo giai on cui) ca Vit Nam vn cho nng sut la cao, nng sut la tng thm t 3,5 t/ha [8], [32], [33]. Liu lng bn cho 1 ha: 8 tn phn chung + 120 kgN + 90 Kg P2O5 + 60 kg K2O. Kt qu thi k bn cho thy rt r hiu qu ca phn m trn t ph sa sng Hng t cao nht thi k bn lt t 50- 75% tng lng m, lng m bn nui ng ch t 12,5- 25% [6]. 2.5.2 Kt qu nghin cu v phn ln i vi cy la

Theo kt qu ca Nagai nm 1959, ln c ht trong 42 ngy u tin sau cy th chuyn ln bng, c tc dng r rt n nng sut la, cn ln c ht sau , phn ln c r v trong rm r [50]. Kt qu nghin cu hiu sut tng phn ca ln i vi vic to thnh ht thc ca Kamurava v Ishizaka nm 1996 cho thy: thi k ln c hiu sut cao nht l thi k u sau cy 10 20 ngy [67]. Tanaka c nhn xt: hiu qu ca bn phn ln cho la thp hn so vi cy trng cn. Tuy nhin, bn ln xc tin qu trnh sinh trng ca cy trong thi k u, c th rt ngn thi gian sinh trng, c bit l nhng vng lnh th hiu qu cng r. Kt qu ca Buba nm 1960 cho bit, la nc l loi cy trng cn t ln, do kh nng ht ln t t mnh hn cy trng cn [67]. Nghin cu ca Brady, Nylec nm 1985 cho thy, hu ht cc loi cy trng ht khng qu 10 13% lng ln bn vo t trong nm, c bit l cy la, ch cn gi cho ln c trong t khong 0,2 ppm hoc thp hn mt cht l c th cho nng sut ti a. Tuy vy, cn bn ln kt hp vi cc loi phn khc nh m, kali mi nng cao c hiu qu ca n [67].

mi thi k, la ht ln vi lng khc nhau, trong c hai thi k ht mnh nht l thi k nhnh v thi k lm ng. Tuy nhin, xt v mc th la ht ln mnh nht vo thi k nhnh [54], [73].


Trung bnh to ra mt tn thc, la ht khong 7,1kg P2O5. Ln trong t l rt t, h s s dng ln ca la li thp, do phi bn ln vi liu lng tng i kh. n , bn phn ln vi mc 60kg P2O5/ha c th tng nng sut la ln trung bnh 0,5-0,75 tn thc/ha. i Loan, theo Lian nm 1989, vi mc khong 50-60kg P2O5/ha cho nng sut bi thu cao nht [65]. nng cao hiu qu ca vic bn ln cho cy la ngn ngy, trong iu kin thm canh trung bnh (10 tn phn chung, 90-120N, 60 K2O/ha) nn bn ln vi lng 80-90 P2O5/ha v tp trung bn lt [21]. Theo nhiu tc gi cho bit, lng phn bn cho la cn thay i theo thi tit, ma v v tng loi t. Trn a s cc loi t, chn la cao sn thng bn lng ln 60kg P2O5/ha, ring i vi t xm bc mu c th bn 80-90kg P2O5/ha. Theo Nguyn Vn B, Bi nh Dinh v cng s [4], nhu cu v ln ca la lai khng c g khc bit so vi cc ging la thng c cng thi gian sinh trng. La lai vi nng sut 7 tn/ha, cy la ht 60-70kg P2O5/ha.

Nm 1996, theo Mai Thnh Phng v mt s tc gi cho rng, trn t phn nng, mun trng la c hiu qu cn phi lin tc ci to: s dng nc ngt ti ra phn, bn phn ln liu lng cao trong nhng nm u tch lu ln. Trn t ph sa sng Cu Long c bi hng nm, bn ln vn c hiu qu rt r. V ng Xun 20 Kg P2O5/ha tng nng sut c 20%

so vi cng thc khng bn ln. Tuy nhin, bn thm vi liu lng cao hn, nng sut la c tng nhng khng r cho nn rung thm canh thng c bn phi hp t 20- 30 kg P2O5 l . Trong v H Thu, cy la c nhu cu lng ln cao v hiu qu xut hin r hn v Xun, bn 20 kg P2O5 th bi thu c 43,7%, tip tc bn tng lng ln, nng sut la c tng nhng khng r [47].


Nm 1994, kt qu th nghim bn ln cho la ca trng i hc Nng nghip II ti x Thu Dng- Huyn Hng Thu (Tha Thin- Hu) cho thy: trong v Xun, bn ln cho la t 30- 120 kg P2O5/ha u lm tng nng sut la t 10- 17%. Vi liu lng bn 90 kg P2O5 l t nng sut cao nht v nu bn hn liu lng 90 kg P2O5/ha th nng sut c xu hng gim. Trong v H Thu, vi ging la VM1, bn Supe ln hay ln nung chy u lm tng nng sut rt r rt [54], [56]. Tt c cc th nghim trong chu v ngoi ng u cho thy, hiu sut

s dng ln la lai l 10- 12 kg thc/kg P2O5, so vi la thun l 6-8 kg thc/ kg P2O5 [10]. 2.5.3 Kt qu nghin cu v phn kali i vi cy la c im dinh dng kali ca cy la c nhiu tc gi trong v ngoi nc nghin cu. S. Yoshida (1985) cho bit, ch khong 20% tng lng kali cy ht l c vn chuyn vo ht, lng cn li c tch lu trong cc b phn khc ca cy (trong rm r).

Theo Matsuto, gia vic ht m v kali c mt mi tng quan thun, t l N/K thng l 1,26. Theo nhiu tc gi khc cho bit t l N/K rt quan trng, nu cy la ht nhiu m th d thiu kali, do thng phi bn nhiu kali nhng rung la bn nhiu m [53], [69].

Theo inh Dnh [17], cy la ht kali ti tn cui thi k sinh trng. Nhu cu kali r nt nht hai thi k nhnh v lm ng. Thiu kali vo thi k nhnh nh hng mnh n nng sut, la ht kali mnh nht vo thi k lm ng.

Bi nh Dinh (1985) cho bit: t l kali cy la ht trong cc thi k sinh trng tu thuc vo ging la, giai on t cy n nhnh l 20,0-21,9%; t phn ho ng n tr l 51,8-61,9%; t vo chc n chn l 16,9-27,7%.


Theo o Th Tun (1970), lng kali cy la ht v nng sut la c mi quan h thun. Vo nhng thp k 60-70, hiu lc phn kali bn cho la

rt thp, hu ht cc loi t nghin cu: ng bng sng Hng, hiu

qu ch t 0,3-0,8kg thc/1kg kali. Hin nay, hiu lc ca phn kali bn cao

hn trc, vi la trn t bc mu, hiu qu cao nht t 8,1-21,0kg

thc/1kg kali. Trn t bc mu, tr lng kali trong t t, do vy cn phi

cung cp phn kali t phn bn th la mi c dinh dng kali, ng thi

cy la cng ht m c d dng hn. Hiu sut ca phn kali trn t ph

sa sng Hng ch t 1,0-2,5 kg thc/1kg phn kali (KCl), trong khi nu trn t bc mu hay t ct ven bin c th t 5-7 kg thc/1kg KCl. V vy,

trn t ngho kali, bn cn i m-kali c ngha rt quan trng. Theo V Hu Ym (1995), hiu sut phn kali cao nht trn t bc

mu vi mc bn 30kg K2O/ha. Bn n 120kg K2O/ha th hiu sut kali vn

cn cho 4-6 kg thc/1kg K2O.

Kt qu nghin cu ca Nguyn Nh H (1999) cho thy, trong iu kin thm canh cao, la ngn ngy, lng kali cy ht t ti 28-31 kg

K2O/tn thc.

Cc nh khoa hc Trung Quc kt lun rng: cc ging la lai c nhu cu cao v kali, thm ch cn cao hn m. Trung Quc, t nng sut 15 tn thc/ha/nm th tng lng kali cy la ht t 405-521 kg K2O/ha [58]. Kt qu nghin cu ca tri th nghim Cuban (Lin X c) cho bit, thu c 4 tn thc/ha cn bn 35-50 kg K2O, trung bnh l 44 kg K2O/ha

[58], [70]. Vit Nam, kt qu nghin cu kali bc u cho thy c nhiu kin khc nhau:


Theo Trn Thc Sn (1995), lng kali la ngn ngy ht to 1 tn thc trn t ph sa sng Hng l 14,2-21,8 kg K2O/ha, cn theo Phm Tin Hong (1995) l 28,4-32,7 kg K2O/ha.

Mc d c nhng kin khc nhau v lng ht kali ca la, nhng trn thc t sn xut th tc hi ca vic bn tha kali vn cha thy m ch thy tc hi ca vic thiu kali. Do vy, cn cung cp kali y cho la lm ht thc my v sng hn, lm tng trng lng nghn ht, t tng nng sut v cht lng la.

Theo Mai Vn Quyn (2002) cho bit: trn vng t xm c Ho- Long An, Vin Khoa hc Nng nghip min Nam (nm 1993) th nghim vi 2 ging la KSB 218- 9- 3 v ging 2B cho thy, cc cng thc bn t mc 30 n 120 kg K2O/ha u lm cho nng sut la cao hn i chng t 15,8- 32,4% vi ging KSB- 218 v t 6- 18,7% i vi ging 2B. Dinh dng kali l mt trong 3 yu t dinh dng quan trng i vi cy la, trc tin l cy la ht kali, sau ht m. thu c 1 tn thc, cy la ly i 22- 26 kg K2O nguyn cht, tng ng vi 36,74- 43,4 kg KCl (60% K), kali l nguyn t iu khin cht lng tham gia vo cc qu trnh hnh thnh cc hp cht v vt cht cc hp cht , kali cn lm tc dng cho t bo cy cung cp, tng t l ng, gip vn chuyn cht dinh dng nhanh chng v hoa v to ht [8], [16], [42]. Theo kt qu th nghim ca IRRI tin hnh ti 3 im khc nhau trong 5 nm 1968- 1972 cho thy: kali c nh hng rt r ti nng sut la c 2 v trong nm. Trong iu kin ma kh, vi mc 140kgN, 60kgP2O5 v bn 60kg K2O/ha th nng sut la t 6,78 tn/ha, cho bi thu nng sut do bn kali l 12,8 kg thc/kg K2O. Trong ma ma, vi mc 70kgN, 60kgP2O5; bn 60 kg K2O/ha th nng sut la t 4,96 tn/ha [65], [68]. Trn t ph sa sng Hng trong thm canh la ngn ngy, t c nng sut la hn 5 tn/ ha v Ma v trn 6 tn/ha v Xun, nht thit phi bn kali. t nng sut la Xun 7 tn/ha, cn bn 102- 135 kg


K2O/ha/v (vi mc 193 kg N/ha, 120 kg P2O5/ha) v nng sut la v ma t 6 tn cn bn 88-107 kg K2O/ha/v (vi mc 160kg N/ha/v, 88kg P2O5/ha/v). Hiu sut phn kali c th t 6,2- 7,2 kg thc/ kg K2O [22].

Vai tr cn i m v kali cng ln khi lng m s dng cng cao. Nu khng bn kali th h s s dng m ch t 15- 30%, trong khi bn kali th h s ny tng ln n 39- 49%. Nh vy, nng sut tng khng hn l do kali (bi bn kali ring th khng tng nng sut) m l kali iu chnh dinh dng m, lm cho cy s dng c nhiu m v cc dinh dng khc nhiu hn. Trong v Xun min Bc, nhit thp, thi tit m u nn hiu lc s dng phn kali cao hn, cho nn cn bn kali nhiu v ny [16]. La lai s dng kali cao hn m, ht kali mnh vo giai on la lm ng n giai on la tr hon ton. Thi gian la ht kali ko di hn la ht m v ln, la ht kali n cui thi k sinh trng [31]. Nhu cu kali ca cy la r nht 2 thi k: thi k nhnh v lm ng. Nu thi k nhnh thiu kali th nh hng n nng sut la. Tuy nhin, la ht kali nhiu nht thi k lm ng, t cui giai on nhnh n tr, la lai hp thu kali nhiu hn la thun. Sau khi tr bng, la thun gim dn ht kali, trong khi la lai vn hp thu kali mnh [8], [16]. Kali c s dng trong nguyn sinh cht t bo nh mt tc nhn kch thch cc hot ng chuyn ho vt cht v c thnh hu c, ng thi thc y qu trnh vn chuyn sn phm quang hp vn chuyn ln l, vo hoa v ht. S c mt ca kali thi k sau tr ca la lai l mt u th thc y qu trnh my ca ht, gip nng cao nng sut. La lai c kh nng ng ho dinh dng cao nht l m vi kali. Lng m ht thng trn 20- 22 kg N/tn thc v lng ht kali cng tng t. Trong v Xun, t nng sut cao th cn phi bn sm. Bn kali l yu cu bt buc vi la lai ngay c trn t giu kali [31].


PHN III VT LIU, NI DUNG V PHNG PHP NGHIN CU

3.1. Vt liu nghin cu 3.1.1 Phn bn Phn bn N:P:K vi t l 1: 0,75 : 0,75, liu lng tng ng vi mc m l 0, 60, 90 v 120kgN/ha. 3.1.2 Ging

- TH3-3 l ging la lai 2 dng do vin Sinh hc Nng Nghip - Trng i Hc Nng Nghip I to ra t t hp T1S-96/R3(H96). Cc dng b m c chn to v sn xut ti Vit Nam. TH3-3 l ging la lai ngn ngy, nng sut cao, cht lng tt, chng chu su bnh kh, chu hn kh, c nhiu trin vng trong v xun mun, ma sm min Bc Vit Nam.

- P6 l ging la thun do Vin Cy lng thc v Cy thc phm chn lc t IR2588/Xun s 2 theo phng php lai hu tnh. P6 l ging la thun trung ngy, cht lng tt, chng chu su bnh kh, chu hn kh.

3.2 Ni dung nghin cu - Th nghim gm 2 yu t:

+ Yu t chnh: Phn bn gm 4 mc (P) P0: 0 kgN 0 kgP2O5 0 kgK2O P1: 60 kgN 45 kgP2O5 45 kgK2O P2: 90 kgN 67,5 kgP2O5 67,5 kgK2O P3: 120 kgN 90 kgP2O5 90 kgK2O + Yu t ph: Ging gm 2 ging (G) G1: TH3-3 G2: P6

- Th nghim gm 8 cng thc c b tr theo kiu Split - plot vi 3 ln nhc li. Tng s th nghim 24 , din tch mi th nghim l 20 m2


- S th nghim:

Di bo v

P1G2 P1G1 P3G2 P3G1 P2G2 P2G1 P3G2 P3G1 P0G2 P0G1 P3G2 P3G1 P2G2 P2G1 P2G2 P2G1 P1G2 P1G1 P0G2 P0G1

Rnh

n

c P1G2 P1G1

Rnh

n

c P0G2 P0G1 D

i b

o v

Di bo v

Di

bo v

3.3 Phng php nghin cu Th nghim ng rung c b tr theo khi ngu nhin hon chnh

3.4 Cc ch tiu theo di v phng php theo di 3.4.1. Thi k rung cy: Theo di 2 tun 1 ln, mi th nghim ly 5 khm

- Chiu cao cy: o t mt t n u mt l

- S nhnh trn khm: m tng s nhnh/khm

- Din tch l: LAI = m2 l/ m2 t

- Ch s dy l (SLA-Specific Leaf Area): Ly 2 l trn cng ca 2 nhnh m hon ton ri o din tch l, cn trng lng cht kh.

SLA = Din tch l (cm2)/trng lng l kh (gam) - o ch s SPAD (mt ch tiu nh gi hm lng dip lc) bng

my SPAD- 502 (Nht Bn), mi l o 3 ln - Trng lng cht kh trn ton cy (DM): Nhng cy o din tch l

sau em sy mu nhit 800C trong 48 h. - Tc tch lu cht kh (CGR) (g/m2 t/ngy)

P2 P1 CGR = x mt

t


Trong : - P2, P1 l trng lng cht kh ca khm ti thi im ly mu - t l thi gian gia 2 ln ly mu

- Hiu sut quang hp thun(NAR) (g/m2 l/ngy) P2 P1

NAR = x ( L1 + L2) x t Trong : - P2, P1 l trng lng kh ca cy hai thi im ly mu - L1, L2 l din tch l hai thi im

- t l thi gian gia 2 ln ly mu

3.4.2. Thi k chn: Mi ly 10 khm - o chiu cao cy: tnh t st mt t n u mt ca bng cao nht,

khng k ru (cm)

- S bng/khm:

- Tng s ht/bng - S ht chc v t l ht chc/bng - Khi lng 1000 ht: Cn 2 ln mi ln 500 ht, sai s gia hai ln

cn khng vt qu 2%. - Chiu di bng: o t t c bng n u mt bng. - Nng sut l thuyt (NSLT) = S bng/m2 x Tng s ht trn bng x

T l ht chc x Khi lng 1000 ht x10- 4. - Nng sut thc thu: tnh m 13% theo quy nh ca IRRI - Nng sut c th: khi lng ht thc trung bnh ca mt khm

m 13%. - Nng sut sinh vt hc: bng phi kh rm r (khng k r) cn cng

vi khi lng ht kh ca 5 khm ly mu. Nng sut c th

- H s kinh t = Nng sut sinh vt hc


* Phn tch m tng s theo phng php Kendal. - Tin hnh: Mu l sy cho n khi trng lng khng i th ly ra v

ct nh ri nghin thnh dng bt, bo qun trong ti nilon, em phn tch. Cn 0,5g mu, cho vo bnh cng ph cng vi axit sunfuric 98%

lng 4ml, sau un 5 pht, cho 10 ml H2O2 t t vo. un tip 10 pht n khi cng ph hon ton, biu hin ht mu en, sau ngui hn. Tip b giy thm lc ri s dng nc ct n liu lng 100ml th dng.

- Chun b cc bnh phn tch: bng bnh Kendal + Bnh i chng l bnh Blank: ht 10ml H3BrO3 4%, cho 6-7 git hn

hp metylen (MRMBS), sau em chun bng bnh Kendal (10ml nc ct + 10ml NaOH 40%) n khi bnh Blank t 60ml th dng.

+ Bnh mu: ht 10ml H3BrO3 4% cho 6-7 git hn hp metylen (MRMBS), chun bng bnh Kendal (10ml nc ct + 10ml NaOH 40%) n khi bnh mu t 60ml th dng.

+ Bnh iu khin (Control): 60ml nc ct + 6-7 git MRMBS - Chun : s dng dung dch H2SO4 0,01mol/l. + Chun bnh Blank: sau khi mu xanh ca bnh Blank chuyn sang

mu ging bnh iu khin th dng, ghi li th tch H2SO4 0,01mol/l. + Chun bnh mu: sau khi mu xanh ca bnh mu chuyn sang

mu ging bnh iu khin th dng, ghi li th tch H2SO4 0,01mol/l. - Tnh ton kt qu:

(V2-V1).N.0,028 %N = x 100

C Trong : V1: th tch dung dch H2SO4 0,01mol/l chun bnh mu (ml) V2: th tch dung dch H2SO4 0,01mol/l chun bnh Blank (ml) C: khi lng mu em phn tch (g) N: nng ng lng dung dch chun axit (0,01mol/l)


3.5. Bin php k thut p dng - Thi v:

Ngy gieo Ngy cy Ngy thu hoch V Ma

TH3-3 16/06/2007 13/10/2007 P6 17/06/2007 13/07/2007 25/10/2007

V Xun TH3-3 18/01/2008 7/6/2008

P6 18/01/2008 9/03/2008 22/6/2008 - Thi gian tin hnh: v Ma 2007 v v Xun 2008. - a im tin hnh th nghim: Th nghim c tin hnh trn khu

th nghim B mn Cy lng thc - Khoa Nng Hc Trng i Hc Nng

Nghip H Ni. - K thut bn phn:

Bn lt: 100% P2O5 + 30%N. Bn thc hai ln:

- Ln 1 sau cy 1 tun bn: 50%N + 50%K2O. - Ln 2 bn thc ng (trc tr) bn: 20%N+50%K2O.

- S dnh cy: 2 dnh/khm. - Mt : 40 khm/m2. - Chm sc v phng tr su bnh: Theo quy trnh k thut p dng cho cc th nghim ca B mn Cy lng thc

3.6. Phng php phn tch s liu Cc s liu thu c trong qu trnh th nghim c tng hp v x l

thng k theo phng php phn tch phng sai (ANOVA) bng chng trnh IRRISTART 4.0 v EXCEL.


PHN IV KT QU NGHIN CU V THO LUN

4.1 nh hng ca liu lng phn bn n mt s ch tiu nng ho trong t

Kt qu phn tch mt s ch tiu nng ho trong t cc th nghim c trnh by bng 4.1.

Bng 4.1: Kt qu phn tch mt s ch tiu nng ho trong t cc th nghim

Ging Mc phn pHH2O OM (%) N tng

(%) NO3

(ppm) NH4

(ppm) P0 6,37 2,90 0,17 15,75 4,11 P1 6,47 3,35 0,23 27,88 5,02 P2 6,26 3,56 0,23 15,59 3,53

TH3-3

P3 6,28 3,46 0,17 41,11 6,02

P0 6,56 3,52 0,17 12,38 5,75 P1 6,26 3,69 0,17 16,38 3,9

P2 6,21 3,52 0,17 21,89 3,44 P6

P3 6,27 3,60 0,14 4,65 3,36 Nn 7,45 3,67 0,16 0,17 6,51

Qua s liu bng 4.1 cho thy tr s pHH2O gia cc cng thc bn phn chnh lch khng nhiu, dao ng t 6,26-6,56 v u mc chua nh (FAO). T c th thy rng bn phn lm cho t chua. Hm lng cht hu c ca t a s u thp hn so vi thi im trc th nghim, s d nh vy l do s phn hu cht hu c trong t din ra rt chm v trong qu trnh sinh trng v pht trin, cy trng ly i dinh dng t t. m tng s trong t cc cng thc th nghim l khng sai khc nhau v nh gi mc trung bnh. Nng NO-3 cc cng thc cao hn t 3-7 ln NH+4, ch ring cng thc P3 vi ging P6 th chnh nhau khng nhiu. iu ny cho thy s tch lu di dng NO-3 trong t l rt ln.


4.2. nh hng ca liu lng phn bn n thi gian sinh trng ca ging la TH3-3 v P6 qua cc giai on sinh trng Bng 4.2: nh hng ca liu lng phn bn n thi gian sinh trng ca

ging la TH3-3 v P6 qua cc giai on sinh trng (ngy)

V trng Ging

Mc phn

Gieo -cy

Cy -KTN

KTN -Tr

Bt u tr - KTT

KTT- Chn

Tng TGST

P0 27 33 18 8 31 117

P1 27 34 18 9 32 120 P2 27 34 18 9 33 121

TH3-3

P3 27 35 19 9 33 123 P0 26 36 24 10 33 129 P1 26 36 24 10 34 130 P2 26 37 25 11 34 133

V

Ma

P6

P3 26 38 25 11 34 134 P0 51 35 18 7 30 141 P1 51 35 19 8 30 143 P2 51 36 20 8 30 145

TH3-3

P3 51 37 21 8 31 148

P0 51 39 24 9 31 154 P1 51 41 25 9 32 158 P2 51 42 26 10 32 161

V

Xun

P6

P3 51 42 27 10 32 162 Ghi ch: KTN: Kt thc nhnh; KTT: Kt thc tr; TGST: Thi gian sinh trng

Trong v ma, thi gian t cy n kt thc nhnh i vi ging

TH3-3 l 33-35 ngy, ging P6 l 36-38 ngy. Kt thc nhnh, cy la

bc vo thi k lm t, lm ng. i vi ging TH3-3, thi gian t kt

thc nhnh n tr dao ng t 18-19 ngy, ging P6 t 24-25 ngy. Nhn


chung, cc cng thc bn vi liu lng khc nhau khng nh hng nhiu

n thi gian lm ng ca c 2 ging.

Thi gian tr bng ca TH3-3 bin ng t 8-9 ngy, P6 bin ng t

10-11 ngy. Thi im la tr vo ngy 14-16/9, gp iu kin ngoi cnh

thun li nn la tr u v tp trung (bng s liu kh tng - phn ph lc). Thi gian kt thc tr n chn ca TH3-3 bin ng t 31-33 ngy, P6

l 33-34 ngy.

Tng thi gian sinh trng ca TH3-3 trong v ma trn cc cng thc

bn vi cc liu lng khc nhau dao ng t 117 123 ngy, P6 dao ng t

129-134 ngy. Tuy bin ng v thi gian sinh trng khng ln, song cc

cng thc khng bn th tng thi gian sinh trng c xu hng rt ngn hn

so vi cc cng thc bn t v bn nhiu. iu ny c th do cc cng thc

bn phn la sm t s nhnh ti a, nhanh kn hng hn so vi cc cng

thc khng bn.

Trong v xun, thi gian sinh trng ca cc ging di hn so vi v

ma, do khi gieo m gp thi tit rt m rt hi ko di (30 ngy) nn giai on m ko di ti 51 ngy.

Nh vy, khi tng liu lng phn bn th thi gian sinh trng ca 2

ging c s khc nhau nhng s chnh lch l khng ln.

4.3. nh hng ca liu lng phn bn n chiu cao cy ca ging TH3-3 v P6 cc giai on sinh trng

Chiu cao cy trn ng rung l mt ch tiu quan trng xc nh ton

b tnh hnh pht trin ca cy la cc mc phn bn khc nhau. Chiu cao

cy ca cy la chnh l kt qu ca s tng trng thn l t khi ny mm

n lc hnh thnh t, vn lng v tr bng hon ton.


Bng 4.3: nh hng ca liu lng phn bn n tng trng chiu cao cy ca ging TH3-3 v P6

Chiu cao cy ca cc ging cc tun sau cy (cm) V trng

Ging Mc phn 2 TSC 4 TSC 6 TSC 8 TSC 10 TSC 12 TSC

P0 54,8 72,2 90,3 104,5 110,6 111,8 P1 55,4 73,9 93,6 108,5 115,2 117,1 P2 57,5 76,2 96,2 111,2 118,0 120,2

TH3-3

P3 59,8 78,7 98,9 114,1 121,3 124,9 Trung bnh 56,9 75,3 94,8 109,6 116,3 118,5

P0 53,4 61,3 74,1 88,7 93,0 98,3 P1 57,6 66,3 80,2 94,2 98,9 104,5 P2 58,9 68,8 83,2 97,8 102,7 108,5

P6

P3 60,1 70,4 86,3 100,9 106,1 111,3 Trung bnh 57,5 66,7 81,0 95,4 100,2 105,7 LSD 0,05 3,67 5,92 6,85 14,90 10,71 10,41

V Ma

CV(%) 3,4 4,4 4,1 7,7 5,3 4,9 P0 43,2 61,4 84,2 93,9 100,3 105,3 P1 42 64 87,5 97,3 104,2 111,3 P2 45,6 69,3 93,1 103,7 110,8 118,6

TH3-3

P3 45,7 70,1 95,2 104,5 112,3 127,8 Trung bnh 44,1 66,2 90,0 99,9 106,9 115,8

P0 32,3 45,5 60,1 76,8 86,3 94,6 P1 34,5 48,1 64,3 82 91,9 100,5 P2 35,4 50,5 68,4 86,4 96,3 103,1

P6

P3 38 53,7 71,8 91,1 100,5 106,8 Trung bnh 35,1 49,5 66,2 84,1 93,8 101,3 LSD 0,05 7,09 4,58 12,82 12,09 13,58 6,49

V Xun

CV(%) 9,5 4,3 8,7 7,0 7,2 3,2


S tng trng chiu cao cy nhanh hay chm ph thuc vo nhiu yu t nh: nhit , nh sng, mt cy, lng phn bn c bit l phn m c nh hng rt ln n qu trnh sinh trng, pht trin ca cy la. Kt qu theo di v ng thi tng trng chiu cao cy ca ging la TH3-3 v P6 qua cc giai on sinh trng c trnh by bng 4.3. Trong v Ma do iu kin thi tit thch hp nn cy la tng trng chiu cao nhanh. Giai on 2-4 TSC, gia cc cng thc t nh hng n chiu cao cy, c s sai khc mc phn P3 (TH3-3), mc phn P2-P3 (P6) Giai on t 6-10 TSC, khi tng liu lng phn bn lm tng chiu cao cy. n tun th 12 sau cy, ging TH3-3 c chiu cao cy thp nht mc phn P0 (111,8 cm) v t cao nht mc phn P3 (124,9 cm), cn ging P6 chiu cao cy thp nht mc phn P0 (98,3 cm) v cao nht mc phn P3 (111,3cm). Trong v Xun, giai on t cy n sau cy 2-4 tun do cy m va bn r hi xanh nn chiu cao cy u tng rt chm, s khc nhau v chiu cao cy gia cc liu lng phn bn l khng ln. T tun th 6-12 TSC chiu cao cy tng mnh v y l giai on cy la vn lng, lm ng. Chiu cao cy tng ln r rt khi liu lng phn bn khc nhau, khi tng liu lng phn bn chiu cao cy tng dn c 2 ging. i vi ging TH3-3, thi im 12 TSC, chiu cao cy thp nht mc mc phn P0 (105,3 cm) v cao nht mc phn P3 (127,8 cm). i vi ging P6, chiu cao cy thp nht mc phn P0 (94,6 cm) v cao nht mc phn P3 (106,8 cm). Nh vy, qua kt qu theo di tng trng chiu cao cy ca 2 ging cho thy khi tng liu lng phn bn, chiu cao cy ca ging TH3-3 tng mnh hn ging P6, iu ny cho thy ging la lai mn cm m hn so vi la thun. Kt qu ny hon ton ph hp vi cc cng trnh nghin cu ca Phm Vn Cng v cs, 2005.


4.4. nh hng ca liu lng phn bn n tc tng trng chiu cao cy ca ging TH3-3 v P6

Tc tng trng chiu cao cy nhanh hay chm ph thuc vo cc

yu t nh: thi v, c tnh nng sinh hc ca ging, nhit , nh sng,

phn bn, mt cy v k thut chm sc.

Kt qu theo di tc tng trng chiu cao cy ca ging TH3-3 v

P6 qua cc giai on sinh trng c trnh by bng 4.4.

Tc tng trng chiu cao cy ca c 2 ging tng dn qua cc giai

on sinh trng v t cao nht thi im sau cy 4-6 tun (TH3-3) v 6-8 tun (P6), sau tc tng trng chiu cao cy bt u gim dn. Giai on 2-4 tun sau cy, tc tng trng chiu cao cy ca

TH3-3 t cao nht mc bn P3 (18,90 cm/tun) v thp nht mc bn P0 (17,4 cm/tun). i vi ging P6, tc ny t cao nht mc bn P3 (10,3 cm/tun) v thp nht mc bn P0 (7,9 cm/tun). Trong v xun, tc tng trng chiu cao cy ca c 2 ging cao

nht mc P3 (TH3-3 l 24,4cm/tun, P6 l 15,7cm/tun) v thp nht mc bn P0 (TH3-3 l 18,2 cm/tun, P6 l 13,2 cm/tun ).

Giai on 4-6 tun sau cy, c 2 v, tc tng trng chiu cao cy

ca ging TH3-3 t cao nht. Tc tng trng chiu cao cy ca c 2

ging cao nht mc P3 (TH3-3 l 20,2cm/tun, P6 l 15,9 cm/tun) v thp nht mc bn P0 (TH3-3 l 18,1 cm/tun, P6 l 12,8 cm/tun).

Trong v ma, tc tng trng chiu cao cy ca c 2 ging cao

nht mc P3 (TH3-3 l 25,1cm/tun, P6 l 18,1cm/tun) v thp nht mc bn P0 (TH3-3 l 22,8 cm/tun, P6 l 14,6 cm/tun).


Bng 4.4: nh hng ca liu lng phn bn n tc tng trng chiu cao cy ca ging TH3-3 v P6 (cm/tun)

Giai on sinh trng V trng

Ging Mc

phn 2-4 TSC 4-6 TSC 6-8 TSC 8-10 TSC 10-12 TSC P0 17,4 18,1 14,2 6,1 1,2

P1 18,5 19,7 14,9 6,7 1,9

P2 18,7 20,0 15 6,8 2,2 TH3-3

P3 18,9 20,2 15,2 7,2 3,6

Trung bnh 18,4 19,5 14,8 6,7 2,2

P0 7,9 12,8 14,6 4,3 5,3

P1 8,7 13,9 14 4,7 5,6

P2 9,9 14,4 14,6 4,9 5,8 P6

P3 10,3 15,9 14,6 5,2 5,2

V

Ma

Trung bnh 9,2 14,3 14,5 4,8 5,5

P0 18,2 22,8 9,7 6,4 5,0

P1 22,0 23,5 9,8 6,9 7,1

P2 23,7 23,8 10,6 7,1 7,8 TH3-3

P3 24,4 25,1 9,3 7,8 15,5

Trung bnh 22,1 23,8 9,9 7,1 8,9

P0 13,2 14,6 16,7 9,5 8,3

P1 13,6 16,2 17,7 9,9 8,6

P2 15,1 17,9 18,0 9,9 6,8 P6

P3 15,7 18,1 19,3 9,4 6,3

V

Xun

Trung bnh 14,4 16,7 17,9 9,7 7,5


Giai on t 6-8 tun sau cy tr i, trong c 2 v, tc tng trng chiu cao cy ca ging TH3-3 u gim, tc tng trng chiu cao ca ging P6 t cao nht v gim dn sau cy 8-10 tun. Trong giai on u, ging TH3-3 c tc tng trng chiu cao cy cao hn so vi ging P6 l do la lai c kh nng hp thu m thp hn la thun. giai on sau, tc tng trng chiu cao ca ging P6 cao hn ging TH3-3, do c tnh ca ging P6 l ging di ngy hn so vi ging TH3-3.

4.5. nh hng ca liu lng phn bn n tng trng s nhnh ca ging TH3-3 v P6 qua cc giai on sinh trng

nhnh l mt c tnh sinh hc ca cy la, s nhnh lin quan cht ch n qu trnh hnh thnh s bng hu hiu v nng sut sau ny. Song kh nng nhnh ca cy la li ph thuc vo rt nhiu yu t nh: iu kin thi tit, ch dinh dng, mt , ngun nc cng nh iu kin k thut canh tc. Kt qu theo di tng trng s nhnh ca 2 ging 4 liu lng phn bn khc nhau c trnh by trong bng 4.5.

Trong v Ma do iu kin thi tit thch hp nn cy la tng trng v s nhnh rt nhanh. S nhnh t ti a sau 6 TSC (TH3-3) v 8 TSC (P6). Sau s nhnh v hiu bt u li dn i v n nh vo giai on hnh thnh bng hu hiu. Giai on 2-4 TSC l giai on cy la hi xanh, bt u nhnh, s nhnh cc cng thc khng khc nhau mc ngha. Giai on 6 TSC l giai on TH3-3 nhnh ti a nn tng trng s nhnh/khm giai on ny l cao nht. Khi tng liu lng phn bn c nh hng nhiu n tng trng s nhnh ca c 2 ging. S nhnh ca c 2 ging t cao nht mc bn P2 (TH3-3 l 11,0 nhnh, P6 l 10,9 nhnh ) v thp nht l cng thc P0 (TH3-3 l 7,9 nhnh, P6 l 9,4 nhnh).


Bng 4.5: nh hng ca liu lng phn bn n tng trng s nhnh ca ging TH3-3 v P6

S nhnh ca cc ging cc tun sau cy (nhnh/khm) V trng

Ging Mc

phn 2 TSC 4 TSC 6 TSC 8TSC 10 TSC 12TSC P0 5,9 7,6 7,9 6,1 5,9 5,4 P1 6,4 8,3 9,5 6,3 6,0 6,0 P2 6,7 9,0 11,0 7,4 6,9 6,0

TH3-3

P3 6,3 9,2 10,6 6,9 6,7 6,4

Trung bnh 6,3 8,5 9,8 6,7 6,4 6,0

P0 5,8 7,2 8,4 9,4 6,7 6,6 P1 5,9 7,6 8,6 10,7 7,6 6,7 P2 6,0 7,9 8,8 10,9 8,7 8,4

P6

P3 6,1 7,5 8,5 10,1 7,6 6,7 Trung bnh 6,0 7,6 8,6 10,3 7,7 7,1 LSD (0,05) 0,68 1,05 1,39 1,59 1,24 1,61

V

Ma

CV% 6,2 7,3 8,5 10,5 10,0 13,8 P0 2,9 7,5 7,9 7,2 6,7 5,5 P1 2,9 7,7 8,0 7,4 6,8 5,9 P2 3,5 7,8 8,8 8,2 7,7 6,7

TH3-3

P3 3,3 7,6 8,2 7,5 6,8 6,2 Trung bnh 3,2 7,7 8,2 7,6 7,0 6,1

P0 2,5 8,8 9,9 10,0 7,3 6,2 P1 3,1 9,1 10,1 10,5 7,6 6,2 P2 3,0 9,9 13,4 14,1 8,7 7,7

P6

P3 2,9 9,8 10,4 12,1 8,3 6,0

Trung bnh 2,9 9,4 11,0 11,7 8,0 6,5 LSD (0,05) 0,5 1,2 2,1 1,4 1,6 1,0

V

Xun

CV% 9,6 7,4 11,6 7,8 11,7 8,6


giai on 8 TSC (TH3-3) v 10 TSC (P6) l giai on la gim dn tng trng s nhnh v n nh hnh thnh bng hu hiu. nh hng ca liu lng phn bn n s nhnh ca cc ging la cng khc nhau gia 2 v. Trong v Xun, giai on t cy n 2 TSC do cy m va bn r hi xanh nn s nhnh tng chm, s khc nhau v s nhnh gia cc liu lng phn bn l khng r rt. T tun th 4 tr i, cy la nhnh mnh v s nhnh t ti a 6 TSC (TH3-3) v 8 TSC (P6). S nhnh tng dn khi tng liu lng phn bn v khc nhau c ngha t 6 TSC tr i. i vi ging TH3-3, thi im 12 TSC s nhnh thp nht mc P0 (5,5 nhnh) v t cao nht mc P2 (6,7 nhnh). Ging P6 s nhnh thp nht mc P3 (6,0 nhnh) v cao nht mc P2 (7,7 nhnh) 4.6. nh hng ca liu lng phn bn n tc tng trng s nhnh ca ging TH3-3 v P6 qua cc giai on sinh trng

Tc tng trng s nhnh l mt ch tiu quan trng c lin quan n qu trnh hnh thnh nhnh hu hiu, s bng hu hiu v nng sut thu hoch. Cy la nhnh sm, tp trung s to iu kin thun li cho qu trnh tch lu v sau. Kt qu theo di tc tng trng s nhnh c trnh by bng 4.6. Kt qu cho thy : liu lng bn khc nhau nh hng n tc tng trng s nhnh/khm. Tc nhnh tng mnh nht giai on 2-4 tun sau cy, sau giai on 6-8 tun sau cy, ging TH3-3 c s nhnh gim do li i. Giai on 2-4 tun sau cy, v ma khi tng liu lng phn bn th tc tng trng t 1,7-2,9 nhnh/khm/tun i vi ging TH3-3 v 1,4-1,9 nhnh/khm/tun i vi ging P6. Trong v xun, khi tng liu lng phn bn th ging TH3-3 tng t 4,3-4,8 nhnh/khm/tun, ging P6 tng t 6,0-6,9 nhnh/khm/tun.


Bng 4.6: nh hng ca liu lng phn bn n tc tng trng s nhnh ca ging TH3-3 v P6 (nhnh/khm/tun)

Giai on sinh trng V trng

Ging Mc

phn 2-4 TSC 4-6 TSC 6-8 TSC P0 1,7 0,3 -1,8

P1 1,9 1,2 -3,2

P2 2,3 2,0 -3,6 TH3-3

P3 2,9 1,4 -3,7

Trung bnh 2,2 1,2 -3,1

P0 1,4 1,2 1,0

P1 1,7 1,0 2,1

P2 1,9 0,9 2,1 P6

P3 1,4 1,0 1,6

V

Ma

Trung bnh 1,6 1,0 1,7

P0 4,7 0,4 -0,7

P1 4,8 0,3 -0,6

P2 4,3 1,0 -0,5 TH3-3

P3 4,4 0,6 -0,7

Trung bnh 4,5 0,6 -0,6

P0 6,3 1,1 0,1

P1 6,0 1,0 0,4

P2 6,9 3,5 0,7 P6

P3 6,9 0,6 1,7

V

Xun

Trung bnh 6,5 1,5 0,7 Ghi ch : (-) biu th tc gim


Giai on 4-6 tun sau cy, khi tng liu lng phn bn th tc tng

trng s nhnh c xu hng gim dn.

4.7. nh hng ca liu lng phn bn n ch s SPAD ca ging

TH3-3 v P6 qua cc giai on sinh trng

Ch s SPAD tng quan thun vi hm lng dip lc trong l, ng

vai tr quyt nh n s quang hp ca cy la trong cc thi k sinh trng,

pht trin. Hm lng Chlorophyll ph thuc vo nhiu yu t nh: ging la,

lng m bn, iu kin canh tc v thi tit. Hm lng Chlorophyll trong

l c biu th di dng ch s SPAD. Ch s SPAD c o vo cc giai

on sinh trng ca cy la. Kt qu c trnh by bng 4.7.

S liu qua bng cho thy: SPAD ca cc ging la cao nht ti giai

on nhnh, gim dn giai on tr v thp nht giai on chn sp.

Khi tng liu lng bn th ch s SPAD tng cc ging la trong

tng nhiu ging TH3-3 (43,2-46,0), iu ny xy ra do hiu sut s dng m i vi hm lng Chlorophyll ca la lai cao hn la thun (Phm Vn Cng v cs, 2003, 2005) i vi ging TH3-3, khi tng liu lng bn th ch s SPAD dao

ng t 43,2-46,0 trong giai on nhnh hu hiu, t 39,4-42,0 trong giai

on tr v t 36,2-39,2 trong giai on chn sp. Ging P6, ch s SPAD

thay i khi tng liu lng phn bn. Trong giai don nhnh hu hiu ch

s SPAD tng t 43,6-44,0, giai on tr tng t 35,8-39,0 v giai on chn

sp tng t 32,5-37,4.

Nhn chung, khi tng liu lng phn bn th ch s SPAD tng nhng

s tn

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