Defoliation, Harvest, and Cotton Quality…. Philip Jost University of Georgia
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Defoliation, Harvest, and Cotton Quality….
Philip JostUniversity of Georgia
Fiber QualityDetermined by Many Factors
• Physiology of the plant
• Variety
• Defoliation Timing
• Harvest Timing
• Agronomic Practices
Schubert, A.M., 1975
Fiber Development
• Initiated at pollination of the cotton flower.
• 3 stages of development– Elongation
– Secondary wall thickening (maturation)
– Drying
Fiber Development
• Cotton fibers originate from the outer epidermal cells of the ovule. “Seed Hair”
FIBER ELONGATION
Stage 1
Fiber ElongationStage 1
• Elongation of the fiber is driven by the internal water pressure of the elongating cell.
• Length– Determined in the 18 to
21 days after pollination.– Cell expansion.– Variety sets the bar
• influenced by environment.
Schubert, A.M., 1975
Fiber QualityLength
• Reported to the nearest 32nd of an inch.
• Upper ½ mean length
Upper 1/2 mean length
Mean length
Fiber QualityLength
• Base is 34– Below 34 incurs discounts
– Above 34 may incur premiums depending on color.
• How bad can it hurt?– 33 = -2.2 cents
– 32 = -3.85 cents
– 35 = 1.40 cents
Factors Influencing Fiber Elongation• Temperature
– Affected by extremes in temperature early in development.
• Plant Nutrition– K is essential for maintaining internal water pressure.
• Variety!• Water
– Length usually not affected by water deficit, yield is much more susceptible. ??
KK+ +
accumulateaccumulates in s in primordial primordial fiber cells at fiber cells at initiation of initiation of expansionexpansion
Fiber Length (1993 - 2003)
33 33.5 34 34.5 35 35.5
19931994199519961997199819992000200120022003
% Short Staple (1993 - 2003)
0 10 20 30 40
19931994199519961997199819992000200120022003
10
20
30
40
50
Southwest Central Southeast East
% Short
Rainfall (in)
Southwest
CentralSoutheastEast
%Short vsRainfall2002
Rainfall vs Staple 2001 and 2002
32
32.5
33
33.5
34
34.5
35
13 15 17 19 21 23 25
Rainfall May thru September
Stap
le le
ngth
Timing of Defoliation
4 NACB 7 NACB
Both 60% open
AFIS-Length(n) 1999
0.66
0.67
0.68
0.69
0.7
0.71
0.72
0.73
L(n
) in
ch
es
17
31
55
60
64
80
83
97
10
0
10
0
10
0
10
0
10
0
% Open BollP>F 0.0006
ab
a a aa a
abc
bcdbcd bcd bcdcd
d
AFIS-Length(n) 2000
0.71
0.72
0.73
0.74
0.75
0.76
0.77
L(n
) in
ch
es
9
30
57
58
76
80
88
94
10
0
10
0
10
0
10
0
10
0
% Open BollF = 8.70**
cd ababc
abcd cd
defg defg de efg
fg
g g
Fiber QualityLength Uniformity• Reported as a ratio of
mean length to upper ½ mean length.
• Base is 81• Indirect measure of short
fibers.• How bad can it hurt?
– 79 = -.35 cents– Mill problems – short
fibers
Upper 1/2 mean length
Mean length
Uniformity = MeanUpper 1/2
Fiber QualityShort-fiber content
• Problems– Lower yarn strength
– Reduce spinning efficiency
– Limit the use of the yarn
– Increase imperfections in the yarn
• Causes– Weathering
– Ginning
75
77
79
81
83
85
Macon Memphis Florence B'ham
19992000200120022003
Fiber Uniformity in the S.E. 1999-2003
AFIS-SFC(w) 1999
7.67.8
88.28.48.68.8
99.29.49.6
SF
C(w
) %
17
31
55
60
64
80
83
97
10
0
10
0
10
0
10
0
10
0
% Open BollP>F 0.0071
cdbcd
d dd
d
bcdabcd
abcabc
ab abc a
AFIS-SFC(n) 2000
22
23
24
25
26
27
28
SF
C (
n)
%
9
30
57
58
76
80
88
94
10
0
10
0
10
0
10
0
10
0
% Open BollF = 9.24**
def
fg fgg
efg def
bcdcde bc
aba
abc
a
FIBER THICKENING
Stage 2
Fiber Thickening Stage 2
• Secondary wall thickening occurs from 17 to 53 days after pollination. – Cellulose is deposited inside the
elongated cell.
– The cellulose is deposited at slightly differing angles.
• Fiber thickening will determine fiber fineness, or micronaire.
Fiber QualityMicronaire
• Indirect measure of fiber fineness and maturity.
• The air-permeability of a specimen enclosed in a container of fixed dimensions.
HIGH LOW
Fiber Thickening
• Low micronaire cotton – thin fibers
• High micronaire cotton – thick fibers
• Insufficient carbohydrate supply.• Nutrient deficiency
• Excessive vegetative growth
• Heavy boll set
• Ample carbohydrate supply.• Poor boll set
• Short fibers
Fiber QualityMicronaire
3.5 3.7 4.2 5.0 5.2
-3.65 cents
-4.15 cents
Base Range
Premiums
Deductions
Fiber QualityMicronaire
• How to manage a crop for micronaire.– Variety selection– Irrigation where possible– Insect control– Harvest preparation– Once-over harvesting
34
36
38
40
42
44
46
48
50
Macon Memphis Florence B'ham
Mic
rona
ire
Rea
ding
200120022003
Micronaire in the South East
HVI Micronaire 1998
4
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
Mic
ron
air
e
6
42
69
73
92
10
0
10
0
10
0
10
0
10
0
10
0
10
0
10
0
% Open BollP>F 0.0011
c
bc
c
aba ab ab a ab ab ab ab a
HVI Micronaire 1999
00.5
11.5
22.5
33.5
44.5
5
Mic
ron
air
e
17
31
55
60
64
80
83
97
10
0
10
0
10
0
10
0
10
0
% Open BollP>F 0.0001
e ed bcd cd abc abc
aabc abc abc ab ab
HVI Micronaire 2000
00.5
11.5
22.5
33.5
44.5
Mic
ron
air
e
9
30
57
58
76
80
88
94
10
0
10
0
10
0
10
0
10
0
% Open BollF = 59.40**
gf
e bcde cde bcd bc a de bc bcde ab ab
Fiber QualityStrength
• The breaking strength of the cotton fiber is considered to be the most important factor in determining yarn strength.
• Fiber strength varies along the length of the fiber.
• Reported as grams of breaking load per tex.
Fiber QualityStrength
• Reported in grams per tex.
• Base is ~28– Below 25.5 = discounts– Above 29.4 = premiums
Strength 1998
27282930313233343536
ST
R (
g/t
ex
)
6
42
69
73
92
10
0
10
0
10
0
10
0
10
0
10
0
10
0
10
0
% Open Boll
P>F 0.0001
a
b
c bcc
cde cde
f
cd
ef de
f
def
Strength 1999
24.5
25
25.5
26
26.5
27
27.5
28
ST
R (
g/t
ex
)
17
31
55
60
64
80
83
97
10
0
10
0
10
0
10
0
10
0
% Open Boll
P>F 0.0001
ab a a ab ababc bc
d
bc
d
cd
dd
Strength 2000
23
23.5
24
24.5
25
25.5
26
26.5
27
ST
R (
g/t
ex
)
9
30
57
58
76
80
88
94
10
0
10
0
10
0
10
0
10
0
% Open Boll
F = 13.91**
a a
b bc bcd
cdef defefg
bcde
fg fg fgg
FIBER DRYING
Stage 2
Fiber Drying Stage 3
• Once mature the fiber dries.
• Fiber shrinks in diameter by approximately one-third.
• Drying causes fibers to twist and crimp.
Fiber QualityColor• Determined by the degree of reflectance (Rd) and
yellowness (+b).
• Base is 41-4 (white-strict low middling)– First number determines good middling, strict middling
etc…– Second number determines white(1), light spotted(2),
spotted(3), tinged(4) or yellow stained(5)– Number after “-” determines leaf grade, roughly a
percentage.– Premiums and discounts are relative to length.
Fiber Color
• Most directly linked to growth environment.– Weathering leads to fiber to darkening and loss
of brightness
• Also correlated with overall fiber quality.
Week 1998 1999 2000
0 41 31 42
1 41 31 41
2 41 31 42
3 51 31 41
4 51 31 41
5 52 41 41
6 52 31 41
7 51 41 41
8 51 41 41
9 51 41 51
10 51 41 51
11 61 41 51
12 61 41 51
Color Grades
Application of Harvest-Aids at 60-80% Open Boll:
• Maximized• Length Uniformity• Fiber Length• Lint Yield (1999)• Profit (1999)
• Minimized• Short Fiber Content
Early Management System?
• Why: – TSWV has shifted “prime time” for peanut planting
from mid-April to mid to late May, – Peanut harvest now in October - traditional cotton
harvest time.– A range of maturity spreads out harvest.
• What: Should we consider planting 10 to 20 percent of acreage for harvest prior to September 20?
Concerns - Late Summer/Early Fall Rainfall
0
0.5
1
1.5
2
2.5
3
3.5
Aug 1-15 Aug 16-31 Sep 1-15 Sep 16-30 Oct 1-15 Oct 16-31
Arlington Ft Valley Midville Tifton Vidalia
inches
What/How Early Management
• Manage for harvest prior to September 20– Plant by April 20– Use Pix to encourage earliness– Avoid excessive N– Avoid fruit losses from pest management
mistakes (ex. insects, herbicides)– Be prepared to apply defoliant/boll opener
Aug 20 to Sep 5
Risks of Early Management
• April plantings may encounter stand problems related to cool temperatures
• Significant potential for rainfall events in late August to early September >> boll rot, hard lock, reduced color grade
Other Fiber Quality Questions
Misapplications of glyphosate in RR Cotton adversely affect fiber quality.
True or False?
Misapplications of glyphosate in RR Cotton adversely affect fiber quality.
FALSE
RR Cotton Response to Glyphosate Systems
System Timing RDC Pvt, lint lb/A
Ponder Fm, lint lb/A
Conv PRE, OTT, Prec PDIR
1958 a 1878 a
Roundup 4 lf OTT
Prec PDIR
1953 a 1881 a
Roundup 1,4,9 lf OTT
Slppy Dir
1974 a 1749 b
Cotton Fiber Analysis NS NS2002 results, DP 555 BG/RR
Heavy Stink Bugs in 2003
Stinkbug damage in cotton can adversely affect fiber quality. True or False
S
Severe Stink Bug Damage
• TRUE !
Fiber Length as Influenced by Stink Bug Control, Irwin Co. 2000
0.78 0.8 0.82 0.84 0.86 0.88 0.9 0.92 0.94 0.96
Nodes 5-8
Nodes 9-11
Nodes 12-14
Nodes 15-17
Nodes 18+
Plan
t Zon
e
Len (w) in
Untreated Pyrethroid
Aggressive fertilization with N, K, and B can eliminate fiber quality problems.
True or False?
Aggressive fertilization with N, K, and B can eliminate fiber quality problems.
FALSE…….but K needs study
Which is the most important in avoiding fiber quality problems – variety selection or environmental conditions?
Which is the most important in avoiding fiber quality problems – variety selection or environmental conditions?
ENVIRONMENTAL CONDITIONS…temperature, water, harvest conditions, etc.
There are fiber quality differences among varieties. True or False?
There are fiber quality differences among varieties because of the insertion of transgenes? True or False?
There are fiber quality differences among varieties. TRUE
There are fiber quality differences among varieties because of the insertion of transgenes? FALSE but….
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