Nutrition of Fruit Crops

8/8/2019 Nutrition of Fruit Crops

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Zinc

Functions of Zinc

1. Zinc is involved in synthesis of tryptophan, a precursor of IAA.

2. Involved in synthesis of many enzymes i.e carbonic anhydrase which catalyzes the

breakdown of carbonic acid in to carbon di oxide and water.

3. Zinc is essential component of proteinases and peptidases enzyme systems.

4. RNA and ribosomes contents in the cells are greatly reduced under the conditions of

Zn deficiency.

5. Plays role in protein synthesis

6. Zinc regulates the water relation in plants via auxin synthesis. Zn deficient plants

results in failure of cell walls to grow.

Natural sources of Zn in soil.

Mineral containing Zn are ; Augite, Sphalerite Biotite, Hornblende,

Form Utilized by the plants

Zn is taken up by the plants in form of divalent cation Zn++

Zn fertilizers:

Zn sulphate is extensively used as foliar spray in fruit trees. There are severalother inorganic materials and chelates which are used to supply Zn to the orchard.

Material Formula Zn %

Zinc Sulphate ZnSO4. H2O 36

Zinc Oxide ZnO 78

Zinc Carbonate ZnCO3 52

Zinc sulphide ZnS 67

Zinc chelate Na2ZnEDTA 14

Symptoms of Zn deficiency:



Kinnow: Fading of chlorophyll between the main veins in younger leaves. Bands and

fringes adjacent to those midrib remain green. Later series of irregular chlorotic blotches

and patterns appear on leaves. There is complete fading of chlorophyll in the interveinal

areas with sharp yellow colour during winter with marked reduction of leaf size and

Leaves becomes elongated and also curled. The internodal distance get reduced. In next

spring if deficiency persists small chlorotic leaves appear on weak growth giving rosette

look to the twig. During the summer twig die back starts with multiple bud development

giving bushy look to the plant. Finally defoliation and death of plant may also took place.

In case of oranges and other citrus fruits deficiency symptoms are similar to

Kinnow. The fruits of severely deficient plants become light yellow with smooth and thin

rind. The pulp tends to be woody, dry and insipid.

In apple.

Zn deficiency coincides with flowering. The affected shoots bear sparse foliage,

have short internodes with leaf resetting and die back. The leaf size is reduced and

become laceolated with wavy margins and have diffuse interveinal chlorosis with dark

green marginal rim.

Pear:

Reduction in leaf size with upward curling of leaves.

Stone fruits:

Irregular chlorotic areas develop on the margins which later coalesce to form

continuous yellow bands extending from midrib to margins. Red to purple blotches may

appear within the chlorotic areas, later drying up and falling out, producing shot-hole

effect. Crinkling, cupping and curving of the leaves is common.

Grapes:

Zn deficiency appear in summer when tips of emerging secondary shoot growth

get affected along with those of the primary shoots. Smalling of leaves with typical

chlorosis and particularly widening of the petiolar sinus. There is strangling of clusters in

some cvs with small undeveloped shot berries.

Mango:



The deficiency appears on terminal flushes in the upper part of the tree. As the

deficiency becomes severe, almost all the flushes are affected with narrow, stiff and

deformed leaves. There is interveinal chlorosis. The affected leaves curl backward giving

a cup-shaped appearance. The tips and margins of the curled leaves become chlorotic.

Under very severe deficiency conditions, there is almost total stoppage of flushing and

the death of large twigs and even branches.

Correction of Zn deficiency:

Soil application ZnSO4 did not give proper control of Zn deficiency in fruit plants

in high pH soils. In citrus zinc sprays are given @ 0.3 % to 0.45 % in April, June and

September. In pear and peach 3 kg of ZnSO4 + 1.5 kg of quick lime + 500 litres of water.

In guava 1 kg of ZnSO4 + 500 g of lime + 100 litres of water.

Interactions:

Phosphorus-Zn interaction is well known. Heavy P fertilization resulted in

reduction of Zn uptake. Various mechanisms have been proposed for the P-Zn

antagonism which are;

o A dilution effect of Zn concentration in foliage due to greater plant growth due to

P fertilization.

o Interference during translocation from roots to the leaves.

o Some antagonistic disorder at the functional site.

Zn excess:

In citrus toxicity level in fruit is observed above 200 ppm of Zn concentration

(Opti> 62 ppm; deficient >18 ppm) in leaves. Zn toxicity causes leaf burn, defoliation

and twig die back. The roots become stubby (short and broad), thickened and brownish.



Iron

Physiological Roles;

• Present in chloroplasts hence associated with chlorophyll formation

• Involved in the activity of many enzymes such as catalase, cyrochrome,

ferrodoxin, hematin and cytochrome oxidase.

• It plays role in respirtation.

Natural sources of Iron in the soil

Large amounts of soil Fe are present in primary minerals such as haematite (Fe2O3),

goethite (FeOCH), Magnetite (Fe3O4), pyrite (FeS2), olivine (FeSiO4) and limonite

(Fe2O3. 3H2O).

Forms utilized by plants:

The Fe is taken in ferrous form.

Iron materials and fertilizers:

FeSO4 have most commonly used to control the deficiency of Fe.

Material Formula % Iron

Ferrous Sulphate FeSO4. 7H2O 19Ferrous Oxide FeO 23

Ferric Oxide Fe2O3 69

Fe-chelates Na FeEDTA 5-12

Symptoms of Iron deficiency:

The most striking symptoms of iron deficiency is absence of chlorophyll in the

young leaves.

In citrus, iron deficiency results in darker green veins than the interveinal areas. In later

stages the interveinal area are yellow and eventually the entire leaf may become ivory

colour. In severe case the tree become partially defoliated, causing dieback and sometime

the tree dies. The oranges develop yellow colour like lemons. Iron deficiency may be

confused with deficiencies of Zn or Mn and can be easily distinguished from the latter by

a wide band of green along the leaf veins.



In case of Fe deficient apple plants, the apical leaves become pale and slightly

bronzed. In later stage these developed characteristic symptoms of dark green veins on a

pale green background. The leaves emerging subsequently became increasingly more

yellow, brittle and curved upward from the midrib and finally irregular, orange necrotic

patches developed on the apical leaves.

In peaches smaller veins and the interveinal area loss the green colour while the

main veins remain green and acute cases the main veins also loose the green colour and

the leaves become white. There is breakdown of the tissue and dead tissue drops away.

In grapes Fe deficiency results in characteristic yellowing of leaves. Generally the

first leaves that emerge in spring are of normal green but the later growth is cholorotic.

Interaction of Fe with other elements;

The mutual antagonism of Fe and Mn is well established. Excess of one of these

micronutrients depresses the other and may even cause deficiency symptoms. High Cu

content in acid sandy soils of Florida may cause iron chlorosis, especially if the total Cu

content of soil exceeds 150 ppm.



Boron

Functions of Boron

Boron is claimed to affect the activity of several enzymes such as oxidase and

sucrase. Boron plays important role in flowering and fruiting processes, N metabolism,

hormone movement and action and cell division.

It affects the rate and process of carbohydrate metabolism in to cell wall material.

B helps in translocation of sugars by formation of an ionizable sugar-borate complex.

Under B-deficient conditions, the supply of carbohydrates to the meristematic regions

is thus reduced resulting in tissue breakdown.

It play a role in pollen tube growth in addition to stimulatory effect on oxygen uptake

and on sugars absorption by the germinating pollen.

B posses dehydration properties, prevents hydration of root tips and thus strengthens

the plant roots against the unfavorable and harmful influence of the OH- ions.

Boron is known to play role in synthesis of nucleic acids as B deficiency causes

decrease in RNA content.

Natural sources of Boron in the soils:

Minerals and organic borates and borosilicates are major sources of Boron in the

soils. The main mineral are tourmaline, fluorine borosilicate, borates of calcium,

magnesium and sodium.

Forms utilized by Plants:

It is present in soil solution and taken up plants as H3BO3 (boric acid)

Boron material

In fruit plants Boron deficiency is controlled by boric acid or borax. This material

is very soluble in water is mostly used as spray. Other material such as sodium borate

and calcium borate are also used.



Material Formula % B

Boric acid H3B2O3 17

Borax Na2B4O7.10 H2O 11

Sodium tetraborate Na2B4O7 20

Boron optimum 109 and deficient 21

Deficiency symptoms of Boron

Deficiency symptoms of B are usually characterized by malformed and hard

misshapen fruits. There may be cracking and roughening of skin and pitting on the

exterior. Internally the fruit may develop corky areas in the cortex and browning in the

core region. There is partial defoliation and the tree bark may also split. The twigs and branches also start dying back.

In Kinnow, boron deficiency appears as yellowing of mid-rib and lateral veins of

mature leaves. The older leaves become thickened, leathery and deformed. Curling may

also occur in some leaves. Leaves on newly emerged shoots abscise during rainy season

resulting in die-back of the apical portion followed by multiple bud development.

In apples, B deficiency resulted in purplish pimples on young twigs. Small twigs

showed rough cracked bark. The fruits do not develop properly and are misshapen. The

fruit surface is underlaid by hard cork tissue which rapidly turns brown on exposure to

air. In severe deficiency internal cork spreads to whole of the fruit. In mild deficiency, the

entire fruit surface may be covered with small cracks, giving it rusted appearance.

In B deficient pear trees, irregular, superficial, dark or light coloured bark

cankers with slightly raised, uneven borders appear on young branches. Fewer basal

leaves develop on diseased twigs followed by the die back of twigs. On fruits circular to

angular, blunt bottomed, shallow depressions develop particularly on the calyx end and

often merge into an extended area. Batjer et al (1953) observed ‘blossom blast’, a

disorder caused by incipient (initial) B deficiency on trees growing on heavy soils. This

disorder occurred more frequently in years with above average precipitation and below

average temperature prior to and during the bloom period.



In peaches boron deficiency is characterized by the die back of branches in

spring. A dark green water-soaked spots appeared on every growing tip, about 2.5 cm

back from the end. Gradually this spot enlarged, brown and necrotic, girdling the growing

point. The leaves beyond the affected area wilted and died. Later, the tip slowly died back

for some distance. Older leaves also developed small necrotic areas, irregularly shaped,

which later dropped out, perforating the leaf. Defoliation occurred early, proceeding from

the tip toward the base. The bark became rough brown and rough with many small cork-

like growths. The root system was very poorly developed, consisting primarily of fibrous

roots.

In grapes, the boron deficiency resulted abnormally roughened leaves with raised

areas between veins resulting in cupping of leaves. There was stunting of growth, flower

clusters were developed but twisted, malformed fail to set fruit. B deficiency results in

high percentage of shot berries; or normal set that shatters severely during midsummer.

The shot berries resulting from B deficiency fail to elongate properly and tend to obtain

improper shape. Death of the growing point and abnormally short internodes are also

observed in B deficiency.

In plums, B deficiency symptoms appears mostly on fruit. The brown sunken

areas formed in the fruit flesh may consist of a single small spot or may involve whole

fruit. The brown flesh beneath the sunken areas is firm and in severe cases extends to the

pit. The B-deficient fruit colours up earlier than the normal fruits and drops. In some

cases, gum pockets may be formed in the flesh.

Interaction of B with other elements:

In citrus plants when the B is low the concentration of P increases and the ratio of

inorganic to total P in stems and leaves was highest in the B deficient plants (Smith and

Reuther, 1951). However, Hernandez and Childers (1956) found no effect due to excess

B application on P concentration of peach leaves.

Base elements such as K and Ca significantly affect the B uptake from the nutrient

medium. In grapefruit Ca-salt additions conspicuously depressed B accumulation and B-

toxicity symptom in the leaves. Similarly, K deficiency in lemon cuttings resulted in a

significant accumulation of B in them (Chapman and Brown, 1943). B deficiency and



toxicity have consistently been associated with an unbalanced ration between B and the

three major bases present in the soil complex. Low levels of bases in proportion to B are

conducive to B toxicity and the high levels of the bases are conducive to B deficiency.

High (Ca+ K)/Mg and high (Ca+Mg)/K ratio consistently resulting in B toxicity. But

high (K+Mg)/Ca ratio have had little effect on the appearance of B toxicity. In grapefruit

high B tend to accentuate the expression of Mn deficiency symptoms.



Manganese

Functions of Mn:

• Manganese plays important role in respiration and N metabolism in plants.

•It acts as an activator for the enzymes, nitrate reductase and hydroxylamineredcutase. Mn is involved as an enzyme activator in reactions of Kreb’s cycle.

• It is involved in oxidation-reduction reactions in photosynthesis. Deficiency of

Mn results specifically in inactivation of Hill reaction and the Mn content of

chloroplasts is depressed. According to Nason and McElroy (1963), Mn is

directly or indirectly involved in chloroplast formation and multiplication. Since

chlorosis is common in Mn deficiency workers link it with chlorophyll synthesis

and breakdown.

• An enzyme Indole acetic acid oxidase has been reported requiring Mn++ ions as

high Mn content in avocado leaves depressed rooting of cutting, by activating

IAA oxidases.

• Mn also plays role in pollen tube germination and its growth.

Natural sources of Mn in soil

Natural sources of Mn in the soil are hydrous manganese oxides, carbonates and silicates.

On weathering, where oxygen supply is limited, Mn++ is released in to the soil solution.

This form of Mn which is prevalent in soil below pH 5.5 is immediately available to

plants. As soon as Mn is absorbed it is replenished in the soil solution by exchangeable

Mn held by adsorption to colloidal particles in the soil.

In addition to Mn++, Mn also exists in soil in trivalent (Mn+++) and tetravalent

(Mn++++) forms. The trivalent form which exists as Mn2O2 is favoured by pH values near

neutrality. The tetravalent Mn++++ exists as a very inert oxide, Mn2O and is most likely to

occur at pH values greater than 8.0.



Manganese material:

Manganese sulphate is most common source and it contains 32 per cent of Mn.

Mn is also available in chelated form. MnO is another product containing 48 to 65 per

cent of Mn.

Symptoms of Mn deficiency:

The most common symptoms of Mn deficiency is chlorosis between the veins of

old leaves, generally over the entire tree and the terminal growth showing chlorosis. Loss

of colour is followed by development of necrotic tissue. The entire plant may sometime

be considerably dwarfed.

Kinnow:

Symptoms of manganese deficiency appear on younger as well as older leaves. In

the initial stage (below 20.5 ppm leaf Mn), lamina becomes light green with fine network

of green veins with normal leaf size. The dark green bands along the mid-rib and main

veins develop with yellowish-green areas between veins which is followed by several

colour degradation i.e. light-green to dull pale-green, between main lateral veins. Under

acute deficiency condition, the leaf lamina becomes yellow except narrow green bands

along the mid-rib and lateral veins. New growth appears with marked reduction in leaf

size leading to premature abscission of affected leaves in summer.

In Mango, Mn deficiency cause paling and drooping of plants. There is lightening

of green color between the principal veins, gradually turning yellow with a band of green

along the midrib and the lateral veins in the young leaves. As the deficiency progressed,

there is characteristic mottling of the leaf. Later prominent yellow colour developed with

dark-brown pinhead like spots scattered all over the leaf followed by leaf fall. The size

and shape of leaves remains normal but and the number of leaves and twigs are smaller

than normal.

In deciduous fruit trees, chlorosis between the main veins start near the margin of

the leaf and extends toward the midrib. The areas between the veins remain light green

while the tips remained green. The tip leaves on severely deficient terminal and lateral

shoots failed to size and were light green. Small interveinal necrotic spots also developed.



In banana, Mn deficiency appeared at highly alkaline soils. There is marginal

interveinal chlorosis on the younger leaves leading to coalescent necrotic spots and

finally a necrotic brown leaf margin. There is black-pimply spotting in fruits.

Interaction with other elements:

Availability of Mn was greatly increased by increasing in rate of P application.

There was 2-3 fold increase in leaf-Mn in sour orange seedling associated with higher P

fertilization as compared with normal fertilization. Application of N increased the leaf

Mn content in sweet orange. Similarly, heavy N fertilization from ammonium sulphate

and ammonium nitrate sources significantly increased the Mn concentration in orange

leaves. However nitrogen from Calcium nitrate did not have any such effect. This might

have been associated with the release of Mn from the exchange complex by NH4+ ions of

the fertilization or by H+ ions produced by nitrification. In peaches application of Fe-

chelates ( A heterocyclic compound having a metal ion attached by coordinate bonds to at

least two nonmetal ions) to soil caused a reduction in Mn content in leaves as compared

with trees which were not fertilized.. Fe-Mn antagonism comprises an absorption

relation, interference in translocation and competition at functional site in the plants.



Copper

Functions of Copper:

It is required for oxidation-reduction reactions at the enzymatic level

It plays important role in several Cu-containing enzymes such as cytochrome oxidase,

ascorbic acid oxidase and phenol oxidase.

Cu is reported to be involved in photosynthesis and chlorophyll formation.

It promotes the formation of vitamin A.

It influences the cell wall permeability and the process by which NO 3 –N is reduced to

NH4-N in plants.

Natural sources of copper:

The sulphides containing copper mains sources of copper. The chief Cu mineral is

chalcopyrite (Cu Fe S2). Some carbonate minerals such as malchite (Cu (OH2) CO3) and

azurite and silicate minerals also contain copper.

Form utilized by plants

Plants absorb Cu in divalent ion, Cu++

Copper material

Name Formula % CuCopper sulphate CuSO4. 5H2O 25

Cuprous oxide Cu2O 89

Cupric oxide CuO 75

Chalcopyrite Cu Fe S2 35

Cu Chelate Na2 Cu. EDTA 9-13

Deficiency symptoms of Copper:

Citrus:

In citrus copper deficiency also termed as exanthema, die back and ammoniation.

The most reliable symptom of copper deficiency are the gum pockets at the nodes of

twigs and brownish excrescence (abnormal outgrowth) on the fruit, twigs and leaves.

There are dark, reddish brown, gum soaked areas of irregular shape on fruit surface. The

cracking of fruit occurs. Blister-like gum pockets develop between the wood and bark,

usually near the nodes on the twigs. Leaves may also develop brown stained areas.



Multiple buds may form at the nodes. Severely affected twigs usually die back from the

tip and new twig growth appears from many multiple buds, giving a bushy appearance.

The apples trees growing on a medium-coarse sand and gravel overlying showed

symptoms of Cu deficiency. The first symptoms appear in early July on the terminal

leaves of the current-year shoots as large, irregular necrotic areas accompanied by

upward curling and distortion of the leaves. The lower leaves on the affected shoots were

usually pale green and lusterless, and shows numerous small irregular necrotic areas.

Defoliation of shoots occurred toward the end of july, progressively basipetally and from

September onwards they wither and die. Under severe deficiency conditions the bark of

the main branches and trunk of the trees became very rough and deeply followed by

shedding of bark tissues.

Copper excess:

Plants need very small quantities of copper and thus the satisfactory range for this

element is rather a narrow one. Copper toxicity may develop due to presence of excessive

copper minerals in soil, or due to application of cu material to the soil or in spray

programme for disease control also leads to excess of copper. The copper excess leads to

reduced plant growth and iron chlorosis. Copper toxicity also results in stunting, reduced

branching and thickening and abnormally dark rootlets.

Control of excess:

When cu-toxicity problem in fruit plants is encountered, the application of Cu to

soil should be discontinued. Copper spray for disease control should be avoided. Since

high soil pH reduces Cu availability to plants, the lime should be applied to raise the pH

to near 7.0. In the orchard where cu toxicity cause iron chlorosis, iron chelates should be

applied to control it.

Interaction of Cu with other elements:

P is known to minimize the deleterious effect of Cu excess, since heavy P fertilization of

citrus trees reduces foliar Cu content. Under acid, sandy soil conditions high Cu content

in soil resulted in severe Fe chlorosis in citrus trees. Copper also interferes with the

uptake of Zn. Cu spray on plants of various citrus species increased the intensity of Zn-

deficiency symptoms in leaves indicating an antagonism between Zn and Cu.



Molybdenum

Functions of Mo:



Mo is constituent of two major plant enzymes, nitrogenase and nitrate reductase.

It has a possible role in certain phosphatase systems and ascorbic acid synthesis.

Natural sources of Mo in soil

The principal source of Mo is its stable sulphide, Molybdenite. In addition to this few

fairly insoluble molybdates such as wulfenite, powerllite, and ferrimolybedite are present

in near surface soil environment. On weathering this element is released in to the soil

solution manily as MoO4 ion and again precipitated as Fe and Al molebdates at low pH

conditions.

Form of Mo utilized by plants:

Mo is taken up the plants in form of molybdate, MoO4-.

Symptoms of Mo deficiency

In citrus Mo deficiency appears first as watersoaked areas develop in to large

interveinal yellow spots with gum on the lower leaf surfaces. Badly affected leaves

eventually drop and in extreme cases, the trees become completely defoliated during the

winter. Under severe conditions large, irregular brown spots with a yellow halo may be

found on the fruit, the discoloration going only into the peel and does not penetrate the

albedo. The symptoms of Mo deficiency appears both on both the leave and fruits on

sunny side of tree.

Symptoms of Mo deficiency can be controlled by application of sodium

molybdate or ammonium molybdate.

Interaction with other elements:

Under acidic soil conditions, P application enhanced the uptake of Mo. On the

other hand, in alkaline soils, the uptake of Mo was reduced with excessive P.



Because under acidic soil conditions Mo is released from the exchange complex with

H2PO4 replacement, thus more Mo is available for the plant uptake. Under alkaline

conditions, there is greater fixation and precipitation of molybdates induced by P

application.

Sulpher also competes with Mo for absorption by plants and that there is mutual

antagonism between Cu and Mo. When one of these elements is excess, the toxicity can

be reduced by application of other.



Chlorine And Sodium

Physiological role (Cl):

The exact role of chlorine in plant metabolism is not very clear. This element is

involved in the evolution of O by chloroplast in photosytem II of photosynthesis.

Chlorine ions are associated with turgor production in the guard cells by the osmotic

pressure exerted by imported K ions.

Na:

No exact role of Na in plant metabolism has yet been ascribed. In a sparing effect,

Na, however, can partially replace K as essential element in some enzyme system in

some plant species when K is limited.

Natural sources of Cl in the soil

Sodium chloride is an important source present in sea water and carried to inlands

by clouds and strong winds and brought down by rain. The concentration of NaCl in the

soil is therefore, dependent upon the distance from the sea shore. Chlorine is present in

the soil in form of several minerals in combination with Na, K, Mg and Ca such as

chlorapatite, carnallite, sodalite, halite and sylvite. On weathering Cl is released from

these minerals goes in to solution and not absorbed on the clay complex due to its

negative charge.Sodium is an important cation on the exchange complex of the soil. It is

also an important constituent of oligoclase and albite feldspars. Small amount of sodium

also occurs in micas, pyroxenes and amphiboles, primarily in fine sand and silt fractions.

Forms take up by the plants

It is taken up by the plants as chloride anoin Cl-. Plants can also absorb chlorine

gas from the atmosphere. The plants take up sodium in the form of Na+ cation.

Materials

No fruit crop is know to response to the addition of Na and Cl. So little importance is

given to Na and Cl fertilizers for fruit crop as these elements are present abundantly in

the almost all the soils. Other fertilizers such as sodium nitrate or muriate of potash



supply these elements. Some growth regulators and plant protection chemicals also

contain these elements.

Cl excess:

The deficiency of either Cl or Na in fruit crops is not met under field conditions.

On the other hand, these elements are important because they pose problems ie salinity

and alkality to fruit crops when present in excess amounts. Poor drainage of the soil,

especially in the flat lands situated in the arid zones also results in saline conditions

which are harmful for fruit plants. Irrigation water containing large amount of salts is

another source of soil salinity. Canal waters are usually quite safe for irrigation for

irrigation but subsoil water but sub soil water at several places is unfit for irrigation due

to high salt content.

Chloride toxicity:

In addition to the deleterious effect of increased osmotic pressure in saline media,

high levels of Cl result in depressed growth and specific toxicity symptoms. These

symptoms include depression in tree growth, chlorosis and burning of tips and margin of

leaves.

Chloride injury in citrus first affects the younger leaves and consists of tip burn

and yellowing of leaves with small white spots. The leaves turn bronze due to excessive

Cl accumulation. Smaller twigs die back each year and some defoliation takes place at

several different times. The leaves less severely affected retain their green colour but

have small, light-green dots about the size of pinheads scattered over them. Lemons are

more sensitive to salt injury as compared with other citrus species.

The peach leaves developed marked chlorosis, tip and marginal burning due to

high Cl injury. Many leaves start dying and there was considerable abscission. Some

dieback of small branches also took place.

In mango Chloride toxicity manifests as leaf scorch which starts from the leaf tip,

generally 8-10 months after emergence. As the gets older, the scorch becomes brick-red

and progresses along the leaf margins, slowly covering the major portion of the lamina.

Nearly all the affected leaves which emerge in March start abscising in April of the next

year. After a few years, the young twigs start dying, giving a sickly look to the tree.



According to Pandey and Sharma (1979) the Cl affected mango leaves had 0.02 to 0.09

percent Cl as compared with 0.01 per cent Cl in the healthy leaves on dry weight basis.

Na excess:

Harmful effects of Na on fruit trees are of greater magnitude. Smith (1962) found

that the decline of ‘Valencia’ orange trees in Florida was associated with accumulation of

excess of Na following the continuous use of high rate of sodium containing fertilizers.

The leaf tip becomes brown or brown spots develop on the leaf margins, immediately

before defoliation. There was abnormal curling of leaves, dying of shoot tips, multiple

bud formation and dying of the upper end of trunks.

In peach, typical leaf scorch due to Na toxicity usually occurring in low-lying

patches in the orchards. There was stunting of trees and the most common early symptom

was tip burning of the leaves. Rolling of leaves and lateral scorch of edges also occurred.

Sometimes, there was a leaf scald (burning caused b hot liquid) which consisted of rapid

scorching of the entire leaf.

Methods of Control:

The management and control of saline and alkaline soils is very difficult. The

general recommended measures for amelioration of saline or alkaline soils is use of

gypsum amendments. Sodium is replaced by Ca on the exchange complex by this

process.

The use of irrigation water containing high amounts of injurious salts should be

avoided.

Interaction of Cl and Na with other elements:

Increased nitrate had a depressive effect on Cl absorption. Increasing rate of Na

decreased Ca and increased K absorption from the soil in trifoliate orange seedlings. In

an experiment, Dilley et al (1958) found that increasing the Cl level in the nutrient

solution increased Mn and decreased K in cherry, apple and peach, decreased Ca in

cherry and peach, Mg in peach and grape and B in cherry.





The leaves usually develop chlorosis along their margin and between the main

veins. Under severe Ca def. trees remain stunted foliage is sparse and rounded

appearance of tops.

The veins become yellow and rotting of roots take place.

In Apples

The symptoms of Ca def. appear in early june and consisted of the upwardcupping of the margin of the younger leaves.Leaves develop a uniform interveinal chlorosis and later turns necrotic and

shattered.

On Fruits, the def. first appear on the exposed side which becomes diffused

golden-amber skin coloured similar to sunburn but without the halo of bleached

skin.

The Ca def. results in many disorders of the fruits viz bitter pit, cork spot, internal breakdown, scald, fungal rotting and water core in apples, cork spots of pear,

cracking of cherries, soft nose of mango and leaf tip burn in strawberries.

Correction of Ca def.Ca def usually occurs in the acidic soil conditions due to leaching of Ca. The

addition of lime or single super phosphate will correct the def. On the other hand

Ca def due to alkalinity caused by high Na content, application of gypsum at 2.2 to11.2 tonnes/ha correct the def. of Ca. Spraying of 2 to 5% of CaCl2 before the

harvest increase the Ca content of fruits. Soft nose of mango can be reduced by

heavy application of gypsum and limestone to the tree.

Ca Excess:

The level of Ca in soil increased due to certain soil management practices like use

of high Ca containing irrigation water, excessive use of gypsum, calcium nitrate or

sulphur and over liming.Ca excess reduces the availability of some other elements such as P, K, Mn, Fe

and Zn. There is strong antagonism between K and Ca. When both Ca and K were

present in the medium in equal conc. K was absorbed by the roots more readily

than Ca.

Magnesium

Magnesium: is found in leaves and seed. Generally about .1% of total Mg in plants

and about 10% of the leaf Mg is constituent of chlorophyll.

Fn. Of Mg:

Part of chlorophyll and involved in photosynthesis process.

It acts as a activator of many enzyme system in CHO metabolism.Involved in enzymes which catalize the synthesis of nucleic acids.

Mg is essential for formation of oils and fats and is associated with the

transportation of P within the plants.

Mg is involved in movement of CHO from the leaves to the stem of the plants.

Natural sources of Mg in soil:



Silicate minerals: Biotite, Olivine(8.48% Mg), Serpentine(20% Mg)

Clay minerals: Muscovite, Montmorillonite

In arid zone: Dolomite, Limestone, Magnesite, Epsomite

Form utilized by plants: Mg is absorbed by the plants as a divalent cation, Mg++

Mg fertilizers: Mg is applied to the plants in the form of…

Dolomite (CaCO3+Mg CO3) 7.23% MgMagnesium Sulphate (Mg SO4) 15.98% MgSulphate of potash magnesia (50%K 2SO4, 30%MgSO4) 10.25% Mg

Magnesium oxide (MgO) 36.19% Mg

Magnesium nitrate Mg(NO3)2 18.95% Mg

Natural sources of Mg: FYM, Poultry manure, Rain, Dust particle and marine

salts.

Def. symptoms: Mg is mobile in the plants, so def. appear on the older leaves. Mgaffects the seedy fruit varieties more than the seedless varieties.

In Citrus, appearance of yellowish green blotch near the base of the leaf and the

midrib and the outer edge. This yellow area enlarges until the only green partsremaining are the tip and the base of the leaf and inverted V-shaped area on the

midrib. In severe def. the whole leaf turn yellow and defoliation take place.

In Apples, Mg def appears as brown necrotic or scortched areas between the veinsof the affected leaves which cause curling and finally dropping of leaves. Under

severe def. 80-90% leaves drop, and the fruit remain undersized and immature.

Interaction with other elements: Mg affects the uptake of K and Ca. Soil

application of heavy doses of K may cause Mg def. Nitrogen has beneficial effect

on the uptake of Mg. It has a synergetic effect on Zn and Mn content in citrus

leaves. On the other hand when Mg is present in deficient range, Cu content is

reduced as Mg uptake is increased up to the point where Mg def. disappears.

Nutrition of Fruit Crops

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