The importance of micronutrients in agriculture is truly well recognized and their uses have significantly contributed to the increased productivity of several crops.

3.  Vegetables are non woody herbaceous plant or part of the plant eaten as food by humans in
whole or in part. It is the science of vegetable growing, dealing with the culture of non-woody
(herbaceous) plants for food.
 It is the production of plants for use of their edible parts such as root, fruits, flower bud, bulb,
tubers etc.
 The importance of micronutrients in agriculture is truly well recognized and their uses have
significantly contributed to the increased productivity of several crops.

4.  The nutrient elements which are required comparatively in small quantities are
called as micro or minor nutrients or trace elements, Micronutrients are
essentially as important as macronutrients to have better growth, yield and
quality in plants.
 The requirement of micronutrients (boron, iron, copper, zinc, manganese,
chloride and molybdenum) is only in traces, which is partly met from the soil
through chemical fertilizer or through other sources.

5. Micronutrients improve the chemical composition and general condition of
vegetable crops and are known to acts as catalyst in promoting various organic
reactions in plants.
 Micronutrients play an eminent role in plant growth, development and plant
metabolism. However, their deficiencies may induce several physiological
disorders/diseases in plants and later, can reduce the quality as well as quantity of
vegetable crops.
 The incidence of their deficiencies in crops has increased markedly in recent years
due to intensive cropping, soil erosion, losses of nutrients through leaching, liming of
acid soils, unbalanced fertilizer application including NPK and no replenishment.
 Nowadays, micronutrients are gradually gaining momentum among the vegetable
crops because of their beneficial nutritional support and at the same time ensure
better harvest and returns. The demand for increasing vegetable production will
require a thorough knowledge of micronutrients in vegetable crops.

6. (Source: Indian Journal of Fertilizer’s, 2018)
 In India, an analysis of over 2 lakh soil samples revealed that, on an average, 36.5% of soils were
deficient in zinc; 23.4%, in boron; 12.8%, in iron; 7.1%, in manganese and 4.2%, in copper.
 Zinc deficiency is the most predominant deficiency across all geographies in India, as 36.5% of Indian
soils are deficient in zinc. Medium black soils (39.4%) and mixed red and black soils (36.2%) have
high zinc deficient soils.
 The greatest zinc deficient soils are the ones that are coarser in texture (sandy/loamy sand), high in pH
(> 8.5 or alkali/ sodic soils) and/or low in organic carbon (0.5%) and intensively cultivated.
 Boron deficiency is also prominent in India, as 23.2% of Indian soils are deficient (acute + deficient),
while 21.5 % are marginally (latent) deficient in boron. Also, the very low use efficiency of boron
(seldom exceeding 5%) is an area of concern.

7.  Iron deficiency in India increased from 11.0 % to 12.8% during 1967–1897 to 2011–
17. It is associated with grey brown soils (25.1%) and old alluvial soils (25%).
 In India, the problem of iron deficiency is mainly in calcareous and other alkaline
soils having pH > 7.5.
 The availability of iron is reduced under draught or moisture stress conditions due
to conversion of the ferrous form of iron (Fe2+) into a less-available ferric form
(Fe3+).
 Sometimes, high concentrations of phosphorous, nitrate nitrogen and high organic
matter contents hinder iron availability.
 The deficiency level of manganese has increased from 3.5% in 1987 to 7.1% in 2017.
Though the deficiency level decreases with a rise in soil pH, sand content and
leaching, manganese availability in soil reduces.
 Copper deficiency is insignificant, with only 4.2% of soils deficient. Copper
deficiency mainly occurs in sandy, calcareous, eluviated and organic rich soils.
 Old alluvial soils (7.4%) and laterite soils (4.8%) have a tendency to be deficient in
copper.
 Molybdenum: Most of the soils have adequate levels of molybdenum, but there is a
moderate deficiency in some parts of Maharashtra, Kerala and Odisha.

8. ROLE OF different micronutrients IN VEGETABLES

9. • Iron is the third most limiting nutrient for plant growth and metabolism, primarily
due to the low solubility of the oxidized ferric form in aerobic environments (Zuo
and Zhang, 2011; Samaranayke et al., 2012)
• Vegetable crops need iron to produce chlorophyll and to activate several enzymes
including those involved in the oxidation/reduction processes of photosynthesis and
respiration. (Borlotti et al., 2012)
• Vegetable crops like tomato, onion, carrot and spinach contain high percentage of
Iron. Iron deficiency is common with interveinal chlorosis of young leaves and
veins remain green except in severe cases.
• If the chlorosis is severe and persistent, yellowing increases to the point of
bleaching and burns can develop within this chlorotic area. Because iron does not
move easily within the plant, older leaves can remain green while flushes of new
growth are chlorotic.

10.  Boron is the key element in vegetable production. Boron plays an essential
role in the growth and development of new cells in the meristematic region
of plants.
 Boron is necessary for cell wall formation, development of fruit and seed. It
helps in pollen formation, pollination and flowering of plants (Malek and
Rahim, 2011) .
 The primary role of boron in plants is to improve solubility and
metabolism of Ca and its mobility and also helps in the absorption of
nitrogen (Pandav et al., 2016) .
 Boron does not easily move around the plant and therefore, the deficiency
appears first in young tissues, growing points, root tips and developing
fruits.

11.  Its deficiency may cause sterility, poor fruit set, small fruit size and ultimately lower
yield. Deficiency of boron also leads cracking and distorted growth in fruits (Harris,
2016) .
 The vegetable crops like, Brassica crops, sugar beet, potatoes etc. are highly sensitive
to boron deficiency. The sources of Boron are borax (Sodium tetra borate, 10.5%
boron, Boric acid (17.0% boron) and Disodium octaborate tetra hydrate (20%
boron).

12. • Zinc is an essential micronutrient and it act as a component and activator
of many plant enzymes. Zinc is essential in the formation of carbohydrate
and auxins, which help with growth regulation and stem elongation.
(Pankaj et al., 2018) .
• It is essential for regular growth, development and reproduction of plant.
Furthermore, application of zinc was found to increase the green
pigments of necrotic leaf of plants.
• Zinc is also a constituent of ribosomes and is essential for their structural
integrity (Trivedi et al., 2013).
• Premature shedding of male flowers and impaired pollen tube
development can lead to poor fruit set.

13.  Growth is ceased at the growing point. Its deficiency causes interveinal chlorosis
of older leaves then leaves turn grey-white and fall prematurely or die. Stunted
growth, distortion in shape and clustering of leaves on short branches known as
rosette.
 The crops like tomato, potato, beans and onion are highly sensitive to Zn
deficiency.

14.  Copper is involved with carbohydrate and nitrogen metabolism. Copper
plays pivotal role in regulating multiple biochemical reactions in plants
(Tripathi et al., 2015) .
 Copper is essential for photosynthesis, for the functioning of several
enzymes, in seed development and for the production of lignin which
gives physical strength to shoots and stems.
 Copper activates several enzymes in plant, helps in chlorophyll synthesis
(Ram and Bose, 2000) .
 The deficiency symptoms include restriction of terminal growth, die
back of twigs, death of growing points and sometimes rosetting, and
multiple buds form at the end of twigs.

15.  Molybdenum is an essential trace element for plant metabolism and its
functions in enzyme nitrate reductase which is responsible for reduction
of nitrate to nitrite during N assimilation in plants.
 It helps in protein synthesis and sulphur metabolism. Low and adequate
levels of molybdenum has a positive effect on carotenoid formation.
Molybdenum deficiency can be common in nitrogen-fixing legumes.

16. • Manganese plays an important role in oxidation and reduction process in
plants, such as the electron transport in photosynthesis.
• Manganese also has played a role in chlorophyll production. Manganese has
important role on activates several enzymes which involve to oxidation
reactions, carboxylation, carbohydrates metabolism, phosphorus reactions
and citric acid cycle.
• Dehydrogenase and Decarboxylase in the Krebs cycle (TCA) are also
activated by Mn2+ (Marschner, 1995; Burnell, 1988) .
• Manganese deficiency causes a light green mottle between the main veins
and interveinal chlorotic areas become pale green or dull yellowish colour
(Mousavi et al., 2011).

17.  Chlorine is most commonly used as sanitizer, due to its low cost for maintaining the fruit
quality like appearance, soluble solids content, acidity, pH, texture and flavor, shelf life and
also control microbial growth (Rahman et al., 2012).
 It is essential for photosynthesis (chlorotic tissues), helps in stomatal regulation and raises cell
osmotic potential, necessary for shoot apex and root.
 Vegetable crops like potato and beans are more sensitive to chlorine deficiency (Singh, 2016).

18.  Nickel is component of some plant enzymes involved in N metabolism and biological N fixation.
(W.A. Roach).
 Nickel significantly increased yields of potato (Roach and Barcley, 1946) .
 The deficiency of nickel causes leaf tip necrosis in nitrogen fixing plants.
 The deficiency of nickel also delayed nodulation and reduced efficiency of nitrogen fixation in
leguminous vegetable crops.
 Nickel was needed in cowpea at reproductive phase (Das, 2018).

19.  When nutrient is not present in sufficient quantity, plant growth is affected.
 Plant may not show visual symptoms up to a certain level of nutrient content, but growth is affected,
and this situation is known as hidden hunger.
 When nutrient level still falls, plant show characteristic symptoms of deficiency, these symptoms
through vary with crop, have general pattern.
 These are generally masked by disease and other stresses and so need careful and patient observation
on more number of plants for typical symptoms. These deficiency symptoms appear clearly in crops
with larger leaves.
 Toxicity symptoms may not always be the direct effect of the element in excess element on ne or more
other elements. For example, an excessive level of the potassium (K), in the plants can result in either
magnesium (Mg) and /or calcium (Ca) deficiency, excess phosphorus (P) can result in a result in zinc
(Zn) deficiency & excess Zn in an Iron (Fe) deficiency.

20.  Region of occurrence.
 Presence or absence of dead spot.
 Chlorosis of entire leaf or intervienal chlorosis.
 The region of appearances of deficiency symptoms depends on mobility of nutrients in plants.
 The nutrient deficiency symptoms of N, P, K, Mg & Mo appear in lower leaves because of
their mobility inside the plants.
 These nutrient moves from lower leaves to growing leaves thus causing deficiency symptoms in
lower leaves.
 The deficiency symptoms of less mobile elements (S, Fe, Mn & Cu ) appear on new leaves.
 Since Ca & B are immobile in plants, deficiency symptoms appear on terminal buds, chlorine
deficiency is less common in crops

21. Deficiency
symptoms
Old Leaves
Mg, Mo
Dead spot
Mo
With out
dead spot
Mg
Green viens
Mg
New leaves
Fe, Mn, Cu
Green veins
Fe, Mn
Yellow Veins
Cu
Old & new
Zn
Terminal
Bud
B

23.  Function: Important to plant growth.
 Sign of deficiency: Young leaves are pale green at base, develop yellow spots, then become twisted,
thickened and curl under; leaves are small; multiple buds; dieback from terminal buds; heart rot
(corkiness); internal cork of apples, cracked stem in celery, heart rot and girdle of beets.
 Sign of excess: Leaves turn yellowish red.
 Sources: Clover, composted melon plants, borax (add only if prescribed), granite dust.

24.  Function: Plant growth, utilization of iron.
 Sign of deficiency: Young leaves turn pale and may become mottled and wilt; leaves develop
brown spots; leaf tips dieback; leaves may not grow; growth slows or stops; multiple buds; gum
pockets; lack of leaf development in citrus.
 Sign of excess: Iron uptake blocked.
 Sources: Manure, rock powders, copper sulfate (use with care), neutral copper, composted
dandelions, grass clippings, sawdust.

25.  Function: Plant growth, chlorophyll and carbohydrate production.
 Sign of deficiency: Young leaves turn yellow or very pale but veins remain green (chlorosis); growth is
weakened and stunted.
 Sign of excess: None known.
 Sources: Humus, manure, compost, blood meal, New Jersey greensand; chelated iron, iron sulfate
(copperas).

26.  Function: Growth and plant maturation.
 Sign of deficiency: Leaves mottled yellow and white; brown spots may develop on leaves; plant growth
stunted or plant slow to mature.
 Sign of excess: Tissue dieback in the leaves; dieback surrounded by yellow border.
 Sources: Oak leaves, leaf mold, carrot tops, alfalfa; manganese sulfate (tecmangam).

27.  Function: Essential to many plant functions, converting nitrates into amino acids, conversion of
phosphorus into plant forms.
 Sign of deficiency: Leaves turn yellow and pale between veins; leaves may become bluish green;
leaves do not open completely; plant growth is stunted.
 Sign of excess: Poisonous to livestock.
 Sources: Sodium molybdate.

28.  Function: Fruit development.
 Sign of deficiency: Young leaves mottled yellow, plant tips stop growing; plants wilt easily. Occurs in
peat and alkaline soils: abnormally long, narrow, mottled, yellowed leaves, poor fruiting, dieback.
Small, thin, and yellow leaves; yield low; Deficiency leads to iron deficiency, which it resembles. Also
leaves are thickened and malformed, small and narrow. Growth is stunted.
 Sign of excess: None known.
 Sources: manure, composted corn, ragweed, vetch; zinc sulfate.

29. Nutrients Deficiency symptoms Critical limits in soil (mg/kg)
Boron
Terminal leaves lose colour. Loss of colour starts at the base with eventual death
of the terminal bud. Boron deficiency can develop deformed young leaves and
deformed fruits, cause death of shoot tips and stunted root growth.
0.5
Manganese
Manganese deficiency causes interveinal chlorosis with necrotic spots and stunted
root development.
2.0
Zinc
The leaf is narrow and small. Lamina is often chlorotic, veins remain green.
Necrotic spots develop randomly all over the leaf.
0.6
Iron
Younger leaves are affected with interveinal chlorosis (also known as lime induced
iron chlorosis), with main veins remaining green; in severe cases, the entire leaf
may become bleached.
4.5
Copper
Interveinal chlorosis. Rosetting and permanent wilting of leaves. The leaf detaches
easily from the stem. Copper deficiency causes pollen sterility, yellowing and
curling of leaves and lower density of ear production in cereals.
0.2
Molybdenum
Leaf turns a light green. Dead necrotic spots appear over the leaf except on the
veins. Affected areas may extrude a resinous substance from the under surface of
the leaf. Molybdenum deficiency causes restricted flower formation and stunted
plant growth.
0.1
Chlorine
Chlorine deficiency causes chlorosis and burning of leaf tips, leading to bronzing
and drying; over-wilting and leaf fall reduces the yield.
8.0
Nickel
Nickel deficiency can lead to accumulation of toxic urea in plant tissues. It results
in poor germination, reduced growth, vigour and flowering, dwarfed internodes and
poor kernel filling. Nickel deficiency is linked to dwarf foliage production and
0.1

30. PHYSIOLOGICAL DISORDERS
Some physiological disorders due to micro-nutrients are listed below-
Crop Disorder Deficiency
Tomato Cracking Boron
Cauliflower Whiptail Molybdenum
Browning or brown rot Boron
Carrot Splitting Boron
Beetroot & Radish Brown heart or Crown heart Boron
Celery Cracked stem Boron
Radish Akashin Boron

31. Commercial Name of various micronutrient available in the market
Boron (B)
Sodium tetraborate (14 to 20% B)
Solubor® (20% B)
Liquid boron (10%)
Copper (Cu)
Copper sulfate (13 to 35% Cu)
Copper oxide (75 to 89% Cu)
Manganese (Mn)
Manganese sulfate (23 to 25% Mn)
Manganese oxysulfates (variable % Mn)
Zinc (Zn)
Zinc sulfate (23 to 36% Zn)
Zinc-ammonia complex (10% Zn)
Zinc oxysulfates (variable % Zn)
Zinc oxide (50 to 80% Zn)
Zinc chelate (9 to 14% Zn)
Molybdate (Mo)
Ammonium molybdate (49%)

32. Method of application

33. BAND PLACEMENT
 The efficacy of soil application can be improved by band placement of the products. Lower
application rates can be used to alleviate deficiencies. This supplement can be applied with the
planting action, which will eliminate the cost of additional operations. If a liquid product is used,
the composition can be adjusted to alleviate individual deficiencies on different soils. These
products can be band placed in the root zone of the plant, which will overcome the chemical
limitation of the soil.
 When standard micro-nutrient granular products are used, the composition of the product is
pre-determined, which makes it difficult to address specific deficiencies. If standard products
are used and some micro-nutrients are sufficient in the soil, this can lead to the over-application
of these nutrients.
 The addition of micro-nutrient granules lowers the concentration of micro-elements in granular
fertilizers. It can also have a negative influence on the physical quality of the fertilizer granules.
The use of micro-nutrient granules can lead to inefficient distribution, since the actual amount of
nutrients in a tonne of fertilizer will be very low.

34. BROADCAST APPLICATION
 Broadcast soil application of micro-nutrients is easy as it can be done through a sprayer or an irrigation
system. The product’s composition can be adapted easily according to the varying soil chemistry of
within a field.
 Large amounts of micro-nutrients have to be used when broadcast application takes place.
Incompatibility of micro-nutrients with herbicides and fungicides can influence its functioning, which
can require an additional cultivation. With broadcast application, micro-nutrients can also be fixed in
the soil.

35. FOLIAR APPLICATION
 Micro-nutrient deficiencies are sometimes visible on crops during the growing season despite
supplemental applications before planting.
 These are possibly induced deficiencies due to climatic conditions, for example during cold, wet
conditions. When uptake through the roots is restricted due to climatic or soil conditions, an
adjustment using foliar application will be the most effective method.

36. APPLICATION WITH MIXED FERTILIZERS
 Recommended micronutrient application rates usually are less than 10 kg/ha (on an elemental
basis.). Separately applying micronutrient sources uniformly in the field is difficult at these low
rates.
 Therefore, both granular and fluid NPK fertilizers are widely used as carriers of micronutrients.
 Including micronutrients with mixed fertilizers is a convenient method of application and allow
more uniform distribution with conventional equipment.
 Costs also are reduced by eliminating a separate application of micronutrients.
 Micronutrients can be applied with mixed fertilizers by incorporating them during the
manufacturing process, bulk blending with granular fertilizers, coating granular fertilizers, or by
mixing with fluid fertilizers just before application to soil .

37. INCORPORATION OF MICRONUTRIENTS
 Micronutrients are uniformly distributed throughout NPK fertilizers by incorporation during
manufacture. Because the micronutrient source is in intimate contact with the mixed fertilizer.
 A component under conditions of high temperature and moisture, the rate of chemical reactions
which may reduce the plant availability of some micronutrients is enhanced. For example, when
ZnEDTA or any synthetic chelate is mixed with phosphoric acid before ammoniation, acid
decomposition of the chelate molecule results in decreased availability of the applied Zn.
 Incorporating ZnS04 with superphosphates before ammoniation results in decreased water
solubility of Zn. Immediate plant availability of applied Zn decreases with level of water-soluble Zn
in ammoniated phosphates.

38. CONT…
 After application, soil water moves to the granule site. The soluble fertilizers
dissolve and salts move in solution away from the granule.
 Zinc is immobilized by the formation of insoluble reaction products with the
phosphate fertilizer and by reactions with soil organic matter and the clay
colloids.
 The distance that Zn moves from the granule site depends on the extent of these
reactions. Since more soil is affected by greater Zn movement, more plant roots
may be able to absorb the applied Zn, which increases its effectiveness
 The micronutrient may also applied by coating on fertilizer or mixed with fluid
fertilizer so there are various different and possible ways to apply it accordingly
what to be required and possible.

40.  Nanotechnology helps in the manufacturing of innovative agrochemicals and novel delivery
mechanisms to enhance crop production and decrease the use of chemical fertilizers and
micronutrients.
 It acts as an important tool in agriculture to improve crop growth, yield, and quality parameters
with increased nutrient use efficiency, reduced wastage of fertilizers and cost of cultivation. These
nanostructures have shown slow degradation and controlled release of active ingredient for long
time. Because of the limitation in arable lands and water resources, the development of agriculture
sector is only possible by increasing resources use efficiency with minimum damage to production
bed through effective use of modern technologies.
 These nano-agro-formulations increase nutrient use efficiency, reduce soil toxicity, minimize the
potential negative effects associated with over dosage, and reduce the frequency of the application.
Hence, nanotechnology has high potential for achieving sustainable agriculture, especially in
developing countries like India.

41.  Recent reports and developments conclude that increase in concentration of micronutrients can be
retained in the edible parts during processing, and after consumption by humans, the nutrients are
bioavailable. Biofortification is offering proven technology to combat malnutrition, especially for
those living in poor and developing countries where most people rely on staple food crops which
are inherently low in micronutrient concentrations.
 Micronutrients, though required in relatively tracer amount (at >100 mg kg-1 dry weight) by
plants, play a virtually significant role in a variety of cellular and metabolic processes such as, gene
regulation, hormone perception, energy metabolism and signal transductions etc. Based on their
precise requirement in higher plants, boron (B), chloride (Cl), copper (Cu), iron (Fe), manganese
(Mn), molybdenum (Mo), nickel (Ni), and zinc (Zn) are typically classified under essential
micronutrients.

42.  Each organism requires an adequate supply of these micro elements which
subsequently requires a complete metal homeostasis networking including their uptake
and accumulation inside the plant, mobilization, storage and intracellular trafficking
etc. Insufficient supply or low phyto-availability of these elements would result in
limited crop productivity worldwide. (Ha¨nsch and Mendel, 2009).
 Therefore, plants require an requisite and constant supply of these micronutrients
throughout their entire growth phase for optimal productivity. But, the over expanding
human population and mindless exploitation of natural repositories makes it difficult
for the plants to ensure their adequate supply for future reference and therefore,
causing impulsive challenge for the expertise of science.
 Recently, it has been well elucidated that approximately 2/3 of the world’s population is
being suffering from the risk of nutrient-deficiency. However, the marked deficiency of
mineral nutrient could be reduced by the judicious exogenous supply of mineral
fertilizers or by the cultivation genotypically modified crops (GM crops) with higher
metal concentrations. In addition, crop husbandry, breeding or genetic manipulation
could also be recognized as one of the most efficient, recent and reliable technique of
improving mineral status of soil (White and Broadley, 2009).

43. .
 It is very tough to define the future requirements in micronutrient research in
agriculture, but on expected basis we can summarize that Boron and other trace
elements, such as Cr, Ni, and V, may be required for food‐producing animals, and if
so, dietary requirements of these elements should be determined. Field calibration
data are needed to improve fertilizer recommendations for micronutrient.
 Research is needed in the genetic improvement of crops, which will result in more
efficient mobilization of micronutrients from phloem into the fruit. Future research
on applying micronutrients should pay close attention to determining their effect on
consumption considerations rather than just the health of the crop plant.
 Properly applied fertilizer improves food quality through higher quality of
vegetative products, and thus indirectly of animal products, so that it ultimately
contributes to the health of humans and livestock animals. The majority of foods
consumed by animals and humans are of plant origin.

44.  plant foods are a critical source of nutrients, including the micronutrients. Finding
the appropriate answers on future micronutrient research requires the coordinated
efforts of soil scientists, plant scientists, animal nutritionists and clinical
nutritionists.
 For sure, these above mentioned approaches can definitely create new horizon in the
field of micronutrient application in plant and crop sciences, but in order to achieve
greater successful results, more advanced and scientific research works on this deep
topic are necessarily required.

45. Micronutrients play a central part in metabolism and in the maintenance of tissue function and
indispensable for growth and development of crops in general and vegetables in particular. The
nutritional value of crops is becoming a major issue. Therefore, the application of micronutrients to
sustain soil health and crop productivity besides maintaining the quality of vegetables is of profound
importance. Micronutrients are beneficial for improve yield, quality, earliness, fruit setting, increases
post-harvest life, and develop resistance to biotic and a biotic stresses.