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Back to Plant Nutrition
THE LANGUAGE OF THE PLANT:
"There is apart from mere intellect, in the make-up of every superior human identity, a wondrous something that realizes without argument, frequently without what is called education ( though I think it is the goal and apex of all education deserving the name), an intuition of the absolute balance, in time and space, of the whole of this multifariousness, this revel of fools, and incredible make-believe and general un-settled-ness, we call the world; a soul-sight of that divine clue and unseen thread which holds the whole congeries of things, all history and time, and all events, however trivial, however momentous, like a leashed dog in the hand of the hunter. (Of) such soul-sight and root-center for the mind, mere optimism explains only the surface." Walt Whitman, Specimen Days and Collect, Philadelphia, 1882, p.174.
1. INTRODUCTION
2. DEFINITIONS
3. MAXIMUM YIELDS
4. THE LANGUAGE OF THE PLANT
5. PEST CONTROL WITH NUTRIENTS
6. CONCLUSION
1. INTRODUCTION:
The single most important and vital issue that faces our Nation today is the Production of Food. Hundreds of years of Agriculture have depleted most of our soils. The problem is further compounded by the fact that nutrient inputs are either unavailable; too expensive or chemically unstable and harmful. When we learn that the nutrients that we are using are: not readily available to the plants; lack essential trace elements; are subject to hydrolysis, volatilisation and leaching and are being used in an inefficient manner. We thus realize that we are effectively wasting our meager cash resources. We must understand that yields per acre are not increased by adding more and more chemical macro nutrient fertilizers. It is important to realize that less is more when availability of nutrients is timed with actual requirements. We need to completely change our thinking and understanding of Crop Management. In the words of Jerry Stoller, "Take solutions to Farmers by understanding the language of the plant and treating their problems." This strategy effectively solves the problems of all farmers. However, our main concern is with the small landholders and contract farmers. Small land holdings; expensive inputs and diminishing returns have combined to break their backs. Resultant misery and malnutrition is all too well known and needs no elaboration. Agriculture contributes about 24 % of Pakistan's GDP, employs about 45 % of the labor force and earns roughly 60 % of the total value of exports. The population of the Country stands at about 128 million souls. Cultivated area is about 53.37 million acres. Thus per capita availability is 0.46 acres. About 22 million acres are termed as culturable waste. Yields per acre are abysmally low when compared with other Countries.
2. DEFINITIONS:
It is important to clarify a few terms that will be used in this paper.
ESSENTIAL NUTRIENT ELEMENTS:
Plants need at least 17 essential, naturally occurring elements for growth. Three of these elements (carbon, hydrogen and oxygen) are obtained from the air and water. They comprise 90 % or more of the dry matter. The remaining 14 elements are obtained from the soil. They are:
MACRO-NUTRIENTS:• Nitrogen. ----- N
• Phosphorus.----P
• Potassium. ----K• SECONDARY NUTRIENTS:
• Calcium.---- Ca
• Magnesium. ---- Mg
• Sulfur. ---- S• MICRO NUTRIENTS:
• Manganese. ---- Mn
• Iron. ---- Fe
• Boron. ---- B
• Zinc. ---- Zn
• Copper. ---- Cu
• Molybdenum. ---- Mo
• Chlorine. ---- Cl
• Cobalt. ---- Co• ROLE OF NUTRIENTS IN PLANTS:
• Nitrogen:
Constituent of all proteins, chlorophyll and in coenzymes and nucleic acids.
• Phosphorus:
Important in energy transfer as part of adenosine triphosphate. Constituent of many proteins, coenzymes, nucleic acids and metabolic substrates.
• Potassium:
Functions in regulatory mechanisms as photosynthesis, carbohydrate translocation and protein synthesis.
• Calcium:
FUNCTIONS:
Cell wall component and plays role in the structure and permeability of membranes.
• Utilized for continuous cell division and formation.
• Involved in Nitrogen metabolism.
• Reduces plant respiration.
• Aids trans-location of photosynthates from leaves to fruiting organs.
• Increases fruit set.
• Controls water uptake by cell colloids.
• Plays significant role in vegetative habits of the crop.
• Abundance of Calcium results in production of smaller plants but stimulates early and abundant fruiting.
• Acts as protective sieve for nutrients to seep through in passing into cells
• Neutralizes Organic Acid by-products formed during plant growth by forming Calcium Oxalates.
• Alters availability of some nutrients and prevents toxic effect of others.
FACTORS CONTRIBUTING TO DEFICIENCY:
• Low pH soils (acid) tie up Calcium.
• High Nitrogen applications.
• High Potassium levels.
• Not mobile in the plant.
• Calcium in plants seems to exist in sensitive balance with Magnesium, Potassium and Boron. Imbalance causes abnormal performance of plant function.
• Leaches out of soil as Calcium Bicarbonate and becomes unavailable to the plant.
• Magnesium:
FUNCTIONS:
• Key element of chlorophyll production
• Activator and component of many plant enzymes.
• Improves utilization and mobility of phosphorus.
• Very mobile in plants.
• Vital role in photosynthesis.
• Directly related to Grass Tetany When Mg is dissolved by the soil solutions, it is absorbed by the root system by diffusion or ionic exchange. The competition from Nitrogen, Calcium and particularly from potassium, interferes with the uptake of Nitrogen fertilizer and can cause an imbalance between Nitrogen, Calcium, Magnesium and other minerals. In cattle feeding on such forage the problem is commonly referred to as nitrate poisoning or grass tetany. Where this is a problem it is imperative to maintain Magnesium levels, not as a cure but to reduce incidence).
• Increases Iron utilization in plants.
• Increases plant's ability to withstand unfavorable conditions and disease.
• Influences earliness and uniformity of maturity.
• Uptake and utilization usually occurs in the first 5 to 6 weeks after emergence. Row crops utilize mostly in first 40 days. Small grain crops need most during early growth season. Tree crops need when they make their first vegetative flush. Legumes generally contain more magnesium then phosphates. Sugar producing crops like beets, corn, potatoes and fruit require more magnesium than grain crops like wheat, rye and barley which also benefit from this element.
FACTORS CONTRIBUTING TO DEFICIENCY:
• Low levels of magnesium in the soil.
• High levels of Calcium (Calcium: Magnesium ratio), Sodium and/ or Potassium (interferes with magnesium absorption at the root hair surface, should not be applied with potash unless potassium levels are extremely low).
• Cool weather conditions restrict or inhibit uptake.
• Rapid uptake of Nitrogen fertilizer (when greater than available Magnesium causes deficiency and hinders Nitrogen Fixation by nodule Bacteria in legumes).
• Low soil pH tends to accelerate depletion, since most Nitrogen fertilizers are acid forming, use of high rates will lower soil pH.
• Magnesium rapidly leaches, thus more is lost due to soil mineralization than by crops utilization. In light sandy soils Magnesium deficiency is probably the greatest limiting factor for maximum yields.
• Sulfur: Important constituent of plant proteins.
• Boron:
FUNCTIONS:
• Important in sugar translocation.
• Effects nitrogen and carbohydrate metabolism.
• Protein synthesis.
• Formation of plant hormones.
• Promotes plant maturity by increasing cellular activity.
• Increases set of flowers and fruit and yield and quality.
• Water relations in the plant.
FACTORS CONTRIBUTING TO DEFICIENCY:
• Immobile in the plant.
• Soil pH 6.8 or higher (alkaline).
• Leaching.
• Heavily limed soils.
• High Potassium levels.
• High Nitrogen levels.
• Low Phosphate levels.
• Coarse textured, sandy soils.
• Drought conditions.
• When plant is expanding rapidly or flowering.
• Low Organic matter in soils.
• Iron:
FUNCTIONS:
• Chlorophyll synthesis. Not part of chlorophyll molecule but needed in the sequence of reactions which synthesize components of chlorophyll.
• In enzymes for electron transfer, operates respiratory system of cells.
• Compounds of Iron participate in reactions involving cell division and growth.
FACTORS CONTRIBUTING TO DEFICIENCY:
• Low supply of total Iron in soils.
• Low supply of available Iron (Ferrous vs Ferric).
• High soil pH, Calcareous soils (6.8 and above).
• Land leveling and erosion.
• High soil moisture levels and low soil temperature before and just after planting time.
• Soil compaction.
• High phosphate applications form insoluble Iron Phosphates. Also tends to immobilize Iron in roots and leaves.
• Competitive interaction with Zinc and Manganese.
• Not readily trans-located from old to new leaves, thus a constantly available source is needed throughout the growing season.
• Reactions involving cell division and growth.
• Manganese:
FUNCTIONS:
• Controls several oxidation-reduction systems, formation of O2 in photosynthesis.
• Predominant metal ion in metabolism of Organic Acids.
• In higher plants activates reduction of nitrite and hydroxyl amine to ammonia.
• Part of important enzymes involved in respiration and protein synthesis.
• Serves as activator for a variety of enzyme reactions such as oxidation/ reduction, hydrolysis and group transfer.
• May have direct or indirect influence on chloroplasts and their conversion of sunlight to chemical energy.
FACTORS CONTRIBUTING TO DEFICIENCY:
• Soil pH above 6.5 (alkaline).
• Low Organic matter.
• Over liming on light sandy soils.
• High Calcium and Magnesium interferes with the root system's ability to take up manganese.
• Low Sulfur levels make less manganese available to the plant.
• Copper:
FUNCTIONS:
• Catalyst for respiration.
• Enzyme activator.
• Major function in photosynthesis.
• Major function in Reproductive Stage.
• Indirect role in chlorophyll production.
• Increases sugar content.
• Intensifies color.
• Improves flavor in fruits and vegetables.
• Improves shelf life.
FACTORS CONTRIBUTING TO DEFICIENCY:
• High Organic soils (fixes Copper).
• Sandy soils (by leaching).
• Soil pH above 7.0 (alkaline).
• High Phosphates effect uptake of Copper.
• High concentrations of Aluminum, Zinc, Iron and Manganese ions compete with Copper.
• Does not move from older parts of the plant to younger leaves, therefore a continuous supply is required.
• When released into a soil by natural weathering process, soil collodial particles and micro-organisms along with the plant compete for this element. Thus availability to the plant alone is restricted.
• Soluble Copper reacts with Aluminum Silicates, Phosphates or other metal ions as the pH is reduced and becomes fixed in a form less available to the plant.
• Zinc:
FUNCTIONS:
• In enzyme systems that regulate various metabolic activities like protein synthesis, formation of chlorophyll, transformation of carbohydrates and regulation of the consumption of sugar in the plant.
• Seed and Grain formation.
• Maturation date.
• Height of plant.
• If present in sufficient quantities in the leaf, acts like anti freeze in plants. Demonstrated in Citrus, tomatoes and other crops.
FACTORS CONTRIBUTING TO DEFICIENCY:
• Total and available Zinc in the soil.
• Soil pH, Calcareous soils (pH 6.0 and above).
• High Phosphorous (Phosphate reaction).
• Leaching and erosion.
• Cold, wet springs.
• Low organic matter or high muck (organic matter) in soil.
• Land leveling, deep plowing, building terraces (95% available Zinc in top 6" of soil).
• Over liming.
• High Nitrogen induces Zinc deficiency.
• Soil compaction restricts root growth from where soluble salts like zinc sulfates are available.
• Crop removal at harvest.
• Molybdenum:
FUNCTIONS:
• In nitrogenase needed for nitrogen fixation.
• High Nitrogen using plants, essential for nitrate reduction to protein through the amino acid state.
• Essential for growth (Legume crops need great amounts, cauliflower, broccoli, lettuce and tomatoes have a relatively high requirement). Plants with low Molybdenum content may have high nitrate and low protein levels.
FACTORS CONTRIBUTING TO DEFICIENCY:
• Acid soils below 6.5
• Crop rotation where liming interferes.
• Iron and Aluminum tie-up Molybdenum.
• Sandy soils more deficient.
• Sulfate fertilization can increase deficiency.
• Cobalt:
Essential for symbiotic nitrogen fixation.
• Chlorine:
Activates system for production of O2 in photosynthesis.• SOIL PRODUCTIVITY:
The capability of a soil to produce a specified plant (or sequence of plants) under a specified system of management. This is basically an economic term and not a soil property. The productivity of a soil is usually expressed in kilos per hectare when using a particular management system in which are specified items such as planting date; fertilization; irrigation schedule; tillage and pest control.• SOIL FERTILITY:
The quality of land that enables a soil to provide the proper compounds, in the proper amounts and in the proper balance, for the growth of specified plants when temperature and other factors are favorable.
3. MAXIMUM YIELDS:
The requirement of various plants for nutrients are quantified. Von Liebig's law states that the yield of a crop will be limited by the availability of that element which is in least supply. To illustrate this point, let us assume that there is enough of the following nutrients in a one acre piece of land to grow wheat as follows:
ELEMENT: YIELD:
• Nitrogen. 2 tons.
• Phosphorus. 1.5 tons.
• Potassium. 1 ton.
• Zinc. 0.5 tons.
With good Agricultural practices and favorable weather conditions only 0.5 tons will be obtained and we will be effectively wasting NPK fertilizers. Thus we have raised our input price and lowered our yield expectancy. Without understanding this point if we go on adding NPK fertilizers in the hope of increasing yields, we will be causing unbalanced growth leading to weakness and consequent lodging and susceptibility to diseases. A properly balanced fertilization program will save on inputs and yield better harvests. This proper balancing means providing those elements only when they are needed by the plant. In case elements are provided too early they will become unavailable to the plant either due to leaching or conversion to immobile or non soluble compounds. The period of critical need by plants for 12 soil or foliar applied nutrients are illustrated below by division into three stages.
0 -40 Days after Rapid Growth Fruiting Period/
Planting Period Reproductive StagePhosphorus Nitrogen Calcium
Zinc Potassium Boron
Iron Sulfur Cobalt
Manganese
Copper
MagnesiumThe elements in the 40 day period are not required in large quantities. However, they are not mobile or in other words, they do not flow with the soil water. Root hairs need to come into direct contact with them for effective uptake. In case the root hairs are filled with mobile elements, such as those of the rapid growth period, they will be unable to make space for the nutrients that they actually require at that particular time. Moreover, since high levels of Potassium, Calcium and Sodium salts are quite mobile, this leads to more micro nutrient deficiency in the first 40 days, when the ultimate character of the plant is being formed. Thus the closer these micro nutrients are placed to the seed, the more likelihood of their being used effectively by the plant. This can be done by one of the following methods:
• Coating the seed.
• Banding non mobile nutrients close to the seed.
• Spraying them on the plant when it reaches 4 leaf stage.This introduces three important concepts e.g. Seed Coating; Banding and Foliar Application. Broadcast Application of nutrients, as presently being practiced, is the least effective and most wasteful method of application.
• SEED COATING:
Seed can be coated with micro nutrients; hormones; fungicides and pesticides. In Pakistan, we are using some pesticide coating. However, this protects the seed during storage. If nutrient and hormone coated seed are introduced we will have found an effective method of providing essential nutrients and compounds in the least expensive; least laborious and in a manner that requires the least technical knowledge on the part of the farmer. However, this is true only for he initial growth period. Secondly, not enough additives can be coated on the seed. Thus Banding and Foliar Spray are used to supplement nutrient availability. Seed coating can be done either by the farmer, just before planting, or by the Seed Company. The latter method requires Polymer coating to preserve the additives. Since Polymers are obtained by using Urea as a raw material the method can easily be adopted in Pakistan.• BANDING:
Application of nutrients for row cultivated crops is a much more cost effective as well as efficient method of providing nutrients. Broadcast application leads to uneven distribution and is more easily available to weeds where there are no crop seeds to compete with them. Secondly, more than twice the amount of fertilizer is required. This system lends even more credence to drill placement of seed combined with drill banding in a single operation. The actual practice is to place the nutrients 3 to 4 inches away from the seed in continuos flow form.• FOLIAR APPLICATION:
Roots are fed from the leaves even though they are presently the major source of nutrient uptake. However, they merely take up the nutrients to transport them to the leaves where they are converted into food and redirected to the roots. Radio Chemical Analysis has amply proved that Foliar Application is much more efficient that soil uptake. In clay loams and organic soils it was 6 times more efficient. In sandy loams efficiency increased to 20 times. This is quite significant and needs to be adopted. Availability of backpack sprayers for pesticides makes this method practicable for small farmers.
4. THE LANGUAGE OF THE PLANT:FIVE CATEGORIES OF HORMONES:
• AUXINS:
These are mostly in the leaf tips and control the growing point to light. IAA is the major Auxin, it influences the rate of cell division and enlargement. Low rates increase while high rates retard. Roots are most sensitive at 0.02 ppb, buds follow in sensitivity at 0.1 ppm, while stems are least sensitive at 20.0 ppm. IAA regulates pholem transport as higher IAA attracts more pholem flow. Auxins move only in one direction, i.e. from the tips down and from the roots towards the tip. Auxin concentration is diluted when it moves from the growing point downwards.
• GIBBERELLINS:
Gibberellins cause enlargement of cell walls, particularly internode cells and some fruit cells. They cause breaking of dormancy, move freely in the plant and are produced in the roots and new leaves.
• CYTOKININS:
Cytokinins are produced in the root tips and are carried upwards in the xylem tissue. They loose concentration as they move towards the leaves. Cytokinins effect cell division.
• ETHYLENE:
Ethylene is stimulated by Auxins and can cause "Auxin like" effects. Ethylene stimulates flowering and abscission of flowers, fruit and leaves. This hormone is produced in fleshy fruit and increases ripening. Ethylene is a gas and causes senescence. It is called the aging hormone.
• ABSCISIC ACID... ABA:
This hormone is a growth inhibitor and promotes senescence, bud dormancy and seed dormancy. It is produced in the leaves.Hormones are produced in some organs and move to other organs to change their characteristics. For instance in wheat early growth is dominated by Gibberellins, the middle stage by Cytokinins and the later stages by Auxins. There is growing evidence that hormone regulation in plants is controlled by a central mechanism. This is distribution of Calcium in the protoplasm.
• HORMONE INTERACTION:
• Stem Elongation:
Here Auxin + IAA is necessary, Gibberellins can interfere with this.
• Apical Dominance:
Whenever Auxins and IAA are produced in large quantities, stem growth is greater but bud growth is strongly inhibited. Further away from the growing tip the bud growth is weakly inhibited. When plants are pruned, new buds will form above the apex. Bud growth can be prevented by Ethylene, which is caused by too much Auxin causing Ethylene to be produced in cells. Cytokinins can release bud growth from the effects of Auxins + IAA.
• Root Initiation:
High Cytokinin/ Auxin rates develop shoot growth. It reduces the Auxin+ IAA effect. The above ratios inhibit shoot growth of roots towards the tip. When Cytokinins are lower back from the root tip, branch roots will grow. When Auxin rates get really high, adventitious roots will appear from the stem.
• Senescence and Abscission:
When flowers are fertilized they make Auxins which prevent abscission. Fruit abscission develops when Auxin is reduced in the flower. It may be that Auxins attack Cytokinins from the roots, which prevent abscission and senescence. Evidently ABA reduces Auxin in flowers or fruit. This would increase abscission.
• Dormancy:
Abscisic Acid (ABA) promotes dormancy in seeds and buds. Gibberellins and Ethylene break dormancy. It appears that IAA inhibits fruiting branches and bud break near the growing tip. Higher levels of Cytokinins apparently modify this. It appears that ABA effects bud break all over the plant and seems to be the main group of hormones, along with Ethylene, that cause premature dying.The hormone balance of the plant is responsible for dictating its response to environment factors. This is of prime importance and the major factor for maximum economic yield if response is adequate. Good nutrition is essential for the health of the plant but will fail to provide the desired results in case a plant is unable to use this nutrition. The size, shape and yield of a plant depends upon hormone balance. Fertilizer nutrients do effect this balance but the major factor is the climate. With changes in climate the hormone balance of the plant is altered. This is more in some varieties of plants and less in others. This is dictated by the genetics of that particular plant. It is possible to change the Genetic Expression of a plant so that it can quickly adjust to climate change. Thus it is not essential to change the basic Genetics of a plant, which is quite an expensive proposition. By modifying the genetic expression of a plant we can weather proof it and ensure that climate change has less impact upon yields. Since the last many years we in Pakistan are facing the problem of vagaries in weather that is causing a serious drop in yields. Thus it is important to introduce this alteration of genetic expression.
• METHOD:
For example if the soil remains dry after planting, the root will grow downwards. If the soil remains wet it will cause the roots to grow sideways. The genetic expression of root growth is determined within the first 15 days after germination. Its genetic expression does not change thereafter. Since we plant in wet conditions we ensure sideways development of the root system. In case of root development in the upper area of the soil the plant will be less drought resistant and easily uprooted. Deep penetration will make the plant drought resistant and well anchored. It is possible to treat seed with hormones and make it think that it is growing in dry soil no matter if the soil is actually wet. Our habit of introducing a plentiful supply of nitrogen along with the seed in the shape of urea is in fact harmful and wasteful. Nitrogen causes increase in root mass and does not change root direction. The same is true for growth enhancers and starter fertilizer.
• VEGETATIVE GROWTH PERIOD:
During this period a plant builds its roots system. Calcium and boron are the major nutrients that determine initial root length and lateral branching of major root hairs. These nutrients interact with hormones such as cytokinins; indobutyric acid and small amounts of IAA. To some extent nitrogen has an effect upon these hormones. A plant's disease resistance is determined by the hormones being produced in it's root system. The roots, as we have seen, are primarily developed mostly during the vegetative stage. Thus a plant's disease resistance is at its greatest during this stage. In case there is insufficient usable calcium in the soil, the cell walls of the roots will be weak and result in leaking. Soil borne disease vectors will use this leaking as a "Chemical Taxi (Chemitaxi)" to hitch a ride into the plant. Over abundant nitrogen might also cause rapid root deterioration. Secondly, plants become top heavy as more Auxins and Gibberellic Acid is produced at the growing points above ground. This causes rapid upward growth at the expense of root growth. The farmer is pleased with the apparent health of the plant but is disappointed with the yield. Top heavy plants are also susceptible to lodging and frost damage. It is important that we bear two points in mind, one is that nitrogen in sufficient quantities is essential to plant growth. Over abundance at a particular stage is however harmful. Secondly there must exist an adequate supply of available calcium and boron in the soil. Insoluble calcium is of no use to the plant. Pakistan's calcareous soils are not evidence of sufficient calcium as commonly believed. This is due to the fact that the calcium is inert and insoluble. Dilute Sulphuric, Hydrochloric or Phosphoric Acid can be used to solubilize the calcium in the soil. However, this is a temporary fix as the calcium is later converted to Calcium Sulfate. Calcium Carbonate is of no use to the plant. Calcium Sulfate is 200 times more soluble. However, Calcium Chloride and Calcium Nitrate are 2000 times more soluble. Calcium Chloride is readily available in the market and is required in lesser quantities then Gypsum. Moreover the double positive charge on the Calcium Ion repels the single charged Sodium Ion. Thus Sodium is not allowed to clog the root system and/ or burn delicate vegetable plants. Thus calcium in available form is introduced as well as removes the problem of Sodium. Over and above this Calcium Chloride also stabilizes Urea and keeps it in the Ammonium form. This material is a by product of the marble industry and has been used by the Khidmat Foundation with amazing results in 1998 at Daharki, District Ghothki, Sindh. Five acres of summer vegetables and one acre of experimental wheat were treated. These acres were subject to salinity to varying degrees. Vegetable germination was 98% and came to term. Wheat saw an increase of 800 Kg. However wheat was also treated with hormones and given split foliar applications of urea stabilized with Calcium Chloride.
F REPRODUCTIVE STAGE: This stage of growth triggers the most serious problems for the plant. The Carbohydrate flow is diverted from the roots towards growing points and reproductive tissue such as seed, storage tissue and fruit. Thus root growth decreases and less nutrients are absorbed and fewer hormones are produced. Other hormones are ow effectively in control of the plant such as Ethylene and Putrescine. These cause the following problems:• More disease problems.
• More physiological problems.
• More stress problems.
• More aborting of flowers and fruit.
• Premature ripening.
• Early death of plants.These all effect the hormone balance and cause early death of the plant which in turn effects yields. When yields are high the observation is that stalks and/ or stems are still green. This shows that the plant was still alive. If we can slow down the shift in Carbohydrate flow from the roots to the reproductive tissue, we can elongate the life of the plant. This will allow greater time for the grain to fill or fruit to develop, as the case may be. Thus the lessons learnt so far are that in the Vegetative stage we should help the roots to grow vigorously and in the Reproductive stage we must elongate the roots life. This is done by hormones. Every day that a plant's life is extended results in 4 % additional yield.
• MOVEMENT OF CARBOHYDRATES:
Carbohydrates and Proteins are produced in the leaves of the plant and then transferred to stalks, stems or branches. From here they are used by the vegetative growing points such as roots and shoots. In order to replenish the Carbohydrate supply the leaf must have adequate Potassium, Magnesium and ABA (hormone). If too much IAA (hormone) and Nitrates are present, this may not be possible. Research has revealed that nutrients and hormones can be manipulated in order to induce movement of Carbohydrates out of the leaves. The only way to reduce early dying is to ensure that stalks, stems and branches are full of Carbohydrates when the reproductive stage begins. This is hormone controlled.
• NEGATIVE GROWTH FACTORS (NGF):
Five major factors cause negative growth in plants, these are:
• ALLELOPATHY:
When seeds are planted in close proximity, the roots of one plant cause accumulation of toxins in the neighboring plant. This results in reduction of fruitfulness of each plant. Immunity to this toxin can be induced, this results in shorter plants, stems or stalks with larger diameters; more lateral branching or suckers or tillers; more fruiting points and more fruit; much longer root systems and no tap root. These results were practically observed by the Khidmat Foundation in wheat crop of 2000 in Mung village of Khanpur Tehsil, District Haripur, Hazara of N.W.F.P.
• SOIL BORNE DISEASES:
Where root growth is slower, soil borne diseases are more severe. Low levels of Calcium, as earlier pointed out, cause this and result in Chemitaxi route into the plant for these diseases. Thus there is a requirement of avoiding this and also healing the plant if it is effected.
• FOLIAR DISEASES:
These are more severe during the reproductive stage. This is caused by Ethylene and Putrescine accumulation in the plant. The plant can fight these with hormones produced in the roots and Calcium stored in the Cytosol.
• NEMATODES:
Nematodes attack plant roots and introduce toxins into the plant. These can be controlled by hormones.
• STRESS:
Hot and dry climate conditions cause stress in the plant. This causes:
• Disease.
• Early dying.
• Abortion of fruit or seed.
• Premature ripening.
• Poor storage or shelf life.
• HORMONE CONTROL:
All of the above negative growth factors are hormone related and are not related to nutrients. Nutrients can effect the hormones, e.g. Calcium has a positive effect and Nitrogen has a negative effect. Hormones can speed up a plant's metabolism and result in more efficient use of chemical fertilizers. Thus with the addition of hormones, less fertilizers need to be used. Secondly, with a more complete "Diet" in so far as nutrients are concerned, we can achieve much better results. Hormone treatment of seed and plants, therefore is perhaps even more important than hybrid seed development. The full genetic potential of existing seed is achieved and yields are vastly improved. It is important to note that the cutting down of Macro Nutrients, as presently being used, will result in savings that offset the expense incurred in Hormone Treatment and Micro Nutrient Supply. Secondly, improved yields will more than compensate for the expense and efforts expended. Thirdly, Micro Nutrients and Hormones are naturally occurring elements and compounds. Thus the use of these elements and compounds are environmentally safe and highly desirable. It is important to note that hormone use in plants is nowise similar to indiscriminate hormones use in Poultry Production. The hormones suggested for use with plants are only those that would be normally produced by the plant itself if it were healthy or were to receive a balanced "Diet". These hormone Products should be registered with the EPA and must be natural.
5. PEST CONTROL WITH NUTRIENTS:
• SUCKING INSECTS: APHIDS; MITES; WHITE FLY; THRIPS; OTHERS:
Sucking insects feed upon amines and amino acids in order to form their own proteins. Plant proteins are of no use to these insects. Since the insects life cycle is short it needs massive quantities of proteins in order to lay eggs. Sucking insects usually attack and feed upon new leaves. New leaves have only pholem and no xylem tissue. As such organic compounds are not being manufactured in the new leaves, they rely upon the compounds made in old leaves. Plant sugar can give these insects diarrhea, causing sticky plants. Amines and amino acids move freely in pholem tissue. They are low on Calcium, Boron and other nutrients as they are not mobile or only slowly mobile in new tissue. When sucking insects destroy new leaves or vector in a virus the hormone balance of the plant is disrupted. This causes a major change in the older leaves. Proteins hydrolyze to amines and amino acids and become available to the sucking insects as food. Nitrogen also causes higher amines and amino acid levels in the plant. The more the nitrogen used the greater the threat. Zinc will lower the level of amines and amino acids in the new leaves. Thus, during critical periods, a foliar application of Zinc will treat the leaves. Repeat applications are required every 14 days.
6. CONCLUSION:
The foregoing account is intended to introduce the concepts of Micro Nutrients and Hormones as essential aids for increasing yields. The severity of the problem is increasing day by day and soon a stage will be reached wherein the use of these elements and compounds will be imperative. It must be borne in mind that many other factors effect a plant's yield. Complete and detailed Management System needs to be worked out. We at the Khidmat Foundation are trying to do just this, for the last many years. Our results on ground have been amazing. This is true for small as well as large plantations. However, we have received scant notice.