What is BT cotton Hybrid?

A BT cotton hybrid carries a gene incorporated in it from another species, which gives resistance against bollworm. BT cotton hybrid and a normal hybrid with same parents differ only for a single gene i.e. BT gene. All the current BT cotton hybrids do not rejuvenate quickly (re-activation of plants for yields) after completing its one phase of production. It is more so in the case of BT Cotton Hybrids as they are early and semi-determinate types. Most of the BT cotton hybrids have become earlier in bearing by 20 days when compared to the counterparts.

Need for Rejuvenation of cotton hybrids:

The new generation BT Cotton Hybrids need additional importance in Nutrition Management as they are

A. Genetic Nature:

• Determinate or Semi-determinate types
• Prolific Bearers
• Early maturing types

Due to early and semi-determinate habit of these BT Cotton Hybrids, the rate of growth and rejuvenation capacity of the plant after first flush of flowering is slow. When there is need to have more nutritional requirement after first bearing, the plant could not cope up with the nutritional requirements and necessitates additional nutrition

B. For Higher Yields:

• To explore the potential yield and to achieving higher yields, additional nutrition through different systems (Including Foliar feeding) is required over and above the normal fertilizer recommendation.

C. Soil Problems:

• Generally the Cotton Growing soils in Telangana are light textured with low or poor nutritional status
• Cotton is also being grown in Problematic soils

The poor and problematic soils require additional nutrition

D. Contingencies:

Crop management also requires additional nutrition during Stress Situations that arise due to

• Drought situation.
• Excess Moisture condition during heavy and continuous rains

E. Crop Management Practices :

• Imbalance plant nutrition
• Untimely fertilizers application
• Improper method of fertilizer application
• Irrigated conditions
• Poor field conditions at the time of fertilizer application

Also necessitates higher doses of nutrients

Balanced nutrition and additional care through higher doses of fertilizers are required

• To push the vegetative growth during stress or poor nutrition availability situations
• To reduce the resting period after first flush of heavy bearing by rejuvenation
• To prevent square drop
• To improve boll setting
• To improve and enhance boll development
• To improve boll weight
• To improve lint quality and
• To improve pest and disease tolerance

All the above situations necessitates the need for providing additional nutrition not only through soil but also through foliar. Foliar feeding is one of the most efficient ways of supplying essential nutrients to a growing crop plant. It provides a method of delivering fundamental nutrients at key growth stages when the plant is at peak nutrient requirements and could not be made available through normal stream of root system from soil.

When plant tissue K is in short supply on high yielding hybrid cotton fields, the team of Potassium (K), Nitrogen (N) and Boron (B) can help to improve plant and boll growth. Research has shown that common foliar K sources perform best when solution pH is buffered to levels between 4 and 6. Polyfeed and Multi-K + Boron spray will take care of the spray solution buffer requirements (pH), while meeting the nutritional requirements.

SOLUTIONS WITH FOLIAR FEEDING:

1. For Vegetative growth and Square formation :

These hybrids can be improved in vegetative growth during stress situations and also during rest period after good flush of heavy flowering and boll set (Resting period can be reduced) by providing additional nutrients through foliar feeding. Polyfeed that contains all the major nutrients of N, P & K in addition to all the micronutrients in a balanced form will improve the vegetative growth and square formation in a rapid and efficient manner. Hence Polyfeed foliar spry @ 1.5 to 2 % (15 to 20 grams / liter of water) at the above stress and rest periods at 7 to 10 days intervals based on the crop situation will be benificial.

2. For improving boll set and development:

To prevent square drop, improving boll setting, enhance boll development & boll weight, for improving lint quality and pest and disease tolerance, Potassium (K) application in association with Nitrogen & Boron had proved efficient. Multi - K @ 1.5 to 2 % (15 to 20 grams / liter of water) with Boron @ 0.1 % (One grams / liter of water) as foliar spray has to be given during boll setting and boll development phases at 7 to 10 days intervals based on the crop situation.

3. For Quick Rejuvenation:

The BT Cotton Hybrids can be quickly rejuvenated for second and third phase of vegetative flush, square formation and boll development for getting one or more cycles of yield by foliar application of Polyfeed and Multi-K. Two to three sprays of Polyfeed @ 1.5 to 2 % (15 to 20 grams / liter of water) at 7 to 10 days intervals after the majority of bolls develop fully for initiating vegetative growth. Multi - K @ 1.5 to 2 % (15 to 20 grams / liter of water) with Boron @ 0.1 % (One grams / liter of water) two to three sprays at 7 to 10 days intervals at flowering will enhance boll set and development

4. The general spray schedule with foliar fertilizers is given below for a normal crop:

5. Contingency sprays :

Under poor or problematic soil conditions, stress conditions (Drought and Excess moisture) and also to rejuvenate the crop after severe pest or disease attack, timely sprays with Polyfeed and Multi-K + Boron at the doses indicated above will help in compensating the yield losses.

SOIL FERTILIZER RECOMMENDATIONS IN TELANGANA REGION DOSE AND CRITICAL STAGES OF APPLICATION

For soils with average fertility and with a targeted yield of 7 to 10 Q of Kappas per acre (Average) and assuming all the scientific recommendations in fertilizer application and crop management practices are adopted.

Apply entire P2O5 at land preparation or at sowing in the form of Single Super Phosphate. Calcium Nitrate application just after completion of germination will improve root growth, branching and yields. Nitrogen and Potash are given in three split doses at 30, 60 and 90 DAS as given below.

Schedule of fertilizers: (kg/ha)

1. Basal (before sowing )
SSP - 375 kg
Zinc Sulphate - 50 kg
Farm yard manure - 10-12 tons

Zinc Sulphate may be applied separately and not along with SSP

2. 1^st Top Dressing (10 to 15 Days after sowing)
Double OX Calcium Nitrate Field Grade -25 - 35 kg

3. 2^nd Top Dressing (30 Days after sowing)
Nagarjuna Urea -90 kg
MOP -35 kg

4. 3^rd Top Dressing (60 days after sowing )
Nagarjuna Urea -90 kg
MOP -35 kg

5. 4^th Top Dressing (90 days after sowing )
Nagarjuna Urea -90 kg
MOP -35 kg

Tips:

• Phosphorous in the form of SSP as basal application as furrow placement will not be lost and will improve the soil condition. The Sulphur content in SSP will be beneficial in improving the cotton seed oil content.
• Efficiency of nitrogen increases when the required phosphorous is made available
• Application of Potassium increases the fiber maturity, micronaire value and fiber uniformity
• Uptake of nutrients increases in case of balanced nutrient application

TECHNOLOGY BASE:

Deficiency Symptoms in cotton:

Following signs of Potassium deficiency appear in crop:

• Reduced ground cover by the crop canopy (lower leaf area index)
• Increased leaf temperature when soil moisture seems adequate (leaves warm to the touch)
• Increased incidence of Verticillium wilt
• Premature cutout or plant termination
• Reduction in yield
• Reduced lint turnout
• Loss in fiber quality
• Low fiber micronaire
• Decreased fiber maturity
• Reduced fiber strength

Potassium (K) is an extremely important nutrient in cotton production

Bolls are major sinks for K. Thus, the need for K increases dramatically during early boll set. About 70 percent of uptake occurs after first bloom, and uptake peaks at about 1-1.5 kg/Ac/day. Potassium deficiency may be expressed as a full season deficiency, or it may not appear until late season during the period of greatest demand. When a heavy boll load is set, the demand for K may exceed the ability of the soil and leaves to supply this nutrient, results in deficiency.

As cotton boll numbers increase and bolls enlarge, there is a tremendous translocation demand on potassium (K) in the leaves adjacent to each boll . If adequate K is not stored in each leaf, then K deficiency will develop. If drought or restricted root activity during reproductive growth hampers K nutrition, K deficiencies can rapidly develop.

If the cotton stop yielding early in the season, it means less total seed cotton to be harvested and in some cases lower fiber quality. There can be several causes for this. One is a shortage of potassium (K) during late season boll development. The role of K is to help keep leaves actively producing sugars (photosynthesis) and then helping to move those sugars to the developing bolls.

During the boll development Potash is not available to plants due to its deficiency in soil or due to non- availability of nutrients in soil due to their fixation. This result in the sink source situation on plant, forcing the plant to allow development of the parts or bolls up to the extent only which it can supply the nutrient. Hence, all seeds in boll do not develop due to lack of nutrition. At harvest time, bolls may be smaller and may not open properly. Low K can reduce fiber length and it can also affect seeds and other fiber quality traits. This dot like black aborted seeds in lint are called Motes (aborted seed embryo). It has two effects on yields of cotton:

• Development of few seeds in a boll (embryo abortion of seeds i.e. Motes formation)
• Poor lint quality due to presence of motes, poor lint strength, decreased fiber maturity and hence, purchasers give lesser price for this cotton.

Nutrient Recommendations:

To reduce the risk of nutritional problem, apply needed fertilizer pre-plant and/or side-dressed according to crop need by growth stage. Then, check fields often for unexpected nutrient shortages. Field inspections and plant analysis can help to identify mid-season nutrition shortages.

These nutrient problems can be prevented or reduced, and economic returns can be improved, by aggressive Potash fertilization during crop growth. If plants are suspected of being short of K before blooming, it may be possible to provide some correction with top dressing of K fertilizer. However, care should be taken to assure that leaves are dry when top-dressing, to avoid fertilizer salt injury. Response to top-dressed K application just before reproductive growth also depends on adequate moisture from irrigation or rain to help dissolve the K and allow it to move into the soil for root uptake. The best way to K application at these critical stages is Foliar feeding with Multi-K

On light soils, where potassium may leach, potash applications should probably be deferred as basal dose and my have to plan for top dressing and as foliar feeding with Multi-K. Mid-season foliar K fertilization (Multi-K) is often effective in correcting late season deficiencies. Site-specific potassium management will improve cotton yields and quality.

When plant tissue K is in short supply on high yielding hybrid cotton fields, the team of K, nitrogen (N) and boron (B) can help to improve plant and boll growth. Research has shown that common foliar K sources perform best when solution pH is buffered to levels between 4 and 6. Multi-K spray with Boron will take care of the buffer requirements.

ROLE OF CALCIUM:

• Stimulates root and leaf development.
• Helps to reduce Nitrate nitrogen in the plant
• Activate enzyme systems in the plant
• Neutralize organic acids in the plant
• Nut development in pea nuts
• Reduces toxicity of Al, Fe and Mn in acid soils
• Increases microbial activity
• Required in large quantities for N fixing bacteria.
• Increases molybdenum availability and uptake of other nutrients.

DIFICIENCY SYMPTOMS OF CALCIUM:

• Common symptom is poor root growth. Roots often turn black and rot.
• Ca does not translocate in the plant and hence deficiencies cause gelatinous leaf tips and growing points, since new tissues need calcium pectate for cell wall formation.
• Ca deficiency is common in pea nuts and vegetables.

Extent of deficiency of Calcium:

• Soils containing less than 1.5 me exchangeable Ca per 100 gms of soil or less than 25% of CEC occupied by Ca are considered Ca deficient
• Ca deficiency is seen in acidic soils which occupy 1/3 of soils of India

CALCIUM IN SOIL:

• Ca content in soil ranges from 0.1% to 25%
• Calcareous soils have high levels of Ca
• Organic soils contain very little Ca and therefore have less pH
• Clay soils contain more Ca than sandy soils
• Ca is most dominant cation in soil
• 70% of exchangeable complex contain Ca.
• Ca also is present in soil solution

CALCIUM SOURCES:

Calcium is available in CaO form in

CALCIUM NITRATE:

Calcium Nitrate provides Nitrate nitrogen which is the form preferred by most plants and when the nitrogen is taken up the basic portion, calcium, remains and combines with the insoluble acid clay, thus neutralizing some of its acid and reducing its power to liberate soluble acids.

For fertigation mixing calcium nitrate with phosphorus materials can result in insoluble calcium phosphate. In addition, calcium sulfate can precipitate when calcium nitrate is mixed with magnesium sulfate. To avoid these problems, one stock solution is prepared with calcium nitrate and iron chelate.

Calcium Nitrate can be employed as readily available fertilizers special for acid soil, as quick-effect calcium replenishing agent for plant and as high quality cultivation fertilizer. Therefore, it is entitled as "Best Calcium for Plant "

OBJECTIVE OF FOLIAR FERTILIZATION:

To stimulate the production process of high yielding crops by application at deficit / peak / critical requirements

To promote crop growth under adverse conditions (Stress)

Mechanism of Foliar Absorption:

• Assumed that nutrients enter the leaf only via the stomata.
• The ectodiesmata, microscopic openings in the cell walls and cuticle which extends to the outer surface of the leaf also absorb nutrient solutions
• The cuticle itself swell on absorbing water and also becomes permeable to dissolved substances tp some extent.
• Since the stomata are mostly situated on the underside of the leaf, for a rapid and complete up take of foliar fertilizer it is necessary to spray both the underside of the leaf and the upper surface as evenly as possible.

Ideal Period for Foliar Spray:

• The cuticle is more permeable when swollen.
• Foliar Fertilization should be carried out at times when the relative humidity of the air is high i.e. in the early hours of the morning and in the evening, not during the hot hours of the day..
• Another advantage is, the spray deposit evaporates more slowly and so there is less danger to the leaves being burned by bright sunlight.
• The high humidity in the evenings and during the nigh causes the nutrients from dried spray deposits to be dissolved so that they can enter the leaf.

Rate of Uptake of Nutrients by Plant Leaves:

• The rate of uptake of most nutrients, including potassium is taken up in the space of few hours or up to one day.
• An exception to this is phosphate, which is taken up relatively slowly. Never the less the uptake of phosphate via the leaf is considerably better than the uptake via the roots.

Relationship between Leaf Nutrient Content and Plant Growth:

There is positive correlation between the nutrient content of the leaf and the yield.

Optimum yields can only be achieved when the nutrient level is above the critical level.

An excess of another cannot compromise for a deficiency of one nutrient, on the contrary it shall limit the yield on lower side.

When fertilizer is applied via soil the nutrients must first be taken up by roots and are then transported through the stem and petioles to the leaves. This process takes time and the efficiency of the fertilizer is reduced by nutrients being bound up in the soil and older parts of the plant.

What is Foliar Application of Soluble Fertilizers?

• This refers to spraying of growing plants with suitable fertilizers solutions these solutions may be prepared in low concentration to supply any one-plant nutrient or a combination of nutrients.
• It has been established that all plant nutrients are absorbed through the leaves of plants and absorption is remarkable rapid for some nutrients.

Why Foliar Application of Fertilizers?

Foliar feeding is one of the most efficient ways of supplying essential nutrients to a growing crop. It provides a method of delivering fundamental nutrients at key growth stages when the plant can utilize them the most.

• The nutrients are taken into the foliage and transported to all parts of the plant in a short period of time. Soil-applied nutrients depend upon moisture to dissolve the fertilizer, and much of those nutrients are tied up in the soil.
• A nutrient balance can be maintained by foliar feeding, which may not occur with soil uptake. By foliar feeding the plant, the nutrients are available to the growing crop at key growth stages when the plant needs them the most.
• Research has shown that foliar fed nutrients will move upward and downward from the leaves to which they were applied. This includes the top leaves to the most distant roots with concentration in the most critical parts of the plant.
• In the case of foliar application of fertilizers, the nutrients are supplied directly to where they are required. For this reason nutrients supply by this method is considerably more effective than soil fertilization.

Can Foliar Fertilization be a substitute for Soil Application:

It is theoretically possible to feed a plant completely via, the leaves. In practice, however so many sprays would be required that the process would be rendered uneconomical.

• The best use for foliar application is to cover nutrient requirements during periods of intensive growth and equal out short-term discrepancies between the nutrient requirement of the plant and supply from the soil. Such discrepancies may occur when the daily nutrient needs of the crop exceed the ability of the soil to supply it. A timely application of small amount of foliar can equalize the discrepancy between the supply and demand and enable the plants to achieve its full yield potential.
• In cases of stress, such as water logging or drought, high & low temperatures, disease etc. the uptake of nutrients via the roots may be restricted. To counteract this, nutrients may be supplied to the plant via leaves for the duration of the stress period..
• If a spray is applied to control a pest or disease, then the addition of foliar fertilizer along with pesticide helps the plant to recover from the damage more quickly (Compatibility may have to be checked).
• An additional advantage of foliar fertilization is, it supplies nutrients directly to where they are most required and where an increase in the nutrient concentration is directly translated into an increase in yield.. In most crops it is the younger and upper parts of the plant which are particularly responsible for yield development.

Foliar Fertilizers are not a substitute for soil fertilization but an effective additional means of supplying sudden demands.

Foliar application does not result in a great saving (Cost), but it may be favored under following conditions:

• When visual symptoms of nutrient deficiencies observed during early stages of deficiency
• Unfavorable physical and chemical conditions of soil reduce fertilizer use efficiency
• During flooding and drought conditions where in soil application could not be done due to excess or for want of moisture, foliar application of soluble fertilizers is taken up.
• Under very high and uncontrollable weed population conditions, foliar application of soluble fertilizers is only option.
• Foliar soluble fertilizer application can be made spraying plants with plant protection measures.

Certain difficulties in associated with foliar application of nutrients as detailed below:

• Marginal leaf burn or scorching may occur if higher doses of soluble fertilizer solution are used.
• As solutions of low concentrations (usually three to six percent) are to be used only a small quantities of nutrients can be applied in a single day.
• Several applications are needed for moderate to high fertilizer rates.

Foliar spraying of fertilizers is costly compared to soil application unless combined with other spraying operations taken up for insect or disease control.

BT COTTON HYBRIDS OFFICIALLY PERMITTED FOR MARKETING BY GOVERNMENT OF INDIA IN AP FROM FOLLOWING COMPANIES:

1. Mahyco Monsanto Hybrids (Permitted during last two years and now under review)
- MECH-162 - Normal leaf hybrid
- MECH-12 - Okra leaf type hybrid
- MECH-184 - Okra leaf type hybrid
All above hybrids have maturity period of 140 days and been allowed to be marketed in Southern India except AP.

2. Rassi Seed Company, Attur
RCH -2 - Normal leaf hybrid
RCH-20 - Normal leaf hybrid
This hybrid has a maturity period of 160 days.

3 Nuziveedu Seeds Limited Hyderabad :
- NCS-145 (bunny)
- NCS-207 (Mallika)
Both are 160-day hybrids There are few other hybrids which are in pipeline for release to cultivators and may be given approvals by Government of India for marketing from 2006 Kharif season.