Crop Production Technology for Bt Cotton Varieties in Pakistan

Cotton is the major fiber and non-grain crop in Pakistan and it contribution is 1.6% in GDP of Pakistan. Bt cotton varieties have been developed in the last decade which are high yielding and insect resistant.
The Bt cotton production technology as per the government agriculture department in Punjab is given as under.

SEEDBED PREPARATION

Seedbed preparation is the most important phase for the successful yield from a land. The soil selected for the cultivation for cotton should be well prepared before sowing the seed. The soil should be porous in nature and allow root penetration for normal plant stand.
The residues of previous crops should be mixed well in the soil with some rotavator, disc plough or some other plough. Seedbed should be prepared through deep ploughing followed by laser land levelling. 
The soil should have good water holding capacity and there should be no hard pan in the subsoil layer. In case of green manure crops, the crop should be ploughed into the soil 30 days prior to seed sowing of cotton and the field should be irrigated after 10 days of ploughing. To aid the decomposition process, half bag of urea should be mixed during ploughing.

Levelled field

SEED SOWING

The time of sowing is very critical for a healthy crop stand. It is usual practice among farmers to sow cotton after the harvest of vegetables or when the field is fallow or early sowing is done to avoid virus attack. The important thing is to avoid the low chilling temperatures because cotton favors hot summer temperature with no frost. In case of temperatures as low as 15^oC  , there are possibilities of fungal attack which can destroy the crop at seedling stage. So the minimum temperatures at the time of sowing should not be less than 20^oC. The selection of the variety, Bt or other should be made depending upon the previous years cropping history.

NOTE: At the time of sowing the field with Bt cotton varieties at least 15-20% traditional cotton varieties should also be sown along the Bt cotton varieties so that the pests does not break the resistance level of Bt varieties. In case of two varieties sown together, spray pesticides at when the pests' population reach economic threshold level.

TIME OF SOWING 

The time of sowing for different Bt cotton varieties is varying from 15 April to 15 May.

SEED-RATE

The seed rate for a particular variety should be according to the package label of seed. Healthy, certified and treated seeds should be obtained from trusted sources.

METHOD OF SOWING

1. Seed Drill

Seed Drill

Seed drill should be used. With the drill, the recommended row to row distance is 2-2.5ft and plant to plant distance is 12-15 inches. The seed should be drilled to a depth of 2.5 inches in ground. After the first irrigation of field, the alternate seed rows are earthen down with soil (/make furrows and ridges). This practice helps to reduce water consumption 30-40%.  Other benefits include, good management of weeds, cotton plants of same height, no. of plants per acre is good, and this practice also facilitates other cultural practices in the field like spraying pesticides. Second irrigation should be given 3-4 days after first irrigation of field. 

 2. Sowing by Hand (????)

For sowing by hands, the field should be made into furrow and ridges, then irrigate the 6-7 inches deep furrows. After irrigating the field, sown the seeds by hand at a height of 1 inch from the standing water level of the field. If gaps are left in the field, they should be filled with next irrigation. The furrow method of sowing has same benefits as mentioned with the seed drill method. 

Sowing by hands is helpful in reducing the seed used for sowing. The number of plants per acre are good and the practices like spraying and weeding can be done with rain or irrigation water in the field. Proper crop growth is achieved.

FILLING THE GAPS

The seeds germinate within 4-5 days of sowing in wattar condition. If gaps are seen in the field, then make hole in the soil for seed and put 5-6hr water soaked seed in it; cover it with moist soil. 

In case of seed drill, a long row or portion is not sown with seeds, then a single drill tube can be used to drill the row again. 

No time should be wasted in filling of gaps in the field because, once the wattar condition is gone, the seeds will not germinate properly which will result in lesser no. of plants per acre. 

Crop at 2 weeks stage

THINNING

Thinning in cotton field is very important. The number of plant should be according to the recommended count. This is helpful for proper management of pests. Thinning should be completed within 20-25 days of sowing and it should be done before irrigation. In case of viral attack, thinning should be done after irrigation so that the diseased plants can be rouged. 

WEEDS OF COTTON

Cynodon dactylon

Cotton suffers sever attack from the serious attack of pests and virus. These viruses and pests are firstly present on the weeds present along the banks of fields, water channels and roads. The management of these weeds is important w.r.t control of pests and virus on cotton. The common weeds of cotton are Itsit (Trianthema portulacastrum), Khabbal (Cynodon dactylon), Madhana ghass (Dactyloctenum aegyptium), Jangli cholai (Amaranthus viridis), Kulfa (Portulaca oleracea), tandla (Digera arvensis), hazardani (Euphobia granulata). These weeds not only compete with the crop plants but also serve as secondary habitat for cotton pests and viruses. These weeds should be eradicated by hoeing in wattar condition or hoeing in dry conditions both are equally beneficial. 

IRRIGATION

Fields should be irrigated according to the soil fertility, method of sowing, stage of crop and water requirements of the crop. The signs of water deficiency are first visible on the upper bank of the field, which include bluish appearance of leaves, the internode distance decreases in the upper branches of the main stem, white flowers at the top, reddening of the upper part of stem and roughness of leaves at the top. The field should be irrigated before these signs are visible to avoid loss in  production. 

In case of row cropping, first irrigation is given after 30-35 days of sowing and latter after a gap of 10-12 days. And in case cotton-wheat cropping system, last irrigation should be given till 10 october.

In case of furrow beds, first irrigation is at 2-4 days of seed sowing, second after 6-9 days and subsequent irrigation should be given at 15 days interval.

Irrigation scheduling should can be changed according to the prevailing weather conditions.

FERTILIZER APPLICATION - TIME AND METHOD

Phosphorus, zinc, boron and potash should be completely given at the time of sowing.

For Early sowing,

Nitrogen should be applied in 6 splits. First, with sowing, 2nd after 30-35 days of sowing and later nitrogen dose should be given at the gap an irrigation each.

For sowing in May, 

Split nitrogen in 4 doses.

First dose with sowing, 2nd after 30-35 days of sowing, 3rd at the formation of floral buds, and 4th at boll formation.

Phosphatic fertilizer should be used mixed with farm yard manure (FYM). 

Green manuring should be done to increase the organic matter contents of the field which will be helpful to increase effectiveness of the fertilizer application. It has been found that fertilizer application during evening is more beneficial.

In case of viral attack, half bag of urea should be given with initial four irrigations. 

ZINC AND BORON DEFICIENCY OF COTTON

Zinc and boron can also be sprayed in the field if symptoms of deficiency are visible. In this case, spraying should be done at about 45, 60 and 90th day of seed sowing. The formulation can be easily made as follows;

Boric acid            - 300 gram

Zinc sulfate (33%) - 250 gram

Sodium bicarbonate (ordinary caustic soda) - 50 gram

Water                  - 100 litres

Mix them in a tank and spray in the field. Pesticides should not be mixed in this solution for spraying. Spray the field in the morning or evening only because spraying in mid day can cause burning of leaves.

TOPPING

It refers to the removal of the tips of the main stem, alone or together with the tips of the main branches, a few weeks before the bolls begin to open. This practice, also called pruning is done to ensure a redistribution of the nutritive substance in the plant. It reduces shedding of buds and bolls, improves the light reaching down, accelerates the opening of the bolls, reduces lodging and increase yields.

PICKING/ HARVESTING

Manual Cotton Picking in Pakistan

Cotton bolls in the same fields open at different times. There is a gap of at least 2 months before first and last boll opens. Thus picking should also be done in accordance, at least 2-3 pickings are required to completely harvest the crop. Picking of cotton usually start in September and continues till December or even January. Picking can be both manual or mechanized. The lint from the first and last pickings should be kept separate because the fibre from the last picking is of comparatively low quality w.r.t first one or two pickings. 

Cotton Picker Machine