Seed material preparation

• Gin damaged seeds may exceed 10 percent and such seed will produce abnormal seedlings.
• Seeds with a germinative ability or less than 80 percent should not be used.
• The content of free fatty acids in the seeds may vary from 0.5 to 8 percent, the higher the fatty acid content of the seed is the lower will be the germination rate. Hence, seeds that have a fatty-acid content in excess of 0.75 percent should not be used for sowing.
• The rapidity of germination is also an important characteristic of the seed. It is considered satisfactory if two-thirds of the seeds germinate in one-third of the time that is considered necessary for the completion of germination.
• A number of cotton diseases are seed-borne. Before selection and sowing of seed ensure that the seed is disease-free.

Delinting

Fuzz makes the seeds cling together, thus hampering their free passage through the bowls and tubes of the indigenous seed drill. To remove fuzz, rub the seed with mud, or a mixture of earth (or ash) and fresh cow-dung.

• The seed is treated with strong commercial sulphuric acid, which burns the fuzz, or with chloride of zinc, which dissolves the short fibre.
• In the case of sulphuric acid treatment, the seeds are soaked for two minutes in it, then taken out and washed in running water to remove the chemical.
• In the case of chloride of zinc treatment, the seeds are immersed in its solution for ten to fifteen minutes and then washed.
• The chemical treatments not only remove the fuzz, but they are also said to improve the germinating capacity of the seed, hasten germination and make for easier handling of seed.
• However, these processes are not only costly but also have to be used with caution to avoid injury to the seed.
• They are therefore not recommended.

Seed soaking

• Soaking of desi cotton seed for two or three hours and that of fuzzy American varieties for four to six hours in water before treatment with mud and cow - dung, hastens germination and there by gives a better start to young seedlings and also ensure a more uniform stand of plants.
• The soaking of seed before sowing is a common practice in many parts of the country but where it is not so, it should be advocated for both irrigated and rainfed cottons. Insect-damaged and immature seed floating on the surface of water is removed and discarded.
• The benefits are more pronounced in the case of American varieties and the re-sowing of gaps in a rainfed crops.

Seed Treatment

Seeds required seed treatment before planting. Depending on the requirement one or more of the following seed treatments may be undertaken. Chemical seed treatment Bacterial inoculum

Chemical treatment

• Against seed born diseases.
• Soak the acid delinted seed in 2 grams of carbendazim or 3 grams of mancozeb dissolved in 1 litre of water.

Slurry treatment

• Captan at 2 grams per kg of delinted seed with 5 ml of water per kg of seed.

Bacterial inoculum

Azotobacter

• A free living heterotropic nitrogen fixing bacteria - Inoculate seed with appropriate strain of bacteria.
• Significant inoculant response at different places range from 34 to 247 kg N/ha.

Azospirillum

• An associative micro aerophylic Nitrogen fixer. It is possible to reduce nitrogen requirement 25-30% by seed inoculation.

Mycorhizae : Vascular Arbuscular Mycorhizae (VAM)

• VAM has important effects on phosphorus uptake by plants and availability of other nutrients like Zn, Cu, K,S, Al, Fe etc., Further VAM inoculation improves water relations in plants - Reduces fertilizer requirement by 25-30%.

Phosphatic Bio-fertilizer

• Phosphatic solubilising organisms such as VAM, Aspargillius, Awamori, Penicillium digetatum can grow with insoluble phosphatic sources and convert them into soluble forms, to make them availability to crop plants.

Note:

• Bacterial cultures can be obtained from Bio-fertilizers scheme ANGRAU Amaravathi or UAS, Bangalore or Department of Micro Biology IARI, New Delhi.

Plant Stand

• The optimum number of plants per unit area, and the distance between and within the rows depend on the inherent vegetative habit of a variety and conditions of soil fertility, soil moisture and cultural practices. For instance, the optimum number of plants per unit area in the case of a highly branched monopodial variety is much less than that in the case of a non - branching, sympodial type.
• Similarly, under conditions of good plant growth, such as, greater fertility of the soil, availability of irrigation facilities and early sowing, the number of plants per unit area (particularly of varieties having tall, vigorously branching plants) has of necessity, to be smaller than on relatively poor soil, or under late sowing and un-irrigated conditions in which the plants do not make a vigorous growth and the per plant yield is relatively low.
• In case of non - branching varieties, on the other hand, close spacing gives the best results even on rich soils.
• The optimum number of plants under different conditions varies widely and has to be secured by judicious variations of spacing and seed rate.
• In working out proper seed rate for a variety for a given set of environmental or cultural conditions, due allowance has to be made for the spacing adopted, the seed size, the germination capacity of the seed and the mortality of the plants caused by diseases, insect pests, vagaries of the season and physiological disorders.
• In the case of American cottons the relative fuzziness of the seed has also to be taken into account. However, it may be stated, that in actual practice, most of the cotton growers do not adjust the seed rate to the optimum number of plants suitable heavy seed rate to provide against failure of germination and mortality or young seedlings due to pest or disease or other natural calamities.
• A large number of seeds is also believed to help the emergence of seedlings through surface crust.
• Only the intelligent farmers who make due allowance for these factors and adopt a wider spacing in the case of more fertile soils, and closer spacing when the crop is sown rather late in the season or is grown on rather poor soil.
• Late sown crops and those grown on less fertile soils have to make up the deficiency of yield by a greater number of plants per unit area.
• In intercropping, the seed rate for cotton is not materially reduced if the rows of the subsidiary crop are placed at relatively long intervals.

Time of sowing

• Early sowing of cotton is important for a number of reasons:
• It makes possible the most efficient use of precipitation, whether stored in the soil or occurring during cotton growth.
• Flowering and boll formation (first flush particularly) occur before the month of September usually a wettest month.
• The cotton matures before the onset of cold temperatures, detrimental to boll bursting and the boll maturation period becomes progressively longer.
• Delayed sowing results in delayed flowering and this reduced flower and boll number. Boll size is unaffected.
• Fibre characteristics are only slightly influenced by delayed sowing.

• Crop is usually sown in lines with the help of bullock drawn seed drill to facilitate periodical harrowings.
• In case of hybrids/high yielding varieties/cotton grown in heavy soils it is preferred to sow the seed by dibbling.
• Under conditions of intensive cultivation, the dibbling of seed produces very good results by securing a uniform stand of properly spaced plants.
• This should be recommended particularly in tracts in which the sowing of the crop is not necessarily to be completed in one or two days but can be spread over a longer period.
• Dibbling also produces good stand of plants under conditions of different soil management.
• Seeds are dibbled on the top of ridge at a depth of 25-30 mm. Seeds sown to greater depths may fail to emerge.
• Seeds can be sown on a pre-soaked ridge or on dry ridges, which are soaked later by allowing irrigation water in furrows.
• Ridge sowing ensures better aeration and regulated water supply to the developing seeds.
• Sowing on ridge results deeper roots and better root system.

Cotton is very sensitive to an excessive sowing depth and should not go beyond 5 - 6 cm.

Death of a few plants, whatever the cause, is ignored or considered only the natural way of reducing over crowding. Such natural thinning affords to the remaining plants a chance for better growth, particularly If the variety cultivated has a good branching habit.

• The smaller gaps are covered up by more vigorous growth of plants and the crop yield does not suffer. In some cases, it may actually benefit. Observations showed re-sowing of gaps aggregating upto 20 percent of the stand did not increase the yield. Patches of this degree can be safely ignored; particularly if the variety is a monopodial type and the optimum sowing period is almost passed.
• It has been observed that resowing rather late, say 4 - 5 weeks after the original seedling, is not of much benefit.
• The plants from such late sowings do not make good growth and seldom produce a normal crop. Even plants from re-sowings done only 10 -15 days after the first sowing rarely catch up with the earlier sown plants.
• They remain stunted and produce very few or no balls.

• Excess plants should be thinned as soon as the plants are about 10 - 15 cm height and have two pairs of 'true' leaves.
• Earlier thinning is not desirable, the danger or seedling loss due to unforeseen damage to seedlings.
• Delayed thinning is also having undesirable effects like disturbing the adjacent plants by due to excessive root development by the time of thinning.