Everything you need to know about cotton cultivation. Learn about:- 1. Introduction to Cotton 2. Climate Required For Cultivating Cotton 3. Soil 4. Field Preparation 5. Selection 6. Sowing Time 7. Manure and Fertilizers 8. Water Management 9. Weed Management 10. Use of Cotton Plant Hormones 11. Cropping Systems 12. Intercropping 13. Harvesting and Yielding 14. Growth and Development.
Cotton Cultivation: How to Cultivate Cotton in India [A Guide for Farmers]
- Introduction to Cotton
- Climate Required For Cultivating Cotton
- Soil Required for Cultivating Cotton
- Field Preparation of Cotton
- Selection of Varieties of Cotton
- Sowing Time of Cotton Seeds
- Manure and Fertilizers Required for Cotton
- Water Management of Cotton
- Weed Management of Cotton
- Use of Cotton Plant Hormones
- Cropping Systems of Cotton
- Intercropping in Cotton
- Harvesting and Yielding of Cotton
- Growth and Development of Cotton
1. Introduction to Cotton:
Cotton (Gossypium spp.), one of the most important commercial fibre crops, plays a key role in economic, political and social affairs of the world. It is contributing 40% of raw material to textile industry, besides serving as raw material to over 25 industries. Its natural fibres are the precious raw material for ‘comfort clothing’ production. That’s why this is aptly called as ‘White gold’ and ‘King of fibres’. The Arabic word qutun or kutun has given rise to English word cotton.
Cotton refers to those species of the genus Gossypium which bear spinnable seed coat fibres. Cotton seed bears two types of fibres viz. long fibres known as lint which can be separated from the seed by the process of ginning; and short fibres known as fuzz or linters which remain on the seed even after ginning. The lint is used for spinning purpose. Thus those species of Gossypium which possess lint that can be spun into fine yarn are referred to as cotton.
The organized sector of the Indian Textile industry constitutes the largest single industrial segment in the country in terms of annual value of output and labour employed, both direct and indirect. There are 1,564 non-SSI spinning mills, 223 composite mills in India having an installed capacity of 34.22 million spindles and 105,067 handlooms. The industry provides direct and indirect employment to millions. The decentrilized sector comprising powerlooms and handlooms provide employment to over 2.5 million people.
The fabric quality of handlooms has been widely acclaimed for fineness and comfort. Cotton is chiefly grown for its lint (seed fibre), which is spun into yarn and used in the manufacture of cloth for the mankind. It is also used for several other purposes like making threads, for mixing in other fibres and extracting of oil from the cotton seed. Raw cotton is also used for medical and surgical purposes. The linters are used for stuffing, cushions, pillows, mattresses, etc.
It is also used in the manufacture of high grade paper, rayon, films, explosives, etc. The export of raw cotton, yarn, textiles, garments cotton seed cake, oil and other by-products earn valuable foreign exchange. Out of the total Indian exports, cotton and other textiles account for almost one third and nearly 60 million people are sustained directly or indirectly by cotton production, processing and marketing and trade.
The oil and protein content in the cotton seed is about 17% and 24% respectively. American varieties contain more percentage of oil. The seed is crushed for obtaining seed oil- an edible oil and the residues-hulls, press cakes and press meal are excellent cattle feed. Deoiled cotton seed and cake are also used as organic manure which contains 6, 3 and 2% of N, P2O5 and K2O, respectively.
2. Climate Required For Cultivating Cotton:
Cotton, a semi-xerophyte, is grown in tropical and sub-tropical condition. Cotton is a woody indeterminate shrub, grown under a wide range of climate. The minimum temperature for germination is 15°C, while the optimum being 18-38°C. For vegetative growth, temperatures of 21-27°C is optimum.
For reproductive growth, a night and day temperature of 20 and 30°C respectively is the optimum. Crop is very sensitive to low temperatures during the period of floral bud initiation during which more than 21°C temperature is desirable.
When soil temperature falls below 20°C, even for short periods, the uptake of water is slowed down and the cotton plants may wilt even when there is ample moisture. At still lower soil temperature (<10°C), the geotropism of the cotton roots is affected and abnormal root- growth results.
Excessive high temperatures more than 40°C also have an adverse effects on growth and development of cotton. However, it has the ability.to withstand various degrees of drought. The mean relative humidity in the growing season should be >50%. During fruiting phase, cool nights are required. Abundant sunshine during the period of boll maturity and harvesting is essential to obtain a good quality produce.
Reduced light intensities as a result of cloudiness reduce the rate of boll-set and cause excessive vegetative growth. About 2/3rd cotton is being grown under rainfed condition, hence its production is solely depends on vagaries of monsoon. Cotton can be profitably grown in areas receiving an annual rainfall of 85-110 cm and more than 50 cm well-distributed rainfall is essential for higher yields.
The increased shedding that is frequently observed following rains, which occurs during the growing period of cotton, can probably ascribed to the reduced light intensity rather than to the effects of the rainfall. It is very sensitive to waterlogging conditions.
A frost-less season of 180-240 days is required in north India for successful cotton growing. High temperature of about 45°C during sowing and seedling stage and extremely low temperature with frequent frost during winter coinciding with picking, and moderate rainfall of 30-70 cm usually occur in the northern zone.
In central and southern zones, the climate is more uniform. The maximum temperature during the season varies from 32 to 40°C, while minimum temperature ranges between 10 and 20°C. In Tamil Nadu and Andhra Pradesh, a part of the rainfall is received during September to December through the northeast monsoon.
3. Soil Required for Cultivating Cotton:
Cotton has a wide range of soil adaptation and is grown on extremely diverse soil types. However, a deep (>60 cm), friable, well drained and fertile soil is most suitable. Silty clay to clay soils are the best. Thus, highest yield of cotton is usually obtained on alluvial soils.
Soils in the pH ranges from 5 to 8 and CaCO3 contents of less than 10% in root zone are suitable for cotton cultivation. Highly calcareous soils with more than 30 % free CaCO3 may cause phosphorus fixation and micronutrient deficiency. It is generally considered as fairly tolerant to salinity.
Being a deep rooted crop, soil depth is also an important factor and shallow soils are not suitable in vertisols and associated soil regions. It is raised mainly as a rainfed crop in the black cotton and medium soils and as an irrigated crop in the alluvial soils.
Alluvial soils (predominant in the northern states of Punjab, Haryana, Rajasthan and Uttar Pradesh), Red sandy loams to loams (found in Gujarat, Maharashtra, Madhya Pradesh, Andhra Pradesh, Karnataka and Tamil Nadu) and Laterite soils (found in parts of Assam, Tamil Nadu and Kerala) are some of the predominant types of soil on which the crop is cultivated.
4. Field Preparation of Cotton:
Cotton, being a deep rooted crop, requires well prepared seedbed for germination and growth of the crop. Cotton is sensitive to soil compaction, but no more than most crops. Subsoil tillage operations to aid root penetration may be desirable prior to planting. In cotton – wheat cropping system of north, cotton is sown immediately after harvest of wheat leaving little scope for proper land preparation.
The field is irrigated immediately after rabi crop followed by ploughing to a depth of 15-20 cm deep with MB plough. Thereafter 2-3 harrowing or 3-4 ploughings with deshi plough should be given. After each ploughing, planking is essential to make soil pulverized and leveled. No stubbles of the previous crop should be left in the field.
Under rainfed conditions, land preparation starts with the onset of monsoon. However, a deep summer ploughing is desirable once in 3 years to ward off perennial weeds and also to kill pests and disease propagules hibernating in the soil.
After the start of monsoon, the field is harrowed 3-4 times followed by planking in vertisols of central and southern India. However, in red soils of southern India, 2-3 light ploughings are given before planking. Field preparation costs can be minimized by adopting minimum or zero tillage coupled with use of suitable herbicides.
Cotton is normally cultivated on a flatbed system which leads waterlogging and soil erosion. Thus, improved land configuration systems like broadbed and furrow (BBF) or narrowbed and furrow (NBF) or ridge and furrow (RF) have been found most appropriate system for cotton cultivation. These land configuration systems has been reported to be effective in reducing soil erosion, providing surface drainage, while ensuring water conservation and better stand establishment and crop growth.
5. Selection of Varieties of Cotton:
As a result of intensive research work carried out in the recent phase, India has now a wide range of cotton varieties to meet the varying requirements of the industry. Adoption of pests and disease tolerant crop varieties recommended for specific situations is a key to success in cotton production.
During the first five year plan, out of 11 varieties of cotton released for cultivation, 322H-14, Digvijay, MCU-2 are noteworthy. During second and third year plan varieties like MCU-3, MCU-4, J-34, AK-277, G-67 etc. were released.
There is a mismatch in the supply and demand of ELS cotton. Now only 4-4.5 lakh bales of ELS cotton are produced in the country which is hardly 1/3rd of the requirement of the textile industry. About 2.25 lakh ha are under cultivation of ELS cotton, mainly in Karnataka, Andhra Pradesh, Tamil Nadu and Madhya Pradesh mostly under irrigated conditions.
The major contribution to production of ELS cotton comes from DCH 32 grown in Karnataka and Madhya Pradesh. Varalaxmi, TCHB 213, SARA 2, MCU 5 (super fine) are other contributors of ELS cotton production.
NCS 1332, JK Chamundi, JK Ambika, Chatrapati, NFHB 109 are some of the important ELS varieties/hybrids are adopted in M.P. and Karnataka. Varalaxmi and DCH 32 are adopted in Karnataka, Tamil Nadu, Maharashtra and Ratlam tract of M.P. In Andhra Pradesh, Karnataka and Tamil Nadu MRC 6918 (Bt) and Rasi 625 (Bt) are adopted for cultivation. Farmers need to be motivated to grow ELS cotton which will fetch them better returns in view of better price.
6. Sowing Time of Cotton Seeds:
The climate, varieties/hybrids and growing conditions (rainfed/irrigated) determine the optimum sowing time for cotton. The optimum time of sowing is 1st week of May in northern cotton belt under irrigated conditions.
However, sowing may be extended up to 3rd week of May to the first week of June with selection of new compact varieties. In Central and Southern zone, where in almost 85 % and 60 % area cotton is grown under rainfed conditions, the sowing starts with onset of monsoon in June and may be extended up to first week of July.
Under irrigated conditions, the optimum time of sowing varies from first fortnight of March (western Maharashtra) to 2nd to 3rd week of May (Vidarbha region of Maharashtra and Khandwa tracts of Madhya Pradesh). In Tamil Nadu cotton is planted during September-October under both irrigated and rainfed conditions.
The time of sowing in rice fallows depends on the harvest of rice crop from October-November. For spring cotton, February is the optimum time of sowing. In M.P. sowing should be done in Second fortnight of May for irrigated cotton and in June to July for rainfed cotton. Seed can be dry seeded or sown at optimum soil moisture conditions.
Early sowing of cotton is important for a number of reasons:
1. It makes possible the most efficient use of precipitation, whether stored in the soil or occurring during cotton growth.
2. Flowering and boll formation (first flush particularly) occur before the month of September usually a wettest month.
3. The cotton matures before the onset of cold temperatures, detrimental to boll bursting and the boll maturation period becomes progressively longer.
4. Delayed sowing results in delayed flowering and this reduced flower and boll number. Boll size is unaffected.
5. Fibre characteristics are only slightly influenced by delayed sowing.
De-Linting of Cotton Seed:
The seed is covered by short fibre called ‘fuzz’ in most of the American cottons that makes sowing difficult owing to clinging of seeds. Thus, cotton seed used for planting must be delinted. Delinting is essential for ease of sowing. Delinting is the process of removing the fuzz from the cotton seed. Three types of delinting procedures are used.
(i) Mechanical Delinting:
Mechanical delinting of seed cotton is usually done in big ginneries to get the fuzz removed which is utilized for filling in bed covers (Gaddas), pillows, sofa cushions, etc. Mechanical delinter usually a saw delinter which crops up the fuzz by its sharp blades working very close to the seed testa surface. This may damage the micropylar end of the seed and hence may result in poor germination. Moreover, fuzz is not fully removed by this method.
(ii) Non-Chemical Method:
The seeds are soaked in water overnight, and then rubbed with cowdung and wood ash or saw dust to separate fuzz from seeds. The seeds are dried in shade before sowing. The rubbing also helps in crushing the pink boll worm affected seeds.
(iii) Chemical Method:
In chemical delinting acid is used for the purpose. Acid delinted seeds are better separated by removing the fuzz completely. Sowing of such seeds ensures better germination due to softening of seed testa. These seeds can also be sown with tractor or bullock-drawn seed drills.
In addition to delinting, this process may also destroy harmful seed-surface disease organisms and thus promotes excellent stands. For delinting with acid seed is put in to some plastic container (like plastic tub or shallow buckets) and then commercial grade sulphuric acid (H2SO4) is added into container in 10:1 (Seed: acid) ratio.
Seed is then stirred quickly with wooden rod. After fuzz is burnt, the seed is washed 2-3 times with ordinary water followed by washing with lime water to neutralize the seed from residual acid. The seed should be dried in shade and then in sun. After drying it is ready for storage. Using this process 20-25 kg seed can be delinted in an hour.
For chemical seed treatment, wood or metal container should not be used. The operator should wear the plastic gloves. The water containing acid and alkali residue should be properly disposed off in the waste land. Inadequate washing or delayed washing of the seed after seed treatment and residual acid on the seed if not neutralized may impair the germination of seed.
Treat cotton seed with a fungicide or insecticide, or both, to ensure protection from diseases and/or insects during germination and emergence. For linted and uncertified seeds, dressing with appropriate insecticides like Imidachloprid 70 WS @ 5 g/kg or Thiomethoxam 70 WS @ 5 g/kg or Carbosulphan 25 SP @ 5 g/kg of seed to save the crop from soil borne insects.
Seed treatment with Paushamycin/Plantomycin 100 mg + Carbox in 1 g/liter of water should be undertaken to protect the seed and seedling from seed borne diseases. One g of succinic acid in 10 litres of water may also help to promote good establishment of plant stand, and better early growth.
Seed Rate and Spacing:
In cotton usually first and last pickings are not utilized for seed purpose, the reason being there is high percentage of small and immature seeds, which would result in poor germination, week seedlings and bad crop condition.
The seed rate varies with species, growing zone and availability of irrigation. Maintenance of optimum plant population per unit area is important for getting maximum yields. This varies with plant type, its growth (variety/hybrid), soil fertility condition, soil moisture, cultural practices and growing conditions.
A soil of good fertility and adequate stored moisture is suitable for adopting wider spacing. In case of dwarf compact varieties closer spacing with higher population has given best results. A highly branching monopodial variety/hybrid requires more spacing than non-branching sympodial types. With the evolution of compact varieties, the concept of wider row planting has been changed to closer planting systems which can accommodate more plant population.
In parts of Gujarat and Andhra Pradesh, wider spacings of 150 x 60 cm and 120 x 60 cm are followed for hybrid cottons like G.Cot. Hyb.6, RCH.2, Vikram and Nath hybrids. However, in many regions, 90 x 60 cm is followed for hybrids and high yielding varieties under high yielding situations. Increase in yield owing to closer spacing and higher population has been reported.
In dense population, vegetative growth is curtailed and very few or no vegetative branches are formed. The number of bolls per plant is the only character affected by plant densities; the number of seeds per boll, the total weight of the individual seeds and the amount of fibre per seed are almost unaffected.
Therefore, plant density affects yield mainly by determining the number of bolls per unit area. Excess plant density may delay maturity, probably because conditions for boll maturation become less favourable. Excess plant density leads to lodging some times. A dense stand may reduce the evaporation from soil and competes effectively with weeds. Dense stand may avoid crusting of soil – more rapid and uniform development of plants.
The above advantages are seen – provided the density is not excessive. In order to ensure the required plant density, in some places sowing more seeds than are required for producing the desired number of plants, when the plants have reached a stage of development, the plants are thinned to the desired stand.
Plant density or otherwise spacing adopted between and within the rows is mainly depends on the species chosen and the plant type of the variety. In general seed rate varies from 2 to 12 kg/ha. It is advisable to select delinted seed for getting higher germination. Normally 8-10, 6-8 and 2-2.5 kg seed/ha is recommended for American, desi and hybrid varieties of cotton, respectively.
Ultra Narrow Planting:
The concept of ultra-narrow row (UNR) cotton planting is gaining popularity in USA because it facilitates early fruiting and growth control. The UNR cotton is spaced at 19 x 19 cm spacing and produced 27,700 plants/ha. This system saves water, pest control and harvesting costs.
Methods of Sowing:
Cotton 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 2.5-3.0 cm. 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 deeper root system, better aeration and regulated water supply to the developing seeds.
In case of desi cottons, line sowing behind the seed drill is common. However, in case of hybrids and Bt cotton, seed dibbling is preferred owing to higher seed costs. Square planting are beneficial than rectangular planting methods.
Under rainfed conditions, seed should be placed at a depth of optimum soil moisture for better germination and stand establishment. Deeper sowing may be done in light dry soils and at shallow depth on moist heavy soils. The optimum depth of sowing is 4-5 cm.
7. Manure and Fertilizers Required for Cotton:
Cotton is a heavy feeder of nutrients. Thus, it requires adequate supply of nutrients for optimum production. Cotton soils are universally deficient in N, but are moderate to adequate in respect to phosphorus and potassium. This shows the importance of N nutrition. For moisture conservation and better response to applied nutrients, FYM application @ 5-10 and 10-20 t/ha under rainfed and irrigated conditions is recommended. It is applied at the last ploughing for proper incorporation into the soil.
Nitrogen is essential for establishment of crop, root and vegetative growth and seed cotton yields. Cotton responds favourably to nitrogen application both under irrigated and rainfed conditions. Excess nitrogen has a deleterious effect on both quality and quantity of cotton. Nitrogen stress at reproductive phase leads to more shedding of fruiting bodies. Nitrogen deficiency at any stage of crop results in poor growth and yield.
The N dose varies from 40-60 kg/ha (rainfed) to 100-150 kg/ha (irrigated conditions). Similarly desi cotton requires less N than hybrids. The N demand of crop is spread over from sowing to boll development. Nitrogen fertilizers being soluble in water are prone to losses by leaching due to high rainfall or irrigation.
Research findings indicate that 2-3 splits of N are found more beneficial than single basal application. Therefore, split application is desirable. The number of splits may vary from 2-3. In case of 3 splits, 50%, 25% and 25% of total N is applied at sowing, square formation and flowering. In hybrids, spot application of top-dressed N is more efficient than broadcast.
Application of phosphatic and potash fertilizers should be based on soil test values. The P2O5 dose varies from 30-40 and 40-60 kg/ha under rainfed and irrigated conditions respectively. It should be applied as basal at sowing and placed at 7-10 cm below soil for efficient utilization.
The response to K fertilization is rare in India. However, hybrids under irrigated conditions with high N and P fertilization usually respond to K fertilizer. It is also applied basally at the time of sowing. However, split application of potash at 30, 60 and 90 DAS along with N is also recommended.
Inoculation of cotton seed with Azotobacter and Azospirillum has been found effective in meeting N requirement of cotton to the extent of 30 kg/ha. Azotobacter, a free living heterotropic nitrogen fixing bacteria – Inoculate seed with appropriate strain of bacteria. Significant inoculant response at different places ranges from 34 to 247 kg N/ha.
Azospirillum is an associative micro aerophylic Nitrogen fixer. It is possible to reduce N requirement 25- 30% by seed inoculation. VAM (Vascular Arbuscular Mycorhizae) 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 and reduces fertilizer requirement by 25-30%.
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 available to crop plants. Bacterial cultures can be obtained from reliable sources. Use of phosphate solubilizing microbes (Bacillus, Pseudomonas, Aspergillus) along with rock phosphates are more effective than rock phosphates alone. Responses to S and Zn fertilizers have also been reported. Zn deficiency is accentuated with alkalinity of soils.
In special cases, spraying of urea can be done @ 1.5 (%) and 2-2.5 (%) at initial and later growth stages respectively, besides this 3-4 spray of DAP @1-1.5 (%) can be done after flower initiation at 15-20 days interval. Among micronutrients, application of zinc sulphate @ 25 kg ha-1 at two years interval is also recommended in zinc deficient soils.
If the deficiency is seen on the crop, spray 0.2% ZnSO4 2-3 times or 0.1% chelated Zn 2-3 times till the plants become normal. When crop is water logged for a week at 30-40 days age, spray 1% urea or 1% KNO3 solution immediately for rejuvenation. Proper drainage for better crop growth is essential.
8. Water Management of Cotton:
Cotton, a predominantly rainfed crop, has only 35% of the total area under irrigation. Hence, both moisture conservation and water management are equally important. Rainfed crops have low yields owing to erratic and uneven rainfall.
Normally cotton requires about 700-1200 mm water depending upon soil and climatic conditions. The water requirement during seedling to first flower is low ranging from 2.5-3.8 mm/day, maximum during peak bloom (8-10 mm/day) and declined steadily till about 4-5 mm/day during the boll maturation phase.
The water requirement of cotton in M.P. ranges from 660-685 mm. Scheduling of irrigations in cotton depends on soil type, crop growth, cultural practices and climatic conditions. Crop should be irrigated as per the crop requirement. Presowing irrigation for seed germination is must for proper germination of seeds. Water requirement of cotton indicates that the crop requires moderate quantities upto 75 days after germination while the water requirement is more from 75 to 120th days during peak bloom period.
Flowering and boll formation are the most critical stages for irrigation in cotton. Moisture stress at 75 and 90 DAS resulted in to pre-mature flower drop, boll shedding, poor development of bolls, low ginning percentage and ultimately lower the cotton yield. Stop irrigating the crop after boll opening stage.
Moisture stress during reproductive phase is most harmful to the crop performance. Water deficit results in fruit abscission and excess water leads more vegetative growth. In cotton, four critical stages of irrigation have been identified viz. commencement of sympodial branching (60-70 DAS), flowering (90-100 DAS), boll formation (125 DAS) and boll bursting (140 DAS). Depending on rainfall and soil types, the number of irrigations (each of 7.5 cm) may vary from 2 (sandy loam of Delhi and clay soils of Akola) to 13 in red sandy loam of Bhavanisagar.
In heavy soils, cotton withstands up to 75% depletion of available soil moisture (DASM), while in sandy loams, it is 50% DASM only. For timely sowing of succeeding crops, irrigation should be withheld from 50% boll bursting stage onwards. About 8 irrigations at an interval of 15-25 days in heavy soils and 12 irrigations at an interval of 10-15 days in light soil may be sufficient for higher yields of cotton.
Irrigation at 0.6 IW/CPE (irrigation water cumulative pan evaporation) ratio has been found promising. Cotton can also be irrigated at 75% depletion of available soil moisture in clay soils and at 50% available soil moisture in sandy loam soils.
Drip or ridge and furrow method of irrigation has been found beneficial for better water use efficiency and higher crop yields. Under limited water resources, alternate furrow irrigation is beneficial as it saves about 30-50% water, facilitates early crop establishment and increased yields by 15- 50 percent.
It is an important component of rainfed cotton cultivation. Erratic and uneven distribution of rains causes yield reduction in cotton to a great extent. Rainfed cotton often experiences excessive rains during vegetative growth phase and terminal drought situation during flowering and boll development periods.
Several measures have been recommended to conserve rain-water in situ or harvest/collect excess run-off water into farm ponds and recycled it, to provide supplementary irrigation or life-saving irrigation at flowering and boll formation stage.
Ridge sowing on 0.4% slope and tieing ridges at 6.0 m interval just before normal withdrawal date of monsoon conserves water. Moreover, cotton cultivation on ridges across the slopes conserves more water, reduces soil erosion and improves yield.
Application of straw mulches or bio-mulches like Sesbania sp. between the two rows of cotton or light harrowing/inter-culturing prevents development of soil cracks and reduces evaporative losses. Use of farm yard manure and effective weed management are conducive for moisture conservation.
Thinning and Gap Filling:
As the crop is grown at wider spacing, the gaps arising due to failure of seed germination or seedling mortality or incidence of pests/disease must be filled by sowing water soaked seeds. To ensure full stand, 2-3 seeds/hill are dibbled. After germination, the weak/diseased/damaged seedlings are removed by keeping a healthy seedling/hill.
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, as the danger or seedling loss due to unforeseen damage to seedlings may occur. Delayed thinning is also having undesirable effects like disturbing the adjacent plants due to excessive root development by the time of thinning.
9. Weed Management of Cotton:
Weeds interfere with cotton production by reducing yields, quality and value of the harvested crop. Weeds reduce yields by competing with the crop for space, moisture, nutrients and light. Cotton grows slowly and is not competitive with weeds early in the growing season.
Once a dense canopy is developed, cotton is quite competitive with weeds. Therefore, weeds must be controlled early in the growing season to avoid yield losses. Late season weeds usually do not reduce yields, but can interfere with harvest and contaminate the harvested lint.
Weed contamination significantly lowers the value of the cotton lint and may make marketing a problem. Consequently, good, season-long weed control is essential to produce a successful cotton crop. In wide spaced crops like cotton, weeds pose serious threat to realizing the optimum yields. A weed free period of 50-60 days from sowing is required. The profuse vegetative growth beyond this period may suppress the weed growth. Uncontrolled weeds may cause 60-80% reduction in yields.
In the northern cotton-wheat region, the major weeds are Trianthema sp.; Echinochloa sp.; Digera arvensis, and Cyperus sp. In the central region, Celosia argentea, Cyanotis, axillaris, Digitaria sanguinalis, Dinebra retroflexa, Euphorbia sp., Echinochloa sp.; Ipomea and Cyperus sp. are commonly found. In the southern zone, the predominant weeds are Trianthema portulacastrum and Cynodon dactylon. Water loving weeds like Portulaca oleraceae, T. portulacastrum and E. crusgalli are major weeds in the rice fallows.
Manual, mechanical and chemical methods of weed control either alone or in combination are followed for effective weed management. Inter-cultivation with blade harrows (Guntakaor bukhar) is to be done at least 3-4 times at an interval of 10-15 days. This facilitates weed free field and loosening top soil for better absorption of rain water.
Intra row weeding with manual labour is to be attended at least twice to keep the weeds under check upto 60 days. Hoe two or three times, the first hoeing should be done before first irrigation. For hand weeding, use of a wheel hoe is recommended. A tractor drawn cultivator or bullock driven Triphali can also be used in the early stages of the crop growth but their use after fruit initiation should be avoided.
The first manual hoeing 5-6 weeks after sowing or before first irrigation is essential for removal of weeds at an early stage. Later hoeings either by hand or bullock drawn implements should be done after each irrigation or rain. The inter-culture operations not only aid in weed control, but also help in creation of mulch, aeration of soil and better intake of water.
In the Central zone, weed control is accomplished by repeated hoeings using locally fabricated blade harrows, either unidirectional (in case of rectangular planting geometry) or bi-directional (in case of square planting). Often because of continuous rains, and unavailability of labours, mechanical weeding becomes impossible particularly in black soil areas. In such times, chemical weed control becomes a necessity.
Field selection and early planting can help avoid possible weed control and herbicide related concerns. Several herbicides, including atrazine, pursuit, etc. can carry over from the previous herbicide use, and injure cotton seedlings. Cotton is extremely susceptible to 2, 4-D and other auxin-type herbicides. Pesticide sprayer equipment must be thoroughly cleaned to remove any herbicide residues prior to use on cotton. Avoid spraying adjacent fields with 2, 4-D, if possible.
Among the herbicides, pendimethalin (pre-emergence) or fluchloralin (pre-plant incorporation) @ 1 kg/ha are found effective in controlling grassy weeds for the initial 2 months. For broad leaved weeds, post-emergence herbicides like diuron + paraquat (0.5 + 0.3 kg/ha) for directed spray against weeds was recommended. In developed countries, bromoxynil and glyphosate resistance has been introduced into cotton for spray for effective post-emergence weed control.
A combination involving pre-emergence application of pendemethalin @ 1.5 liter/ha and one hand weeding at 35 days after sowing is proved to be very effective for weed control in cotton. Earthing up and covering the basal stem with soil is one of the important cultural practices to reduce the stem weevil incidence in cotton. Once or twice scrapping of top soil will loosen the soil and help the plant to grow well. Soil is earthed up with ridge plough or manual labour and new ridges are formed.
Cotton plants tend to grow taller under favourable conditions and put forth more vegetative growth. The excessive vegetative growth should be terminated in order to enhance fruiting points and finally more bolls. This can be accomplished by clipping the terminal growing point (apical buds).
This process is known as topping or nipping. It is done once from each plant at a height of 1 to 1.2 m or between 80-90 days of crop growth. This practice arrests further terminal growth and encourages sympodial branching and boll development. It also facilitates spraying operations and picking of cotton. Topping is essential if monopodia growth continues to more than 15 nodes.
10. Use of Cotton Plant Hormones:
Cotton is indeterminate plant and it has been observed that the cotton plant sheds the greater proportion of the squares and flowers at any stage between bud formation and boll maturity under normal growth conditions. The use of growth regulators may be important for cotton, especially on irrigated fields. In dryland fields where good soil moisture and high levels of residual nitrogen are present, the application of growth regulators may also be advantageous.
Growth regulators will reduce cotton height, may aid in boll retention at desired positions, and often enhance early maturity. Growth regulators can cause fruit shed if plants are stressed and if applied in excess quantities.
Naphthalene acetic acid (a -NAA) known as planofix @ 40 ppm is sprayed twice at flower appearance (2nd or 3rd week of August) and its second spray at 20 days after the first spray. The NAA spray is beneficial to prevent the dropping of squares and flowers and thereby boll setting percent is increased and consequently the seed cotton yield is enhanced.
In case of American cotton, spray cycocel (50% CCC) at the rate of 32 ml/ha dissolved in 320 litres of water at square formation stage of cotton is recommended when more than the normal vegetative growth is expected. It can be mixed with insecticides also at the time of spraying.
11. Cropping Systems of Cotton:
A cropping system refers to a combination of crops in space and time. An ideal cropping system should make the most efficient use of the natural resources, and provide stable and high returns. Cropping systems should also be ecologically sustainable. Sequential cropping refers to growing crops in sequence within a crop year, one crop being sown after the harvest of the other.
When two or more crops are grown in a year on the same land, the system is referred to be double cropping or multiple cropping. It is always advisable to avoid growing cotton continuously in the same fields and proper rotation is a must, which has numerous advantages. Thus, crop rotation is an important agronomic practice which should be followed preferably with legumes and oil seeds.
The most important cotton based rotation in irrigated areas of Punjab, Haryana, northern Rajasthan and Uttar Pradesh is cotton-wheat. The growing of berseem and clusterbean (guar) has been found to have beneficial effect on the succeeding cotton crop. In central and western India, cotton-sorghum, cotton-pearl millet, cotton-wheat, cotton-gram and cotton-sesame are the useful rotations followed.
The common traditional practice of cotton cultivation in many parts of central and south India is strip cropping of 1 or 2 rows of pigeonpea after every 8-10 rows of cotton, 3- 5 rows of ragi Otemated with 1 row of cotton.
12. Intercropping in Cotton:
Mixed cropping refers to growing more than one crop in the same land area as a mixture. The crops are grown without any definite proportion or pattern. Mixed cropping is practiced in traditional subsisting farming to meet the domestic needs of the farmer’s family. Thus, the number of crops grown mixed varies depending on the family needs. Cotton is grown mixed with maize, sorghum, sesame, pulses or vegetables in many parts of central India.
Intercropping with ragi or other millets or groundnut is also quite common in parts of Tamil Nadu, Karnataka and Andhra Pradesh. Intercropping and mixed cropping under rainfed conditions serve both as an insurance against crop failures and as a preventive measure against soil erosion. Intercropping is growing of two or more crops of dissimilar growth pattern on the same piece of land, with a view to optimize the total yield and net profits per unit area.
Intercropping of cotton with blackgram was much superior to growing greengram and cotton alone, both in terms of yield of cotton as well as profit. Another study with blackgram and setaria with different row ratios showed both intercrops had no adverse effect on cotton production.
An ideal intercropping should aim to produce higher yields per unit area through better use of natural resources. Offer greater stability in production under biotic and abiotic stresses. Meet the domestic needs of the farmer. Provide an equitable distribution of farm resources.
Rainfed cotton preferably is grown as major component of intercrops which had several advantages, particularly in reducing the pest and disease build up. Intercropping is one of the important agronomic practice particularly under rainfed conditions. Hence, intercropping with cotton should invariably be encouraged under rainfed situations.
13. Harvesting and Yielding of Cotton:
The flowering season usually starts from 2-21/2 months after the sowing of seed and lasts for a period of 8-10 weeks. The crop produces only a few flowers during the first 8-10 days but after that, the rate of flowering increases rapidly. The peak rate continues for 3-4 weeks and then it gradually tapers off.
As a result of this phenomenon, the production of ripe fruits or bolls is also gradual being spread over a period of 3-4 months. Cotton is harvested in 3 or 4 pickings by hand as the bolls mature. The number of picking may vary with the maturity habit of the variety. The season of harvesting also varies with time of sowing and the duration of variety.
Generally, crop sown in April-June is harvested in October-December, while those sown in June-September and September-October are harvested from November to March and March to June respectively. Generally, the crop in northern and central parts of India is harvested from October to December, whereas in Gujarat, from January to March/April. In the states of Tamil Nadu, Andhra Pradesh and Karnataka, the harvesting season is November to June.
Cotton is harvested by frequent hand pickings of the burst bolls. Picking should be done generally in the morning hours so that the kapas will be free from dust and leaf bits. When the dew is there, just wait for a little time before picking. Cover heads with hat caps in order to avoid hair contamination.
Bolls with bad opening, yellow stains, insect attacked and rottened should be picked separately. While picking the kapas all the segments should be picked at one time, otherwise fibres will be broken and thus fibre quality will be reduced.
After picking, kapas should be dried under shade on a clean drying floor. Seed cotton from the first and last pickings should not be mixed with middle pickings. The middle pickings will be of better quality and fetch higher price. Kapas should be picked dry, free from trash with no dew on it. Store kapas in damp proof and rat-free room.
Store different varieties separately. The first and the last picking are usually of low quality and should not be mixed with rest of the produce. High-grade kapas mixed with low grade kapas sell at a relatively low price.
14. Growth and Development of Cotton:
Cotton is a perennial plant native to tropical regions and requires warm days and nights for optimum growth and development. Cotton seedlings are sensitive to cool temperatures during germination and emergence. They will emerge in 4-10 days, depending on soil temperature and depth of planting. Cotyledons, or seed leaves, emerge first; true leaves follow.
Flower buds, called squares, are visible about 30 days after plant emergence. The first fruiting branch normally will be at the sixth to ninth node. Though variety selected does play a part, day length and temperature are the primary influences on fruiting branch initiation. Temperature at germination can also determine the branch on which flowering begins. The boll, a capsule containing the seed, linters (fuzz) and lint, attains maximum size 20-25 days after bloom, and opens 60-75 days after initial bloom.
Nearly 75 percent of the yield will be from the third to eighth fruiting branches. Eighty-five to ninety percent of the lint yield will be produced at the first and second boll positions on the branch. Cotton plants, like soybeans, abort many flowers even under ideal conditions. Only 35-40 percent of blooms make bolls. Cotton varieties vary greatly in maturity. Early maturing varieties, 120 days are best adapted to the relatively short growing season.
In the wild state, cotton is a perennial plant, attaining height of 5-6 m. However, most of the cultivated cottons are annuals. Cultivated cotton is a herbaceous plant, which attains a height of 75-200 cm.
Cotton plant has a tap root with secondary roots that branch laterally from primary root. Maximum root depth varies from 1.5-3 meters under favourable conditions.
The main stem is erect and monopodial with leaves and branches without flower. The branches develop from buds located at the nodes of the main stem. Cotton plants exhibits two types of branches viz. monopodial and sympodial branches. Monopodial branches are the vegetative branches usually present at the base of main stem and devoid of flowering bud or flower.
Sympodial branches are the branches usually arise laterally well above the base and each sympodial branch will bear square/flower and boll. An ideal well developed cotton plant consists of 3-4 monopodial branches and 15-16 sympodial branches. Hybrids possess more sympodial branches than varieties.
There are 2 buds at the base of each leaf petiole. The true axillary buds develop into a vegetative branch, which only bear leaves and no flowers. The accessory bud generally develops into sympodial or fruiting branch. Vegetative branch may arise either from axillary or an accessory bud. There is tendency for the lower branches to be vegetative, while the upper ones as fruiting branches.
The leaves are spirally arranged on the main stem and vegetative branches, except on fruiting branches, where they form 2 alternate rows. The leaves are petiolate. The outline of leaf is more or less cordate with 3-9 lobes depending on variety. The leaves are green, but in some species such as arboreum, leaves contain some purplish colour.
The flowers develop at the node of opposite to a leaf in fruiting branches only. The flower buds which appear as small, pyramidal shaped green structure are called as ‘square’ which consists of three triangular-shaped leafy structure known as ‘bracteoles’ and the flower bud. Square formation is the first stage of flowering and continues 48 days after sowing.
The flowers open about 18-24 days after the squares are formed. In the initial stage flowers are yellow in colour and after full development they will turn into pink colour and then will shed leaving behind well-developed boll. Flower consists of pistil, the stamens arranged in a tube-like staminal column that envelops the style of the pistil, 5 petals and 5 green sepals, joined together to form a cup like calyx.
The fruit is the enlarged ovary that develops into 3-5 loculed capsule or boll. The bolls vary in size and shape, but are usually more or less egg shaped. When the boll is ripe, the capsule cracks or splits along the lines or sutures where carpels meet, and the cotton within expands greatly in a white fluffy mass.
The number of seed in the boll varies from 24 to 50. The cotton fibre is simply an elongation or outgrowth of an epidermal cell of the seed coat. The long outgrowth forms the ‘staple’ or ‘lint’, while shorter outgrowth forms ‘fuzz’.
Commercial cotton seed is produced after ginning seed-cotton (kapas) for the staple fibre. Cotton seed has three principal parts viz. linter, hulls and kernel (meat). The linters consist mainly of cellulose. The minor constituents are pectin, minerals, waxes, resins, pigments, and water soluble carbohydrates etc.
The hull or seed coat is brownish – red to jet-black in colour. The main constituents of the hulls are cellulose complexes, lignin and furfural, and the minor constituents are tannins, mineral matter, colouring matter and other substances. In between the inner surface of the hull (spermoderm) and the kernel (embryo) there is a thick membrane which forms the attachment to the cotton seed hull at the chalazal cap.
It has two cotyledons, the axial organs and the enveloping membrane. It contains largely oil and protein besides the pigment glands. The pigment glands contain pigment materials which impart the characteristic yellow-red colour to the cotton seed meal and oil.
The major constituent of cotton seed are fat, protein, moisture, crude fibre and carbohydrates. The minor constituents are pigments, phosphorus compounds, sterols, antioxidants, mineral compounds and other substances. All these reside entirely or mostly in the kernel.
(i) Gossypol – It is one of the cotton seed pigments. It is a complex polyphenols compound, yellow in colour, molecular formula C3O H3O O8.
(ii) Gossypurpurin – Purple coloured pigment of the cotton seed.
(iii) Gossyfulvin – Orange coloured pigment of the cotton seed.
(iv) Gossycaerulin – Blue coloured pigment of the cotton seed. 11 other pigments are also present in the cotton seed.
By adopting improved package of practices, it is possible to harvest about 1.5-2.0 tonnes of seed cotton (kapas)/ha. However, much higher yields may be obtained from hybrid cottons. Cotton lint production is 1/3rd of kapas production, while cotton to seed production is 2/3rd of kapas production. Oil to seeds crushed is 14-18% and cake to seeds crushed is 82-86%.
Seed cotton or kapas, as harvested, contains both lint and seed, the latter forming about two-third of the weight of kapas. Cotton is ginned, on a cottage industry basis, in the charkha and the Foot Roller. Now most of the cotton is ginned in ginning machines.
Ginned cotton is marketed in the form of pressed bales. The ginning and pressing of cotton is regulated by the Cotton Ginning and Pressing factories Act, 1929. In 1818 Bowreah Cotton Mill Company, was started at Calcutta. Now, Bombay holds the leading position among the States in the Indian cotton mill industry. In the cotton mill, cotton is cleaned and the spinning machines spun the cotton into yarn.
A cotton gin removes burs, sticks, dirt, leaves and other foreign matter to obtain clean lint and seeds. The lint is packed in bales weighing 170 kg and sent to textile mills. The seed goes to oil mills or is rolled or crushed for cattle feed. Marketing involves the sale of ginned cotton to textile mills.
The value of cotton is determined from the samples taken from each bale. These samples are classified according to staple and grade. Staple is a measure of the length of the cotton fiber. The longer the fiber, the more valuable the cotton. Colour and amount of foreign matter determine grade.
Important Steps to Increase Cotton Yields:
1. Avoid mono-cropping, adopt crop rotation invariably and practice inter cropping in cotton.
2. Select a variety or hybrid recommended/suitable to soil and climate of a region.
3. Test the seed for its germination percentage well in advance before sowing.
4. Take up seed treatment as per recommendation as per the situation.
5. Ensure there should be sufficient moisture at sowing.
6. Sow HYV or hybrids preferably on ridges.
7. Deep sowing should be avoided (3 – 5 cm optimum depth).
8. For short duration varieties reduce spacing in between and within rows (75 x 75 cm2 or 90 x 90 cm2) and for long duration varieties give wider spacing between and within the rows (105 x 105 cm2 or 120 x 120 cm2).
9. Fill the gaps within ten days after sowing (grow cotton seedlings in the polythene bags on the day of sowing and fill the gaps with these plants to avoid age difference).
10. Inter cultivate 2-3 times with a blade harrow in between rows within 30-40 days after sowing (rainfed cotton) helps in reduction of evaporation losses and better infiltration of water into the soil (if there is rain) since the soil is loose. In irrigated cotton after each top dressing and irrigation, run the blade harrow between the rows of cotton.
11. Thin out excess seedlings at 20 days after seeding and maintain one seedling per hill (hybrids) and two seedlings per hill (varieties).
12. To avoid/reduce square and flower drop – spray NAA twice @ 1ml/4lit of water at 45 and 65 DAS for full coverage of squares and flowers.
13. Fertilize crop at with nitrogen at 30, 60 and 90 days after sowing in equal splits (irrigated cotton), phosphorus at the time of last ploughing and potash at 30 and 60 days after sowing in equal splits.
14. Use only recommended doses of fertilizers, pesticides and other chemicals if any at right time in right method.
15. Placement/pocketing of fertilizer at 7 – 10 cm away from plant at 7 – 10cm depth.
16. If Nitrogen deficiency is seen in standing crop spray 2% urea twice.
17. If Magnesium deficiency is observed spray 1% MgSO4 (10g of MgSO4 in one litre of water) at 45 and 75 days after sowing.
18. If Zinc deficiency is seen apply 50 Kg ZnSO4 in the last ploughing. If soil application could not be taken up spray 0.2% ZnSO4 (2g of ZnSO4 in one litre of water) twice at an interval of 4-5 days.
19. If Boron deficiency is observed spray 0.1% (1g of Boric acid in one litre of water) at 60 and 90 days after sowing.
20. Schedule the irrigation promptly and avoid excess irrigation.
21. Sufficient soil moisture should be there at the time of top dressing of N fertilizer.
22. Careful monitoring of crop for pest / disease incidence.
23. Take up appropriate plant protection measures.
24. Save first flowering at any cost – otherwise – excess vegetative growth leads to reduction in yield.
25. Spray pesticides on bottom of the leaves for sucking pests.
26. Spray pesticides on flower, fruits and vegetation in case of borers.
27. Use pyrethroids insecticides, only under extra ordinary conditions only once or twice during crop period.
28. Use of alternate methods (BT, NPV, Chrysopa, Trichogramma & Neem products) instead of insecticides, use pesticides when ETL level is reached.
29. Use of Neem products and Endosulphan initially when insecticide use is warranted. Both are relatively safer to natural enemies.
30. Top the plant to arrest excess growth after putting 15-16 sympodial branches for every plant.
31. Quality of first two pickings is high, thus always keep the produce separately for higher price.
32. Do not mix undeveloped lint, insect or disease damaged lint or spoiled lint with quality lint. Remove cotton stubbles after last picking.