Studies on Performance of Bt Cotton Hybrids against Jassids (Amrasca bigutulla bigutulla Ishida) During Summer Season

Cotton (Gossypium hirsutum. L) is indeed a significant cash crop grown in three agro-climatic zones of India. The Indian subcontinent is considered the birthplace of cotton, and it has been a crucial part of human civilization for centuries. It is renowned as the most important natural fibre or vegetable wool and has been cultivated for both domestic consumption and export purpose for proximately 111 countries worldwide. Cotton is a vital crop that plays a significant role in the global economy. It provides livelihoods for over 250 million people worldwide and accounts for nearly 7% of the labour force in developing countries. The field experiment was carried out at Agricultural Research Station (ARS), Adilabad, Telangana during summer 2022-23. A Total of 8 Bt cotton hybrids were evaluated against jassids of cotton under unprotected conditions. Lowest population of jassids were recorded in hybrid NCS-2778 (3.76 jassids per 3 leaves), followed by RCH-659 (5.41 jassids), PRADEEP (6.27 jassids), MOKSHA (6.45jassids per 3 leaves). The highest population of jassids were recorded in JADHU (9.91 jassids) and MONEY MAKER (7.70 jassids).

CROPGRO-Cotton Model Application for Predicting Cotton Sowing Time in Nagarkurnool District of Telangana State, India

Aims: A study was carried out to find out the optimum sowing time with the validated CROPGRO-Cotton model using DSSAT v 4.7 seasonal analysis tool under rainfed situation at mandal level in Nagarkurnool district of Telangana state, India.Study Design: CROPGRO-Cotton model using DSSAT v 4.7 seasonal analysis tool.Place and Duration of Study: Nagarkurnool district, 2023.Methodology: Cotton production was affected with changing climate in several ways and its impact on rainfed agriculture was higher and influences the Indian economy. The prevailing weather conditions during different phenophases of the crop influences the seed cotton yield. There is a need to optimize the sowing time so that the timing of critical growth stages to minimize stresses and enhance resource utilization. The adjusting of sowing environment proved to be an adaptation management technique for realising higher seed cotton yield.A well calibrated and validated model was used for long term simulations using DSSAT seasonal analysis tool programme with Mallika Bt as test variety for 100 different scenarios (20 mandals × 5 sowing dates) using 32 years historical daily weather data from 1991 to 2022 starting sowing time from 1st June to 1st August at 15 days interval in twenty mandals of the district.Results: The simulation results showed, significantly higher seed cotton yield (1505 kg ha-1) was predicted with crop sown on 1st June followed by 1st July sown crop (1337 kg/ha) which was comparable with 16th June (1324 kg/ha) and significantly differed with delayed sowings of 16th July sown crop (1203 kg/ha) and 1st August sown crop (1192 kg/ha). Among the different mandals of the district, the model simulated higher seed cotton yield (2136-2530 kg/ha) in Amrabad mandal and lower yields in Thimmajipet mandal (596-997 kg/ha) under different sowing environments. Conclusion: Based on simulation scenarios, higher seed cotton yield can be obtained when crop sown between 1st June to 1st July in different mandals of the Nagarkurnool district of Telangana State. The mandals which have less yield potential and realising poor yields by the farmers can be advocated with location specific alternate best management practices to get the higher cotton yield.

Sowing Time and Spacing Influenced Yield, Quality and Economics of Bt Cotton (Gossypium hirsutum L.)

A field study was conducted in the 2019 kharif season at the Agronomy Instructional Farm, SDAU, SKNagar, Gujarat, India. To investigate that the sowing time and spacing influenced yield, quality and economics of Bt cotton (Gossypium hirsutum L.) in loamy sand soil. Twelve treatment combinations were examined, involving three sowing times (T1: 3rd week of May, T2: 1st week of June, T3: 3rd week of June) and four plant spacings (S1: 90 cm × 60 cm, S2: 90 cm × 45 cm, S3: 60 cm × 60 cm, S4: 60 cm × 45 cm). Four replications of a split plot design were used for the experiment. The third week of May was consistently the best time to sow cotton, according to the results, producing the maximum yields of seed cotton and stalk cotton. The quantity of monopodial branches/plant, harvest index and plant population as well as quality parameters such as oil content and ginning percentage were not significantly impacted by sowing time. The 3rd week of May sowing also yielded the highest benefit cost ratio and net realization. In terms of plant spacing, the spacing of 60 cm × 45 cm promoted highest plant population, taller plants and increased yield attributes like the bolls/plant, boll weight and seed cotton yield/plant. The highest seed cotton yield and stalk yield were achieved with this spacing. Harvest index and quality parameters were unaffected by plant spacing. The narrow spacing of 60 cm × 45 cm also resulted in the highest benefit cost ratio and net realization. The interaction effect between sowing time and plant spacing did not significantly influence growth, yield, yield attributes and quality parameters of Bt cotton.

Evaluation of Growth Rates of Bt. Cotton (Gossypium hirsutum L.) Hybrid NHH-44 as Influenced by High Density Planting and Weed Management Practices under Rainfed Conditions in Marathwada Region of Maharashtra, India

A field experiment was conducted at experimental farm, AICRP on Integrated Farming Systems, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani (M.S.) during kharif seasons of 2020-21 on to study the “Impact of high density planting and weed management practice on growth and yield of Bt. cotton. (Gossypium hirsutum L.)” Treatment consist of Twelve treatment combinations comprising Three planting densities in main plot that is (S1-120 cm x 45 cm (18518 plants ha-1), S2- 80 cm x 60 cm (20833 plants ha-1) and S3- 90 cm x 45 cm (24691plants ha-1) and four weed management practices that is W1 - Stale seedbed technique + PoE Pyrithiobac Sodium 10% EC @ 62.5 g ha-1 + Quizolfop-ethyl 5% EC @ 50 g ha-1 + Straw mulching, W2 - Stale seed bed technique +PoE Glufosinate ammonium 13.5% SL @ 0.7 kg ha-1 + Hand weeding, W3 - Weed Free and W4 - Weedy Check.The mean maximum AGR for plant height were recorded under high density planting 90 cm x 45 cm. Among different growth intervals 61-90 DAS recorded maximum AGR for plant height (1.664 cm day-1 plant-1), while mean maximum AGR for dry matter (2.358 g day-1 plant-1) were recorded between 91-120 DAS under high density planting 120 cm x 45 cm. Among weed management practices, weed free treatment recorded mean maximum AGR for plant height (1.645 cm day-1 plant-1) 61-90 DAS interval, while mean maximum AGR for dry matter (2.441 g day-1 plant-1) were recorded between 91-120 DAS. The mean CGR, RGR and LAI were also maximum under weed free treatment.

Resource use efficiency of cotton in improved vs conventional planting geometry with exogenous application of bio-stimulant and synthetic growth retardant / Eficiência do uso de recursos do algodão na geometria de plantio melhorada vs convencional com aplicação exógena de bioestimulante e retardante de crescimento sintético

Abstract Plant growth regulators and improved planting density are the innovative techniques in the establishment of more productive cotton crop. A field study was planned to assess the role of growth regulators in the resource utilization efficiency of cotton cultivars under different row spacing at Agronomic Research Area, Bahauddin Zakariya University Multan and Usmania Agricultural Farm, Shujaabad during Kharif 2012. The study was comprised of cotton cultivars viz. CIM-573 and CIM-598, cultivated under conventional (75 cm), medium (50 cm) and improved ultra-narrow row spacing (25 cm) and foliar spray of growth regulators viz. moringa leaf extract (MLE) and mepiquat chloride (MC), either alone or in combination, distilled water as a control. The application of MLE alone and in combination (MLE + MC) showed the promoting effect on crop growth rate, net assimilation rate, leaf area index, leaf area duration, sympodial branches and number of bolls leading to higher seed cotton yield of both cotton cultivars grown under conventional row spacing. While application of MC averts the plant growth without considerably improving the productivity. MLE being rich source of growth promoting hormone and nutrients showed its potential to a far greater extent under conventional row spacing in efficient utilization of available resources compared to MC and distilled water.

Resumo Reguladores de crescimento de plantas e melhor densidade de plantio são técnicas inovadoras no estabelecimento de culturas mais produtivas de algodão. Um estudo de campo foi planejado com o objetivo de avaliar o papel dos reguladores de crescimento na eficiência de uso de recursos de cultivares de algodão sob diferentes espaçamentos na Área de Pesquisa Agronômica, da Universidade Multil de Bahauddin Zakariya, e na Fazenda Agrícola da Usmania, Shujabad, durante o Kharif 2012. O estudo foi composto de cultivares de algodão CIM-573 e CIM-598, cultivados em espaçamento de linhas convencional (75 cm), médio (50 cm) e superestreito (25 cm) e de pulverização foliar de reguladores de crescimento, a saber, extrato de folhas de moringa (MLE) e cloreto de mepiquat (MC), isoladamente ou em combinação, e água destilada como controle. A aplicação de MLE isoladamente e em combinação (MLE + MC) mostrou efeito promotor na taxa de crescimento da cultura, taxa de assimilação líquida, índice de área foliar, duração de área foliar, ramos simpodiais e número de cápsulas levando à maior produção de algodão nas cultivares com espaçamento de linha convencional. Em contrapartida, a aplicação de MC evitou o crescimento da planta sem melhorar consideravelmente a produtividade. O MLE, por ser uma rica fonte de hormônio promotor de crescimento e nutrientes, mostrou seu potencial em uma extensão muito maior sob o espaçamento convencional entre as linhas no uso eficiente dos recursos disponíveis em comparação com o MC e a água destilada.

Resource use efficiency of cotton in improved vs conventional planting geometry with exogenous application of bio-stimulant and synthetic growth retardant

Abstract Plant growth regulators and improved planting density are the innovative techniques in the establishment of more productive cotton crop. A field study was planned to assess the role of growth regulators in the resource utilization efficiency of cotton cultivars under different row spacing at Agronomic Research Area, Bahauddin Zakariya University Multan and Usmania Agricultural Farm, Shujaabad during Kharif 2012. The study was comprised of cotton cultivars viz. CIM-573 and CIM-598, cultivated under conventional (75 cm), medium (50 cm) and improved ultra-narrow row spacing (25 cm) and foliar spray of growth regulators viz. moringa leaf extract (MLE) and mepiquat chloride (MC), either alone or in combination, distilled water as a control. The application of MLE alone and in combination (MLE + MC) showed the promoting effect on crop growth rate, net assimilation rate, leaf area index, leaf area duration, sympodial branches and number of bolls leading to higher seed cotton yield of both cotton cultivars grown under conventional row spacing. While application of MC averts the plant growth without considerably improving the productivity. MLE being rich source of growth promoting hormone and nutrients showed its potential to a far greater extent under conventional row spacing in efficient utilization of available resources compared to MC and distilled water.

Resumo Reguladores de crescimento de plantas e melhor densidade de plantio são técnicas inovadoras no estabelecimento de culturas mais produtivas de algodão. Um estudo de campo foi planejado com o objetivo de avaliar o papel dos reguladores de crescimento na eficiência de uso de recursos de cultivares de algodão sob diferentes espaçamentos na Área de Pesquisa Agronômica, da Universidade Multil de Bahauddin Zakariya, e na Fazenda Agrícola da Usmania, Shujabad, durante o Kharif 2012. O estudo foi composto de cultivares de algodão CIM-573 e CIM-598, cultivados em espaçamento de linhas convencional (75 cm), médio (50 cm) e superestreito (25 cm) e de pulverização foliar de reguladores de crescimento, a saber, extrato de folhas de moringa (MLE) e cloreto de mepiquat (MC), isoladamente ou em combinação, e água destilada como controle. A aplicação de MLE isoladamente e em combinação (MLE + MC) mostrou efeito promotor na taxa de crescimento da cultura, taxa de assimilação líquida, índice de área foliar, duração de área foliar, ramos simpodiais e número de cápsulas levando à maior produção de algodão nas cultivares com espaçamento de linha convencional. Em contrapartida, a aplicação de MC evitou o crescimento da planta sem melhorar consideravelmente a produtividade. O MLE, por ser uma rica fonte de hormônio promotor de crescimento e nutrientes, mostrou seu potencial em uma extensão muito maior sob o espaçamento convencional entre as linhas no uso eficiente dos recursos disponíveis em comparação com o MC e a água destilada.

Toxicity of Bacillus thuringiensis Cry2Ab and the inheritance of Cry2Ab resistance in the Pink bollworm, Pectinophora gossypiella (Saunders).

Though the insecticidal crystal (Cry) proteins produced by Bacillus thuringiensis (Bt) are effective against insect pests, evolution of resistance remains an issue of great concern. Here, we explored the ability of pink bollworm, Pectinophora gossypiella (Lepidoptera: Gelechiidae), a key pest of cotton, to evolve resistance to Cry2Ab and characterized it in terms of inheritance. Sixteen day bioassay of Bt Cry2Ab toxin against 5-day old pink bollworm larvae showed median lethal concentration (LC50) ranging 0.16-1.44 µg/g diet for five different populations collected from Srivilliputtur (Tamil Nadu), Jalgaon (Maharashtra), Bharuch (Gujarat), New Delhi (Delhi) and Sri Ganganagar (Rajasthan). Selection of pink bollworm for evolution of Cry2Ab resistance led to the maximal of 37.75-fold resistance vis-à-vis the most susceptible strain. Further studies on inheritance using above parental populations showed autosomal and semidominant nature of Cry2Ab resistance, with dominance h values of 0.69 and 0.79 for two reciprocal crosses. The inheritance of Cry2Ab resistance appeared to be governed by multiple alleles/genes. Cry2Ab resistance was associated with fitness costs in terms of prolonged larval and pupal period when resistant parent population was reared on the diet without toxin. Fitness cost in terms of larval period appeared to be inherited in F1, F2 and backcross progenies. F2 progeny also inherited these differences in larval and pupal periods. These studies clearly advocate rigorous monitoring of Cry2Ab resistance and compliance of resistance management in the pink bollworm for ensuring Bt cotton sustainability.

Assessment of Bt trait purity in different generations of transgenic cottons.

Adequate expression of Bt (Bacillus thuringiensis) toxins and purity of seeds of Bt-transgenic cottons are important for controlling bollworms, and thereby increasing the cotton productivity. Therefore, we examined the variability in expression of Bt toxin proteins in the seeds and in leaves of different cotton (Gossypium hirsutum (L.) hybrids (JKCH 226, JKCH 1947, JKCH Durga, JKCH Ishwar, JKCH Varun KDCHH 441 and KDCHH 621) expressing Bt toxins in F1 and F2 generations, using bioassays against the cotton bollworm, Helicoverpa armigera (Hübner), and the lateral flow strip (LFS) test. Toxicity of Bt toxin proteins in the seeds of Bt-transgenic cottons to H. armigera correlated with their toxicity in the leaves in one-toxin Bt cotton hybrids. The Bt-F1 and Bt-F2 seeds of JKCH 1947 were more toxic to H. armigera than those of JKCH Varun seeds. The seeds and leaves of F1s showed greater toxicity than the F2 seeds or leaves of one-toxin (cry1Ac) Bt cotton hybrids. However, no significant differences were observed for the two-toxin (cry1Ac and cry2Ab) hybrid, KDCHH 621. Toxicity of leaves to H. armigera increased with crop age, until 112 days after seedling emergence. The Bt trait purity in F1 seeds of four two-toxin Bt cotton hybrids ranged from 86.7 to 100%. The present study emphasizes the necessity of 95% Bt trait purity in seeds of transgenic cotton for sustainable crop production.

Yield and fibre quality associated with cotton leaf curl disease of Bt-cotton in Punjab.

Cotton leaf curl disease (CLCuD), caused by Gemini virus and transmitted through whitefly (Bemisia tabaci ) is a serious problem in Northern India, affecting the productivity to a great extent. Depending upon the severity of infection in susceptible varieties, the disease can cause upto 90.0 % yield losses besides this, it also causes deterioration in fibre quality. The objective of the present study was to determine the effect of cotton leaf curl disease on seed cotton yield and fibre characters of two popular Bt-cotton hybrids in Punjab. The disease caused 52.7 % reduction in number of bolls and 54.2 % in boll weight in Bt cotton hybrid RCH 134. Similarly, it reduced the fibre length from 29.1 to 26.2 mm (9.9%); fibre uniformity from 68.9 to 68.1 % (1.1%); fibre strength from 29.1 to 26.9 g per texture (7.5%) and miconaire value from 5.2 to 5.0 g inch-1 (3.8%). Similar results were reported in Bt cotton hybrid MRC 6304, where the disease reduced the boll number and boll weight by 46.1 and 43.4 %, respectively. However, to the fibre quality was not much affected by varying level of disease severity. The studies clearly reflect the adverse impact of CLCuD on yield and fibre quality especially 2.5% span length. Thus suggesting the management of disease using integrated disease management strategies to avoid quantitative and qualitative losses.

Impact of transgenic cotton varieties on activity of enzymes in their rhizosphere.

The impact of five Bacillus thuringiensis (Bt) cotton varieties and their respective isogenic non-Bt(NBt) isolines (ANKUR-2534, MECH-6304, RCH-317, ANKUR-651 and MECH-6301) was assessed on the key soil enzymes i.e., dehydrogenase, alkaline phosphatase and urease in their rhizosphere at four growth stages of the crop, namely vegetative, flowering, bolling and harvesting. These varieties were grown on farmer’s field in villages 22 miles and 24 miles of Ganganagar District of Rajasthan State in India. Results showed that dehydrogenase, alkaline phosphatase and urease activities were higher in rhizosphere of Bt isolines as compared to NBt isolines of all the varieties. Except phosphatase, differences in dehydrogenase and urease activities in rhizosphere of Bt and NBt isolines of all five varieties were significant (P<0.05). Maximum enhancement in the three enzymes activities was observed in MECH-6304 Bt isoline rhizosphere. Maximum and minimum activities of dehydrogenase and urease were observed in MECH-6304 and RCH-317 Bt isolines, respectively, whereas phosphatase activity was maximum and minimum in MECH-6304 and ANKUR-651 Bt isolines, respectively. Maximum dehydrogenase and urease activities were observed at boll formation and minimum at flowering and harvesting stage, respectively, while maximum phosphatase activity was observed at vegetative stage and minimum at harvesting stage. In conclusion, all the studied Bt isolines of cotton varieties showed no adverse effect on dehydrogenase, alkaline phosphatase and urease activities in the rhizosphere.