Soybean is grown predominantly under rainfed conditions where weather variability is high. To analyse the effects of climate change on soybean growth and production, CROPGRO model (DSSAT v 4.5) was applied with four different sowing dates for the diverse environment of akola region of Vidarbha, India. Environmental modification simulated with up scaling of maximum temperature from 1 °C to 5 °C decreased the yield by-4.7-50.4% under 27 MW sowing whereas the magnitude of yield reduction was to a greater degree with delayed 30 MW sowing recorded-8.1 to 78.8% reduction. The down scaled minimum temperature increased the yield by +1.2% at 1 °C downscale. Subsequently, downscaled minimum temperature by 2 to 5 °C decreased the seed yield by-2.5 to-23.7% under 27 MW sowing whereas downscaled minimum temperature by 1 to 5 °C decreased the seed yield by-1.6 to-42.9% under 30 MW sowing. Simulation of CO 2 concentration raised by 100, 200 and to 300 ppm, over the base value (392 ppm) increased seed yield by 16.5 to 38.6% under 27 MW sowing whereas under 30 MW, it increased the seed yield only by 12.8 to 30.4%. Elevated CO 2 concentration of 100 ppm coupled with elevated maximum temperature level by 1, 2 and 3 °C decreased the yield level by-5.4 to-25.7% under 27 MW sowing and-28.4 to-50.8 under 30 MW sowing. Thus overall results show that delay in sowing date in rainfed regions has more negative consequences on soybean productivity under different climate change scenario than early sowing of soybean. CROPGRO model, climate change, sowing date, soybean productivity

Soybean production is widely fluctuating in response to agro-environmental conditions year to year in Vidarbha region. Weather variations are the major determinants of soybean growth and yield. It is also important to study the response of suitable soybean varieties to varying weather parameters. So a field investigation was carried out to study the crop weather relationship of soybean and to optimize the sowing date with different soybean varieties. The results revealed that soybean crop sown up to 27 th MW accumulated higher growing degree days (1640.5 0 C day), photothermal units (20498.1 0 C day hour) and recorded significantly higher seed yield (839 kg ha -1 ) and biological yield (2773 kg ha -1 ) with maximum heat use efficiency (0.51 kg ha -1°C day -1 ) and water productivity (2.49 kg ha-mm -1 ). Later sowings i.e. 30 th MW sowing caused decreased amount of rainfall and increased maximum temperature regime across the total growing period with consequently lower seed yield (530 kg ha -1 ), GDD (1539.2 0 C day), PTU (18689.9 0 C day hour), heat use efficiency (0.34kg ha -1 °C day -1 ) and water productivity (2.05kg hamm -1 ). Soybean variety TAMS 98-21 recorded significantly higher seed yield (734 kg ha -1 ) and highest biological yield (2649 kg ha -1 ) with maximum heat use efficiency (0.44 kg ha -1 °C day -1 ), GDD (1650.5 0 C day ) and water productivity (2.41 kg ha-mm -1 ). Thus, the results of this study illustrated the importance of early sowing with suitable variety of soybean and indicates that sowing upto 27 th MW with variety TAMS 98-21 is optimum for maximizing the yield in the Akola region of Vidarbha.

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A B S T R A C TPlanting density is the most active factor and plays pivotal role in crop management practices. Hence plant density is the enduring topic for crop production improvement. The rational plant population is an important attribute to high yield of cotton, because it can provide a beneficial micro-environment within the canopy for plant growth and development as well as yield formation. A field investigation was carried out at the field of All India Coordinated Research Project on Agro-meteorology, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola (MS) during Kharif season of 2015-16.Three cotton genotypes viz. G.hirsutum cotton AKH-081, G. arboretum cotton AKA-7 and G. hirsutum hybrid Bt. cotton Balwan with three plant densities with the population level of 100,150and 200 per cent of normal for respective genotypes were laid out in Factorial Randomized Block Design with three replications. The results revealed that, cotton genotype G. arboreum AKA-7 with 150 to 200 per cent planting density recorded maximum fraction of PAR, lowest fraction of transmitted PAR and canopy temperature with high canopy temperature depression and greater tolerance to environment stress with comparative to genotypes AKH-081 and Bt. cotton Balwan recorded significantly higher number of picked bolls, boll weight, higher seed cotton weight and harvest index (17.59 g, 3.21 g, 56.49 g and 39.50 %) as compared to genotype AKA-7 and genotype AKH-081. However, AKA-7 registered significantly higher seed cotton yield, cotton stalk yield and biological yield (1715, 3038 and 4753 kg ha -1 ) than Bt. cotton Balwan and hirsutum cotton genotype AKH-081. Normal plant density recorded higher number of picked bolls plant -1 , seed cotton weight plant -1 (11.67 and 33.97 g) which are significantly more over high planting density of 150 and 200 per cent of normal population. However, normal planting at 100,150 and 200 per cent population was recorded being at par. High density planting (200 per cent of normal density) produced maximum seed cotton yield, cotton stalk yield and biological yield i.e.1802, 3338 and 5140 kg ha -1 , respectively. Whereas, high density planting at 100 per cent of normal density produced maximum harvest index (38.08 %) which are significantly higher than 200 per cent high density planting (35.07%) an statistically at par with high density planting of 150 per cent. Different cotton genotype as well as plant density were statistically not significant in respect of quality studies of cotton. K e y w o r d s

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