Corn (Zea mays L.) takes up more than half of its total N after tasseling. An experiment was conducted to determine how the availability of N and the N form, NH4 or NO3, during the post‐tasseling period affect corn plant growth, ear development, and nutrient composition. In this experiment, corn hybrid ‘Pioneer 3343’ plants were grown hydroponically in pots outdoors with 50:50 NH4:NO3 up to the emergence of tassels and then the plants were either deprived of N or changed to various ratios of NH4:NO3 nutrition and grown to maturity. Nitrogen deprivation reduced both vegetative (stalk and leaf) and reproductive (cob, total kernel, and individual kernel) dry matter accumulation. Continuous supply of 50:50 ratio of NH4:NO3 produced greater vegetative dry matter than changing to either higher or lower ratios of NH4:NO3. The ratio of NH4:NO3 did not affect the ear dry matter production. Nitrogen deprivation decreased both leaf and kernel N concentration. While 50:50 NH4:NO3 ratio increased the leaf N concentration, all NH4 increased the kernel N concentration compared to other ratios. Nitrogen deprivation also reduced the concentrations of Mg, Fe, Mn, Zn, and B in the leaves but had no effect on the kernel nutrient composition. The cation and anion concentrations in the leaves and kernels were not according to the NH4 and NO3 effects (viz., uptake of cations greater and anions lower with NH4 than with NO3 nutrition), which were previously observed before tasseling. This difference may be due to a change in the uptake capacity for these nutrients after tasseling.

The impact of climate change on agricultural crops is a major concern and threats to the global food security. It also limits the potential of crops and cropping system in a given area. Therefore, the present study was aimed to assess the combined effect of positive (CO2 fertilization, lesser temperature and higher rainfall) and negative (higher temperature, lower rainfall) impacts of the futuristic climatic scenarios on productivity of soybean using APSIM (Agricultural Production Systems sIMulator) model. We have followed the Climate-Crop Modeling Project (C3MP) methodology and generated ninety-nine sensitive test to achieve each test’s temperature, rainfall and CO2 concentration range. Using 30 years of climate data (1980-2010) of Central India as base, the simulation results showed that increasing CO2 concentrations alone resulted in increased soybean yield. Similarly, reduction in rainfall amount indicated negative impact on it. This effect further compounded with increase in temperature and thus, reduced soybean yield. Increasing the temperature with 10% decrease in rainfall declined the soybean yield by 10%. Whereas, increase in temperature along with increase in rainfall also not resulted favorably soybean growth. Decreasing the temperature from the base by 1oC and increasing the rainfall by more than 10% benefitted the soybean productivity, whereas increasing the temperature by 1oC with no change in rainfall resulted decline in soybean productivity by 10-15%.

Quantifying the yield potential of maize at any given site is a key to understand the existing yield gaps and to identify the most important constraints in achieving optimal yield and profit. A well parameterized and validated APSIM model was used to assess the productivity and yield gap of maize cv Kanchan 101 from multi-year long-term and completed experiments. A total of 30 districts with 74 soil profiles of Madhya Pradesh were considered for the study. For the 30 selected sites, the rainfed potential yield of maize (Ywp) ranged from 3.3 to 5.2 t ha-1 whereas the districts mean yield (Yf) ranged from 0.7 to 3.1 t ha-1 giving yield gaps ranging from 1.7 to 3.1 t ha-1. It was observed from the long-term simulation study that there is a good potential to improve the grain yield of maize crop by 3.0 t ha-1 provided optimum dates of sowing and good management practices are followed in the state.

The Semi-arid alfisols are predominant in rainfed agriculture having very low water holding capacity and surface crusting necessitating the adoption of water conservation technologies for drought management. Laboratory experiments were conducted in loamy sand for physical characterization of super absorbent polymers. Four polymer products (P1, P2, P3 and P4) of the commercial value with different concentrations (0.25%, 0.75%, 1.25% and 1.75%) were used and compared with control (soil without polymer). Among four polymer products tested, SAP P3 showed maximum water absorption of 312 g g-1. Maximum soil moisture content of 42% and minimum of 20% was observed at field capacity (0.3 bar) and permanent wilting point (15 bar) with 1.75% SAP concentration. The experiment on water productivity with tomato was carried out with P3 having maximum water absorption at 50 and 80% moisture depletion levels and 0.25, 0.5 and 0.75% polymer concentrations in growth chambers. Significant difference (p=0.05) was observed among different polymer concentrations at 50% soil moisture depletion level. The maximum yield in tomato (2.71 kg/plant), water productivity (318.52 kg m-3), water saving (69.3%) and 90% enhanced root growth were obtained with 0.75% polymer concentration (P3) at 50% soil moisture depletion.