Evaluating corn production under different plant spacings through integrated modeling approach and simulating its future response under climate change scenarios

The use of advanced resource conservation techniques is the need of time for higher crop production under the challenges of water scarcity and climate change. The present study was planned (1) to evaluate different plant spacing of corn, sown under raised bed planting (RBP) for higher productivity, (2) calibrate APSIM model for experimental treatments and (3) simulate future (2022-2100) crop response under different scenarios of climate change. The two-year research experiments were conducted on corn with four different plant spacings (S1:15 cm, S2:17.5 cm, S3:20 cm and S4:22.5 cm) under RBP. The crop response was evaluated in terms of leaf area index (LAI), plant height, flowering date, grains per cob, grain yield, biomass yield, harvest index (HI) and water productivity. The S1 treatment produced the highest productivity in terms of grain yield (7.16 Mg/hm2), biomass yield (16.57 Mg/hm2), HI (0.44) and water productivity (1.33 kg/m3). APSIM model was calibrated and its ability to simulate crop response during validation was confirmed from the values of RMSE, NRMSE, R2, CRM and NSE as 0.4, 0.21, 0.83, 0.04 and 0.68 for grain yield. The RMSE and NRMSE were 0.79 and 0.14 for biomass yield. The value of R2 ranged from 0.69 to 0.85, CRM from -0.03 to 0.005, NSE from 0.69 to 0.86 for biomass yield, plant height and LAI. During scenario simulations, the model run was performed against different plant spacing for optimization and results revealed that 10 cm plant spacing produced highest corn yield and growth parameters. Further simulations (2022-2100) were performed using climatic data, acquired from different general circulation model (GCMs) for two rcps (4.5 and 8.5) and results revealed the reduction in grain and biomass yields by 8-14 % and 10-28 %, respectively against different data sources (GCMs). Optimized plant spacing (10 cm) under RBP produced 35.5 % more grain yield and 29.3 % more biomass yield than that under control treatment (ridge-furrow system). Based on the research findings, it is recommended that conservation technique like RBP needs to be adopted in semi-arid regions to mitigate the impact of climate change in terms of future temperature rise for better corn production.