Assessment of Maize Yield (S.C. 704) Responses to Appropriate Planting Date and Deficit Irrigation Using Multivariate Analysis

Arid and semiarid climate in many parts of Iran dictates the employment of agronomic practices. With this approach, a statistical experiment was set up in split-plot based on randomized complete block design with three replicates during 2015 and 2016 cropping seasons. The experiment took place in College of Agriculture and Natural Resources, University of Tehran. Experimental treatments scheduled on three planting dates: (21st April, 11th May and 31th May) and four irrigation regimes: I100: 100%ETc, I80: 80%ETc, I60: 60%ETc and I40: 40%ETc, based on plant water need. The highest value of water productivity of economical yield (1.19 kg.m-3) and the greatest value of water productivity of biological yield (1.03 kg.m-3) obtained in early-planting date in both years, respectively. Path analysis showed that ear weight with direct effect (1.27) and water productivity of biological yield (0.973), positively contributed to the final yield determination under irrigation regimes I100 and I60, respectively. According to principal component analysis (PCA), the variables such as grain yield, ear weight, biological yield, total number of grain, kernel weight and harvest index as agronomic traits in PC1 and water productivity of economical yield and biological yield as physiological traits in PC2 were accounted for 70% of the final yield variations in total. Due to interactions of planting date and irrigation level on the grain yield (p ≤ 0.01), early planting of grain maize and deficit irrigation management as early season strategies will have great potential to achieve optimal yield and higher water productivity by mitigating early abiotic factors.