Yield and Healthy Trait Harvest of Maize with Adjustment of Sowing Timing and N Rate in a Monsoon Region under the Changing Climate

Maize (Zea mays L.) is important for grain and fodder; its optimal production ensures food security. The seasonal shift of monsoon rain is becoming a threat to high maize production in Pakistan. This study addressed changes in phases of the crop lifecycle and their effects on yield. The experiment was conducted in 2017 and 2018 at the Agronomy Research Farm of the University of Agriculture Peshawar, Pakistan, as split plot in randomized complete block design with three replications. Sowing timing (ST) from June 6 to July 16 with 10-day intervals was the factor in main plots, and N rate (NR) 160, 180, 200, and 220 kg ha⁻¹ was the factor in subplots. Results revealed significant changes (p < 0.05) in the crop lifecycle, with a significant decrease in the reproductive versus the vegetative phase of growth for each 10-day delay from June 16. Likewise, a decrease in grain yield was observed by limiting NR from 200 kg ha⁻¹, with no change (p < 0.05) from 220 kg ha⁻¹. A decrease in yield caused by delayed sowing was mainly due to low floret fertilization with fewer grains per row and limited grain weight overall due to fewer days of reproductive growth, which affected grain yield accordingly. High NR of 200 kg ha⁻¹ is advantageous for crops facing flood irrigation with a heavy monsoon season for harvesting optimal production. The study concludes that maize planted after wheat (or any other crop) should be planted early in the season, in June, to avoid monsoon rain damage for optimum density and to ensure high production with healthy traits for future food security.