Late‐sown winter wheat requires less nitrogen input but maintains high grain yield

Abstract

AbstractIncreased attention on the agricultural impacts to environment has revealed excessive N input to be a major concern. Sowing date reportedly impacts crop N uptake, however, few studies have assessed the effects of late sowing with reduced N apply on crop N status and grain yield. We evaluated three treatments: normal sowing (8 October), late sowing (22 October), and optimized late sowing (22 October, with 75% N application) over two wheat (Triticum aestivum L.) growing seasons (2017–2019), and assessed their effects on crop N status, N allocation and use, net photosynthetic rate (Pmax), grain yield, and soil N budget. Compared to normal sowing, optimized late sowing resulted in near‐optimum N status, improved nitrogen use efficiency (NUE), nitrogen utilization efficiency (UTE), and nitrogen uptake efficiency (UPE), while maintaining a high yield. Although aboveground N uptake of late and optimized late sowing at anthesis was lower than that of normal sowing, N distribution was more optimized, mainly manifesting as: unchanged N allocation to the individual plant, but increased N allocation to flag leaf, and steeper green leaf area N in the canopy under optimized late sowing. Optimized N nutrition index and N distribution under late sowing contributed to a higher Pmax, which resulted in a higher dry matter accumulation rate during post‐anthesis, and ultimately a consistent grain yield among the three treatments. Moreover, N input reduction under optimized late sowing decreased the final mineral N in the 0–100‐cm soil layer at harvest and apparent N loss, which reduced environmental pollution and resources waste.