Impact of nitrogen and water management to grain yield, yield components and traits, and grain quality of two contrasting wheat classes

Abstract

Wheat (Triticum aestivum L.) breeders and physiologists must consider not only grain yield but also its quality. Physiological selection may be an important tool to aid breeders achieve improvements more rapidly. However, different genotypes may have distinct responses to agronomic management and environments. The relationship between those traits also may vary according to wheat class. In the present study we characterized the grain yield, yield components and traits, and quality parameters response of four hard red and four soft white spring wheat cultivars subjected to various nitrogen (N) levels and moisture regimes (stressed vs non-stressed environment) over two years. About one-third grain yield reduction from 2016 to 2017 could be attributed to heat stress. Overall, soft whites had higher grain yield than hard reds, but a stronger negative grain yield-grain protein content relationship. Considering a given year, increments in grain yield also resulted in higher grain protein in hard reds except when N was very low. The cultivar with Gpc-B1 gene for higher grain protein, had similar grain yield to its parent material and to other well adapted hard red cultivar. Vida, characterized by extended green leaf duration after heading (stay-green trait), was better adapted to water and heat stress than the rest of hard reds. Grain fill duration was an important trait especially under heat and drought stress for both wheat classes. We found that, across moisture regime environments and year, productive tiller number had consistently a direct relation with kernel number per area, which was strongly related to grain yield. During the heat and drought stressed year, kernel weight was an important yield component and had neutral relation with kernel number. Nitrogen fertilization had effect on grain yield only during the hot and dry year with irrigation, but no effect was observed under rainfed conditions for this year. Based on the lower grain protein requirement as well the lack of N effect on grain yield for the tested conditions, soft whites may be grown with lower N input than hard reds.