Response surface optimization of nitrogen fertilization and grain density for sustainable wheat yield

Given the escalating demand for wheat and the imperative to mitigate the environmental consequences stemming from excessive chemical fertilizer use, this study investigated the combined effects of grain density and nitrogen fertilizer levels on wheat grain yield and its components under sustainable agricultural conditions. Utilizing the response surface methodology (RSM) and a central composite design (CCD), the impact of three grain density levels (100, 160, and 220 kg ha − 1 ) and three nitrogen fertilizer levels (0, 110, and 220 kg ha − 1 ) was evaluated on parameters such as grain yield, plant height, number of spikes per unit area, number of grains per spike, and grain weight per spike. The results indicated that both factors significantly affected the studied variables, with nitrogen fertilizer identified as the primary factor. A reduction in grain density considerably improved grain yield and augmented the positive effects of nitrogen. The regression models, exhibiting a high coefficient of determination (R 2 > 0.97), provided accurate predictions of the responses ( P < 0.05). Findings suggest that increasing nitrogen application enhances yield and yield components, while decreasing grain density can amplify this trend for grain yield, number of grains per spike, and grain weight per spike. A grain density of 100 kg ha − 1 is proposed as the optimal treatment for enhancing yield while minimizing chemical fertilizer consumption. This represents an effective and sustainable approach to improving wheat production efficiency, offering an environmentally and economically viable solution for sustainable agriculture.