Optimizing root architecture with nitrogen fertilization to improve nitrogen accumulation and yield in soybean

Area of Science:

• Agronomy
• Plant Physiology
• Soil Science

Background:

• Xinjiang, a major Chinese soybean producer, faces challenges with low nitrogen use efficiency (NUE) impacting yields.
• Optimizing nitrogen (N) fertilization is crucial for enhancing soybean productivity in this region.

Purpose of the Study:

• To determine the optimal nitrogen application rate for improving soybean root development, nitrogen metabolism, and yield in Xinjiang.
• To evaluate the effects of different nitrogen levels on soybean cultivars Xindadou 27 and Xinnongdou 2.

Main Methods:

• A two-year field experiment (2022-2023) using a split-plot design.
• Tested four nitrogen rates (0, 120, 180, 240 kg N ha^-1) on two soybean cultivars.
• Analyzed root growth parameters, nitrogen metabolism enzyme activities (NR, GS/GOGAT), and nitrogen accumulation.

Main Results:

• 180 kg N ha^-1 significantly improved root growth (density, length, surface area) and nitrogen metabolism enzyme activity in the 0-60 cm soil layer.
• This rate enhanced nitrogen uptake, translocation, shoot nitrogen accumulation, and ultimately, soybean yield.
• Excessive nitrogen (240 kg N ha^-1) negatively impacted root development and nitrogen metabolism, reducing accumulation.

Conclusions:

• Application of 180 kg N ha^-1 at the beginning pod stage is recommended for spring soybean in Xinjiang.
• This strategy promotes root development, boosts nitrogen use efficiency, and achieves sustainable high yields.
• Optimized nitrogen fertilization is vital for maximizing soybean production in Xinjiang's specific agro-ecological conditions.