Abstract
This study aims to determine variability among soybean (Glycine max (L.) Merr.) cultivars under drought conditions and how nitrogen metabolites, metabolism-related enzymes, and gene expression vary during soybean growth. Three soybean cultivars, Shennong17 (CV.SN17), Shennong8 (CV.SN8), and Shennong12 (CV.SN12), were grown in pot culture and subjected to drought stress at reproductive stages for 45 days. The results showed that long-term drought stress decreased biomass allocation to reproductive organs, weakened antioxidant capacity, and reduced seed weight, effects that were less pronounced in CV.SN12 compared with those in CV.SN8 and CV.SN17. Drought stress decreased the concentrations of nitrogen and soluble protein but increased nitrate concentration in leaves. This was related to the significantly reduction of nitrogen metabolism efficiency, including decreased activities of nitrogen metabolism enzymes, and downregulated expression of GmNR, GmNiR, GmGS, and GmGOGAT. Drought stress increased the concentrations of free amino acid, proline, and soluble sugar in leaves to enhance the osmotic adjustment ability. Furthermore, soybean seed weight showed significantly correlation (p < 0.05) with nitrogen-metabolism-related parameters. Based on the performance of growth, nitrogen metabolism, and yield attributes, CV.SN12 showed the highest tolerance to drought, followed by CV.SN8 and CV.SN17. In addition, these nitrogen-metabolism-related parameters could be used in soybeans to select for drought tolerance.
Highlights
Drought stress is one of the most unfavorable environmental stress factors and can severely reduce crop yield and quality [1,2]
Drought stress during reproductive stages significantly inhibited the accumulation of biomass in root, stem, pod wall, and seed and reduced pod and seed number; more reduction was observed in CV.SN17 and CV.SN8 than CV.SN12
This study showed that drought-stress-reduced soybean seed weight was due to the reduced biomass accumulation of organs and decreased biomass allocated to seed
Summary
Drought stress is one of the most unfavorable environmental stress factors and can severely reduce crop yield and quality [1,2]. Drought stress can interfere with numerous physiological processes, including oxidative stress [3], membrane integrity [4], and enzyme activity [5], all of which could lead to plant growth inhibition. Understanding the effect of drought stress at reproductive stages on physiological and molecular mechanisms of crops is beneficial to grain yield improvement. Plants have evolved various mechanisms, including changing morphological structure, regulating water transport, regulating nutrient synthesis and redistribution, superoxide anion scavenging mechanism, osmotic substance regulation, and hormone regulation, to adapt to adverse conditions [8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
