Soybean, an essential economic crop used in producing high-quality livestock feed and as an oil source, is highly vulnerable to various abiotic stresses, particularly drought, which can cause over 40% yield loss. A recent study has explored the effects of exogenous nitric oxide (NO) on the physiological properties and essential endogenous hormones in soybean under drought conditions.
The researchers used two soybean varieties, Hei Nong65 (HN65) and Hei Nong44 (HN44), with different abilities to resist stresses such as drought. They simulated drought stress using PEG-6000 as an osmotic substance regulator and sodium nitroprusside (SNP) as the exogenous NO donor.
The study found that the NO content of HN44 leaves increased significantly under drought stress. The NO concentration in soybean leaves increased with the extension of treatment time at 100, 200, 500, and 1000 μmol L−1 SNP concentration. The NO concentration in soybean leaves increased with SNP concentration at 1, 3, 5, and 7 days after treatment.
Drought stress resulted in a significant increase in SOD, POD, and APX activities in HN44 leaves. Under drought conditions, exogenous NO further improved the activities of SOD, POD, and AXP, and with an increase in exogenous NO content, enzyme activity gradually increased.
The findings of this study suggest that the application of exogenous NO can enhance the drought tolerance of soybeans by improving their physiological properties and essential endogenous hormones. This could provide a theoretical basis for selecting a suitable concentration and method for exogenous NO application during the later stage of soybean development and facilitate future studies to explore how exogenous NO regulates crop drought resistance.