The effect of sodium nitroprusside levels on germination indices and antioxidant enzyme activity in soybean (Glycine max) seedlings under accelerated aging test

Soybean is among the most important oil crops of the world. Currently, 55% of the world's oil is supplied by soybean. Seed aging, an undesirable feature of agriculture, is one of the main problems in agriculture that leads to economic losses. Although aging is an irreversible process, its speed is delayed by proper storage and optimal storage methods. While kept under inappropriate conditions after harvesting, its quality during storage declines. Priming has a direct and indirect effect on the growth and development of plants, and its indirect effects are more beneficial than its direct effects. Priming improves the longevity of low-vigor seeds. During the priming of these seeds, a long time can occur to repair metabolic damage before any progress in germination, which ultimately prevents further deterioration. Several studies have shown that seed treatment with sodium nitroprusside during reaction with reactive oxygen species and increased activity of antioxidant enzymes is essential to protecting plants against stress. The aim of this study was to the investigate the effect of sodium nitroprusside levels on germination indices and antioxidant enzyme activity in soybean seedlings under accelerated aging test.

This experiment was conducted in 2023 as a factorial in the form of a completely randomized design with 3 replications at the University of Mohaghegh Ardabili. Experimental treatments included accelerated aging treatment at three levels (0, 24, and 48 hours) and three levels of sodium nitroprusside (0, 100, and 200 ppm).

The results showed that aging reduced germination indices including germination percentage (GP), germination value (GV), and mean daily germination (MDG). Also, priming with different levels of sodium nitroprusside, especially the 200 ppm level, improved these traits, but priming with sodium nitroprusside decreased the mean germination rate (MGR) and the mean germination time (MGT). The superoxide dismutase and ascorbate peroxidase enzyme activity due to priming with sodium nitroprusside 200 ppm compared to the control showed an increase of 22 and 26%, respectively. Also, the content of peroxidase enzyme activity showed an increase of about 34% compared to the control in priming with sodium nitroprusside 200 ppm and 48 hours aging compared to the control. The lowest catalase enzyme (7.7 units mg protein-1 min-1) was in pretreatment with sodium nitroprusside 100 ppm and without aging.

The results of this study show that among the different treatments, pre-treatment of seeds with sodium nitroprusside 200 ppm may be considered an effective way to improve germination indices and antioxidant enzymes activity of soybean and can be used as a treatment to deal with salinity conditions in soybean seedlings and improve their growth.