Salicylic acid priming before and after accelerated aging process increases seedling vigor in aged soybean seed

Seed vigor in soybean (Glycine max (L.) Merr.) declines under environmental stresses, and seed shows signs of aging. The aging effects may be alleviated, however, by seed priming with certain chemicals, such as salicylic acid (SA). The objective of this study was to investigate the effects of SA priming on activities of certain enzymes and lipid peroxidation in soybean seedlings under accelerated aging (AA) process. A factorial, completely randomized design with three replicates was used. Different aging durations (48 h and 72 h), SA priming solutions (0, 300 and 600 mu M) and priming times (before aging, after aging and both before and after aging, i.e., double priming) were the experimental factors. Increasing aging duration significantly increased mean emergence time (MET) but decreased carotenoid content. Nonetheless, SA solution mitigated the adverse effect of seed deterioration on germination-related traits by increasing enzyme activity and reducing malondialdehyde (MDA) content, especially under double priming. A strong negative correlation (r = - 0.99**) was found between MDA content and chlorophyll a and chlorophyll b content. By contrast, the correlation between MDA content and MET (r = 0.95**) was found to be positive. The results suggested that double SA priming was an appropriate practical technique to improve seedling establishment from aged soybean seed.