Effects of salicylic acid on the physio-biochemical quality of aged tomato seeds

Seed aging adversely affects germination, vigor, and biochemical efficiency, resulting in reduced seed performance and crop growth. The present study addressed the effects of SA priming at varying concentrations (0.10, 0.25, 0.50, 0.75, and 1.00 mM) on the physiological and biochemical attributes of aged (10-, 11-, 12-, 13-, and 14-month-old) tomato seeds. Results revealed that 0.50 mM SA priming significantly enhanced the seed vigor index–I (SVI-I) from 19.6% to 41.3% over the control in 10- and 14-month-old seeds, respectively. Similarly, protein levels were increased by 27%, dehydrogenase (29%) and α-amylase (19%) compared to the control. At 14-month-old seed, electrical conductivity was reduced to 28% over the control. In contrast, higher SA concentrations (0.75 and 1.00 mM) negatively impacted seedling growth, highlighting a threshold beyond which SA becomes inhibitory. The lowest root length was recorded in 1.00 mM SA-primed seeds. The controlled treatment showed higher root length than 1.00 mM SA-treated seeds. The seed germination (%) of 10-month-old seeds varied between 78.66% and 89%, which were significantly different (P = 0.05). This study demonstrates that the optimal SA concentration is crucial for effective seed priming, providing new insights into the physiological and biochemical pathways activated in aged tomato seeds. These findings contribute to the unexplored field of seed aging and establish 0.50 mM SA as an effective concentration for improving seed quality.