Gibberellic acid biosynthesis during dehydration phase of priming increases seed vigour of tomato

Priming of seed is intended to reduce the time to germination through activation of pre-germinative processes. Seed priming is controlled hydration followed by a drying (dehydration) process. The physiological processes during hydration (imbibition) were studied in detail in tomato. In contrast, gibberellic acid changes during the dehydration phase were not studied in detail. We hypothesize that there would be a change in the GA concentration during the dehydration phase of the seed priming process, which may influence the vigour characteristics of the resultant seedling. The objective of the study was to understand the influence dehydration phase of seed priming on GA biosynthesis and its subsequent effect on seed germination and seedling traits of tomato. First, the hydroprimed and unprimed seeds were re-imbibed for 3 h, 6 h, 9 h, and 12 h to initiate the germination process, and the GA concentration and seedling vigour associated parameters were recorded. In the second experiment, the imbibed seeds were dehydrated for 3 h, 6 h, 9 h, and 12 h, then re-imbibed for 3 h, 6 h, 9 h, and 12 h to understand the effect of dehydration on the GA concentration and its associated traits. Results revealed that hydroprimed seeds had a higher GA concentration and seedling vigour than unprimed seeds. The seeds that are completely dehydrated for 12 h had the highest GA and seed vigour parameters. Therefore, increased vigour of hydroprimed seeds is due to the higher levels of GA accumulated during the dehydration phase of seed priming, which can improve seed germination and seedling vigour of tomato.