Comparative efficacy of priming treatments and storage periods in overcoming seed dormancy in round gourd (Praecitrullus fistulosus (Stocks) Pangalo)

Abstract: Owing to its hard seed coat, the seeds of Praecitrullus fistulosus exhibit dormancy which impairs the germinability and subsequent seed establishment. To overcome this dormancy, the seeds are required to be stored for a minimum of 45 days after harvest (DAH). In north Indian plains, round gourd seeds are harvested in mid-June and are required to be sown immediately in June-July. Therefore, priming treatments were employed to overcome seed dormancy in a short interval. To assess the effect of various priming treatments in overcoming dormancy, the seeds were stored at room temperature for various durations and at the end of the storage period, the seeds were primed by soaking in solutions of GA₃ (150 µgmL^-1, 500 µgmL^-1,1000 µgmL^-1 gibberellic acid), cytokinin (150 µgmL^-1, 500 µgmL^-1,1000 µgmL^-1kinetin), ethylene (150, 500, 1000 ethrel), KNO₃ (150 and 500 µgmL^-1), HNO₃ (150 and 500 µlL^-1) and water, at 25⁰C for 12 hours and 24 hours, respectively. Among all the priming treatments, 500 µgmL^-1 KNO₃ for 24 h enhanced percentage germination to more than 60 per cent in freshly harvested seeds to more than 80 per cent in seeds stored for 15 DAH. It also enhanced the length of seedling, vigour index (SVI-I and SVI-II), and coefficient of rate of germination (CRG) with a reduction in the mean days taken for germination (MDG).