Effect of Seed Priming on Seed Germination and Vigour in Fresh and Aged Seeds of Cucumber

Seed priming (seed invigouration) has gained a lot of importance in recent times as it emerged as a most promising area of seed quality enhancement technique. Priming is a pre-sowing treatment, that involves exposure of seeds to a low external water potential that limits hydration,(controlled hydration of seed) to a level that permits pre-germinative metabolic activity to proceed, but prevents actual emergence of the radical. Fresh seeds of cucumber was artificially aged as per ISTA standards to obtain low vigour seed lots. Both high vigour (unaged) and low vigour (aged) seeds were subjected to seed priming with various chemicals (water, KH2PO4, ,K2HPO4,oxalic acid,gibberellic acid,KNO3,calcium chloride, salicylic acid) and results were compared to identify the best priming treatments. Changes in physiological ( per cent germination, total seedling length, total seedling dry weight, seedling vigour index I and II). In cucumber seed priming improved seed germination and vigour significantly over unprimed. The response of low vigour (aged) seeds to seed priming was much higher when compared to high vigour (unaged) seeds. In cucumber, among various priming chemicals tested, seed priming with KH2PO4 10-3M, K2HPO410-3M, KNO3 0.5% were found best as there was 8, 8 and 8 % more germination in high vigour seeds and 15, 15 & 10 % higher germination in low vigour seeds over unprimed (control).Priming with these chemicals also showed better germination per cent in both high and low vigour seeds, over hydropriming, in both the crops. Besides germination, marked increase in vigour as evident from seedling vigour index I and II was noticed due to seed priming in both the crops when compared to unprimed. In cucumber, there was 56 and 53 % higher SVI in less vigour seeds due to priming with KH2PO4 10-3M and K2HPO410-3M,respectively,compared to unprimed, with respect to SVII, the values were 73 and 62 % more due to priming with KH2PO4 10-3M and K2HPO410-3M, respectively, compared to unprimed in cucumber. Priming with chemicals appears beneficial as there was high per cent vigour when compared to priming with water (hydropriming). In cucumber, priming with KH2PO4 10-3M increased SVI by 39 and 36.7 % and SVII by 35 and 26.6 % over hydropriming.