Effect of ageing and priming on seed germination and vigour in onion (Allium Cepa L.)

Onion is one of the important cash crops because of its importance as a vegetable crop, domestic income creation, medicinal use, and high export potential. India is the second largest producer of onions in the world after China. Onion seeds show low storability even under favourable condition due to high lipid peroxidation and an increase in free radical generation. In this study, attempts were made to improve germination and vigour of aged onion seeds. Fresh onion seeds were showing high germination (90%), which was reduced to 36% after two years of storage. A total of 13 priming treatments were used along with the control. Electropriming (EP) and Hydroelectropriming (HEP) were used with hormonal and holopriming. Best germination (82.96%) and seed vigour (706.31) were reported in electropriming treatments 15 Volts and 20 Volts for 2 minutes, respectively. CAT, POD, and SOD activity were also increased after priming. Maximum CAT activity was reported in seeds with GA₃ priming, while maximum SOD activity was reported in EP and HEP. But largely the increase in germination and seedling vigour was the collective effect of CAT, POD and SOD activity, as reported in EP and HEP. These techniques can be further used to improve the viability and vigour of onion seeds stored in seed banks.