Reversal of Age-induced Seed Deterioration Through Priming in Vegetable Crops - A Review

Vegetables play a vital role in human diet as well as in improving farm income. Good quality of seed is the basic input for success in vegetable production programme. However, age-induced seed deterioration of vegetable crops is an inexorable phenomenon which gets in the way of successful vegetable production. As such seed deterioration caused by ageing and its repair during early germination determine the success or failure of vegetable production system. Seed deterioration can be defined as the loss of quality, viability and vigour either due to ageing or effect of adverse environmental factors. While as ageing may be considered as progressive decline in biological functions accompanied by an increased risk of degenerative changes and death over time. The rate of deterioration rapidly increases with increase in seed moisture content, storage duration or temperature of storage. Loss of seed viability following ageing has been attributed to a series of metabolic defects that accumulate in embryonic and non-embryonic structures. At the cellular level, seed ageing is associated with various alterations including loss of membrane integrity, solute leakage, reduced energy metabolism, impairment of RNA (protein synthesis), and DNA degradation. Seed priming treatment i.e. slowly imbibing and then re-drying of seeds accomplished by soaking of seeds in a solution of low water potential, has been shown to reinvigourate the aged seeds. The reversal of ageing effects by seed priming has been explained by reduction of malondialdehyde (MDA) and free radicals production and maintenance of antioxidant activities due to DNA repair and favorable metabolic balance.