Effect of seed priming with potassium nitrate on growth, fruit yield, quality and water productivity of cantaloupe under water-deficit stress

Drought stress poses a serious challenge to sustainable production of agricultural crops necessitating the adoption of proper technique to minimize the harmful effect of this abiotic stress in crop production. Cantaloupe is susceptible to water-deficit stress and seed priming with potassium nitrate (KNO3) could be a potential alternative to mitigate the adverse effect of water-deficit stress and sustain crop productivity. Laboratory and polyhouse experiments were conducted to evaluate the effect of seed priming with KNO3 in alleviating water-deficit stress on cantaloupe measured in terms of growth, fruit yield, quality and irrigation water productivity. In the laboratory experiment, seeds were grown on petri dishes after primed with 25, 50 and 100 mM KNO3 along with a non-primed control and hydropriming. Non-primed seeds had lower germination rate, germination energy and germination rate index, while higher germination time than priming doses of 25, 50 and 100 mM KNO3. In the polyhouse experiment, cantaloupe was grown in pots subjected to five priming treatments (non-primed control, hydropriming and osmopriming with 25, 50 and 100 mM KNO3) under three soil moisture regimes (50%, 75% and 100% field capacity [FC]). The results revealed a drastic reduction in fruit yield and irrigation water productivity (68% and 32%, respectively) at 50% FC compared with 100% FC. Plants grown from seeds primed with KNO3 had an overall better response than the non-primed control and hydroprimed plants. Priming dose of 100 mM KNO3 resulted in 45%, 35% and 48% higher fruit yield than the non-primed control plants at 100%, 75% and 50% FC, respectively. A similar trend was also observed in fruit quality parameters and irrigation water productivity. There was no difference in fruit yield and irrigation water productivity of plants raised from seed priming doses of 50 and 100 mM KNO3 at moisture-deficit conditions of 75% and 50% FC, while seed priming dose of 100 mM exhibited better results than all other priming doses when soil moisture was sufficient (100% FC). Priming seeds with optimum dose of KNO3 corresponding to the available soil moisture level might be a promising approach to maintain productivity of cantaloupe; however, seed priming with KNO3 might not produce marketable fruits under severe soil moisture deficit condition.