Water stress mitigation in vegetable cowpea by plant growth regulators

Vegetables are the most susceptible group of crops to water stress, and consume more water through irrigation. Vegetable cowpea is an important protein catering vegetable, largely consumed in Kerala. Water stress is one of the major abiotic stresses that limit crop production and it hampers the physiological and biochemical mechanisms in plants, which lead to reduction in growth and yield. A field experiment was conducted during summer season (January - March) to study the effect of exogenous application of plant growth regulators (PGRs) for mitigating water stress in vegetable cowpea variety Kashi kanchan. The treatments comprised of foliar spray of cycocel (CCC) @ 10 mg/L and 20 mg/L, salicylic acid (SA) and ascorbic acid (AA) each @ 1% and 2%, naphthalene acetic acid (NAA) @ 20 mg/L and 40 mg/L, brassinolide @ 0.5 mg/L and 1 mg/L, coconut water spray and water spray along with three controls treatments viz, farmers’ practice (irrigation at 2 days interval), irrigation at 5 days interval, and irrigation at 5 days interval with no irrigation during water stress imposed period. Results showed that foliar application of plant growth regulators during water stress imposed period resulted in an increased pod yield, stover yield and dry matter production compared to no treatment. Salicylic acid @ 2% also recorded the highest relative leaf water content and total chlorophyll content. Among the foliar applied plant growth regulators, salicylic acid @ 2% and NAA @ 40 ppm were superior in terms of pod yield and stover yield respectively. The present study revealed that foliar application of salicylic acid @ 2% or NAA @ 40 ppm can mitigate water stress in vegetable cowpea.