Biochemically Triggered Heat and Drought Stress Tolerance in Rice by Proline Application

Abstract

Abiotic stresses are the prime coercion to sustainable crop production in changing climate scenario. Heat and drought stresses at reproductive as well as vegetative stages of rice cause extensive reduction in its yield. Being a multifunctional amino acid, proline is being used to diminish numerous biotic and abiotic stresses of plants. A pot experiment was conducted in summer season 2018, to check the effectiveness of foliar applied proline in mitigating the concurrent effects of heat and drought stresses on rice, at greenhouse/screenhouse of Faculty of Agriculture, University of Agriculture, Faisalabad, Pakistan. Experiment was carried out under completely randomized design with split arrangement having three replications. Stress was imposed at anthesis with treatments viz. drought stress, heat stress and heat plus drought stress as a main factor, and various levels of exogenously applied proline viz. no proline/water spray, 10, 20 and 30 mM concentrations were maintained as subfactor. A control (no stress imposed) was upheld for comparison. Stress treatments: drought, heat and heat plus drought stress at anthesis stage depressed the production of antioxidants, osmoprotectants and chlorophyll contents while causing overproduction of malondialdehyde content. Exogenous proline application upregulated activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), total soluble proteins (TSP), leaf proline and glycine betaine contents and diminution in lipid peroxidation resulting into improvement in chlorophyll contents and eventually yield per plant. Concurrent heat and drought stresses were more perilous as compared to individually applied heat or drought stress and 30 mM proline application gave maximum alleviation against stress.