PJB-2018-877
HEAT TOLERANCE SCREENING STUDIES AND EVALUATING SALICYLIC ACID EFFICACY AGAINST HIGH TEMPERATURE IN RICE (ORYZA SATIVA L.) CULTIVARS
Asma
Abstract
High temperature retards plant growth and developmental processes that lead to reduction in crop yield. Major objective of this study was to assess heat tolerant potencies of forty rice cultivars at seedling stage and check the significance of salicylic acid (SA) in improving their thermo-tolerance. Rice seeds were sown in plastic bowls containing sand and heat stress was applied on 15-days old seedlings at 45°C for 12 h and 24 h in growth incubators. Seedling growth stress tolerance indices were used as screening tools. Out of forty cultivars, two heat sensitive (Rambir (EF) and DM 15-1) and heat tolerant (RP 2 and DM 1-30-15-04) were selected for SA studies. SA spray (100 mg L-1) was used on 15-days old seedlings and heat stress (45°C) was imposed on 19-days old seedlings for 12 h and 24 h duration. Growth (root and shoot lengths and fresh and dry biomasses) and biochemical (nitrate and nitrite reductase enzyme, total soluble sugars and proteins, nitrogen, potassium, phosphorous and magnesium) attributes were measured. Heat shock reduced the seedling growth, enzymatic activities and mineral contents. However, SA enhanced fresh and dry seedling biomass, ameliorated the concentration of organic and inorganic solutes in all genotypes under heat stress. SA improved thermo-tolerance in RP2 and DM1-30-15-04 genotypes as compared to Rambir and DM 15-1. These heat tolerant genotypes have the capability to give better growth and seedling stand establishment.
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