Influence of drought stress and brassinosteroid on growth and physio-biochemical characteristics of apple plants

The experiment was conducted to study the effect of drought stress and brassinosteroid on growth and physio-biochemical responses of one-year-old apple plants of 'Super Chief' and 'Red Chief' varieties. These plants were treated with foliar application of brassinosteroid 0.05 ppm and 0.10 ppm, three days prior to 15 days and 30 days of drought stress. The maximum reduction in growth parameters were registered by plants subjected to 30 days of drought stress as compared to 15 days of drought stress. The transpiration rate owed significant reduction under drought stress. Osmoregulating substances like free amino acid, total soluble sugar content and antioxidant enzyme such as catalase activity enhanced during drought stress which helped in enhancing drought tolerance. Maximum reduction of soil moisture content was registered in 30 days of drought stress over 15 days. However, brassinosteroid at both concentrations could help in maintaining vital growth and physio-biochemical processes under drought stress conditions. Foliar spray of brassinosteroid (0.05 ppm) before the imposition of stress can pave the way to minimize the deleterious effects of drought stress on apple plants.