LAUSR

Abstract Trehalose (Tre) is a nonreducing glucose disaccharide. It modulates diverse physio-biochemical processes in crop plants. A randomized pot experiment was designed to investigate whether the leaf-applied Tre could improve the growth, photosynthesis, leaf biochemistry, cell viability and yield of Indian mustard. Uniform surface sterilized seeds of mustard were sown in earthen pots. The plants were sprayed with four graded doses of Tre, viz. 0, 10, 20 or 30 mM using a hand sprayer twice at 50 and 70 days after sowing (DAS). The crop performance was assessed in terms of morpho-physiological, biochemical, microscopical and histochemical parameters at 80 DAS and yield attributes at harvest (120 DAS). The spray concentration of 10 mM Tre proved efficacious for all parameters studied, i.e. growth traits, relative water content, gas exchange parameters, enzyme activities, leaf glycine betaine and proline content, stomatal size and width, carbohydrate and mineral content, root cell viability and yield parameters. Moreover, foliar feeding of 10 mM Tre also reduced the generation of superoxide anion and hydrogen peroxide in mustard leaves, which were further confirmed with the fluorescence microscopy and histochemical localization examinations. The spray concentrations higher than 10 mM Tre were either equally or less effective. The foliar spray of 10 mM Tre increased shoot dry mass by 15.81%, chlorophyll content by 17.64%, photosynthetic rate by 17.04%, carbohydrate content by 22.40% and seed yield by 21.85% over the water-sprayed control. The data revealed the overall superiority of 10 mM Tre for improving the performance of Indian mustard.