IMPROVING GROWTH AND PHYSIOCHEMICAL ATTRIBUTES OF Leymus chinensis THROUGH EXOGENOUS BRASSINOLIDE, UREA AND POTASSIUM DIHYDROGEN PHOSPHATE IN ARID GRASSLAND

Abstract

Leymus chinensis (Trin.) is a dominant grass species in the Northeastern China Plain and the Inner Mongolia Plateau of China; however, this grass is under sever threat due to abiotic stresses such as drought and other human-induced practices. There are strategies to compensate the stress injuries and some plant growth substances show the potential to ameliorate the damaging effects. Therefore, an experiment was conducted with the objective to improve stress tolerance of L. chinensis through exogenous concentrations of urea, potassium dihydrogen phosphate (KH2 PO4 ) and brassinosteroid (BR). The experimental site was Inner Mongolia Xilinguole, China. The experimental design was Randomized Complete Block (RCB) and treatments were T1 =1 % urea + 0.5 % KH2 PO4 +0.2 mg L-1 BR; T2 =2 % urea + 1 % KH2 PO4 + 0.2 mg L-1 BR; T3 =3 % urea + 2 % KH2 PO4 + 0.2 mg L-1 BR, and NT=water spray (control). The fresh, dry weight and plant height of treatments were enhanced as compared to control. Besides, treatments significantly increased biosynthesis of chlorophyll, carotenoids, and activities of glutathione reductase and peroxidase. Higher doses of mixed fertilization (T2 ) improved accumulation of soluble proteins, sugars, free amino acids, and activities of ascorbate peroxidase, superoxide dismutase and catalase: 56 %, 58 %, 44 %, 33 %, 7 % and 47 %, respectively, over control. It is concluded that improvements in physiochemical attributes enhanced accumulation of fresh, dry weight and plant height of L. chinensis.