Effects of brassinosteroids on growth, nodulation, phytohormone content and nitrogenase activity in French bean under water stress

Effect of pre-treatments of 1 and 5 muM epibrassinolide or homobrassinolide prior to water stress induction on changes in root nodulation and contents of endogenous abscisic acid (ABA) and cytokinin trans-zeatin riboside (ZR), and nitrogenase activity was investigated in the nodulated roots of Phaseolus vulgaris L. cv. Arka Suvidha. Brassinosteroids in the unstressed plants increased root nodulation, ZR content and nitrogenase activity, and also ameliorated their stress-induced decline in the nodulated roots. The ABA contents in the nodules of control or stressed plants were not altered by brassinosteroids treatment. There was an increase in pod yield by brassinosteroids treatment ( 5 muM) in the irrigated control as well as stressed plants without influencing pod number or pod length. Among the brassinosteroids, epibrassinolide was relatively more effective.