Cytokinin enhanced biomass and yield in wheat by improving N-metabolism under water limited environment

Abstract

Drought is an important limiting factor for wheat production in most agricultural areas of the world. A study was conducted to analyze the effect of cytokinin [benzyl amino purine (BAP), 40 µM] on growth and yield vis-a-vis nitrogen metabolism in two contrasting wheat cultivars, viz., C-306 (drought tolerant) and PBW-343 (drought susceptible) under water deficit stress condition. Water deficit stress significantly decreased yield and total biomass, while cytokinin-treated wheat plants retained higher biomass and yield. Positive effect of cytokinin on yield and biomass was due to cytokinin induced N-metabolism under both water regimes. Water deficit stress decreases activity of two major enzymes of nitrogen assimilation pathway, viz, nitrate reductase (NR) and glutamine synthetase (GS) and increased total protease activity. Cytokinin enhanced the activity of NR and GS enzymes and reduced the protease activity in both the cultivars and water regimes, which also led to increase in level of total nitrogen and total protein content. Overall, cytokinin was able to delay senescence of leaves under water deficit stress conditions by enhancing N-metabolism in general and specifically at the reproductive stage, contributing to increase in grain yield of both the cultivars under both the water regimes.