Abstract

Glycine betaine is an osmoprotectant quaternary ammonium compound that accumulates in response to stress in plants. In order to evaluation stress tolerance, determination of yield amount and vegetative characteristic of Glycine max L. cv. DPX, an experiment was performed under potting conditions in factorial randomized complete block design with 4 replications in natural environmental conditions. Treatments include different levels of drought stress (30, 50, 70 and 100% of field capacity) and exogenous glycine betaine in four levels (0, 2.5, 5 and 7.5 kg ha^-1). Morphological index including plant height, number of branch, number of seed per plant, seed weight 1000, and yield were measured after harvesting. The results indicated that plant height decreased significantly as stress rate increased, but different concentrations of glycine betaine had no significant effect on the plant height. The number of branch, number of seed per plant and seed weight 1000 increased significantly with application of exogenous glycine betaine in different levels of drought stress in comparison with control. This research indicated the role of exogenous glycine betaine in reduction of harmful effects of drought stress and its useful effects on yield and yield components.

Key words: Drought stress, exogenous glycine betaine, soybean, yield.