Comparison of bean resistance to drought stress during germination stage using polyethylene glycol

Due to the geographical location of Iran, drought stress is the most important environmental stress affecting plant growth. Germination is the most sensitive stage of plant growth under drought stress. So, different types of bean were compared in a factorial experiment based on a completely randomized design with four replications at the Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran. The factors were four types of bean (red bean, white bean, pinto bean and cowpea) and four levels of drought stress (0, -3, -6 and -9 bar). The osmotic potentials for drought stress were prepared by adding different amounts of polyethylene glycol 6000 to water using Mitchel and Kaufman equation (1973). Analysis of variance showed that the simple effects of drought stress and cultivar, as well as their interaction, were statistically significant on germination percentage, germination rate, mean daily germination, seedling vigor index, radicle, and plumule length, radicle, and plumule weight. Seed germination characteristics and seedling vigor were reduced in all types of beans by decreasing osmotic potential. But the reaction rate of different types of beans varied with the intensity of drought stress. In general, comparison of beans showed that their resistance to drought stress during germination stage was as: cowpea, white bean, red bean and pinto bean, respectively.

Keywords:

Germination rate , Osmotic potential , Seedling vigor , Drought stress