Effect of drought on germination and seedling of Vigna radiata L.

In Algeria, agricultural production is severely limited by several abiotic constraints, the main one being drought. In light of this limiting factor, any attempt to improve and select criteria involved in plant adaptation to water deficit becomes essential. Germination is the most critical stage in the plant life cycle. This process is the basis of plant success and development, and determines uniformity and crop stand density. Successful germination establishes the seedling, which is crucial for the plant’s survival and future growth. The aim of the present work is to study the effect of osmotic and water stress on two crucial developmental stages of Vigna radiata.

Osmotic stress at the germination stage was induced by increasing concentrations of polyethylene glycol (PEG₆₀₀₀) (0, -0.50, -10.27, -13.68, and -17.57bars), while water stress was applied at the seedling stage. All pots were normally watered for three weeks before the application of drought stress, at which point watering ceased.

The results showed that Vigna radiata had a high germination ability, with the germination rate exceeding 90% under an osmotic potential of -10.75 bar, indicating that mung bean seeds are resistant to water deficiency. However, germination was inhibited at -17.57 bar. Applying water stress to seedlings resulted in a gradual decrease in relative water content, accompanied by a slowdown in stem length and leaves number. The root dry biomass/stem dry biomass ratio and root fresh biomass/stem fresh biomass ratio increased in stressed seedlings, indicating that resources were allocated to root elongation at the expense of stem growth in stressed leaves.

The germination of mung bean seeds shows strong resistance to water deficiency, which is a major advantage for the establishment of this species under unfavorable conditions. Water stress leads to morphological changes from the first week of drought stress application.