Effect of boron and high irradiance stresses on chlorophyll, protein and starch content in leaves of cowpea (Vigna unguiculata L. Walp. P152)

The effect of boron (B) and high irradiance (HI) stress on changes in photosynthetic pigments, soluble proteins, and soluble starch in seedlings of cowpea (Vigna unguiculata L. Walp. P152) were investigated under controlled growth conditions. Under both the stress conditions, the photosynthetic pigments and soluble proteins decreased significantly in Bdeficient and B-excess leaves, the degree of decrease being greater in B-excess leaves. Starch accumulated in B-deficient leaves, but not in B-excess leaves. Moreover, the recovery rate from the imposed HI stress was too low in B-deficient and B-excess leaves. Thus, the cowpea plants seem to be highly susceptible to excess B and HI. To the best of our knowledge, this is the first report on the effect of B stress combined with HI stress in cowpea plant.