Ibrahim A. Hassan, Hanan M. Aou Zeid, Jalal Basahi
Bean plants grown under field conditions were exposed to drought stress (DS) and supplementary ultraviolet-B radiation (sUV-B) singly and in combination (DS + sUV-B). The effects of these two stresses on net photosynthetic rate (PN), stomatal conductance (gs), quantum efficiency of photosystem II (�?�?¤PSII), variable to maximum chlorophyll (Chl) fluorescence (Fv/Fm), photochemical (qp) and non-photochemical (NPQ) Chl fluorescence, biomass and yield were investigated. PN, gs, chlorophyll (Chl) content, and NPQ were dramatically reduced due to exposure to DS by 54, 41, 29, and 12% and by 19, 19, 16 and 12% due to exposure to s UV-B, respectively. This reduction resulted in a change in assimilate allocation in favour of shoot growth leading to a decrease in root to shoot ratio and eventually to a decrease in relative growth rate (RGR) of both root and shoot. Seed yield was decreased by 27 and 23% due to DS and s UVB, respectively. Their interaction was more than additive. qp showed no significant response to sUV-B. There was antagonistic interaction between DS and sUB-V showing that DS effectively protects against the adverse effects of sUV-B
Share this article