K. Uzunova, Z. Zlatev
Abstract. Laboratory experiments were conducted to study the effect of soil drought on photosynthesis of young cowpea plants (Vigna unguiculata L.) – cv. Lagoa and cv. 1183. Drought conditions were imposed on 2-week-old plants by withholding water for 10 days. It was established that drought seriously inhibits net photosynthetic rate (A) and transpiration rate (E). Minimal (F ) fluorescence increases and maximal (F ) and variable (F ) fluorescence decrease. In light 0 m v adapted leaves a significant decrease in quantum yield (Y), photochemical quenching (qP) and electron transport rate (ETR) of PSII occurred. In conclusion, it is considered that the photosynthetic apparatus of cv. Lagoa is more tolerant and of cv. 1183 more sensitive to drought.