Cowpea (Vigna unguiculata L.) is one of the promising legume crops, landraces of which have been traditionally grown mainly in the Southern parts of Bulgaria. It has a high tolerance for dry conditions. Therefore, it is a promising crop for growing under rainfed conditions. The objective of this study was to analyse some photosynthetic parameters in cowpea plants during dehydration and rehydration. The studies were conducted with two landraces. Seeds were sown in pods of 5l. Soil moisture was raised to 75- 80 % of soil humidity and maintained weight. In each pod were grown in four plants. Plants of each landrace were divided in 2 groups: (1) plants with water regime 75 - 80 % of full soil humidity and (2) plants, with water regime 35 - 40 % of soil humidity for 10 days period. After drought soil humidity was restored to a level 75 - 80 %. Net photosynthetic rate (Pn), stomatal conductance (gs) and transpiration (E) were severely decreased by water deficit. A gradual reduction in leaf water potential was observed too. In light-adapted leaves a significant decrease in quantum yield (Y) and electron transport rate (ETR) of PSII was occurred.
Changes in Photosynthetic activity in Vigna (Vigna Unguiculata L.) under drought conditions