STOMATAL AND NONSTOMATAL EFFECTS OF SALINITY ON PHOTOSYNTHESIS IN FABA BEANS (VICIA-FABA L)

The effect of salinity (40 and 80 meq/l NaCl) on stomatal conductance, chlorophyll content, ultrastructural damage and photosynthetic performance of six cultivars of faba beans (Vicia faba L.) from different agroclimatic regions were investigated. Low levels of salinity (40 meq/l NaCl) increased chlorophyll content in some cultivars but did not lead to simultaneous increase in photosynthesis (P). Increased salinity levels (80 meq/l NaCl) decreased chlorophyll content and stomatal conductance. Ultrastructural damage was observed in sensitive cultivars even at low salinity levels. Based on the parameters investigated, there was no concrete evidence to suggest that the physiological processes of cultivars from arid and semi-arid regions are less affected under saline conditions as compared to cultivars from temperate regions. The results suggested increased salinity affects P not only due to its effect on stomatal closure but also due to other non-stomatal effects like ultrastructural damage and decrease in chlorophyll content below a threshold level.