Investigation of positive effects of boron in different wheat genotypes under salt stress

In this study, the physiological and biochemical changes of salt (NaCl, 150 mM), boron (H3BO3; 30 µM) and salt+boron (NaCl, 150 mM+ H3BO3; 30 µM) applications were comparatively investigated in two different wheat (Triticum aestivum L.) genotypes (Momtchil and Pamukova-97). Chlorophyll a fluorescence measurements showed that salt+boron application decreased photosynthetic activity in Pamukova-97 while salt+boron application induced it. Changes in some chlorophyll a fluorescence parameters, such as V/to (accumulation rate of closed reaction centres), 0/(1-0) (performance indicator of the dark reactions), RC/ABS (the amount of active reaction centres per antenna chlorophylls in PSII), ABS/RC (average anttenna size of PSII per reaction centres), TRo/RC (the maximum amount of trapped energy per reaction centres which reduces QA), DIo/RC (the amount of dissipation energy in PSII per reaction centres), indicated that salt+boron application ameliorated photosynthetic activity in Momtchil which was reduced by salinity to some extent. It has been determined that all applications led to the lower ascorbate-glutathione cycle activity, as evaluated with the lower ascorbate peroxidase and glutathione reductase activities. However, salt+boron application caused to higher level of membrane peroxidation, reduced total carotenoid content and degredation in photosynthetic pigments in Pamukova-97. As a result, it could be said that salt+boron application inhibited the ascorbate-glutathione cycle and affected antioxidant system negatively in the leaves of both genotypes. However, we may conclude that salt+boron application ameliorate the negative metabolic effects of salinity because of the lower MDA accumulation and higher photosynthetic activity and photosynthetic pigment content in the levaes of Momtchil.