Effect of potassium bicarbonate on photosynthetic parameters of Setaria viridis under drought conditions

Abstract

The current study set out to investigate the effects of drought stress and potassium bicarbonate (KHCO3) on green foxtail (Setaria viridis (L.) Beauv.) photosystem II (PSII) photochemistry under a moderate and severe drought. The plants at phenological stage 13 (according to BBCH scale) were divided into three groups and sprayed with water or with 10, 20 and 30 mg l-1 KHCO3. The plants of the first group (well-watered) were hand-watered every second day. The plants of the second (moderately stressed) and third (severely stressed) groups were used for drought stress treatment by withholding water. The results indicated that drought conditions resulted in a decrease in maximum quantum yield and effective quantum yield most likely due to the expected photoinhibition of photosystem II. Decreased gas exchange parameters revealed that the reduction in photosynthesis of green foxtail under drought stress was caused by the stomatal factors. A significant increase in the maximum quantum yield, effective quantum yield and gas exchange parameters in KHCO3 treated plants showed that KHCO3 protects photosystem II of green foxtail from drought, and may have potential benefit for other C4 plants.