The effect of CaCl on calcium content, photosynthesis, and chlorophyll fluorescence of tung tree seedlings under drought conditions.

The study investigated the effects of different CaCl concentrations (2, 5, and 10 mM) on photosynthetic enzymatic activities, photosynthesis, and chlorophyll fluorescence of tung tree seedlings under drought conditions. Plants were sprayed with either CaCl or distilled water until run-off. Irrigation was then withheld to induce drought stress. The strength of drought stress was evaluated by relative leaf water content and soil water content, which was 27.3 and 9.5% on day 0 and day 12, respectively. Drought stress decreased activities of ribulose-1,5-bisphosphate carboxylase/oxygenase and phospho enolpyruvate carboxylase, chlorophyll ( a+b) content, net photosynthetic rate, stomatal conductance, transpiration rate, electron transport rate, the maximal quantum yield of PSII photochemistry, and effective quantum yield of PSII in tung tree seedlings. The CaCl pretreatments alleviated the negative effect of drought stress to some degree on all the parameters mentioned above. [ABSTRACT FROM AUTHOR]