The effects of high air temperature and waterlogging on the growth and physiological responses of hot pepper

This study was conducted to investigate the effects of waterlogging on the net photosynthetic rate, root activity and fruit yield of hot pepper. Plants were grown in two greenhouses: extractor fans and side ventilators began to operate when the inside temperature reached 25°C in one greenhouse and 35°C in the other. Waterlogging treatments were performed 54 days after transplanting (when fruit setting at the second flower truss was complete). The plot in each greenhouse was divided into five sections, and each section was watered for 0, 12, 24, 48 or 72 h using drip irrigation. Plants under 25°C and non - waterlogging treatment exhibited in the greatest growth among treatments. Plant growth generally decreased as the waterlogging period increased. The net photosynthetic rate was highest under non - waterlogging and 25°C treatment and lowest under 72 h waterlogging and 25°C treatment. The root activity decreased as the waterlogging period increased, except for plants under 72 h waterlogging treatment at 35°C. The number and weight of red pepper fruits per plant were highest under non - waterlogging treatment at 35°C. The greatest fruit yield was also observed under non - waterlogging treatment at 35°C, with production reaching 3,697 kg/10a. At the appropriate temperature for hot pepper (25°C), yields were reduced by 25 - 30% under 12, 24 and 48 h waterlogging treatment compared to non - waterlogging treatment. These results indicate that longer waterlogging periods reduce the growth, net photosynthetic rate, root activity and yields of hot pepper. However, the net photosynthetic rate and stomatal conductance of hot pepper plants grown under 72 h waterlogging treatment recovered nine days after growth under normal growth conditions.