Photosynthesis-Involvement in Modulation of Ascorbate and Glutathione in Euterpe oleracea Plants Exposed to Drought

The present study aimed to determine if photosynthesis interferes with the modulation of antioxidant compounds in young Euterpe oleracea plants exposed to water deficiencies. A factorial, completely randomised experimental design was employed, and two water conditions (water deficit and control) and four evaluation points (0, 6, 12 and 18 days) were used, resulting in a total of eight measurements. The measured parameters included the water content and temperature of the leaf, gas exchange, electrolyte leakage, and antioxidant content. Compared to the control treatment, the net loss of photosynthesis due to water restriction increased by approximately 100% on the 18th day of drought. The ascorbate levels decreased due to water restriction, presenting significant differences on the 12th and 18th day. In some cases, the water deficit increased the glutathione content; however, significant effects were only observed on the 18th day after irrigation suspension. Water deficits had a negative impact on stomatal conductance, net photosynthesis rate, transpiration rate, and instantaneous carboxylation efficiency. Additionally, increases in the glutathione content, electrolyte leakage, and malondialdehyde content were observed; however, the ascorbate content decreased. Our results confirmed that the rate of photosynthesis interfered with the modulation of ascorbate and glutathione in young Euterpe oleracea plants exposed to drought.