WATER-RETAINING POLYMER MITIGATES THE WATER DEFICIT IN Schinus terebinthifolia: PHOTOSYNTHETIC METABOLISM AND INITIAL GROWTH

ABSTRACT The use of water-retaining polymer (hydrogel) can mitigate the damage to the photosynthetic apparatus and increase the robustness of young plants under water deficit conditions. Thus, the aim of this study was to evaluate the effect of water-retaining polymer on the morphophysiological aspects of Schinus terebinthifolia Raddi submitted to water deficit. The studied water regimes were characterized by three plant irrigation management: 1) control: irrigated daily, 2) stress: water deficit (irrigation suspension) and 3) stress + hydrogel: water deficit + water-retaining polymer. The plants were submitted to irrigation suspension until photosynthesis approached zero [1st P0], followed by resumption of irrigation (REI) for 15 days. After REI, until recovery of photosynthetic rate of plants, the maintenance of irrigation of all plants for 90 days, characterizing the final recovery (125th day of experiment). The photosynthetic rate reached values close to zero in plants under stress on the 20th day of water restriction, whereas the plants in conditions with hydrogel did not show a decrease in leaf metabolism. Excluding intercellular CO2 concentration, physiological parameters were lower on 1st P0 in plants under water deficit grown without hydrogel than those in plants grown with hydrogel, but all plants showed physiological plasticity. The use hydrogel contributed to the maintenance of the photosynthetic capacity of S. terebinthifolia under water deficit.

摘要 保水聚合物（water-retaining polymer，hydrogel）可在水分胁迫条件下减轻对光合机构的损伤，并提升幼苗的抗逆性。因此，本研究旨在探究保水聚合物对水分胁迫下巴西乳香（Schinus terebinthifolia Raddi）形态生理特性的影响。本研究设置了三种灌溉管理模式的水分处理：1）对照组：每日灌溉；2）胁迫组：水分胁迫（停止灌溉）；3）胁迫+水凝胶组：施加保水聚合物的水分胁迫处理。试验中将供试植株停止灌溉，直至光合速率趋近于零[首次P0节点]，随后恢复灌溉（REI）并持续15天。恢复灌溉结束后，对所有植株维持灌溉90天，直至其光合速率恢复至正常水平，以此表征最终恢复阶段（试验第125天）。在水分限制第20天时，胁迫组植株的光合速率降至接近零的水平，而施加水凝胶的植株叶片代谢并未出现下降。除胞间CO₂浓度外，在首次P0节点，未施加保水聚合物的水分胁迫植株的生理参数均低于施加保水聚合物的植株，但所有供试植株均表现出生理可塑性。施加保水聚合物可维持水分胁迫下巴西乳香的光合能力。