Silicon Alleviates Damages on Photosynthetic Apparatus and Increases Resilience in Young Inga vera Plants Exposed to Water Deficit

Foliar application of silicon (Si) can alleviate damage to photosynthetic apparatus and increase the resilience of plants, in addition to delaying visual stress symptoms under water deficit. The aim of this study was to evaluate and alleviate the potential to mitigate the stressful effect of water deficit in young Inga vera Willd. plants and help in the physiological recovery on post-stress. The plants were cultivated under five cultivation conditions: control: (1) daily irrigation in the substrate, (2) water deficit by restriction (WR): total irrigation suspension, (3) WR + 0.84 g Si, (4) WR + 1.68 g Si, and WR + 3.36 g Si, and evaluated until they had water deficit symptoms, and the irrigation resumption was performed for 30 days, characterizing the recovery (REC, post-stress). Untreated plants and plants with 3.36 g Si presented water deficit symptoms at the 7th day of water restriction, while 0.84 and 1.68 g Si tolerate until the 9th and 11th day of water restriction, respectively. Foliar application of 0.84 g Si alleviates the damage to the photosynthetic apparatus and water use efficiency, and favored the physiological recovery. Plants with 0.84 g maintained 38.57% P-N compared to those grown under water deficit without Si application. Si beneficial effect in the reaction centers occurred with 0.84 g by favoring the increase of photochemical efficiency in photosystem II in the post-stress. I. vera is a species that has resilience potential due to physiological plasticity; despite the initial growth is negatively affected by the water restriction, there was recovery after the water supply resumption. Si application of 0.84 and 1.68 g is a promising practice for contributing to I. vera gas exchange regulation during water deficit and post-stress.