Physiological and Morphogenetic Responses of Panicum maximum cv. BRS Zuri to Hydrogel and Silicon Application Under Different Water Replacement Levels

This study evaluated the isolated and combined effects of silicon and hydrogel on plant responses to water stress in Panicum maximum cv. BRS Zuri under different water replacement levels. The experiment was conducted in a greenhouse using a randomized complete block design with four replications. Treatments were arranged in a 3 × 3 factorial scheme, comprising three mitigation strategies (silicon, hydrogel, and silicon + hydrogel) and three water replacement levels (40%, 60%, and 80% of field capacity), plus a control maintained at 100% of field capacity. Water restriction significantly reduced ( p < 0.05) relative water content, leaf area, chlorophyll content, leaf appearance rate, leaf elongation rate, and total dry matter. Under severe water deficit (40% of field capacity), the combination of silicon + hydrogel resulted in lower electrolyte leakage and higher relative water content, total chlorophyll, and leaf area than the other treatments under the same water regime. The combined treatment also favored the maintenance of live leaves, leaf elongation rate, and crude protein content. Principal component analysis explained 79.5% of the total data variability, with treatments under severe water deficit characterized by greater electrolyte leakage and leaf senescence, whereas the control and 80% water replacement were associated with greater growth, dry matter accumulation, leaf area, and relative water content. Overall, the combined application was associated with improvements in some physiological and morphogenetic traits under severe water deficit; however, responses in forage production were limited, and the results do not establish a consistent synergistic effect of the two technologies. These findings should be interpreted within the scope of the greenhouse conditions evaluated.