Silica Application Facilitates Vegetative Growth of Winter Squash (<i>Cucurbita maxima</i> L.) Under Water-Saving Irrigation

Abstract

Silicon (Si) is used to alleviate abiotic stress in plants. Applying siliceous fertilizer in combination with regulated deficit irrigation may reduce water consumption during plant vegetative growth period. In this study, winter squash ‘East Elite’ was irrigated with 0.5, 1.0, and 1.5 mM SiO₂ under a field capacity—that is, the water content of 60% (C60, water-saving irrigation). The SiO₂ treatments promoted plant growth including stem diameter, plant height and leaf number; however, the plant growth under water-saving irrigation was slightly (but significantly) lower than that under regular irrigation (C₈₀). Silicon application in the water-saving irrigation can increase the accumulation of fresh and dry weight in the aboveground and underground of plant, but there is no significant difference between the treatments with different concentrations of silicon. Silicon application treatments was significantly higher chlorophyll content (SPAD) than C₆₀, and followed by C₈₀. The SiO₂ in the plants increased with increasing SiO₂ treatment concentration; however, the difference was nonsignificant. The 1.0 and 1.5 mM treatments increased the leaf transpiration rate and stomatal conductance. The growth of the plants treated with 1.5 mM SiO₂ was greater than that of the plants left untreated. The 1.5 mM SiO₂ treatment increased the activity of leaf catalase and peroxidase and reduced the leaf malondialdehyde content of the mild water stressed plants. Irrigation with a SiO₂ solution in a water-saving irrigation system can stabilize plant growth and increase water use efficiency.