Impact of salicylic acid and biosilica application on plant growth of shallot under water deficit

Shallot is a horticulture crop with a fibrous root system, which is susceptible to water deficit, particularly in the bulb formation stage. This study was carried out to examine the effects of salicylic acid (SA) and biosilica (Si) exogenous induction on plant growth of shallot grown under water deficit in plastic baskets. A factorial 4×2 experiment was laid out in a randomized complete block design with four blocks. The first factor of treatments was a four-level exogenous induction, i.e., 0.5mM SA, 6mM Si, combination (0.5mM SA and 6mM Si), and control (0 without SA and Si). The second factor was a level of interval irrigations i.e, one-day interval and three-day interval. The results showed that the treatment of combination 0.5mM SA and 6mM Si can maintained a plant height and the number of leaves was better than the control under water deficit. Avoidance was one of the mechanisms of shallot in dealing with water deficit, namely by reducing the stomatal density. Decreased stomatal density was negatively correlated with water use efficiency.