Foliar spraying of aqueous garlic bulb extract stimulates growth and antioxidant enzyme activity in eggplant (Solanum melongena L.)

Recently, botanical extracts are gaining popularity as biostimulants in vegetable production. In present study, the effect of aqueous garlic bulb extract (AGE) was studied on the growth and physiology of eggplant grown in plastic tunnel. AGE was foliage sprayed with various frequencies, i.e., 0, S1 (once), S2 (twice) and S3 (three times) at two independent growth stages, pre-and post-transplant. The results showed that the treated plants exhibited stimulatory responses in growth and physiology in accord with the repetition of AGE spray and growth stages of the plants, respectively. A single foliage sprayed pre-transplant resulted in improved growth, i.e., plant morphology and biomass, and enhanced antioxidants enzymes (superoxide dismutase, SOD; peroxidase, POD), photosynthesis and chlorophyll abundance observed at vegetative, first flowering and fruit setting stages, respectively. However, thrice application inhibited the plant growth and development and resulted in lipid peroxidation, i.e., increased malondialdehyde (MDA) content. In addition, the post-transplant application also showed growth stimulation and interestingly, an overall positive influence was observed with respect to the AGE application and no significant increase in the MDA content indicated the post-transplant seedlings responded well. Our findings demonstrate that AGE can act as a biostimulant to enhance the eggplant growth in plastic tunnel production.