Gibberellins (GAs) are important phytohormones that regulate many developmental processes in plants.  Clove, as the reproductive organ of garlic, dramatically affected garlic bulb development.  Considering the potential of gibberellins in plant development and our previous studies, we investigated the effect of soaking two types of seed cloves (seed clove-I: without root/shoot sprouting; seed clove-II: with root/shoot sprouting) in GA₃ solution on axillary bud development and examined the effect of soaking seed cloves in GA₃ solution on bulb development, phytohormone level and sugar content in this study.Results indicated seed clove types, soaking liquids and their interaction significantly affected the number of cloves per bulb and the rate of single-clove bulb.  Moreover, soaking seed cloves in 1 mmol L^–1 GA₃ solution for 24 h not only promoted axillary bud formation and secondary plant growth (equal to tillering or branching), but also slightly increased the number of cloves per bulb and changed bulb structure with a low yield and marketable quality.  On the 40th day after GA₃ treatment (at axillary bud outgrowth stage), zeatin riboside (ZR) and soluble protein in stem were sharply increased with the increase of GA₃, sucrose, fructose and soluble protein in leaf.  However, GA₃, indole-3-acetic acid (IAA), soluble sugar and sucrose in stem (3.52 ng g^–1 fresh weight (FW), 19.88 ng g^–1 FW, 237.3 mg g^–1 FW, and 8.24 mg g^–1 FW, respectively) were significantly decreased on the 40th day after GA₃ treatment, compared to the control of water treatment (5.56 ng g^–1 FW, 32.96 ng g^–1 FW, 263.6 mg g^–1 FW, and 10.37 mg g^–1 FW, respectively).  To our knowledge, these novel results indicate seed cloves soaked in GA₃ solution promotes axillary bud formation and outgrowth that caused the changes in plant architecture and bulb structure.  Meanwhile, our findings suggest that the level of endogenous plant hormone (GA₃, IAA and ZR) cooperates with the content of sugar (sucrose and fructose) in leaf and stem to regulate axillary bud outgrowth in garlic.

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.