Variation in Morphological and Quality Parameters in Garlic (Allium sativum L.) Bulb Influenced by Different Photoperiod, Temperature, Sowing and Harvesting Time

Photoperiod (light) and temperature as abiotic factors having significant impact on the garlic bulb morphology and quality. In various bulb plants including garlic, bulbing is affected by photoperiod, temperature, sowing date and the plant age. In this backdrop experiments were performed to understand the effect of different photoperiods (10 h/14 h, 12 h/12 h and 14 h/10 h (light/dark)), temperatures (25 °C/18 °C and 30 °C/20 °C (light/dark)), sowing dates (D₀₈₀₁: 1^st August, D₀₉₀₁: 1^st September and D₁₀₀₁: 1^st October) and plant ages (A₈₀, A₆₀ and A₄₀: 80, 60 and 40 days after planting) on garlic cultivars viz; G103, G024 and G2011-5. Parameters including morphological (plant height, fresh weight and pseudostem diameter), bulb attributes (diameter, weight, height and bulbing index), growth period and bulb quality related traits (total soluble solid (TSS), contents of soluble protein, soluble sugar, total sugar, glucose, sucrose, fructose, starch, total phenol and total flavonoid) were assayed. Longer photoperiod (14 h), higher temperature (30 °C), early sowing (D₀₈₀₁) and maximum plant age (A₈₀) had maximum morphological and bulb quality related traits for cv. G103. These results showed that early sowing, maximum plant age, longer photoperiod and higher temperature are important for garlic bulb formation and quality. Moreover, the regulation of garlic bulb morphology and quality is achievable over the switch of sowing date, plant age, light and growth temperature.