Heat Unit Requirement for Different Phenophases in Mango Varieties under South Gujarat Conditions

The present investigation was conducted at Navsari Agricultural University, Navsari, Gujarat, India during the year 2019-20 and 2020-21. The, requirement of heat units viz., growing degree days (GDD), photo thermal units (PTU) and heliothermal units (HTU) for each phonological event was assessed for seven mango varieties viz., Sonpari, Alphonso, Amrapali, Kesar, Dashehari, Totapuri and Rajapuri. Alphonso consumed minimum heat units viz., GDD, PTU and HTU for attaining flower bud differentiation (1436.90, 17682.21 and 6805.82°C, respectively) and grain stage fruits (38.68, 424.52 and 284.10°C, respectively). For panicle initiation, Kesar required minimum GDD (40.73°C) and PTU (452.23°C). However, HTU requirement was minimum in Sonpari (275.61°C). For initiation of flowering, Sonpari required minimum GDD (37.53°C) and PTU (420.67°C). The requirement for HTU was minimum (316.19°C) in cultivar Dashehari. For attaining pea stage fruits, Alphonso required minimum GDD (48.70°C) and PTU (542.44°C). Whereas, HTU requirement was minimum (357.60°C) in Kesar. Dashehari consumed minimum GDD (93.15°C) followed by PTU and HTU for attaining marble stage fruits. However, minimum requirement of GDD (733.58°C), PTU (9201.91°C) and HTU (6717.69°C) for maturity was observed in Sonpari.