Phenological growth stages and heat unit requirement of Indian blackberry (Syzygium cumini L., Skeels)

Indian blackberry (Syzygiwn cumini) is an important underutilized tropical fruit crop of India possessing high nutraceutical value. In this study phenological growth phases of Indian blackberry have been defined according to the extended BBCH (Biologische Bundesantalt, Bundessortenamt und Chemische Industrie) scale using three-digit numerical system. A total of 40 secondary growth stages of Indian blackberry have been defined within its seven principal growth stages viz; bud development (0), leaf development (1), shoot development (3), inflorescence development (5), flower development (6), fruit development (7) and fruit maturation (8). Heat unit requirement for each phenological growth stage was also worked out in terms of growing degree days (GDD). It was observed that more accumulated heat unit was required for shoot development and fruit development. Description of phenological growth stages and their heat unit requirements will not only be helpful in ensuring efficient orchard management but also in assessing the response of crop to climate variables and its adaptive potential.