Thermal requirement of pomegranate varieties growing in Maharashtra

A field experiment was carried out to quantify growing degree days (GDD) requirement of 10 pomegranate varieties (i.e. Bhagwa, Ganesh, Mridula, Arkata, Jyoti, G-137, P-13, Kandhari, Bassein Seedless and Jalore Seedless) at ICAR-NRCP, Solapur, situated at 17° 10^’’ north latitude, 74° 42^’’ east longitude and 483.5 m above mean sea level. The water requirement through drip irrigation system at 90% efficiency for Mrig bahar (rainy season flowering) ranged from 5.7–13.0, 8.0–18.2, 9.2–20.8 and 10.3–23.4 l day⁻¹ tree⁻¹ for 2^nd to 5^th year pomegranate trees. The seasonal values of water applied to 2^nd to 5^th year pomegranate trees were estimated as 1259, 1763, 2015 and 2266 l bahar⁻¹ tree⁻¹, respectively. Total GDD accumulations of all the varieties ranged from 2948 to 4105°D from defoliation to harvesting period. The growing degree days ranged from 947 to 1278°D at flowering stage and 2134 to 3306°D at fruiting stage. The lowest and highest GDD build up from defoliation to harvesting period were 2948°D for ‘G-137’ and 4105°D for ‘Bhagawa’, respectively. Photo-thermal index (PTI) at flowering and fruiting stages and heat use efficiency (HUE) of ten varieties ranged from 16.6 to 17.4°D/day, 16.5 to 18.3°D/day and 3.2 to 4.0 kgha⁻¹ degree day⁻¹, respectively. The growing degree days (°D), photo-thermal index and heat use efficiency indices may be used to assess the crop performance with respect to suitability of the variety to a particular locality depending on the prevailing thermal environment.