Determination of effective heat requirements between full bloom to harvest dates of important Prunus salicina L. cultivars

Abstract

Prunus salicina L. is the most common commercial plum species. Breeding and adaptation studies on Japanese plums have identified suitable varieties for specific regions. Heat requirements are defined as the total temperature required by plants between phenological stages, and problems in this section lead to serious quality losses on fruits. The study aimed to determine the effective heat requirements from full bloom (BBCH scale: Principal growth stage 6: Flowering, Code 65) to fruit ripening (harvest) (BBCH scale: Principal growth stage 8: Maturity of fruit and seed, Code 87) of four Japanese plum varieties in Ödemiş/İzmir conditions. Heat requirements were determined by the Growing Degree Days (GDD) and Growing Degree Hours (GDH) (Anderson and Richardson) methods, using 2-year-phenological data. When the years and varieties were examined together, the Julian days of full flowering and ripening were determined between 74 and 206, respectively. When we look at the number of days from full bloom to harvest, the difference between the varieties was found to be statistically significant and the average number of days from full bloom to harvest was determined as Black Diamond: 118.5, Black Splendor: 92, Fortune: 119,5, Show Time: 98,5 on the basis of varieties. GDD, GDH parameters were found to be statistically significant among the varieties. GDD was determined between 1,055–1,731 among the varieties. The results for GDH (Anderson and Richardson) methods were determined as 29,855–43,382 and 28,818–43,266, respectively. Additionally, correlations between days between full bloom and harvest, Anderson method, Richardson method and GDD were found to be statistically significant with R values in the range of 0.8456–0.998. It is thought that the results will provide significant contributions both to those who will grow plums in choosing the location where they will establish a plum orchard and to researchers in their studies on this subject.