Thermal requirement and phenological characterization of papaya varieties cultivated under subtropical climate

Abstract

The thermal sum has been widely used to correlate phenological phases of a culture, a technique used to quantify the time required for any phenological phase in any type of environmental conditions, independently of the species. In view of the above, this study aimed to evaluate the thermal requirement and phenological characterization of papaya varieties cultivated under subtropical climate. It was measured the following phenological stages length: from planting to flowering (PF), from flowering to harvest (FH) and from planting to the beginning of harvest (PH), by measuring the time elapsed between each phenological phase. Female and hermaphrodite flowers were considered for measuring the growth curves of fruits by evaluating length (LF) and diameter (DF) of the fruits at 15-day intervals. The thermal requirement was measured by the accumulation of thermal sum in degree-days (DD) during different phenological phases and fruits development period. In current study conditions, it was possible to infer that Sunrise Solo variety and hybrid Tainung n° 1 are earlier, with an approximately 10-month interval between planting and the beginning of the harvest; therefore, necessitating accumulation of 1722.2 and 1798.1 degree-days, respectively.