Carpellody is a phenomenon that affects hermaphrodite flowers of papaya, and consists in the transformation of the stamens into additional carpels, resulting in ovary malformation that consequently affects fruit shape and diminishes its market value. The objective of this study was to quantify the incidence of flower carpellody in papaya, and the effect of temperature on this phenomenon. An experiment was carried out between October of 2006 and January of 2007 at ”Los Diamantes” Agricultural Experiment Station, located in the province of Limón. Four breeding lines and four experimental hybrids were arranged in a randomized complete block design with four replications. The analyzed variables were the carpel number for ovaries of hermaphrodite flowers and the daily temperature during a 60-day period prior to floral anthesis of each evaluated flower. The carpel number of lines and hybrids differed significantly each week (p≤0,03). Line and hybrid averages also differed significantly during the twelve-week period (p<0,0001). The cross between a strong carpellodic line and a stable or a weak female-sterile line resulted in a hybrid that exhibited carpellody, which suggests that carpellody is dominant. The correlation between carpel number and temperature suggests that the amplitude of temperature fluctuations during the day was a determinant factor in the induction of carpellody.

Keywords: hermaphrodite-flower, carpels, female-sterility, temperature amplitude.