PHENOLOGY AND HEAT UNITS OF PAPAYO GENOTYPES IN SOUTHERN TAMAULIPAS, MÉXICO

Abstract

Phenology and its relationship with the accumulation of heat units (HU) was evaluated upon four papaws genotypes (Carica papaya L.): ‘Maradol roja’ (MR), ‘Maradol amarilla’ (MA), ‘Zapote’ and ‘Tabasco’. A randomized complete blocks experimental design was used with six repetitions. Evaluated variables were: plant height, crown diameter, youth stage, flowering process, fruit set and harvest stage. A positive relationship was found between growth variables and HU accumulation upon four evaluated genotypes, with coefficients of correlation higher than 0.92. Between December and February plants grew slower, at an average of 4.8 accumulated HU d^-1, but in March plant growth turned faster, with 6.6 accumulated HU d^-1. As for HU requirements by phenological stage, it was determined that during youth stage MA was the earliest with 472 HU, and ‘Tabasco’ was the latest with 865 HU (P ≤ 0.05). The completed flowering process per flower required between 272 and 350 HU; MR and MA flowered earlier than ‘Zapote’ and ‘Tabasco’. There was a considerable increase in fruit set between 1936 and 2293 HU, where varieties MA and Tabasco outstanded. MA showed the earliest harvest with 2800 HU and the highest yield with 130.5 t ha^-1.