Evaluation of growth of papaya (Carica papaya L.) fruits in plants propagated from seeds and by grafting, as a result of the accumulated degree-days

Abstract

An efficient way to study the development of papaya as a function of temperature is to relate it to the accumulation of heat, expressed in degree-days (DD), which has been used to estimate the amount of heat required for the growth and maturation of fruit. Temperature has a strong influence on the development of papaya fruits. We evaluated the growth in length and diameter in two different periods of the year (autumn/winter and spring/summer) in plants of three cultivars of papaya (‘Tainung 1’, ‘Golden’ and ‘Solo Sunrise’), some grafted and some propagated by seeds. According to the analysis of variance, there was a difference between the evaluation periods for autumn/winter and spring/summer. However, no significant difference for the different treatments within the same period of the year were found, within the same group of cultivars, the Solo and the Formosa groups, for the grafted and ungrafted plants. During autumn/winter, fruits took 175 days from anthesis to maturity, while in spring/summer, time maturity decreased to 112 days. The differences of climatic dry and wet seasons of the Mid-West region of Brazil make papaya production seasonal. The specific grafting processes in the evaluated papaya cultivars did not interfere with fruit development differently, but in grafted plants, fruit growth in the first load was slightly higher than in non-grafted plants, probably due to lower competition that these plants had to sustain at the beginning of cultivation and due to the greater availability of nutrients.