Thermal units or degree day systems can both be used to quantify relationships between plants and air temperature. The Northern Fluminense region holds no tradition for irrigated papaya (Carica papaya L.) cropping and, because of the need for irrigation, it is important knowing its growth and development characteristics under these conditions. This study aimed to determine the relationship between growth rate of papaya plants and degree days, and its effect on crop productivity, under different irrigation levels. An experiment was set up with the cultivar "Improved Sunrise Soil 72/12", in a randomized blocks design, with seven irrigation water depths and three repetitions; crop growth and yield parameters were evaluated. There were significant correlations between water depths and degree days. Polynomial models of 2nd and 3rd order appropriately fitted the relationships degree day versus plant height, stem diameter, crown diameter and number of emitted leaves, for each water depth. Growth parameters related to degree days and to the applied treatments are indicative of yield potential. The total water depth that promoted the greatest fruit yield was 2,937 mm.
irrigation management; development; papaya; productivity
