ACCUMULATED HEAT UNIT FOR THE BEAN CV. ‘CARIOCA’ SOWING-MATURATION SUB-PERIOD IN COLORADO DO OESTE, RONDÔNIA STATE, BRAZIL

Abstract

Heat unit (degrees-day) was determined for the bean (Phaseolus vulgaris L.) cv. ‘Carioca’ sowing-maturation sub-period. Tests were based on phenological data from field experiments carried out during break crop period with irrigation, in 2006, and regular harvest period with and without irrigation, in 2007. Experiments were conducted at the Instituto Federal de Rondônia (IFRO), in Colorado do Oeste, Rondônia State, Brazil. The degrees-day sum (DD) was determined by using two methods. The first method consisted of three different lower base-temperatures (Bt), 10°C, 12°C, and 15°C, and the second one consisted of three different lower base-temperatures (Bt), 10°C, 12°C, and 15°C, and a higher base-temperature (BT), 35°C. Daily air temperature values were obtained at the IFRO weather station, located near the experiments field. There were no significant differences between methods, averaging from 686 to 1,261.9 degrees-day, with Bt of 15°C for the regular harvest period with irrigation and 10°C for the break crop period, respectively. The results show that the accumulated heat unit conditions for bean cultivation are favorable, especially in the regular harvest period with irrigation.

KEY-WORDS: Phaseolus vulgaris L.; bean plant; degrees-day; base-temperature; physicochemical conditions.