A HEAT UNIT MODEL TO PREDICT GROWTH AND DEVELOPMENT OF MUSKMELON TO ANTHESIS OF PERFECT FLOWERS

Growth of 'Earligold' muskmelon (Cucumis male L.), expressed as plant dry weight from transplanting to anthesis, could be predicted using a multiple linear regression based on air and soil temperatures for 11 m ulch and rowcover combinations. The two independent variables of the r egression model consisted of a heat unit formula for air temperatures, with a base temperature of 14C and a maximum reduced threshold of 40C , and a standard growing-degree day formula for soil temperatures with a base temperature of 12C. Based on 2 years of data, 86.5 % of the va riation in the dry weight (on a log scale) could be predicted with thi s model. The base temperature for predicting developmental time to ant hesis of perfect flowers was established at 6.8C and the thermal time ranged between 335 and 391 degree days in the 2 years of the experimen t.