Temperature Effects on Phenological Development and Yield of Muskmelon

Abstract

Our goal was to construct a simple muskmelon phenology model that could be run with easily obtainable weather station data and used by growers to quantify phenological development and aid in projecting harvest dates. A growth chamber experiment was conducted with two cultivars of muskmelon (‘Gold Rush’ and ‘Mission’) to determine how main vine leaf appearance rates responded to temperature. We identified three cardinal temperatures for leaf appearance rate: the base temperature (10°C) at which leaf appearance rate was zero; an optimum temperature (34°C) at which the rate of leaf appearance was maximal; and an upper threshold temperature (45°C) at which leaf appearance rate returned to zero. Using these three cardinal temperatures, we constructed a simplified thermal unit accumulator for hourly measurements of air temperature. Main vine plastochron interval (PI), thermal time to harvest, and final yield were determined for three cultivars of muskmelon (‘Explorer’, ‘Gold Rush’ and ‘Mission’) grown in the field at Overton, TX, USA, over six transplanting dates from March to June 1998. PI was calculated for each cultivar×transplanting date combination as the reciprocal of the slope of main vine node number vs. accumulated hourly thermal units (ΣTu). PI was significantly affected by both cultivar and transplanting date. Final yield was sharply reduced in the last two planting dates, presumably due to high temperature stresses impairing reproductive development. As air temperatures increased during the field experiment, the time interval from transplanting to 10% final harvest was reduced by 21 to 28d among the three cultivars and the first four transplanting dates. Main vine node number was a useful descriptor of vegetative development for muskmelon.