Submitted to: Annals Of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2001
Publication Date: N/A
Citation: N/A Interpretive Summary: A temperature experiment was conducted on two varieties of cantaloupe to determine how leaf appearance rates are controlled by air temperature. Using this information, we constructed a daily heat unit accumulator which could be used to predict leaf appearance rates and final harvest in the field. In a planting date experiment, we measured the leaf appearance rate and the number of hourly heat units required to reach harvest. In the field experiment, final-melon yields were sharply reduced due to excessively high temperatures. As air temperatures warmed, the time interval from transplanting to 10% final harvest was reduced by 21 to 28 d among the three cantaloupe varieties and the first four transplanting dates. Our goal was to construct a simple muskmelon phenology model which could be run with weather station data and used by growers to quantify phenological development and aid in projecting harvest dates. We also wanted to test whether a main vine node number was a useful description of vegetative development for muskmelon.
Technical Abstract: A temperature experiment with two cultivars of muskmelon (cvs. 'Gold Rush' and 'Mission') was conducted in growth chambers to determine how main vine leaf appearance rates responded to temperature. We identified three cardinal temperatures for leaf appearance rates: a base temperature (10 C) at which leaf appearance rate was zero, an optimum temperature where leaf appearance rate was at a maximum (34 C), and an upper threshold temperature (45 C) where 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 was determined for three cultivars of muskmelon (cvs. 'Explorer', 'Goldrush' and 'Mission') grown in the field over six transplanting dates. The 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. The PI was significantly affected by both cultivar and transplanting dates. Final yields were sharply reduced in the last two planting dates, presumably due to high temperature stresses impacting reproductive development. As air temperatures warmed, the time interval from transplanting to 10% final harvest was reduced by 21 to 28 d among the three cultivars and the first four transplanting dates. Our goal was to construct a simple muskmelon phenology model, which could be run with weather station data and used by growers to quantify phenological development and aid in projecting harvest dates. We also wanted to test whether main vine node number was a useful description of vegetative development for muskmelon.