Effects of Heating Initiative Temperature and CO2 Fertilizing Concentration on the Growth and Yield of Summer Squash in a Greenhouse

Abstract

This study was conducted to find out the efficiency of heating initiative temperature and carbon dioxide fertilization in summer squash (Cucurbita moschata D.). The heating start temperature experiment was performed at 9°C, 12°C, and 15°C using an electric heater and operated when the temperature was lower than the target temperature. The CO 2 fertilization concentration experiment was performed from 7 to 12 with the control, 500 µmol•mol -1 , and 800 µmol•mol -1 using liquefied carbon dioxide. Investigation items were plant height, stem diameter, number of leaves, leaf area, fresh weight, dry weight, also economic analysis was conducted by surveying only fruits exceeding 100 g. Photosynthesis was measured for the upper leaf position to calculate the saturation point according to the control. The photo saturation point was 587 µmol•m -2 •s -1 , and the CO 2 saturation point was 702 µmol•mol -1 . A max values by carbon dioxide were 13.4, 17.8, 17.2, 19.6, and 17.5 µmolCO 2 •m -2 •s -1 in the order of 9°C, 12°C, 15°C, 500 µmol•mol -1 , and 800 µmol•mol -1 . In the temperature experiment, 9°C in growth did not grow normally and no fruiting was performed. 12°C and 15°C were higher than 9°C, but there was no significant difference in growth and production. The CO 2 fertilization experiment showed no significant difference between the treatment in growth, but the productivity of 800 µmol•mol -1 was the best. Comprehensively, the heating initiative temperature of 15°C was good for crop growth and production, but there is no significant difference from 12°C, so it is good to set the heating start temperature to 12°C economically, and maintaining of 800 µmol•mol -1 is effective in increasing production.