Influência da temperatura do ar na emissão de folhas, ramificações e flores em híbridos de melancia

Abstract

The aim of this study was to evaluate the growth and development of watermelon hybrids in relation to air temperature by obtaining the thermal time for vegetative and reproductive subperiods for the hybrid cultivar Manchester and Top Gun, both early cycle were used. The experiment was conducted in an area belonging to the Federal University of Santa Maria/Campus Frederico Westphalen-RS, from September to December 2014. During the execution of the experiment, evaluations were performed every two days for the following characteristics: emission nodes/leaves, development of primary and secondary vines, and issuance of staminate flowers and pistillate. The spacing used was 1.5 m between plants and 3.0 m between rows of the crop. The values obtained for the evaluated criteria differ significantly where the hybrid Manchester demonstrated superiority over the hybrid Top Gun which presented average values of plastichrone with 16.6 °C day-1 node, the amount of nodes on the main vine was 45.8 nodes, the thermal sum for the issuance of secondary vines was 18.1 °C growing degree days-1 vine, and the final number of secondary vines and vines of 26.6, and a total number of growing degree days for staminate flower emission of 9.6 °C day-1 flower. The hybrid Top Gun was superior to the hybrid Manchester for the final number of primary vines, emitting on average 14.6 vines per plant and an accumulated growing degree day for pistillate flower emission of 51.9 °C day-1 flower. In the variables of thermal time on the main stem, primary stem, and growing degree day, the thermal time for primary and secondary vines, final number of staminate flowers and pistillate hybrids showed no statistical difference in mean values.