PRUNING AND SKIRTING EFFECTS ON CANOPY MICROCLIMATE, GROWTH, AND FLOWERING OF 'ORLANDO' TANGELO TREES

摘要

Pruning and skirting effects on canopy temperature and relative humidity (RH), vegetative growth and flowering of 'Orlando' tangelo trees [Citrus paradisi Macf. x Citrus reticula-ta Blanco] on Carrizo citrange rootstock [C. sinensis (L.) Osb. x Poncirus trifoliata (L.) Raf.] were studied at the University of Florida Fifield Farm in Gainesville, Fla. during 1997-98. Two skirting (skirted or non-skirted) and three pruning (gable-top, flat-top or non- pruned) treatments were evaluated. Trees were skirted and pruned in Mar. 1997. Vegetative regrowth and flowering were measured using frame counts and shoot length was measured at the end of each growth flush in 1997 and 1998. Large diurnal fluctuations in RH were observed throughout the season in all treatments. The RH in the bottom-inside canopy decreased to about 50% during the day and increased to 100% at night. Diurnal fluctuations in RH were greater in the upper than lower canopy. RH in the bottom of skirted trees was similar to that of non-skirtedtrees and was also similar for all pruning treatments. Skirting and pruning did not affect air temperature in the bottom canopy. In contrast, temperature in the upper canopy of flat-topped trees was 18°F higher than that of gable-topped and non-pruned trees and reached more than 114°F during spring and summer. Shoot number and length were the same for all treatments during the season of pruning, but total length was higher for skirted, gable topped and non-skirted, non-pruned trees than for other treatments. The following season, shoot number was the lowest in gable-topped trees. Flowering the following season was not affected by pruning or skirting treatments. The upper canopy had more leafy and leafless inflorescences than the sides of the tree for all treatments.