This work aimed to evaluate the seasonal variation in vegetative growth of Hamlin orange plants grafted on Swingle citrumelo rootstocks grown in a subtropical climate. Biometric evaluations were conducted monthly on the East and West canopy positions of 12 plants between December 2005 and December 2006. On average, three shoots emerged per stem between December and February, while other four shoots appeared in two periods between July and September: two shoots between July and August, and two other shoots between August and September. This pattern of vegetative flush occurred during an atypical year, with high water deficit (between April and November) and increase in air temperature starting in May. The number of leaves per stem increased following the same seasonal pattern of shoot emergence. The amount of purely vegetative shoots (given by the ratio between number of leaves and number of shoots) was 2.5 times higher on the first flush in relation to the others. The main vegetative flush responsible for stem growth and increase of leaf area occurred during the summer. Stem growth was interrupted by endogenous aspects (summer) and by unfavorable environmental conditions (winter). There were no differences between the evaluated variables when comparing canopy positions.
bud sprouting; Citrus sinensis; ecophysiology; vegetative flush
