RESUMO -O controle do desenvolvimento vegetativo é fundamental na cultura da macieira, a fim de aumentar a eficiência produtiva e a qualidade dos frutos produzidos. O desenvolvimento dos ramos pode ser reduzido pelo uso de substâncias inibidoras da biossíntese de giberelinas, como o proexadione cálcio, sendo a resposta deste fitorregulador dependente do padrão sazonal do crescimento da parte aérea. O objetivo do trabalho foi avaliar o efeito de diferentes épocas de aplicação de proexadione cálcio no controle do desenvolvimento vegetativo de macieiras 'Imperial Gala', nas condições climáticas do Sul do Brasil.
APPLICATION TIMING OF PROHEXADIONE CALCIUM ON VEGETATIVE GROWTH CONTROL OF 'IMPERIAL GALA' APPLESABSTRACT -The control of vegetative growth is crucial in apple orchards in order to increase production efficiency and fruit quality. The shoot development may be reduced by inhibitors of gibberellins synthesis, as prohexadione calcium, and the response of this plant growth regulator depends on the seasonal pattern of shoot growth. The objective of this study was to evaluate the effect of different application timing of prohexadione calcium on vegetative growth control of 'Imperial Gala' apple trees, in the climatic conditions of Southern Brazil. In 2008/2009 growing season, the following application timings of prohexadione calcium at 330 g ha -1 were evaluated: 28, 58, 88, 118, 148 and 178 days after full bloom -DAFB, and in 2009/2010 growing season, the application timings were: 20, 50, 80, 110, 140, 170 and 200 DAFB, and a control treatment. Applications of prohexadione calcium (330 g ha -1 ) performed at 20 to 28 days after full bloom reduced the average length and average fresh weight of shoots pruned in 'Imperial Gala' apple trees.