Ethephon has been used in the tropical and subtropical regions of Brazil, where the vegetative growth of grapevine is continuous, with different finalities. However, little is know about the effects of this treatment on the distribution and accumulation of nutrients and carbohydrates and on the growth of grapevine. For this purpose, young plants of SO4 rootstock were sprayed with ethephon solution (72 mg.L-1). After the application, the dropped leaves of the treated plants were collected daily until the last leaf fell. At this point, the leaves of untreated plants were hand picked. In the next cycle, the number of sprouted buds and growth of leaves (number) and branches (number and length) were evaluated in each plant. Fifty seven days after bud sprout, the plants were collected and separated in leaves, branches, stem and roots. Each part was dried and N, P, K, Ca, Mg and starch were determinate. In the senescence leaves from the first cycle, a reduction of N and an increase of starch and P by ethephon treatment were observed. In the following cycle, the treated plants have increased the number of bud sprouts (+50%) but with a reduced growth of branches and leaves. During this second cycle the ethephon also increased the concentration of N and Mg in leaves and N in roots. However, during this cycle the concentration of starch in leaves and amount of N, K and Ca in branches were reduced. In general, the results emphasized that ethephon changes the dynamic of nutrient and carbohydrates as well as the physiology of growth in the following cycle after its application in grapevines.
Vitis spp.; growth regulator; ethylene; defoliation; macronutrients; starch
