Differential assimilation of nutrients in paclobutrazol-treated peach trees

Paclobutrazol (Pbz) is a triazol that effectively inhibits vegetative growth in peach. Changes in mineral element concentration have been generally found. However, uneven distribution of the elements in the soil may partially account for these differences. To ascertain these effects, an experiment was designed under controlled conditions, in which sugar beet, used as a model plant, was grown hidroponically, treated with Pbz and the results compared to those from unbearing peach trees grown in the open. The beets were treated with 1 M Pbz at the first trifoliate stage, and the peach trees with 2 g Pbz/tree shortly AFB. A reduction of 85 % in leaf area and of 70 % in dry weight were recorded in Pbz-treated beet plants, while in Pbz-treated peach these were of 40 % in leaf area and 29 % in dry weight. Nutrient concentration on dry weight basis varied little (about 8 % in beet and 11 % in peach). However, but global assimilation of nutrients on a leaf basis, when compared with controls, decreased up to the same extend as dry weight in beet (70 %) while in peach it was of 25 %. From these results it can be inferred that the mineral fertilization in Pbztreated peach trees can be reduced to the same extend as the expected reduction in vegetative growth, consequently reducing production costs and environmental contamination.