EFFETTI DEL PACLOBUTRAZOLO (PP333) SU PIANTE DI NOCCIOLO SOTTOPOSTE A POTATURA DI RICOSTITUZIONE
In 1988, 1989, and 1990 data were collected on: photosynthesis, carbohydrate, starch and chlorophyll content by monthly recording from July to October. Shoot lenght, vegetative and flower buds and staminate ament number were recorded per shoot at the end of each year. Foliar and soil application of Paclobutrazol reduced vegetative activity and promoted flower bud induction. Similar effects were obtained by summer pruning by shoot thinning. The leaves of treated trees were richer in chlorophyll and carbohydrates resulting in more active photosynthesis.
The treatments of Paclobutrazol repeated in 1989 and 1990 confirmed the results of 1988. In 1990 Paclobutrazol showed a residual effect only on trees submitted to foliar application. The effect of Paclobutrazol on growth is similar to thinning of shoots but the mechanism of action is different. Summer pruning reduces shoot lenght by reduction of availability of metabolites, instead, Paclobutrazol does not change leaf number, but modifies the hormonal balance. The residual effect of Paclobutrazol lasts about 1 year after foliage applications.