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.

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To study the stomatal contribution to total leaf gas exchange in leaves of paclobutrazoltreated peach trees (Prunus persica (L.) Batsch), counts and measurements of stomata were made. Peach trees (cv. Catherine) were treated with different doses of paclobutrazol at bloom, and later in summer, counts of stomata per unit area of leaf showed that the density increased linearly with the doses, while the length of the stomata also decreased linearly.

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Pear trees cv 'Agua de Aranjuez' A-840 (VT) clon, budded in the nursery at 15 and 50 cm from the soil were planted with the union at 10 and 50 cm high, and growth and cropping during the first two years recorded. Scion trunk-cross-sectional area was smaller on the high-worked trees from the time of planting, and stock area at soil level was also smaller on the high-budded trees from the first year after planting. Almost all the high-worked trees carried a crop on the second year of growth, while a few (20%) of the low-budded carried some fruits, which were smaller in size. Differences in size of both scion and stock were greater by the end of the second year. -Introduction'Agua de Aranjuez' is a very vigorous pear variety (P y r u s c o m m u n i s L.) usually grown in Spain on pear seedling rootstocks, for wich the adult tree attains a very large size. The need for a growth control has led to the use of quince rootstocks, and first reports are showing that 'Agua de Aranjuez' A-840 (VT) clon grafted on Quince C (EM) results in a tree of small size and early cropping, but which needs staking because of poor anchorage and twisting down of the aerial part of the stock.Van Oosten (1978) and Parry (1986) have shown that in apple, high working increases the dwarfing effect of the rootstock, allowing the use of more vigorous rootstocks. To test this effect on pear trees, a preliminary trial has been carried out and the results on growth and cropping during the first two years after planting are presented here. -Materials and MethodsQuince A rootstocks were grafted in the nursery in 1981 at two different heights: 15 and 50 cm from the ground with 'Agua de Aranjuez'A-840 buds. Ten trees of each height of budding were chosen as uniform as possible and of the best quality, in terms of tree height and number of feathers. The trees were planted in a row at 3.5 m apart,