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The first objective of this study was to search for a possible correlation between accumulation of calcium Ca, potassium K, and magnesium Mg and fruit transpiration in developing apricot Prunus armeniacaL. fruit. Secondly, the work aimed to determine the significance of transpirational flux on Ca nutrition. We hypothesized that if the fruit transpiration is the determining factor of Ca accumulation phloemimmobile element then the import of Ca would be suppressed by restriction of fruit water loss, while the import of phloemmobile nutrients i.e., K and Mg would not be. To test this hypothesis, the seasonal changes of transpiration and of Ca, K, and Mg concentrationaccumulation were assessed in fruits left to naturally transpire or under restricted transpiration bagged fruits. Fruit transpiration was measured on detached fruits using a portable gasexchange equipment ADCLCA4, ADC BioScientific Ltd, Hoddesdon, England. Results demonstrated that 83 of total fruit Ca content was gained within the first 4 weeks after fruitset, and that Ca import ceased concomitantly to a reduction of transpiration. In spite of the limitation of fruit transpiration, Ca entered the nontranspiring fruits, and its concentration was about 45 of that in control fruits suggesting that other factors operated for Ca accumulation. This study provides the evidence that fruit transpiration accounted for 55 of total Ca that entered a fruit. We conclude that optimal soil Ca availability and apportioning to the fruit during the early 4 weeks of growth are essential to sustain the fruit demand of this nutrient and that some cultural practices e.g., summer pruning, irrigation should be tested as possible tools to improve fruit Ca nutrition viaincreasing fruit transpiration.

The aim of this work was to evaluate the effects of 2 soil management systems, so called ‘innovative' (INN) and ‘conventional' (CON), on genetic and metabolic diversity of soil microbial communities of peach and kiwifruit orchards. INN system included minimum tillage, organic matter inputs from compost and cover crops, winter pruning, and adequate irrigation and fertilisation. CON system was characterised by conventional tillage, zero organic input, empirical pruning, strong chemical fertilisation, and excessive irrigation. After 4 years of treatments, soil samples were collected in different orchard sites. In peach and kiwifruit INN orchards, average fruit yields were significantly higher than in CON. INN orchards had a significantly higher total number of bacteria. The patterns of denaturing gradient gel electrophoresis of bacterial 16S rDNA/RNA from peach orchard showed differences between soils under drip emitters and along the inter-rows, whereas those from kiwifruit orchard clearly distinguished between INN and CON for both bacteria (16S rRNA) and fungi (18S rDNA/RNA). Shannon's substrate diversity index, evaluated by Biolog®metabolic assay, was affected by soil treatment in peach orchard and by soil depth in kiwifruit orchard. Principal component analysis of Biolog®values clearly discriminated INN and CON soils of both orchards. The results revealed qualitative and quantitative changes of soil microbial communities in response to an innovative and sustainable soil management.

The effects of drought on the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (POD), indoleacetate oxidase (IAAox) and polyphenol oxidase (PPO) were studied in 2-year old Olea europaea L. (cv. ?Coratina') plants grown under high temperatures and irradiance levels and gradually subjected to a controlled water deficit. After 20 d without irrigation, mean predawn leaf water potential fell from ?0.37 to ?5.37 MPa, and decreases in net photosynthesis and transpiration occurred. The activities of SOD, APX, CAT and POD increased in relation to the severity of drought stress in both leaves and roots. In particular, a marked increase in APX activity was found in leaves of plants at severe drought stress. CAT activity increased during severe water deficit conditions in leaves and fine roots. The patterns of POD and IAA oxidase activity ran in parallel and showed increases in relation to the degree of drought. In contrast, PPO activity decreased during the progression of stress in all the tissues studied. The results show that the ability of olive trees to up-regulate the enzymatic antioxidant system might be an important attribute linked to drought tolerance. This could limit cellular damage caused by active oxygen species during water deficit.