Study of energetic properties of different tree organs in six Olea europaea L. cultivars

Pruning is an important horticultural practice for the management of olive orchards (Olea europaea L.) that generates a considerable amount of residues every year. Olive orchards are increasingly expanding beyond the Mediterranean Basin to new growing Countries (Australia, California, Argentina, Chile and Uruguay) and this will certainly lead to larger availability of pruning material. Currently, the interest in use of olive tree pruning residues for energy purposes is increasing but unfortunately, the information on the differences among organs of the tree, in terms of calorific value and ash content, is scarce. Another unknown aspect is the effect of cultivar vigour on dry matter partition among different tree organs, these are important traits to establish the energetic quality of pruning residues. The aim of this research was to study energetic aspects of six olive cultivars, largely grown in the Sicilian olive industry and characterized by different vigour. The trees taken into consideration in the study were selected in an experimental orchard to avoid any effect due to differences in environmental conditions and management. The energetic characteristics, calorific value and ash content, were evaluated for the various tree organs particularly shoots, leaves and branches; also root system was evaluated, although the roots can only be used once the trees are uprooted. Significant differences were observed in the calorific values among the different tree organs and the cultivars. Regarding the ash, shoots and leaves showed the highest content with respect to the other organs, thus causing a possible tendency in slagging with fouling and corrosion of boiler components

Seasonal changes in starch content in pistachio organs as related to crop load

The alternate bearing in pistachio (Pistacia vera L.) results from inflorescence buds abscission differentiated on current season growth during the year of heavy crop. Inflorescence bud drop has been directly correlated with the presence of fruits on 1-year shoot, and in particular with the kernel grow that acts as the major sink of nutrients. Experimental evidences suggest the involvement of competition between reproductive organs for the available resources. The annual carbohydrates storage was analysed in mature pistachio trees characterized by low, medium and high crop load (about 1, 7 and 11 kg tree-1 of dry in-shell nuts). The experiment was carried out in 2013 in a commercial pistachio orchard, using ‘Bianca’ grafted onto P. terebinthus L. in Sicily (Italy, 37°30’ Lat N). Starch concentration was measured in sample tissues of trunk wood, current-year shoot, one-year-old and two-year-old shoots throughout the season from the dormancy phase (March) until the post-harvest period (September). During dormancy, the trunk represented the main storage organ having starch concentration ranging from 60 to 120 mg g-1 of dry weight, whereas the tissues of the other organs examined showed values below 20 mg g-1 of dry weight. The deepest decrement of starch concentration after bud-break until bloom was observed in the trunk, whereas, starch concentration started increasing after the initial growth flush. The patterns of starch in the tissues varied according with the crop load; trees bearing the highest crop load (11 kg tree-1) showed a constant starch concentration during the growing season, in contrast with the trees characterized by lower crop load values. Before the onset of dormancy, starch rapidly increased in all the shoots type and in the trunk wood and no effects of tree crop load were observed

Propagation techniques for three Mediterranean native shrubs with potentential as ornamental outdoor plants

Grande are three Mediterranean shrubs with interesting ornamental features. The exploitation of wild plants for ornamental purposes implies knowledge on the factors influencing the propagation methods. To study the influence of temperature on germination, seeds of Teucrium flavum, Prasium majus and Micromeria fruticulosa were germinated in incubators at constant temperatures of 14, 20, 24 and 28°C. Highest germination, 45 % and 86%, occurred at 20°C in Teucrium flavum and Prasium majus, respectively. Micromeria fruticulosa seeds subjected at 24 or 28°C had a germination percentage significantly higher than at 20 or 14°C. To study the influence of auxin treatments on vegetative propagation, cuttings of each species were either dipped in a 500 ppm 1H-indole-3-butyric acid (IBA) solution or not treated (control). Rooting percentage and root number of the three species were strongly affected by IBA treatments

A carbon budget model to predict branch carbohydrate deficiencies as a function of water stress and crop load in pistachio (Pistacia vera L.)

The effect of irrigation and crop load on alternate bearing was studied in pistachio tree using a “branch carbon budget model” developed to calculate branch carbohydrate balance. Experiences were conducted in Sicily (37°26’N, 14°03’E, 360 m a.s.l.) on female trees of ‘Bianca’. Two treatments were applied: rainfed (T0) and 100 mm of irrigation (T100). At 29, 44, 65, 86, 103 and 121 DAFB, on one fully expanded leaf selected on three trees per treatment, were monitored leaf gas exchanges. At 15 days interval, three branches treatment-1 were excised and, in the lab, the following parameters were measured: total photosynthetically active leaf surface; number of leaves, fruits, shoot fresh weight (FW) and dry weight (DW). Photosynthetic response curves to PPFD were calculated on the base of data published in the literature. Irrigation positively affected branch carbon budget that resulted positive (6.87 g of C) at the end of the season, whereas in rainfed trees the carbon budget was negative (-13.98 g of C). In rainfed trees seasonal branch carbon assimilation was 44% lower as a consequence of reduced leaf area. 28 days after full bloom, when leaves reached full development, leaf area fruiting branch-1 in rainfed trees was 920 and 1300 cm2 in branches of irrigated tress. Branch of rainfed trees also showed intense leaf drop and yellowing that strongly reduced late season assimilation rate (Amax 4.5 µmol m-2 s-1 in branches of rainfed trees vs. 10 µmol m-2 s-1 in irrigated ones), affecting total seasonal carbon assimilation. Referring to the carbon budget of the branches, considering the interaction between crop load and irrigation, one cluster was the maximum sustainable crop load in rainfed trees while irrigation enabled the branches to sustain up to three clusters, maintaining a positive carbon budget until fruit ripening. The results reported confirm that the “branch carbon budget model”, after further validation, will be a valid tool to predict carbohydrate budget as function of crop load and irrigation, useful to help to manage orchard to reduce the severity of alternate bearing