Boris Basile

Leaf potassium concentration, CO2 exchange and light interception in almond trees (Prunus dulcis (Mill) D.A. Webb)

Abstract The goal of this study was to determine the effect of tree potassium status on CO2 exchange and light interception of field-grown almond trees (Prunus dulcis (Mill) D.A. Webb). Treatments consisted of four levels of potassium fertilization applied for three consecutive seasons. Potassium deficiency negatively affected tree light interception. Defoliation after mechanical harvesting indicated that potassium deficiency accelerated premature leaf senescence and premature leaf abscission. CO2 exchange rates were curvilinearly related to leaf potassium concentration during mid-summer after most vegetative shoot growth was completed. Leaf potassium concentrations less than 0.5–0.6% appeared to limit leaf CO2 exchange rate. Large variations in leaf potassium concentration were found in the non-fertilized trees. Indeed, most of the response curve of leaf CO2 exchange rate to leaf potassium concentration could be described by analyzing the leaves of non-fertilized trees. Stomatal conductance was not affected significantly by leaf potassium concentration and leaves with low potassium concentration had the highest calculated internal CO2 concentrations. Thus it appears that potassium deficiency in almond affected the leaf photosynthetic capacity via biochemical limitations and not through an effect on stomatal conductance.

Phenological Sensitivity of Cabernet Sauvignon to Water Stress: Vine Physiology and Berry Composition

There is little information on the sensitivity of berry composition to early-season water stress and how it compares to the effects of late-season stress. This study aimed to quantify the effects of water stress on berry growth and composition of Cabernet Sauvignon grapevine at three phenological stages: anthesis to fruit set, fruit set to veraison, and veraison to harvest. Potted vines were used to facilitate imposing water stress early in the season. Four irrigation levels (0%, 25%, 50%, and 100% of calculated crop evapotranspiration, ETc) were applied and midday leaf water potential and leaf gas exchange were measured. Berry composition was evaluated by measuring titratable acidity and concentrations of soluble solids, anthocyanins, and polyphenols. Water stress decreased net CO2 exchange rate and vine green leaf area. Berry composition significantly correlated with the vine water status, but the nature of the relationship depended on the phenological stage and on the parameter measured. Berry composition (in terms of concentration of anthocyanins and polyphenols) was improved when no water stress occurred from anthesis to fruit set (irrigation replacing 100% of ETc), with mild water stress between fruit set and veraison (irrigation replacing 25% and 50% of ETc), and with moderate to severe water stress in postveraison (irrigation replacing 0% of ETc).

Intra-canopy variability of fruit growth rate in peach trees grafted on rootstocks with different vigour-control capacity

Summary The aim of the present research was to study intra-canopy variability in fruit growth under conditions of low fruit-to-fruit competition in peach trees grafted on rootstocks with differing size-controlling capacity. The experiment was conducted on adult peach trees of two cultivars, each grafted on five rootstocks. Tree canopies were divided vertically into five layers. The diameter of 12 fruit per canopy layer was measured early in the growing season and at harvest. At harvest, the fresh weight of each selected fruit was also determined. After harvest, thirty shoots per tree bearing the selected fruit were harvested, and several parameters related to local carbon source availability, competition between vegetative and reproductive organs, vigour of the fruiting shoot, and position of the fruit on the fruiting shoot were measured. The results demonstrated that fruit variability within peach trees is very large, even when fruit-to-fruit competition is low. Fruit size at harvest decreased significantly and progressively from the top layers to the bottom layers of the canopy. Fruit growth was positively correlated with specific leaf weight, leaf area, and vigour of the fruiting shoot, and was negatively correlated with the vigour of current-season shoot growth on the fruiting shoot. However, the relative importance of each parameter depended on the cultivar. Rootstock affected the relationship between fruit growth and the measured parameters, and some rootstocks appeared to limit the maximum potential fruit growth rate. The measured parameters did not explain all the intra-canopy variability in fruit growth, suggesting that other factors also played a role. Interestingly, fruit size within 1 month of full bloom increased progressively from the top to the bottom of the canopy.

Heterogeneity in fruit distribution and stem water potential variations in peach trees under different irrigation conditions

Summary The hypothesis that different fruit loads between ‘scaffold branches’ of a tree can induce water status differences was evaluated. Two different experiments were carried out, one under full irrigation conditions and the other under conditions in which peach trees were deficit irrigated (50%). Thinning treatments were applied in both experiments at the begining of Stage III of fruit development: 1) EVEN-max with fruits distributed evenly with maximum crop, not thinned, 2) EVEN-min with fruits distributed evenly with minimal crop (< 90 fruit tree–1), and 3) UNEVEN with fruits distributed unevenly by totally defruiting half of the available main (scaffold) branches per tree and leaving the other half unthinned. Stem water potential ( stem) was measured with a pressure chamber at solar noon, and midday leaf conductance (gl) using a portable steady state porometer. UNEVEN trees always had intermediate stem values between EVEN-max and EVEN-min, independent of irrigation treatments. Maximum fruit load differences between trees (EVEN-max compared to EVEN-min) produced stem differences of 0.12 MPa and 0.25 MPa for full irrigation and deficit irrigation experiments, respectively. Although the magnitude of change in stem was larger for deficit irrigated conditions, extreme differences in fruit load between main branches within an UNEVEN peach tree only induced differences in leaf conductance and had no effect on the water potential of scaffold branches independent of the irrigation experiment. Fruit load effects on branch water status were governed mainly by tree fruit load rather than scaffold branch fruit load. These results indicate that there is either little hydraulic isolation between the main stems, irrespective of tree water status, or an improved hydraulic efficiency associated with defruiting.

Farming in a rural settlement in central Italy: cultural and environmental implications of crop production through the transition from Lombard to Frankish influence (8th–11th centuries a.d.)

Plant macrofossil (carpological) and morphometric analyses were carried out on plant remains from the medieval castle of Miranduolo, Siena, a rural settlement in central Italy with a long sequence of occupation between the 8th and the 11th centuries a.d. The presence of Triticum aestivum/durum and Vicia faba var. minor from the first phase of the Lombard farming village suggests continuity with the agricultural tradition of the preceding Roman world, and the use of good cultivation techniques that allowed quality yields to be obtained from rather poor soils. At the same time, the significant presence of the primitive cereal T. monococcum, compared with the archaeobotanical literature of north-central Italy, allows to us consider it as a “cultural” element of Lombard farming. In the next cultural phases, with the Carolingian manor and then with the feudal castle, the stable presence of T. aestivum/durum and the reduction of T. monococcum in favour of more productive cereals such as Secale cereale and Hordeum vulgare indicate a further improvement in productivity. This is also confirmed by the appearance of fruits and nuts such as Castanea sativa, Vitis vinifera and Prunus persica. The increase in caryopsis sizes of T. monococcum and T. aestivum/durum in the transition from the village to the manorial phase is a consequence of the improvements in farming. The decrease in caryopsis size of T. monococcum from the manor phase to that of the castle testifies the decreasing importance of this cereal. The good date resolution of this research allows us to detect the crops, the storage and the processing practices, as well as the changing role of crop plants in the rural economy. This highlights the geographical, historical-cultural and political factors of the medieval transition from the Lombard to the Carolingian and then to the feudal period in central Italy.

Influence of intensity of post‐veraison defoliation or shoot trimming on vine physiology, yield components, berry and wine composition in Aglianico grapevines

Background and Aims Post-veraison trimming and defoliation have been proposed as strategies to decrease the concentration of berry carbohydrate at harvest and of wine alcohol, but it is unclear which of these two pruning techniques is more suitable and at what intensity they should be applied. The aim of this 3-year study was to compare the suitability of two intensities of post-veraison trimming or defoliation in controlling sugar accumulation in the berries of Aglianico grapevines. Methods and Results Five treatments were compared: two intensities of defoliation, two intensities of shoot trimming and a control. All pruning treatments decreased berry TSS at harvest and wine alcohol concentration. Defoliation and trimming of moderate intensity also improved wine sensory score, whereas intense defoliation and trimming can affect negatively this parameter. Conclusions Post-veraison defoliation and trimming of moderate intensity appear to be suitable strategies for decreasing berry TSS at harvest and wine alcohol concentration. Significance of the Study The selection of the correct intensity of leaf removal appears to be one of the critical factors in correctly designing a suitable strategy of post-veraison summer pruning that aims to decrease sugar accumulation in the berries, whereas the choice of the type of pruning appears to be less crucial.

Effects of Early Shading and Defoliation on Bunch Compactness, Yield Components, and Berry Composition of Aglianico Grapevines under Warm Climate Conditions

Prebloom leaf removal is a canopy management practice used in viticulture to decrease bunch compactness at harvest. However, this practice may not be suitable in dry and warm areas because it may expose bunches to excessive direct sunlight, undesirably decreasing titratable acidity and increasing the pH of berry juice. This study was designed to test the hypothesis that shading between preanthesis and fruit set may be used for Aglianico grapevines as an alternative strategy to decrease bunch compactness without removing leaves around the bunches. This treatment was also thought to maintain berry juice acidity at harvest. The following nine treatments were compared: two defoliations (50 and 90% leaf removal), five whole-canopy shadings (10, 30, 50, 75, and 90% reduction of ambient light), one partial canopy shading (using a 30% shade net), and an unshaded and undefoliated control treatment. Fruit set, berry number per bunch, bunch weight, and yield per vine were significantly affected by several of these treatments. Bunch compactness was reduced only by shading in the range of 50 to 90%. Surprisingly, defoliation decreased fruit set but not bunch compactness because the defoliation caused shortening of the total length of the bunch axes. Berry composition was not negatively affected by 50 to 90% shading, whereas defoliations and 10 to 30% shading decreased titratable acidity and increased the pH of the berry juice at harvest. Flower number per bunch in 2010 decreased linearly with decreasing net photosynthesis per shoot measured in 2009 between prebloom and fruit set. The results of this study suggest that early shading may be an efficient alternative practice to decrease bunch compactness without any negative effect on berry juice composition at harvest.

Dating the beginning of the Roman viticultural model in the Western Mediterranean: The case study of Chianti (Central Italy)

Although domestication of the grapevine (Vitis vinifera L.) has been extensively documented, the history of genotype selection and evolution of vineyard management remain relatively neglected fields of study. The find of 454 waterlogged grapevine pips from a well-dated Etrusco-Roman site in the Chianti district (Tuscany, Central Italy) is an extraordinary chance to gain insights into the progress of viticulture occurring in a key historical period in one of the worlds most famous wine regions. The molecular and geometrical analyses of grape seeds showed (a) the presence in the site of different grapevine individuals and (b) a sudden increase in pip size, occurring at around 200 BC, whic explainable by the selection and introduction of new varieties. In this period, the Etruscans settlers in Chianti were stimulated by northward-expanding Roman culture to use novel vineyard management practices. We hypothesize that one of the most important innovations may have been the introduction of pruning, inducing vine physiological conditions more favorable to pip growth. Such changes were the consequence of specific entrepreneurial choices made by the Romans in a period of economic investment in grape cultivation and wine making to satisfy the increased trade demand after the conquest of the Central-Western Mediterranean basin.

Fruit position within the canopy affects kernel lipid composition of hazelnuts

BACKGROUND The aim of this research was to study the variability in kernel composition within the canopy of hazelnut trees. RESULTS Kernel fresh and dry weight increased linearly with fruit height above the ground. Fat content decreased, while protein and ash content increased, from the bottom to the top layers of the canopy. The level of unsaturation of fatty acids decreased from the bottom to the top of the canopy. Thus, the kernels located in the bottom layers of the canopy appear to be more interesting from a nutritional point of view, but their lipids may be more exposed to oxidation. The content of different phytosterols increased progressively from bottom to top canopy layers. CONCLUSION Most of these effects correlated with the pattern in light distribution inside the canopy. The results of this study indicate that fruit position within the canopy is an important factor in determining hazelnut kernel growth and composition.