Manipulating or shifting annual grapevine growing cycle to offset limitations imposed by global warming is a must today, and delayed winter pruning is a tool to achieve it. However, no information is available about its physiological background, especially in relation to modifications in canopy phenology, demography and seasonal carbon budget. Mechanistic hypothesis underlying this work was that very late winter pruning (LWP) can achieve significant postponement of phenological stages so that ripening might occur in a cooler period and, concurrently, ripening potential can be improved due to higher efficiency and prolonged longevity of the canopy. Variability in the dynamics of the annual cycle was created in mature potted cv. Sangiovese grapevines subjected to either standard winter pruning (SWP) or late and very late winter pruning (LWP, VLWP) performed when apical shoots on the unpruned canes were at the stage of 2 and 7 unfolded leaves. Vegetative growth, phenology and canopy net CO2 exchange (NCER) were followed throughout the season. Despite LWP and VLWP induced a bud-burst delay of 17 and 31 days vs. SWP, the delay was fully offset at harvest for LWP and was reduced to 6 days in VLWP. LWP showed notably higher canopy efficiency as shorter time needed to reach maximum NCER/leaf area (22 days vs. 34 in SWP), highest maximum NCER/leaf area (+37% as compared to SWP) and higher NCER/leaf area rates from veraison to end of season. As a result, seasonal cumulated carbon in LWP was 17% higher than SWP. A negative functional relationship was also established between amount of leaf area removed at winter pruning and yield per vine and berry number per cluster. Although retarded winter pruning was not able to postpone late-season phenological stages under the warm conditions of this study, it showed a remarkable potential to limit yield while improving grape quality, thereby fostering the hypothesis that it could be used to replace time-consuming and costly cluster thinning. This preliminary study indicates that proper winter pruning date should be timed so as not to exceed the stage of two unfolded leaves.
Background and Aims The increasing interest by the wine market in sparkling white wines challenges how the desired grape composition can be achieved under the pressure of global warming. The aim of the present study was to assess the viability of summer pruning as a tool to pilot ripening towards desired compositional patterns. Methods and Results Ortrugo was subjected to basal leaf removal applied either at pre‐flowering (ELR) or in lag‐phase (LLR) and to bunch thinning (BT; removal of 50% of crop at lag‐phase) in comparison with untreated control (C). Treatments induced large variation in bunch mass (30% less in ELR vs BT), yield per vine (37 and 21% less in BT and ELR vs C) and total soluble solids at harvest (BT scored 2.9°Brix higher than that of C). Conversely, given the same harvest date, all practices failed to maintain titratable acidity (TA) at the threshold of 6.5 g/L. Conclusions The data suggest that crop regulation achieved in the high yielding Ortrugo, through either BT or ELR, increases sugar accumulation rate so that concurrent optimal TA level (≅6.5 g/L) can be easily achieved by slightly anticipating harvest date. Under conditions of thermal or light stress, or weather conducive to bunch rot, preference should be given to ELR. Significance of the Study Suitable summer pruning techniques might be used as flexible and powerful tools to direct ripening towards the desired crop composition.
Background and Aims: Climate change is advancing grape ripening, decoupling berry technological and phenolic composition and negatively impacting wine quality. The aim for this study was to test the usefulness of late leaf removal (LLR) under different watering regimes to delay harvest in two Spanish red cultivars in a semiarid and temperate-warm climate. The effects on vine physiology, yield, grape and wine composition were investigated. Methods and Results:In two trials carried out in eastern Spain with Bobal and Tempranillo cultivars, vines were partially defoliated above the cluster zone shortly before veraison under rainfed and deficit irrigation conditions during two seasons. Grape ripening rate was significantly affected by the watering regime and canopy management in both cultivars. Vine water status and photosynthesis was improved by irrigation and LLR. However, the treatments harvested later, did not have an overall positive effect on grape nor on wine composition. The resultant leaf area-tofruit ratios of the defoliated treatments appeared to be limiting for both sugars and anthocyanins accumulation. As a consequence, LLR negatively affected wine colour intensity. In addition, yield was constrained by LLR in Tempranillo due to reductions in cluster and berry mass. Conclusions:A reduction in grape sugars accumulation provoked by LLR did not necessarily implies a better coupling between berry technological and phenolic maturity. The effectiveness of the LLR technique seems to depend on its final impacts on leaf area-to-fruit ratio and vine water status, the vine photosynthetic compensation capacity of the cultivar and the environmental conditions.Significance of the Study: Under low vigour vine conditions, severe defoliation cannot be recommended as a strategy to balance grape sugars and phenolic composition, highlighting the importance of applying defoliation at the right time and intensity.
Ground-based proximal sensing of vineyard features is gaining interest due to its ability to serve in even quite small plots with the advantage of being conducted concurrently with normal vineyard practices (i.e., spraying, pruning or soil tilling) with no dependence upon weather conditions, external services or law-imposed limitations. The purpose of the present work was to test performance of the new terrestrial multi-sensor MECS-VINE® in terms of reliability and degree of correlation with several canopy growth and yield parameters in the grapevine. MECS-VINE®, once conveniently positioned in front of the tractor, can provide simultaneous assessment of growth features and microclimate of specific canopy sections of the two adjacent row sides. MECS-VINE® integrates a series of microclimate sensors (air relative humidity, air and surface temperature) with two (left and right) matrix-based optical RGB imaging sensors and a related algorithm, termed Canoyct). MECS-VINE® was run five times along the season in a mature cv. Barbera vineyard and a Canopy Index (CI, pure number varying from 0 to 1000), calculated through its built-in algorithm, validated vs. canopy structure parameters (i.e., leaf layer number, fractions of canopy gaps and interior leaves) derived from point quadrat analysis. Results showed that CI was highly correlated vs. any canopy parameter at any date, although the closest relationships were found for CI vs. fraction of canopy gaps (R2 = 0.97) and leaf layer number (R2 = 0.97) for data pooled over 24 test vines. While correlations against canopy light interception and total lateral leaf area were still unsatisfactory, a good correlation was found vs. cluster and berry weight (R2 = 0.76 and 0.71, respectively) suggesting a good potential also for yield estimates. Besides the quite satisfactory calibration provided, main improvements of MECS-VINE® usage versus other current equipment are: (i) MECS-VINE® delivers a segmented evaluation of the canopy up to 15 different sectors, therefore allowing to differentiate canopy structure and density at specific and crucial canopy segments (i.e., basal part where clusters are located) and (ii) the sensor is optimized to work at any time of the day with any weather condition without the need of any supplemental lighting system.
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