Comparative effects of drought stress on leaf gas exchange, foliar ABA and leaf orientation in four grapevine cultivars grown in Northern Italy.

Drought tolerance varies greatly across Vitis vinifera cultivars, depending on physiological responses and structural and morphological adaptations. In this study, responses to water stress were examined in three extensively cultivated varieties from Northern Italy. Over the course of two seasons, mature potted vines were subjected to a 12 or 13-day period of water restriction. Vine water relations were investigated using measures of water potential, gas exchanges, and leaf ABA content. Leaf angle response to increasing water stress was analysed in the four cultivars as a mechanism that improves stress tolerance. Different physiological responses were observed among cultivars, suggesting a near-isohydric water-use strategy for Moscato and a near-anisohydric one for Garganega, Glera and Merlot. Results of leaf ABA analysis highlighted a variability among the studied varieties, indicating higher contents and lower sensitivity to ABA for the anisohydric ones. In all varieties, a similar increase in midday leaf inclination was observed in response to decreasing stem water potentials, indicating that leaf angle adjustments may represent a common adaptive response to drought. These findings increase the understanding of the leaf physiological and structural mechanisms that contribute to water stress tolerance in grapevine, supporting a more efficient cultivar selection to cope with the expected changes in Mediterranean climate.

Datasets of harmonized risk assessment of grapevine downy mildew and phenological observations in eight Italian regions (2012-2017).

Phytosanitary bulletins released at weekly interval by eight Italian regional plant protection services in the growing seasons 2012-2017 were used to derive an harmonized dataset of grapevine downy mildew infection risk and phenological observations. The downy mildew infection risk (n = 8816) was classified using a 5-point Likert response item ranging from 'very low' (1) to 'very high' (5) by six independent evaluators with domain expertise in agronomy, phytopathology and agrometeorology. Common criteria have been used in the risk assessment, considering (i) the presence of disease symptoms in field surveys, (ii) the host phenological susceptibility, (iii) the weather forecasts in the next week from the bulletin release date, (iv) the advice to apply a fungicide treatment and (v) the outputs of epidemiological models. The phenological observations are provided as BBCH codes (n = 1689), which have been either transcribed from the phytosanitary bulletins or derived from the narrative description of the visual observation. Phenological data refer to the main early and late grapevine varieties in the eight regions (NUTS-2 administrative unit). Each record is associated with the NUTS-2 and NUTS-3 (31 provinces) administrative unit of reference, to the growing season (2012-2017), and refers to the individual risk assessment by the six evaluators. The dataset is hosted by the Centre for Agriculture and Environment of the Italian Council for Agricultural Research and Economics. These data could be helpful to researchers who develop either grapevine phenological models or process-based epidemiological predictive algorithms in order to refine their calibration and evaluation, as well as being a valuable resource for stakeholders in charge of evaluating the effective implementation of Integrated Pest Management in the decision-making process of public plant protection services in Italy. The dataset is freely available here.

A public decision support system for the assessment of plant disease infection risk shared by Italian regions.

Integrated pest management (IPM) practices proved to be efficient in reducing pesticide use and ensuring economic farming sustainability. Digital decision support systems (DSS) to support the adoption of IPM practices from plant protection services are required by European legislation. Available DSSs used by Italian plant protection services are heterogeneous with regards to disease forecasting models, datasets for their calibration, and level of integration in operational decision-making. This study presents the MISFITS-DSS, which has been jointly developed by a public research institution and nine regional plant protection services with the objective of harmonizing data collection and decision support for Italian farmers. Participatory approach allowed designing a predictive workflow relying on specific domain expertise, in order to explicitly match actual user needs. The DSS calibration entailed the risk of grapevine downy mildew infection (5-point scale from very low to very high), and phenological observations in 2012-2017 as reference data. Process-based models of primary and secondary infections have been implemented and tested via sensitivity analysis (Morris method) under contrasting weather conditions. Hindcast simulations of grapevine phenology, host susceptibility and disease pressure were post-processed by machine-learning classifiers to predict the reference infection risk. Results indicate that IPM principles are implemented by plant protection services since years. The accurate reproduction of grapevine phenology (RMSE = 4-14 days), which drove the dynamic of host susceptibility, and the use of weather forecasts as model inputs contributed to reliably predict the reference infection risk (88% balanced accuracy). We did a pioneering effort to homogenize the methodology to deliver decision support to Italian farmers, by involving plant protection services in the DSS definition, to foster a further adoption of IPM practices.

Uncovering Olive Biodiversity through Analysis of Floral and Fruiting Biology and Assessment of Genetic Diversity of 120 Italian Cultivars with Minor or Marginal Diffusion.

The primary impetus behind this research was to provide a boost to the characterization of the Italian olive biodiversity by acquiring reliable and homogeneous data over the course of an eight-year trial on the floral and fruiting biology of 120 molecularly analyzed cultivars, most of which have either low or very low diffusion. The obtained data highlighted a considerable variability to almost all of the analyzed parameters, which given the uniformity of environment and crop management was indicative of a large genetic variability in the accessions under observation, as confirmed through the molecular analysis. Several cases of synonymy were reported for the first time, even among plants cultivated in different regions, whilst all of the varieties examined, with only one exception, showed very low percentages of self-fruit-set, indicating a need for the employment of suitable pollinator plants. Eventually, a fitted model allowed us to evaluate the clear effects of the thermal values on blossoming, particularly in the months of March and April, whereas the climatic conditions during the flowering time had only a modest effect on its duration.

The Book of Vinesprouts of Koszeg (Hungary): a documentary source for reconstructing spring temperatures back to the eighteenth century.

Following an age-old tradition, since 1740, in the town of Koszeg in western Hungary, samples of grapevine shoots are annually harvested on St. George's Day, 24 April, and then are pictorially reproduced in the so-called Book of Vinesprouts. Given the strong relationships between temperature and grapevine phenology, the book represents a potential source for reconstructing past spring temperatures. However, this document has been little utilized so far, due to high varietal heterogeneity and lingering uncertainty regarding cultivar identity. This research developed an approach to address these difficulties, by means of a single-cultivar-based modeling analysis, associated with a set of alternative hypotheses about cultivar early development for the period to be reconstructed. Each hypothesis allowed the calculation of a different past temperature reconstruction, which was evaluated against contemporary independent observational data. The results showed that all the development stages recorded before 1900 were compatible with a vine type with a very low heat requirement for bud burst. Estimates were derived from a model calibrated on a subset of drawings of unknown cultivars executed between 1875 and 1898. The model based on this data subset was the only one giving a consistent reconstruction of spring temperatures, expressed as accumulated growing degree days going back to 1740. Although some uncertainty still exists regarding the reconstruction, the research shows that the Book of Vinesprouts contains generally consistent information about spring temperatures for a period of over 269 years for this region of Hungary.

Relationships between leaf conductance to CO2 diffusion and photosynthesis in micropropagated grapevine plants, before and after ex vitro acclimatization.

In vitro-cultured plants typically show a low photosynthetic activity, which is considered detrimental to subsequent ex vitro acclimatization. Studies conducted so far have approached this problem by analysing the biochemical and photochemical aspects of photosynthesis, while very little attention has been paid to the role of leaf conductance to CO(2) diffusion, which often represents an important constraint to CO(2) assimilation in naturally grown plants. Mesophyll conductance, in particular, has never been determined in in vitro plants, and no information exists as to whether it represents a limitation to carbon assimilation during in vitro growth and subsequent ex vitro acclimatization. In this study, by means of simultaneous gas exchange and chlorophyll fluorescence measurements, the stomatal and mesophyll conductance to CO(2) diffusion were assessed in in vitro-cultured plants of the grapevine rootstock '41B' (Vitis vinifera 'Chasselas'xVitis berlandieri), prior to and after ex vitro acclimatization. Their impact on electron transport rate partitioning and on limitation of potential net assimilation rate was analysed. In vitro plants had a high stomatal conductance, 155 versus 50 mmol m(-2) s(-1) in acclimatized plants, which ensured a higher CO(2) concentration in the chloroplasts, and a 7% higher electron flow to the carbon reduction pathway. The high stomatal conductance was counterbalanced by a low mesophyll conductance, 43 versus 285 mmol m(-2) s(-1), which accounted for a 14.5% estimated relative limitation to photosynthesis against 2.1% estimated in acclimatized plants. It was concluded that mesophyll conductance represents an important limitation for in vitro plant photosynthesis, and that in acclimatization studies the correct comparison of photosynthetic activity between in vitro and acclimatized plants must take into account the contribution of both stomatal and mesophyll conductance.