BUSCADOR RECOLECTA

Achieving more environmentally sustainable vineyards, particularly regarding efficient water use, is paramount in semi-arid grape-growing regions. Rootstocks may be a possible strategy to address these challenges, but require a comprehensive evaluation of their effect on the scion, including ecophysiological traits. The objectives of this study were 1) to characterize the physiological response of Tempranillo cultivar grafted onto five commercial (1103 P, 110 R, 140Ru, 420 A, and SO4), and seven recently bred (RG2, RG3, RG4, RG6, RG7, RG8 and RG9) rootstocks and 2) to elucidate the relationships between agronomic and physiological traits conferred by grapevine rootstocks. This was carried out over three seasons (2018–2020) in a typical Mediterranean vineyard by determining water relations, leaf gas exchange, carbon isotope ratios and vegetative development and yield components. The results highlighted the different behaviour of ‘Tempranillo’ vines due to the rootstock effects on vine water status, photosynthetic performance, hydraulic conductance, vegetative growth and yield parameters. Overall, rootstocks inducing vigour and yield in the scion, such as 140Ru and RG8, showed higher leaf gas exchange rates and hydraulic conductance at the whole-plant level due to less negative water potentials, suggesting a higher water uptake and transport capacity than RG2, RG7 and RG9. The RG rootstocks showed a very wide range of ecophysiological responses, but only RG8 outperformed compared to the most widely used commercial rootstocks. Moreover, this response was modulated by the season and the block soil type, suggesting the importance of rootstock selection according to the edaphoclimatic conditions. Therefore, this study highlights the high potential of rootstocks to adapt to water scarcity by improving crop water productivity in vineyards and provides physiological insights for future studies and breeding programmes., This work has been financially
supported by the Spanish Ministry of Economy and Competitiveness
with FEDER co-financing, grant numbers AGL2017-83738-C3-1R
(WANUGRAPE), PDC2021-121210-C22 (WANUGRAPE4.0), and
PID2021–123305OB-C31 (UPGRAPE), and by the Government of Navarra (VIT-FEET and BEST-FEET, grant no. 0011-1365-2018-000106 and
0011-1365-2021-000068, respectively).

Choosing the most appropriate rootstock(s) is a key decision for the profitability of vineyards; therefore, there must be a sufficient range of
rootstocks in the market adapted to different environmental conditions and production objectives. However, rootstock-breeding programs
have been scarce in recent decades, and most of the rootstocks used today were bred a century ago, when the needs of the sector were very
different from today. In this work, we aimed to evaluate new rootstock candidates before their introduction in the market. An agronomic
evaluation was conducted on eight novel rootstock genotypes obtained from the first generation of the cross-pollination of 41 B Millardet et de
Grasset (41 B) and 110 Richter (110 R) grafted with ‘Syrah’ and ‘Tempranillo’ and planted in a typical vineyard of the Ebro Valley in Spain. During
the four consecutive growing seasons (2016e2019), growth, yield and berry composition parameters at harvest were collected. A linear mixedeffects model was constructed, considering year and block as random effects. Multiple factor analysis and hierarchical clustering on principal
components were performed to establish clusters of genotypes with similar behaviour. The rootstock candidates showed a very wide performance range compared to their parents. The trial allowed us to identify two very promising candidates (RG8 and RG10), whose registration
as commercial rootstocks is already in progress., This work was performed with the financial support of the
Department of Economic Development of the Government of
Navarra (Vit-Foot, Ref.: 0011-1365-2016-000079 and Vit-Feet, Ref.:
0011-1365-2018-000106, projects co-funded with FEDER funds)
and the Spanish Ministry of Science and Technology (project AGL
2017-83738-C3-1-R). Diana Marín is beneficiary of postgraduate
scholarship funded by Public University of Navarre (FPI-UPNA-
2017). Francisco Javier Abad is beneficiary of postgraduate
scholarship funded by INIA (FPI-INIA-2016).

Precise and reliable identification of specific plant diseases is a challenge within precision agriculture nowadays. This is the case of esca, a complex grapevine trunk disease, that represents a major threat to modern viticulture as it is responsible for large economic losses annually. The lack of effective control strategies and the complexity of esca disease expression make essential the identification of affected plants, before symptoms become evident, for a better management of the vineyard. This study evaluated the suitability of a near-infrared hyperspectral imaging (HSI) system to detect esca disease in asymptomatic grapevine leaves of Tempranillo red-berried cultivar. For this, 72 leaves from an experimental vineyard, naturally infected with esca, were collected and scanned with a lab-scale HSI system in the 900-1700 nm spectral range. Then, effective image processing and multivariate analysis techniques were merged to develop pixel-based classification models for the distinction of healthy, asymptomatic and symptomatic leaves. Automatic and interval partial least squares variable selection methods were tested to identify the most relevant wavelengths for the detection of esca-affected vines using partial least squares discriminant analysis and different pre-processing techniques. Three-class and two-class classifiers were carried out to differentiate healthy, asymptomatic and symptomatic leaf pixels, and healthy from asymptomatic pixels, respectively. Both variable selection methods performed similarly, achieving good classification rates in the range of 82.77-97.17% in validation datasets for either three-class or two-class classifiers. The latter results demonstrated the capability of hyperspectral imaging to distinguish two groups of seemingly identical leaves (healthy and asymptomatic). These findings would ease the annual monitoring of disease incidence in the vineyard and, therefore, better crop management and decision making., This research was supported by Public University of Navarre postgraduate scholarships (FPI-UPNA-2017), by the Spanish Ministry of Economy and Competitiveness (AGL2017-83738-C3-1R, AEI/EU-FEDER), and by the Spanish Ministry of Science, Innovation and Universities (PID2019-108392GB-I00, AEI/10.13039/ 501100011033).

The selection of genotypes best adapted to environmental conditions has traditionally focused on agronomic and grape composition parameters. However, to classify the genotypes most adapted to climate change conditions, the aim must be to focus on the ecophysiological responses that will ultimately determine their performance. The variability in water use efficiency of 13 Grenache genotypes over three-seasons was assessed under field conditions at leaf, grape and plant level. Results showed a significant effect of genotype at all three levels, and despite the large interannual variability there was a remarkable consistency among levels. Furthermore, using genotype-specific regressions it was possible to identify significant differences in the intrinsic water use efficiency response of each genotype as a function of the vine water status. The relationship between net photosynthesis and stomatal conductance, as well as carbon isotope discrimination in grapes, were also confirmed as reliable physiological indicators for selecting grapevine genotypes to future environmental conditions. Therefore, the proposed multi-level methodology was useful to quantify the intracultivar variability and the identification of more and less efficient genotypes within Grenache., I. Buesa acknowledges the funding of his postdoctoral position to Margalida Comas program (European Social Fund and the Government of the Balearic Islands). This study received the financial support of Spanish Ministry of Economy and Competitiveness with FEDER co‐funding [WANUGRAPE. AGL2017‐83738‐C3‐1R].

To face the challenges induces by the climate change a better water use in agriculture is needed. One of the ways to get it is the genetic selection and breeding programs of genotypes focused on their water use efficiency (WUE). Grapevine crop is commonly growing under water stress conditions; to improve their WUE is a general goal for viticulture. In this study, we show the variability in WUE among clones of Tempranillo, cvar, grown under both pot and field conditions, all submitted to a large range of water availability, and along three consecutive years. Leaf net photosynthesis rate (A), stomatal conductance (g) were measured, and intrinsic water use efficiency (WUE) was computed as the ratio A/g. Firstly, we observed that the WUE showed important variations among clones. Field-growing plants consistently showed higher WUE than pot growing ones, and an important year effect was observed. The differences among genotypes were significant in pot conditions, but not in field. Nevertheless, the present results show intra-cultivar variability in Tempranillo in WUE, and therefore the possibility to build a selection program based in this criterion., This work was performed with the financial support from the Ministerio de Economía y Competitividad (MINECO, Spain) (project AGL2014-54201-C4-1-R and AGL2017-83738-C3-1-R) and a pre-doctoral fellowship BES-2015-073331). The authors would like to thank Mr. Miquel Truyols and collaborators of the UIB Experimental Field (UIB Grant 15/2015) for their support to our experiments.

One way to face the consequences of climate change and the expected increase in water availability in agriculture is to find genotypes that can sustain production at a lower water cost. This theoretically can be achieved by using genetic material with an increased water use efficiency. We compared the leaf Water Use Efficiency (WUEi) under realistic field conditions in 14 vine genotypes of the Tempranillo cultivar (clones), in two sites of Northern Spain for three and five years each to evaluate (1) if a clonal diversity exists for this traits among those selected clones and (2) the stability of those differences over several years. The ranking of the different clones showed significant differences in WUE that were maintained over years in most of the cases. Different statistical analyses gave coincident information and allowed the identification of some clones systematically that had a higher WUE or a lower WUE. These methods also allowed the identification of the underlying physiological process that caused those differences and showed that clones with a higher WUE are likely to have an increased photosynthetic capacity (rather than a different stomatal control). Those differences could be useful to orientate the decision for vines selection programs in the near future., This work was performed with the financial support from the Spanish Ministry of Science and Technology (project AGL2014-54201-C4-1-R and AGL2017-83738-C3-1-R; Agencia Española de Investigación
AEI; Fondos FEDER) and a pre-doctoral fellowship BES-2015-073331) with a narrow collaboration inside the Associated Unit ICVV-INAGEA.UIB.

The current climate change is forcing growth-adapted genotypes with a higher water use efficiency (WUE). However, the evaluation of WUE is being made by different direct and indirect parameters such as the instantaneous leaf WUE (WUE) and isotopic discrimination of carbon (δC) content of fruits. In the present work, WUE has been evaluated in these two ways in a wide collection of grapevine genotypes, including Tempranillo and Garnacha clones, and Tempranillo on different rootstocks (T-rootstocks). A total of 70 genotypes have been analysed in four experimental fields over two years. The parameters used to measure WUE were the bunch biomass isotopic discrimination (δC) and the intrinsic WUE (WUE), defined as the ratio between net CO assimilation and stomatal conductance. The genotypes with the highest and lowest WUE were identified, differences between them being found to be of more than 10%. Generally, the two parameters showed coincidences in the clones with the highest and lowest WUE, suggesting that both are valuable tools to classify genotypes by their WUE in grapevine breeding programs. However, δC seemed to be a better indicator for determining WUE because it represents the integration over the synthesis time of the sample analysed (mainly sugars from ripening grapes), which coincides with the driest period for the crop. Moreover, the WUE is a variable parameter in the plant and it is more dependent on the environmental conditions. The present work suggests that carbon isotopic discrimination could be an interesting parameter for the clonal selection criteria in grapevines by WUE. The main reasons were its better discrimination between clones, the fact that sampling is less time-consuming and easier to do than WUE, and that the samples can be stored for late determinations, increasing the number of samples that can be analysed., This work was carried out with financial support from the Spanish Ministry of Science
and Technology (FEDER/Ministerio de Ciencia, Innovación y Universidades–Agencia Estatal de
Investigación/_AGL2017-83738-C3-1-R) and a pre-doctoral fellowship (PRE2019-089110) with a
narrow collaboration inside the Associated Unit ICVV-INAGEA.UIB.

13 Pág., Mediterranean viticulture is highly dependent on soil water availability. Moreover, global warming is likely to increase average temperatures and the frequency of heat waves, thus leading to greater water scarcity. To cope with this situation, much research focused on the selection of genotypes with higher water use efficiency (WUE). Several previous studies indicated that WUE varies between genotypes of the Tempranillo cultivar with some showing interesting improvement in the leaf WUE. Here, we assessed the associations between the leaf WUE and physiological parameters in six selected Tempranillo clones. The plants were cultivated in pots and two water conditions were applied sequentially: a well-watered period followed by a moderate water stress and recovery phase. Growth parameters and intrinsic WUE were monitored during both periods. Pressure–volume and AN/Ci curves were measured after the plants were re-watered. At the end of the season, biomass accumulation and total irrigation water were used to calculate whole plant WUE (WUEWP). AN/Ci curves revealed significant differences in several photosynthetic parameters, including mesophyll conductance (gm), maximum velocity of carboxylation (Vcmax) and leaf respiration (R). Clones RJ51 and 1048 both exhibited high WUE, but presented distinct physiological traits: RJ51 had the highest gm, while genotype 1048, had the lowest R. This study confirms that physiological traits generally explain the intracultivar diversity in WUE observed in previous studies., This work was performed with financial support from the Spanish Ministry of Science and Technology (FEDER/Ministerio de Ciencia, Innovación y Universidades–Agencia Estatal de Investigación/_AGL2017-83738-C3-1-R; AGL2014-54201-C4-1-R) and a pre-doctoral fellowship, BES2015-073331., Peer reviewed

20 Pág., Climatic change is affecting grapevines growth and development with clear effects on plant production and grape quality. Drought is becoming a serious threat and water availability is becoming a main limitation for vineyard sustainability. Search for grapevine genotypes of enhanced drought resistance is a priority to face the climatic change because it is an environmental friendly solution. The present review shows different genetic variability sources, which could be of major interest to identify more drought-resistant cultivars. A summary of different sources of genetic diversity is shown from wild grapevines to cultivars, clones and rootstocks, showing wide variability in different drought-tolerant traits, such as water use efficiency. The interest of those genetic resources is enhanced by the progress in genomic tools opening a wide field of research and also the expectative for new cultivars of enhanced drought resistance., This work was performed with financial support from the Ministerio de Ciencia, Innovación y Universidades (Spain) (projects RTI2018-094470-R-C21, RTI2018-094470-R-C22, AGL2017-83738-C3-1-R). I. Tortosa was supported by a predoctoral fellowship BES-2015-073331., Peer reviewed

The use of rootstocks tolerant to soil water deficit is an interesting strategy to face the challenges posed by limited water availability. Currently, several nurseries are breeding new genotypes aiming to improve the water stress tolerance of grapevine, but the physiological basis of its responses under water stress are largely unknown. For this purpose, an ecophysiological assessment of the conventional 110-Rich-ter (110R) and SO4, and the new M1 and M4 rootstocks was carried out in ungrafted potted plants. During one season, these Vitis genotypes were grown under greenhouse conditions and subjected to two water regimes, well-watered (WW) and deficit irrigation (DI). Water potentials of plants under DI down to <-1.4 MPa, and net photosynthesis (A) <5 μmol COms did not cause leaf oxidative stress damage compared to WW conditions in all genotypes. The antioxidant capacity was sufficient to neutralize the mild oxidative stress suffered. Under both water regimes, gravimetric differences in daily water use were observed among genotypes, leading to differences in the biomass of roots and shoots. Under WW conditions, SO4 and 110R were the most vigorous and M1 and M4 the least. However, under DI, SO4 exhibited the greatest reduction in biomass, while 110R showed the lowest. Remarkably, under these conditions, SO4 reached the least negative stem water potential and showed the highest hydraulic conductance values. Conversely, M1 reduced the most stomatal conductance, transpiration and A. Overall, 110R achieved the highest biomass water use efficiency in response to DI, and SO4 the lowest, while M-rootstocks showed intermediate values. Our results suggest that there are differences in water use regulation among genotypes attributed not only to differences in stomatal regulation but also to plant hydraulic conductance. Therefore, it is hypothesized that differences in genotype performance may be due to root anatomical-morphological differences and to several physiological processes such as growth inhibition, osmotic adjustment, antioxidant production, nutrient translocation capacity, etc. Further studies are needed to confirm these differential ecophysiological responses of Vitis species under water stress, particularly under field and grafted conditions., This work received the financial support from the AEI with
FEDER co-funding (WANUGRAPE (AGL2017-83738-C3-1R)
and WANUGRAPE4.0 (PDC2021-121210-C21). E.P. Pérez-Álvarez
and I. Buesa acknowledges the postdoctoral financial
support received from “Juan de la Cierva” Spanish Program
(IJC2019-040502-I and FJC2019-042122-I, respectively).
Thanks are also due to J.S. Rubio, V. Graffato and A. Castellana
for their help in the greenhouse works.