BUSCADOR RECOLECTA

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