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Las temperaturas más altas en los últimos años han generado un avance en la madurez de las bayas y han reducido el número de días a cosecha. También ha generado un desacople entre la acumulación de azúcar respecto a las antocianinas reduciendo el color del vino. La poda tardía se propone como una herramienta para mitigar estos efectos retrasando la fenología y modificando la maduración en las bayas. El objetivo del presente estudio fue evaluar los efectos de la poda tardía sobre la ocurrencia de las principales etapas fenológicas, rendimiento, composición de la uva y del vino. El experimento se llevó a cabo en la Estación Experimental Agropecuaria de Mendoza de Luján de Cuyo, durante las temporadas 2017-18 y 2018-19, en un viñedo cv. Malbec (clon 18) implantado en 2011 a pie franco y regado por goteo. El espaciamiento entre hileras fue de 2.5 m y el espaciamiento entre las plantas fue de 1.5 m. Los tratamientos consistieron en cuatro fechas de poda correspondientes a diferentes estadios fenológicos según Coombe (Coombe, 1995): invierno con yema dormida (estadio 1, control), brotación (estadio 4), 2-3 hojas desplegadas (estadio 9) y 8 hojas desplegadas (estadio 15). Todos los tratamientos se cosecharon con 23 oBrix. En ese momento se registró el rendimiento y sus componentes (producción por planta, número de racimos, peso de racimo y peso de baya). Los vinos de cada repetición se elaboraron en la planta piloto de la EEA Mendoza utilizando un protocolo estándar. Se determinó la composición fenólica global en los vinos terminados. EEA Mendoza Fil: Bustos Morgani, Marianela. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina Fil: Bustos Morgani, Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Sari, Santiago Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina Fil: Gallo, Agustina Eugenia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina Fil: Gallo, Agustina Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Perez Peña, Jorge Esteban. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina Fil: Fanzone, Martí­n Leandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina Fil: Prieto, Jorge Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina

The main objective of this study was to evaluate (i) the mechanisms underlying the long-term acclimation of photosynthesis to elevated temperature and (ii) to determine whether these responses are similar among Syrah and Grenache, two varieties with different behavior in response to environmental factors (Schultz 2003). In our experiment, we imposed an increase in growth temperature (Tgrowth) between 1.5 and 3.6 °C in field-grown plants during the whole season. We compared the thermal acclimation in terms of optimum temperature for photosynthesis (Topt), the photosynthetic rate at Topt (Aopt) and the temperature dependencies of photosynthetic capacity (Vcmax, Jmax), at each growing temperature during two consecutive seasons. EEA Mendoza Fil: Gallo, Agustina Eugenia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina Fil: Gallo, Agustina Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Perez Peña, Jorge Esteban. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina Fil: Prieto, Jorge Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; Argentina

International audience; Drought is the major constraint causing considerable yieldreduction in chickpea. Roots play a critical role in enhancingdrought tolerance. The main objective of the study was to introgressdrought tolerant root traits into Kenyan chickpea varietiesthrough marker assisted breeding (MABC). Eight simplesequence repeat (SSR) markers, linked to quantitative trait loci(QTL) for root and yield traits, were used to screen the parentsat ICRISAT, India. In addition, 1144 single nucleotide polymorphicmarkers (SNPs) were also used in genotyping theseparents at Legume Genomics Center, United Kingdom. Crosseswere made between two selected varieties, ICCV 92944 (ChaniaDesi II) and ICCV 00108 (LDT 068) and ‘QTL-hotspot’ donorparent ICC 4958 that has extensive rooting system. Polymorphic phic SSR and SNP markers were used to select progenies withroot QTL at F1, BC1F1 and BC2F1 that were later advanced toBC2F3. The BC2F3 populations were evaluated for root traitsat Egerton University in randomized complete block designwith two replications in pot experiment. The BC2F3 familieswere significantly different for root dry weight (RDW), shootdry weight (SDW), total plant dry weight (PDW) and root toshoot dry weight (R/S) ratio (R/S) for Chania Desi II x ICC 4958and R/S for LDT 068 x ICC 4958. These lineshad significantlyimproved root traits compared the recurrent parents. MABCis aneffective and efficient method of introgressing complexdrought tolerant traits which leads to improvement in yield especiallyunder drought conditions.

Drought is the major constraint causing considerable yieldreduction in chickpea. Roots play a critical role in enhancingdrought tolerance. The main objective of the study was to introgressdrought tolerant root traits into Kenyan chickpea varietiesthrough marker assisted breeding (MABC). Eight simplesequence repeat (SSR) markers, linked to quantitative trait loci(QTL) for root and yield traits, were used to screen the parentsat ICRISAT, India. In addition, 1144 single nucleotide polymorphicmarkers (SNPs) were also used in genotyping theseparents at Legume Genomics Center, United Kingdom. Crosseswere made between two selected varieties, ICCV 92944 (ChaniaDesi II) and ICCV 00108 (LDT 068) and ‘QTL-hotspot’ donorparent ICC 4958 that has extensive rooting system. Polymorphic phic SSR and SNP markers were used to select progenies withroot QTL at F1, BC1F1 and BC2F1 that were later advanced toBC2F3. The BC2F3 populations were evaluated for root traitsat Egerton University in randomized complete block designwith two replications in pot experiment. The BC2F3 familieswere significantly different for root dry weight (RDW), shootdry weight (SDW), total plant dry weight (PDW) and root toshoot dry weight (R/S) ratio (R/S) for Chania Desi II x ICC 4958and R/S for LDT 068 x ICC 4958. These lineshad significantlyimproved root traits compared the recurrent parents. MABCis aneffective and efficient method of introgressing complexdrought tolerant traits which leads to improvement in yield especiallyunder drought conditions.

International audience; In the face of increased water scarcity as a major consequence of climate change, improving water use efficiency (WUE) becomes crucial for sustaining viticulture in the Mediterranean area. Leeway to improve WUE depends on how water losses are coupled with biomass gain. As water loss at night is not associated with any carbon gain, its reduction could be a good strategy to limit waste of water without altering photosynthesis rate in the daytime. However, genetic and physiological bases of variations in night transpiration are still unclear. The present study aimed at elucidating whether and how variations in night transpiration are genetically controlled in grapevine. A 2 year experiment was conducted on the F1 progeny from a cross between Syrah and Grenache using a phenotyping platform coupled to a controlled-environment chamber. Potted plants of the whole progeny were analysed for night transpiration, both in well-watered and water deficit conditions. A high genetic variability was found and 7 QTLs were detected, of which 3 were stable between years. These results evidenced for the first time the genetic control of water losses at night by identifying underlying locus. We then explored the physiological bases of this genetic variability, deciphering the respective roles of stomata and cuticle. 20 genotypes, chosen within the progeny for their contrasting transpirations at night, were studied in experiments with detached leaves. By feeding leaves with abscisic acid, we showed that stomata remain open at night, and that this residual opening differs among genotypes. We took advantage of the hypostomatic feature in grapevine to study cuticular conductance on the adaxial face. We found a significant genetic control of cuticular conductance, which accounted for up to 30% of the total leaf transpiration at night. These results open new avenues to breed grapevine for lower water losses at night, whose genetic variability appears to be driven both by stomata and cuticle.; Face à la raréfaction des ressources hydriques qui accompagne les changements climatiques, il devient crucial d'augmenter l'efficience d'utilisation de l'eau, notamment dans les systèmes viticoles en zone méditerranéenne. Cependant, le couplage entre gain de biomasse et consommation d'eau par la plante limite les marges d'amélioration. C'est pourquoi la réduction de l'utilisation de l'eau la nuit, en l'absence de photosynthèse, est une cible intéressante. Cette étude visait l'analyse de la variabilité génétique de la transpiration nocturne chez la vigne et l'identification des processus physiologiques sous-jacents. Une expérimentation a été répétée 2 années sur une descendance F1 issue du croisement des variétés Syrah et Grenache. La descendance cultivée en pots a été analysée en conditions de bonne irrigation à l'aide d'une plate-forme de phénotypage couplée à une chambre climatique. Une forte variabilité génétique de la transpiration nocturne (rapportée à la surface foliaire) a été observée dans la descendance et, pour la première fois, des déterminants génétiques de ce caractère ont été localisés sur le génome. Les bases physiologiques de cette variabilité ont été recherchées chez 15 génotypes de la descendance. En alimentant des feuilles détachées avec une solution très concentrée d'acide abscissique pour induire la fermeture stomatique, nous avons montré qu'il existait une ouverture résiduelle des stomates la nuit avec des différences significatives entre génotypes. De plus, les pertes d'eau à travers la cuticule de la face adaxiale, dépourvue de stomates, représentaient une part non négligeable des pertes totales avec des différences entre génotypes. Il apparaît donc possible de sélectionner des variétés avec de faibles pertes d'eau la nuit en jouant à la fois sur les contributions stomatiques et cuticulaires.

International audience; In the face of increased water scarcity as a major consequence of climate change, improving water use efficiency (WUE) becomes crucial for sustaining viticulture in the Mediterranean area. Leeway to improve WUE depends on how water losses are coupled with biomass gain. As water loss at night is not associated with any carbon gain, its reduction could be a good strategy to limit waste of water without altering photosynthesis rate in the daytime. However, genetic and physiological bases of variations in night transpiration are still unclear. The present study aimed at elucidating whether and how variations in night transpiration are genetically controlled in grapevine. A 2 year experiment was conducted on the F1 progeny from a cross between Syrah and Grenache using a phenotyping platform coupled to a controlled-environment chamber. Potted plants of the whole progeny were analysed for night transpiration, both in well-watered and water deficit conditions. A high genetic variability was found and 7 QTLs were detected, of which 3 were stable between years. These results evidenced for the first time the genetic control of water losses at night by identifying underlying locus. We then explored the physiological bases of this genetic variability, deciphering the respective roles of stomata and cuticle. 20 genotypes, chosen within the progeny for their contrasting transpirations at night, were studied in experiments with detached leaves. By feeding leaves with abscisic acid, we showed that stomata remain open at night, and that this residual opening differs among genotypes. We took advantage of the hypostomatic feature in grapevine to study cuticular conductance on the adaxial face. We found a significant genetic control of cuticular conductance, which accounted for up to 30% of the total leaf transpiration at night. These results open new avenues to breed grapevine for lower water losses at night, whose genetic variability appears to be driven both by stomata and cuticle.; Face à la raréfaction des ressources hydriques qui accompagne les changements climatiques, il devient crucial d'augmenter l'efficience d'utilisation de l'eau, notamment dans les systèmes viticoles en zone méditerranéenne. Cependant, le couplage entre gain de biomasse et consommation d'eau par la plante limite les marges d'amélioration. C'est pourquoi la réduction de l'utilisation de l'eau la nuit, en l'absence de photosynthèse, est une cible intéressante. Cette étude visait l'analyse de la variabilité génétique de la transpiration nocturne chez la vigne et l'identification des processus physiologiques sous-jacents. Une expérimentation a été répétée 2 années sur une descendance F1 issue du croisement des variétés Syrah et Grenache. La descendance cultivée en pots a été analysée en conditions de bonne irrigation à l'aide d'une plate-forme de phénotypage couplée à une chambre climatique. Une forte variabilité génétique de la transpiration nocturne (rapportée à la surface foliaire) a été observée dans la descendance et, pour la première fois, des déterminants génétiques de ce caractère ont été localisés sur le génome. Les bases physiologiques de cette variabilité ont été recherchées chez 15 génotypes de la descendance. En alimentant des feuilles détachées avec une solution très concentrée d'acide abscissique pour induire la fermeture stomatique, nous avons montré qu'il existait une ouverture résiduelle des stomates la nuit avec des différences significatives entre génotypes. De plus, les pertes d'eau à travers la cuticule de la face adaxiale, dépourvue de stomates, représentaient une part non négligeable des pertes totales avec des différences entre génotypes. Il apparaît donc possible de sélectionner des variétés avec de faibles pertes d'eau la nuit en jouant à la fois sur les contributions stomatiques et cuticulaires.