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La Poda tardía (PT) ha surgido como una herramienta que podría apoyar la adaptación de la viticultura frente al cambio climático, pudiendo retrasar la maduración y reducir el desequilibro en la madurez entre los azucares, ácidos y compuestos fenológicos, producidos por el incremento de temperatura (T). El objetivo del estudio fue evaluar la PT en cv. Merlot del Valle Central de Chile, en 2 condiciones de temperatura: Ambiente; Elevada y 3 momentos de poda: Invierno; Brotación; Brotes 2-4 cm. Se realizó un seguimiento fenológico, determinación de intercambio gaseoso y crecimiento. Al momento de la cosecha se valoró la calidad de la fruta (brix, acidez, pH) y la concentración de antocianinas. El aumento de T produjo un incremento de la temperatura de hojas por sobre 30ºC, además de caídas en la AN, gs y WUEF, y disminuyo significativamente el rendimiento por planta. Los tratamientos en T elevada presentaron una cosecha adelantada y menor concentración de antocianinas, independiente de la poda, no logrando contrarrestar los efectos de la T. En condiciones de T actual la poda fue capaz de retrasar la cosecha en al menos una semana, sumado a un incremento del 10% de la concentración de antocianinas en piel.

La vitivinicultura tradicional de secano en Chile se basa principalmente en la variedad País, siendo posible encontrar viñedos centenarios en diversas zonas. Si bien en los inicios de la viticultura nacional esta variedad fue la predominante, en la actualidad se encuentra relegada a los sectores de secano, es cultivada casi exclusivamente por pequeños productores y se destina en su mayoría a la elaboración de vinos a granel, obteniéndose bajos precios tanto por su uva como por su vino. El análisis de datos climáticos, en las zonas de producción de la variedad País, muestran que, en las últimas seis décadas, la precipitación ha disminuido en más de un 20%, se han incrementado los días con temperaturas sobre 30 y 35°C y se han intensificado las heladas primaverales. Al evaluar el efecto del alza de temperatura, mediante la utilización de un sistema de estructuras de policarbonato que permiten un calentamiento pasivo, se observaron los efectos sobre el crecimiento de brotes y bayas, la fisiología de la planta y la calidad de uvas. En general los efectos observados frente a un alza de temperatura son menos severos que en otras variedades. Aunque esto puede explicarse desde distintas miradas, se reafirma la rusticidad y aptitud de esta variedad para las condiciones de secano.

The growth and development of green lettuce plants can be modulated by the prevailing light conditions around them. The aim of this study was to evaluate the effect of ambient light enrichment with different LED light spectra on agronomic characteristics, polyphenol concentration and relative gene expression of enzymes associated with polyphenol formation in 'Levistro' lettuce grown hydroponically in a Nutrient Film Technique (NFT) system for 28 days in a greenhouse. The spectra (blue:green:red:far-red) and red:blue (R:B) ratios obtained by enriching ambient light with Blue (B), White (W), Blue-Red (BR) and Red (R) LED light were B: 47:22:21:10, 0.5:1; W: 30:38:23:9, 0.8:1; BR: 33:15:44:8, 1.3:1 and R: 16:16:60:8, 3.8:1, respectively, and photosynthetically active radiation (PAR) under the different treatments, measured at midday, ranged from 328 to 336 µmoles m -2 s -1 . The resulting daily light integral (DLI) was between 9.1 and 9.6 mol m -2 day -1 . The photoperiod for all enrichment treatments was 12 h of light. The control was ambient greenhouse light (25:30:30:15; R:B = 1.2:1; PAR = 702 µmoles m -2 s -1 ; DLI = 16.9 mol m -2 day -1 ; photoperiod = 14.2 h of light). Fresh weight (FW) and dried weight percentage (DWP) were similar among the enrichment treatments and the control. The leaf number increased significantly under BR and R compared to B lights. The relative index of chlorophyll concentration (RIC) increased as plants grew and was similar among the enrichment treatments and the control. On the other hand, the concentration of chlorogenic acid and chicoric acid increased under BR and B lights, which was consistent with the higher relative expression of the coumarate 3-hydroxylase enzyme gene. In view of the results, it is inferred that half of the PAR or DLI is sufficient to achieve normal growth and development of 'Levistro' lettuce plants, suggesting a more efficient use of light energy under the light enrichment treatments. On the other hand, the blue and combined blue-red lights promoted the accumulation of phenolic compounds in the leaves of 'Levistro' lettuce plants.

Foreseen climate change is expected to impact on grape composition, both sugar and pigment content. We tested the hypothesis that interactions between main factors associated with climate change (elevated CO 2 , elevated temperature, and water deficit) decouple sugars and anthocyanins, and explored the possible involvement of vegetative area, photosynthesis, and grape C uploading on the decoupling. Tempranillo grapevine fruit-bearing cuttings were exposed to CO 2 (700 vs. 400 ppm), temperature (ambient vs. + 4 °C), and irrigation levels (partial vs. full) in temperature-gradient greenhouses. In a search for mechanistic insights into the underlying processes, experiments 1 and 2 were designed to maximize photosynthesis and enlarge leaf area range among treatments, whereas plant growth was manipulated in order to deliberately down-regulate photosynthesis and control vegetative area in experiments 3 and 4. Towards this aim, treatments were applied either from fruit set to maturity with free vegetation and fully irrigated or at 5-8% of pot capacity (experiments 1 and 2), or from veraison to maturity with controlled vegetation and fully irrigated or at 40% of pot capacity (experiments 3 and 4). Modification of air 13 C isotopic composition under elevated CO 2 enabled the further characterization of whole C fixation period and C partitioning to grapes. Increases of the grape sugars-to-anthocyanins ratio were highly and positively correlated with photosynthesis and grape 13 C labeling, but not with vegetative area. Evidence is presented for photosynthesis, from fruit set to veraison, and grape C uploading, from veraison to maturity, as key processes involved in the establishment and development, respectively, of the grape sugars to anthocyanins decoupling.

Although plant performance under elevated CO2 has been extensively studied in the past little is known about photosynthetic performance changing simultaneously CO2, water availability and temperature conditions. Moreover, despite of its relevancy in crop responsiveness to elevated CO2 conditions, plant level C balance is a topic that, comparatively, has received little attention. In order to test responsiveness of grapevine photosynthetic apparatus to predicted climate change conditions, grapevine (Vitis vinifera L. cv. Tempranillo) fruit-bearing cuttings were exposed to different CO2 (elevated, 700ppm vs. ambient, ca. 400ppm), temperature (ambient vs. elevated, ambient +4°C) and irrigation levels (partial vs. full irrigation). Carbon balance was followed monitoring net photosynthesis (AN, C gain), respiration (RD) and photorespiration (RL) (C losses). Modification of environment (13)C isotopic composition (δ(13)C) under elevated CO2 (from -10.30 to -24.93‰) enabled the further characterization of C partitioning into roots, cuttings, shoots, petioles, leaves, rachides and berries. Irrespective of irrigation level and temperature, exposure to elevated CO2 induced photosynthetic acclimation of plants. C/N imbalance reflected the inability of plants grown at 700ppm CO2 to develop strong C sinks. Partitioning of labeled C to storage organs (main stem and roots) did not avoid accumulation of labeled photoassimilates in leaves, affecting negatively Rubisco carboxylation activity. The study also revealed that, after 20 days of treatment, no oxidative damage to chlorophylls or carotenoids was observed, suggesting a protective role of CO2 either at current or elevated temperatures against the adverse effect of water stress., (Copyright © 2014 Elsevier GmbH. All rights reserved.)

Photosynthetic carbon fixation (A(N) ) and photosynthetic electron transport rate (ETR) are affected by different environmental stress factors, such as those associated with climate change. Under stress conditions, it can be generated an electron excess that cannot be consumed, which can react with O₂, producing reactive oxygen species. This work was aimed to evaluate the influence of climate change (elevated CO₂, elevated temperature and moderate drought) on the antioxidant status of grapevine (Vitis vinifera) cv. Tempranillo leaves, from veraison to ripeness. The lowest ratios between electrons generated (ETR) and consumed (A(N) + respiration + photorespiration) were observed in plants treated with elevated CO₂ and elevated temperature. In partially irrigated plants under current ambient conditions, electrons not consumed seemed to be diverted to alternative ways. Oxidative damage to chlorophylls and carotenoids was not observed. However, these plants had increases in thiobarbituric acid reacting substances, an indication of lipid peroxidation. These increases matched well with an early rise of H₂O₂ and antioxidant enzyme activities, superoxide dismutase (EC 1.15.1.1), ascorbate peroxidase (EC 1.11.1.11) and catalase (EC 1.11.1.6). Enzymatic activities were maintained high until ripeness. In conclusion, plants grown under current ambient conditions and moderate drought were less efficient to cope with oxidative damage than well-irrigated plants, and more interestingly, plants grown under moderate drought but treated with elevated CO₂ and elevated temperature were not affected by oxidative damage, mainly because of higher rates of electrons consumed in photosynthetic carbon fixation., (Copyright © Physiologia Plantarum 2011.)