Midday measurements of leaf water potential and stomatal conductance are highly correlated with daily water use of Thompson Seedless grapevines

A study was conducted to determine the relationship between midday measurements of vine water status and daily water use of grapevines measured with a weighing lysimeter. Water applications to the vines were terminated on August 24th for 9 days and again on September 14th for 22 days. Daily water use of the vines in the lysimeter (ETLYS) was approximately 40 L vine−1 (5.3 mm) prior to turning the pump off, and it decreased to 22.3 L vine−1 by September 2nd. Pre-dawn leaf water potential (ΨPD) and midday Ψl on August 24th were −0.075 and −0.76 MPa, respectively, with midday Ψl decreasing to −1.28 MPa on September 2nd. Leaf g s decreased from ~500 to ~200 mmol m−2 s−1 during the two dry-down periods. Midday measurements of g s and Ψl were significantly correlated with one another (r = 0.96) and both with ETLYS/ETo (r = ~0.9). The decreases in Ψl, g s, and ETLYS/ETo in this study were also a linear function of the decrease in volumetric soil water content. The results indicate that even modest water stress can greatly reduce grapevine water use and that short-term measures of vine water status taken at midday are a reflection of daily grapevine water us

Response of the photosynthetic apparatus to a flowering-inductive period by water stress in Citrus

The photosynthetic responses to a flowering-inductive water-stress period and recovery were studied and compared in two Citrus species. Under greenhouse conditions, Fino lemon and Owari satsuma trees were subjected to moderate (-2 MPa at predawn) and severe (-3 MPa) water stress levels and were re-watered after 60 days. Vegetative growth was inhibited during the stress assays, and strong defoliation levels were reported, especially in Fino lemon. In both species, bud sprouting was induced after re-watering. Flowers and vegetative shoots developed in Owari satsuma after a drought period, and the development was independent of the stress level. In Fino lemon, vegetative shoots and flowers were primarily formed after moderate and severe stress, respectively. The photosynthetic rate and stomatal conductance were reduced by water stress, and a marked increase in water-use efficiency at the moderate water deficit level was observed. Nevertheless, the photosynthetic apparatus was not damaged, since the maximum quantum yield, photosynthetic pigment concentrations and Rubisco level and activity did not change. Furthermore, the measured malonyldialdehyde (MDA) and peroxidase activity indicated that oxidative stress was not specifically triggered by water stress in our study. Therefore, the gas exchange, fluorescence and biochemical parameters suggested that diffusional limitations to photosynthesis predominated in both of the studied Citrus species, and explained the rapid recovery of the photosynthetic parameters after rehydration. The net CO 2 fixation rate and stomatal conductance were recovered within 24 h in Fino lemon, whereas 3 days were required in Owari satsuma. This suggests the presence of some metabolic limitations in the latter species. Furthermore, the sensibility of the defoliation rates, the accumulation of proline and the stomatal behaviour in response to water stress indicated a higher drought tolerance of Fino lemon, according to its better acclimation to hot climates. © 2011 Springer-Verlag.The authors thank Dr. J. Moreno and co-workers from the Departamento de Bioquimica of the Universidad de Valencia for his help and support in the Rubisco assays, and Dr. F. Fornes, Dr. A. Calatayud and Dr. E. Primo-Millo for the critical review of the manuscript. This work was funded by the Universitat Politecnica de Valencia, Spain (Ayudas para primeros proyectos de investigacion PAID06-06).Ávila Reséndiz, C.; Guardiola Barcena, JL.; González Nebauer, S. (2012). Response of the photosynthetic apparatus to a flowering-inductive period by water stress in Citrus. Trees - Structure and Function. 26(3):833-840. https://doi.org/10.1007/s00468-011-0657-4S833840263Addicott FT (1982) Abscission. University of California Press, BerkeleyBajji M, Kinet JM, Lutts S (1998) Salt stress effects on roots and leaves of Atriplex halimus L. and their corresponding callus. Plant Sci 137:131–142Barbera G, Fatta-del-Bosco G, Lo-Cascio B (1985) Effect of water stress on lemon summer bloom: the Forzatura technique in the Sicilian citrus industry. Acta Hortic 171:391–397Bates LS, Waldren RP, Teare ID (1973) Rapid determination of free proline for water stress studies. Plant Soil 39:205–207Bota J, Medrano H, Flexas J (2004) Is photosynthesis limited by decreased Rubisco activity and RuBP content under progressive water stress? New Phytol 162:671–681Bradford MM (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72:248–254Cassin J, Bourdeaut A, Fougue V, Furon V, Gaillard JP, LeBourdelles J, Montagut G, Moreuil C (1969) The influence of climate upon blooming of Citrus in tropical areas. Proc Int Soc Citrus 1:315–323Castel JR, Buj A (1990) Response of Salustiana oranges to high frequency deficit irrigation. Irrig Sci 11:121–127Chaikiatitiyos S, Menzel CM, Rasmussen TS (1994) Floral induction in tropical fruit trees: effects of temperature and water supply. J Hortic Sci 69:397–415Chaves MM, Flexas J, Pinheiro C (2009) Photosynthesis under drought and salt stress: regulation mechanisms from whole plant to cell. Ann Bot 103:551–560Costa JM, Ortuño MF, Chaves M (2007) Deficit irrigation as a strategy to save water: physiology and potential application to horticulture. J Integr Plant Biol 49:1421–1434Davenport TL (1990) Citrus flowering. Hortic Rev 12:249–408Davies FS, Albrigo LG (1994) Citrus. CAB International, Wallingford, pp 126–134Domingo R, Ruiz-Sánchez MC, Sánchez-Blanco MJ, Torrecillas A (1996) Water relations, growth and yield of Fino lemon trees under regulated deficit irrigation. Irrig Sci 16:115–123Erismann ND, Machado EC, Tucci MLS (2008) Photosynthetic limitation by CO2 diffusion in drought stressed orange leaves on three rootstocks. Photosynth Res 96:163–172Flexas J, Bota J, Galmés J, Medrano H, Ribas-Carbó M (2006) Keeping a positive carbon balance under adverse conditions: responses of photosynthesis and respiration to water stress. Physiol Plant 127:343–352Gallé A, Florez-Sarasa I, Tomas M, Pou A, Medrano H, Ribas-Carbó M, Flexas J (2009) The role of mesophyll conductance during water stress and recovery in tobacco (Nicotiana sylvestris): acclimation or limitation? J Exp Bot 60:2379–2390Galmés J, Medrano H, Flexas J (2007) Photosynthetic limitations in response to water stress and recovery in Mediterrenean plants with different growth forms. New Phytol 175:81–93García-Luis A, Kanduser M, Santamarina P, Guardiola JL (1992) Low temperature influence on flowering in Citrus. The separation of inductive and bud dormancy releasing effects. Physiol Plant 86:648–652García-Sánchez F, Syvertsen JP, Gimeno V, Botía P, Pérez-Pérez JG (2007) Responses to flooding and drought stress by two citrus rootstock seedlings with different water-use efficiency. Physiol Plant 130:532–542Genty B, Briantais JM, Baker NR (1989) The relationship between quantum yield of photosynthetic electron transport and quenching of chlorophyll fluorescence. Biochim Biophys Acta 990:87–92Gómez-Cadenas A, Tadeo FR, Talon M, Primo-Millo E (1996) Leaf abscission induced by ethylene in water-stressed intact seedlings of Cleopatra mandarin requires previous abscisic acid accumulation in roots. Plant Physiol 112:401–408Gordo O, Sanz JJ (2010) Impact of climate change on plant phenology in Mediterranean ecosystems. Glob Chang Biol 16:1082–1106Heath RL, Packer L (1968) Photoperoxidation in isolated chloroplasts. I. Kinetics and stoichiometry of fatty acid peroxidation. 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The Physiology and Proteomics of Drought Tolerance in Maize: Early Stomatal Closure as a Cause of Lower Tolerance to Short-Term Dehydration?

Understanding the response of a crop to drought is the first step in the breeding of tolerant genotypes. In our study, two maize (Zea mays L.) genotypes with contrasting sensitivity to dehydration were subjected to moderate drought conditions. The subsequent analysis of their physiological parameters revealed a decreased stomatal conductance accompanied by a slighter decrease in the relative water content in the sensitive genotype. In contrast, the tolerant genotype maintained open stomata and active photosynthesis, even under dehydration conditions. Drought-induced changes in the leaf proteome were analyzed by two independent approaches, 2D gel electrophoresis and iTRAQ analysis, which provided compatible but only partially overlapping results. Drought caused the up-regulation of protective and stress-related proteins (mainly chaperones and dehydrins) in both genotypes. The differences in the levels of various detoxification proteins corresponded well with the observed changes in the activities of antioxidant enzymes. The number and levels of up-regulated protective proteins were generally lower in the sensitive genotype, implying a reduced level of proteosynthesis, which was also indicated by specific changes in the components of the translation machinery. Based on these results, we propose that the hypersensitive early stomatal closure in the sensitive genotype leads to the inhibition of photosynthesis and, subsequently, to a less efficient synthesis of the protective/detoxification proteins that are associated with drought tolerance

Contribution of topographically-generated submesoscale turbulence to Southern Ocean overturning

The ocean’s global overturning circulation regulates the transport and storage of heat, carbon and nutrients. Upwelling across the Southern Ocean’s Antarctic Circumpolar Current and into the mixed layer, coupled to water mass modification by surface buoyancy forcing, has been highlighted as a key process in the closure of the overturning circulation. Here, using twelve high-resolution hydrographic sections in southern Drake Passage, collected with autonomous ocean gliders, we show that Circumpolar Deep Water originating from the North Atlantic, known as Lower Circumpolar Deep Water, intersects sloping topography in narrow and strong boundary currents. Observations of strong lateral buoyancy gradients, enhanced bottom turbulence, thick bottom mixed layers and modified water masses are consistent with growing evidence that topographically generated submesoscale flows over continental slopes enhance near-bottom mixing, and that cross-density upwelling occurs preferentially over sloping topography. Interactions between narrow frontal currents and topography occur elsewhere along the path of the Antarctic Circumpolar Current, which leads us to propose that such interactions contribute significantly to the closure of the overturning in the Southern Ocean

Integrated analysis of climate, soil, topography and vegetative growth in Iberian viticultural regions

The Iberian viticultural regions are convened according to the Denomination of Origin (DO) and present different climates, soils, topography and management practices. All these elements influence the vegetative growth of different varieties throughout the peninsula, and are tied to grape quality and wine type. In the current study, an integrated analysis of climate, soil, topography and vegetative growth was performed for the Iberian DO regions, using state-of-the-art datasets. For climatic assessment, a categorized index, accounting for phenological/thermal development, water availability and grape ripening conditions was computed. Soil textural classes were established to distinguish soil types. Elevation and aspect (orientation) were also taken into account, as the leading topographic elements. A spectral vegetation index was used to assess grapevine vegetative growth and an integrated analysis of all variables was performed. The results showed that the integrated climate-soil-topography influence on vine performance is evident. Most Iberian vineyards are grown in temperate dry climates with loamy soils, presenting low vegetative growth. Vineyards in temperate humid conditions tend to show higher vegetative growth. Conversely, in cooler/warmer climates, lower vigour vineyards prevail and other factors, such as soil type and precipitation acquire more important roles in driving vigour. Vines in prevailing loamy soils are grown over a wide climatic diversity, suggesting that precipitation is the primary factor influencing vigour. The present assessment of terroir characteristics allows direct comparison among wine regions and may have great value to viticulturists, particularly under a changing climate

Effects of Soil Water and Nitrogen on Growth and Photosynthetic Response of Manchurian Ash (Fraxinus mandshurica) Seedlings in Northeastern China

Soil water and nitrogen (N) are considered to be the main environmental factors limiting plant growth and photosynthetic capacity. However, less is known about the interactive effects of soil water and N on tree growth and photosynthetic response in the temperate ecosystem. seedlings. The seedlings were exposed to three water regimes including natural precipitation (CK), higher precipitation (HW) (CK +30%) and lower precipitation (LW) (CK −30%), and both with and without N addition for two growing seasons. We demonstrated that water and N supply led to a significant increase in the growth and biomass production of the seedlings. LW treatment significantly decreased biomass production and leaf N content, but they showed marked increases in N addition. N addition could enhance the photosynthetic capability under HW and CK conditions. Leaf chlorophyll content and the initial activity of Rubisco were dramatically increased by N addition regardless of soil water condition. The positive relationships were found between photosynthetic capacity, leaf N content, and SLA in response to water and N supply in the seedling. Rubisco expression was up-regulated by N addition with decreasing soil water content. Immunofluorescent staining showed that the labeling for Rubisco was relatively low in leaves of the seedlings under LW condition. The accumulation of Rubisco was increased in leaf tissues of LW by N addition. seedlings, which may provide novel insights on the potential responses of the forest ecosystem to climate change associated with increasing N deposition

Exploring the three PIPs and three TIPs of grapevine for transport of water and atypical substrates through heterologous expression in aqy-null yeast

Aquaporins are membrane channels that facilitate the transport of water and other small molecules across the cellular membranes. We examined the role of six aquaporins of Vitis vinifera (cv. Touriga nacional) in the transport of water and atypical substrates (other than water) in an aqy-null strain of Saccharomyces cerevisiae. Their functional characterization for water transport was performed by stopped-flow fluorescence spectroscopy. The evaluation of permeability coefficients (Pf) and activation energies (Ea) revealed that three aquaporins (VvTnPIP2;1, VvTnTIP1;1 and VvTnTIP2;2) are functional for water transport, while the other three (VvTnPIP1;4, VvTnPIP2;3 and VvTnTIP4;1) are non-functional. TIPs (VvTnTIP1;1 and VvTnTIP2;2) exhibited higher water permeability than VvTnPIP2;1. All functional aquaporins were found to be sensitive to HgCl2, since their water conductivity was reduced (24–38%) by the addition of 0.5 mM HgCl2. Expression of Vitis aquaporins caused different sensitive phenotypes to yeast strains when grown under hyperosmotic stress generated by KCl or sorbitol. Our results also indicate that Vitis aquaporins are putative transporters of other small molecules of physiological importance. Their sequence analyses revealed the presence of signature sequences for transport of ammonia, boron, CO2, H2O2 and urea. The phenotypic growth variations of yeast cells showed that heterologous expression of Vitis aquaporins increased susceptibility to externally applied boron and H2O2, suggesting the contribution of Vitis aquaporins in the transport of these speciesinfo:eu-repo/semantics/publishedVersio

Within-individual phenotypic plasticity in flowers fosters pollination niche shift

Authors thank Raquel Sánchez, Angel Caravante, Isabel Sánchez Almazo, Tatiana López Pérez, Samuel Cantarero, María José Jorquera and Germán Fernández for helping us during several phases of the study and Iván Rodríguez Arós for drawing the insect silhouettes. This research is supported by grants from the Spanish Ministry of Science, Innovation and Universities (CGL2015-71634-P, CGL2015-63827-P, CGL2017-86626-C2-1-P, CGL2017- 86626-C2-2-P, UNGR15-CE-3315, including EU FEDER funds), Junta de Andalucía (P18- FR-3641), Xunta de Galicia (CITACA), BBVA Foundation (PR17_ECO_0021), and a contract grant to C.A. from the former Spanish Ministry of Economy and Competitiveness (RYC-2012-12277). This is a contribution to the Research Unit Modeling Nature, funded by the Consejería de Economía, Conocimiento, Empresas y Universidad, and European Regional Development Fund (ERDF), reference SOMM17/6109/UGR.Phenotypic plasticity, the ability of a genotype of producing different phenotypes when exposed to different environments, may impact ecological interactions. We study here how within-individual plasticity in Moricandia arvensis flowers modifies its pollination niche. During spring, this plant produces large, cross-shaped, UV-reflecting lilac flowers attracting mostly long-tongued large bees. However, unlike most co-occurring species, M. arvensis keeps flowering during the hot, dry summer due to its plasticity in key vegetative traits. Changes in temperature and photoperiod in summer trigger changes in gene expression and the production of small, rounded, UV-absorbing white flowers that attract a different assemblage of generalist pollinators. This shift in pollination niche potentially allows successful reproduction in harsh conditions, facilitating M. arvensis to face anthropogenic perturbations and climate change. Floral phenotypes impact interactions between plants and pollinators. Here, the authors show that Moricandia arvensis displays discrete seasonal plasticity in floral phenotype, with large, lilac flowers attracting long-tongued bees in spring and small, rounded, white flowers attracting generalist pollinators in summer.Spanish Ministry of Science, Innovation and Universities (EU FEDER funds) CGL2015-71634-P CGL2015-63827-P CGL2017-86626-C2-1-P CGL2017-86626-C2-2-P UNGR15-CE-3315Junta de Andalucia P18-FR-3641Xunta de GaliciaBBVA Foundation PR17_ECO_0021Spanish Ministry of Economy and Competitiveness RYC-2012-12277Consejeria de Economia, Conocimiento, Empresas y Universidad SOMM17/6109/UGREuropean Union (EU) SOMM17/6109/UG