Plant water use efficiency (WUE) is becoming a key issue in semiarid areas, where crop production relies on the use of large volumes of water. Improving WUE is necessary for securing environmental ...sustainability of food production in these areas. Given that climate change predictions include increases in temperature and drought in semiarid regions, improving crop WUE is mandatory for global food production. WUE is commonly measured at the leaf level, because portable equipment for measuring leaf gas exchange rates facilitates the simultaneous measurement of photosynthesis and transpiration. However, when those measurements are compared with daily integrals or whole-plant estimates of WUE, the two sometimes do not agree. Scaling up from single-leaf to whole-plant WUE was tested in grapevines in different experiments by comparison of daily integrals of instantaneous water use efficiency ratio between CO2 assimilation (AN) and transpiration (E); AN/E with midday AN/E measurements, showing a low correlation, being worse with increasing water stress. We sought to evaluate the importance of spatial and temporal variation in carbon and water balances at the leaf and plant levels. The leaf position (governing average light interception) in the canopy showed a marked effect on instantaneous and daily integrals of leaf WUE. Night transpiration and respiration rates were also evaluated, as well as respiration contributions to total carbon balance. Two main components were identified as filling the gap between leaf and whole plant WUE: the large effect of leaf position on daily carbon gain and water loss and the large flux of carbon losses by dark respiration. These results show that WUE evaluation among genotypes or treatments needs to be revised.
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.
Water is critical for viticulture sustainability since grape production, quality and economic viability are largely dependent on water availability. The total water consumption of vineyards, 300 to ...700 mm, is generally higher than the annual average precipitation in many viticultural areas, which induces a risk for sustainability of vineyards. Improving vineyard water use efficiency (WUE) is therefore crucial for a sustainable viticulture industry in semi-arid regions. Increased sustainability of water resources for vineyards can be achieved using both agronomical technology and cultivar selection. Here, we review advances in grapevine water use efficiency related to changes in agronomical practices and genetic improvements. Agronomical practices focus on increasing green water use by increasing soil water storage capacity, reducing direct soil water loss, or limiting early transpiration losses. Cover crops for semi-arid areas show a favorable effect, but careful management is needed to avoid excessive water consumption by the cover crop. Canopy management practices to reduce excessive water use are also analyzed. This is a genetic based review focused on identifying cultivars with higher WUE.
There is currently a high requirement for field phenotyping methodologies/technologies to determine quantitative traits related to crop yield and plant stress responses under field conditions.
We ...employed an unmanned aerial vehicle equipped with a thermal camera as a high-throughput phenotyping platform to obtain canopy level data of the vines under three irrigation treatments. High-resolution imagery (< 2.5 cm/pixel) was employed to estimate the canopy conductance (
) via the leaf energy balance model. In parallel, physiological stress measurements at leaf and stem level as well as leaf sampling for primary and secondary metabolome analysis were performed.
Aerial
correlated significantly with leaf stomatal conductance (
) and stem sap flow, benchmarking the quality of our remote sensing technique. Metabolome profiles were subsequently linked with
and
via partial least square modelling. By this approach malate and flavonols, which have previously been implicated to play a role in stomatal function under controlled greenhouse conditions within model species, were demonstrated to also be relevant in field conditions.
We propose an integrative methodology combining metabolomics, organ-level physiology and UAV-based remote sensing of the whole canopy responses to water stress within a vineyard. Finally, we discuss the general utility of this integrative methodology for broad field phenotyping.
Water stress experiments were performed with grapevines (Vitis vinifera L.) and other C3 plants in the field, in potted plants in the laboratory, and with detached leaves. It was found that, in all ...cases, the ratio of steady state chlorophyll fluorescence (Fs) normalized to dark‐adapted intrinsic fluorescence (Fo) inversely correlated with non‐photochemical quenching (NPQ). Also, at high irradiance, the ratio Fs/Fo was positively correlated with CO2 assimilation in air, with electron transport rate calculated from fluorescence, and with stomatal conductance, but no clear correlation was observed with qP. The significance of these relationships is discussed. The ratio Fs/Fo, measured with a portable instrument (PAM‐2000) or with a remote sensing FIPAM system, provides a good method for the early detection of water stress, and may become a useful guide to irrigation requirements.
► Stomata remain open during the night in grapevines. ► Water stress reduces night-time stomatal conductance (gnight) leading to values approaching cuticular conductance. ► Night-time stomatal ...conductance responds to changes in ambient vapor pressure deficit (VPDambient). ► Night transpiration and grapevine water balance could be partially or fully compensated by dew deposition in low VPDambient conditions.
Night-time transpiration (Enight) is potentially an important factor affecting whole-plant water balance and, thus, water use efficiency. The aims of the present study were: to evaluate night-time changes of stomatal conductance (gnight) and transpiration under different soil water availability conditions for seven grapevine cultivars and to compare leaf-level estimates of night-time water losses with more realistic whole-plant estimates in plants growing outdoors. Two experiments were conducted on seven grapevine cultivars (Vitis vinifera L.) growing in pots maintained at field capacity and drought stress conditions. Night transpiration was evaluated by leaf gas exchange and plant mass measurements. Results showed that Enight and gnight were far above cuticular values, suggesting sustained stomatal aperture during night-time which was reduced under drought stress. Differences between cultivars were found in the extent of drought stress-induced reduction of Enight (from a 36% reduction in Escursac to 82% in Malvasia). However, transpiration losses calculated on the basis of leaf gas exchange measurements often over-estimated the actual whole plant water loss, suggesting the presence of some water inputs to pots/plants during the night, presumably due to dew deposition. Significant stomatal opening persists during the night in irrigated grapevines, leading to substantial water losses by transpiration. Those water losses are significantly reduced under drought stress. It is remarkable that night-time plant water losses can be partially or fully compensated by dew deposition. Therefore, instantaneous leaf gas exchange measurements can result in an over-estimation of the night water losses. The present study shows for the first time that night transpiration due to partially open stomata can be compensated by dew deposition.
An understanding of fruit gas exchange is necessary to determine the carbon balance in grapevines, but little attention has been paid to the relationships among fruit respiration, plant water status ...and genetic variability. The effect of plant water status and genotype on cluster respiration was studied over two seasons (2013 and 2014) under field conditions using a whole cluster respiration chamber. Whole cluster CO2 fluxes were measured in growing grapevines at hard‐green, veraison and ripening stages under irrigated and non‐irrigated conditions, and under light and dark conditions in two grapevine varieties, Tempranillo and Grenache. A direct relationship between cluster CO2 efflux and plant water status was found at hard‐green stage. Genotype influenced the fruit CO2 efflux that resulted in higher carbon losses in Tempranillo than in Grenache. Fruit respiration rates decreased from the first berry developmental stages to ripening stage. The integration of fruit respiration rates under light and dark conditions showed the magnitude of fruit carbon losses and gains as well as interesting variety and environmental conditions effects on those processes.
Water scarcity is a main challenge in vineyards sustainability in most of the grapevine areas now and even more in near future due to climatic change perspectives. In consequence, water use ...efficiency (WUE) measurements are of the highest interest to improve the sustainability of this crop. The vast majority of WUE measurements relays on measurements of leaf carbon and water fluxes at leaf-level. However, less data are available at the whole-plant level, and for the moment those data are not totally coincident with conclusions reached at leaf scale. In this study, we used whole-plant chambers able to enclose an entire plant of 12 years old to measure at the same time water and carbon fluxes under realistic field grown conditions. The main objectives were to identify the technical issues interfering the whole-plant measurements and track the environmental and other abiotic factors that can affect water and carbon balance, i.e., WUE at the whole-plant scale. To achieve those objectives, we measured whole-plant water and carbon fluxes in grapevine exposed to two different water regimes at three phenological stages pea size (July), ripening (August), and harvest (September). In September, measurements were repeated under high CO
to also check its effect at the whole-plant scale. The results indicate that water and carbon fluxes are well coordinated under both water availability treatments. Under drought conditions, both fluxes were drastically reduced, but surprisingly the estimated WUE resulted not improved but decreased, contrarily to what is shown at the leaf scale. The phenology (September) also strongly decreased both water and carbon fluxes when compared to measurements in July. We hypostatized that harvest load respiration rates could have an important weight on the whole-plant net carbon exchange (NCE). Finally, high CO
measurements, after correction for leaks, indicated an increase of whole-plant NCE as well as increased whole-plant WUE, as expected. Several technical issues were identified, like 1/instability of CO
during the night period that prevent robust estimation of whole-plant respiration and 2/condensation during last night and sun-rise hours which may affect the estimation of daily plant transpiration.
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 (WUEi) and isotopic discrimination of carbon (δ13C) 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 (δ13C) and the intrinsic WUE (WUEi), defined as the ratio between net CO2 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, δ13C 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 WUEi 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 WUEi, and that the samples can be stored for late determinations, increasing the number of samples that can be analysed.
Almond, one of the most characteristic crops in the agricultural landscape of Mallorca Island, cultivated mainly under rainfed conditions and from native cultivars, represents an important source of ...income for the Island. Nowadays, modern cultivars were introduced to meet the almond demand, agronomical needs, and climate change issues. Consumption has considerably increased in the last years and the SARS-CoV-2 virus contributed to consumer behavior changes. The present work aimed to characterize 14 cultivars of which 9 were modern and 5 natives. In general, the natives cultivars presented a lower weight (1.3 g), size (21 mm), darker skin (L = 38), softer texture (107 N), with more benzaldehyde flavor (2-fold change) and “twins” (16%), but with a greater thickness, fiber, and linoleic acid (0.1-fold change, respectively). Modern cultivars offered greater weight (1.5 g), size (24 mm), lighter skin (L = 39), and harder texture (121 N), with no or low benzaldehyde flavor and no “twins”. Finally, ‘Belona’, ‘Ferragnès’, ‘Marta’, ‘Masbovera’, ‘Penta’, ‘Soleta’, ‘Vairo’, ‘Duareta’, ‘Jordi’ and ‘Vivot’ met all the requirements to be certified under the quality guarantee Protected Indication of Origin “Almendra de Mallorca”. However, each cultivar presented its own profile which makes them suitable for different purposes in the food industry.
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