Leaf Water Potential Values Research Articles

Nitrate reductase activity in ‘Syrah’ grapevine under three irrigation strategies

The objective of this study was to evaluate the activity of the enzyme nitrate reductase in ‘Syrah’ grapevine under three irrigation strategies. Irrigation was applied by a drip system, and the treatments were started 45 days after production pruning. The statistical design was completely randomized in a 3 x 5 factorial, corresponding to three irrigation strategies: controlled deficit irrigation, deficit irrigation and full irrigation, and five collections along the cycle: at 54, 60, 73, 87 and 101 days after pruning. Deficit irrigation and controlled deficit irrigation treatments caused longer water deficit to plants and reduced nitrate reductase activity. Full irrigation treatment promoted the highest values of leaf water potential and nitrate reductase activity at the end of the cycle. Leaf water potential and leaf age influence nitrate reductase activity.

Organic soil amendment effects on soil hydrology in an almond orchard evaluated using time-lapse electrical resistivity tomography

Adding organic amendments to soils in orchards has been suggested as a climate-smart agricultural practice that can increase resilience to extremes such as drought. The benefits of adding almond hulls and shells to soil include releasing potassium into the soil, improving water infiltration, reducing soil water evaporation, and enhancing water-holding capacity. In this study, soil infiltration and root water uptake (RWU) patterns of almond trees in amended and control soil treatments were investigated. An almond orchard was mulched with a mixture of almond hulls and shells used as surface-applied organic matter amendments. The combined use of time-lapse electrical resistivity tomography (ERT), stem water potential (SWP) and leaf water potential (LWP) measurements were used to evaluate RWU, soil infiltration patterns, and tree water status at different times during the study. The results of the ERT showed that the RWU patterns for the almond trees are distinct between the amended and the control treatments after the irrigation was applied. Compared to the control treatment, the amended treatment allowed the soil to store more water. Regardless of treatment, the majority of RWU patterns were observed in the top 0.5–1 m root zone depth. Almond trees began to recover from stress, as indicated by the SWP and LWP values, four hours after the start of irrigation. In addition, this was demonstrated by the ERT measurements, which revealed the RWU activity four hours after the irrigation had been applied. This research reveals that time-lapse ERT surveys combined with soil and tree water status data can infer patterns of RWU in almond trees grown with organic soil amendments and under controlled conditions. Furthermore, it was concluded that using almond hulls and shells as organic matter amendments can help almond growers improve infiltration, making almond production more resilient to climate change-related extremes such as droughts.

Identifying Bioactive Compounds in Common Bean (Phaseolus vulgaris L.) Plants under Water Deficit Conditions

Deficit irrigation (DI) strategies are becoming increasingly common in areas where water resources are limited. The application of moderate levels of DI can result in water savings with a small reduction in yield but with a higher quality of the product. The aim of this work was to evaluate the effect of applying a certain level of water deficit (40% water holding capacity) on the yield and quality of the common bean (Phaseolus vulgaris L.), specifically the cultivar ‘Triunfo-70’. Bioactive compounds were investigated by applying an LC-MS-based untargeted metabolomics approach as an analytical tool for identifying novel markers associated with a water deficit in beans. The results showed that beans harvested 30 days after DI application experienced water stress, as indicated by the decrease in the leaf water potential and gas exchange values (stomatal conductance and photosynthesis). In addition, the number of pods per plant was significantly reduced by the DI treatment. The water deficit induced significant alterations in various bioactive compounds (including organic acids, polyphenols, hydroxybenzoic acids, lipids, and phospholipids) when compared to the control treatment. Additionally, twelve new biomarkers were identified in this study for the first time in the common bean under DI. These findings suggested that DI acted as an elicitor, increasing phenylpropanoid metabolism, while concurrently reducing the production of compounds associated with fatty acid metabolism. Additionally, new metabolites were tentatively identified in common beans. This study represents the successful application of the untargeted metabolomics approach to finding bioactive secondary metabolites in beans under different irrigation conditions.

Assessment of leaf water potential and stomatal conductance as early signs of stress in young hazelnut tree in Willamette valley

Corylus avellana L. is a species highly susceptible to water stresses caused by vapor pressure deficit and high temperature. Under such conditions, transpiration is strongly constrained even with good soil water availability. This is due to ineffective drought resistance mechanisms and indicates the need to identify early indicators of plant stress that are easy to measure, effective and efficient. This research explored the possibility of using stomatal conductance and leaf water potentials as early indicators of stress. For this purpose, an experiment was set up in a commercial 5-year-old Corylus avellana L. var. 'McDonald' orchard located in Willamette valley. The experimental designed featured irrigated and rainfed trees, and potential stress indicators were monitored at different times of the day in canopy sections aligned to cardinal directions.Results show that hazelnut trees rapidly reduced leaf stomatal conductance when the vapor pressure deficit increased to 2 and 2.5 kPa during the diurnal cycle in both irrigated and rainfed trees, even with good water availability. This suggests leaf stomatal conductance can be an efficient and effective early indicator of stress. In addition, results suggest that stomatal conductance should be measured on leaves on the west and north aspects of the canopy, where they showed lowest and highest values respectively. Leaf and stem water potential values increased during the measurement period and show a strong correlation, but their mean values do not show statistically significant differences between treatments. In Willamette valley conditions, stomatal conductance provided earlier indication of stress than water potential. The results obtained are of methodological importance for the future design of experimental plans.

Tane heterojenitesine göre sınıflanan Cabernet-Sauvignon (Vitis vinifera L.) üzüm çeşidi salkımlarının bazı morfolojik özellikleri

Two experiments were conducted in two vineyards consisting of vines from the organic-certified Cabernet-Sauvignon/1103P graft combination and the conventional cultivation Cabernet Sauvignon/5BB graft combination. Vines were identified based on pre-dawn leaf water potential values according to stress levels in a Split-Plot Experimental Design. Grapevines were classified as <-0.8 MPa and >-0.8 MPa. These vines were further grouped into dryland-shallow soil and bottomland-deep soil areas, and for each area-soil type, Control, Stress 1, and Stress 2 levels were created. At harvest, the berries were divided into four groups based on their diameter: 10mm-12mm, 12mm-14mm, 14mm-16mm, and 16mm-18mm (In some measurements, no berries belonging to the 16-18mm category could be found). The grapes were grouped as Control, Stress 1 (S1 > -0.8 MPa), and Stress 2 (S2 < -0.8 MPa) based on size groups and stress levels, and certain morphological characteristics of the clusters were examined. The width and length of the clusters were not significantly affected by the area-soil type. Cluster weight, cluster volume, and number of berries per cluster criteria were influenced by stress levels. It was determined that organic vineyards with higher stress levels had fewer clusters compared to conventional vineyards. The number of berries in the clusters showed significant differences based on vineyard area and soil type, water stress levels, and berry size. In conclusion, in the Tekirdağ province, to obtain high-quality grapes from the cv. Cabernet-Sauvignon, it is considered suitable to utilize berries ranging from 10mm to 12mm in size, in conjunction with dryland-shallow soil conditions where the water potential (Ψpd) can decrease to as low as -0.8 MPa during the ripening period.

Plant-based monitoring techniques to detect yield and physiological responses in water-stressed pepper

Today, the use of sensors and imaging techniques, which are used to obtain information about plants and soil in smart irrigation systems, is rapidly becoming widespread. This study aimed to investigate the usability of leaf turgor pressure and thermal images from plant-based monitoring techniques to detect water stress and the irrigation time of pepper (Capsicum annuum L. cv. "California Wonder") and to determine their relationship with physiological traits in Canakkale/Türkiye in 2017 and 2018. The four irrigation treatments (100%, 75%, 50%, and 25%) were applied in the experiment. Leaf turgor pressure (Pp), thermal images and physiological measurements were carried out during the growing season. Soil moisture and Pp were monitored in real time by remote. Thermal and physiological measurements were made before each irrigation. As a result of the study, the average evapotranspiration (ETc) was 697 mm, and the yield value was 83.7 t ha−1 under non-stress conditions. Depending on the decrease in ETc, yield values also decreased significantly. Leaf water potential and stomatal conductivity values were statistically different in all irrigation treatments. The change in the activity of catalase (CAT) due to water stress was greater than that of superoxide dismutase (SOD). In this case, it can be said that other physiological traits are more successful than SOD in distinguishing water stress. According to the regression models, significant relationships were determined between both the indices calculated from the thermal images and Pp, yield, and physiological traits. The predictive ability of Pp values has been strengthened with the addition of meteorological properties to the model in general. The highest correlation (R2 =0.63) was between Pp + meteorological properties and CAT. All the regression models between physiological traits and indices calculated from thermal images were statistically significant. The highest R2 values were obtained in August. In this month, the highest correlations were between Crop Water Stress Index (CWSIp) and leaf water potential / stomatal conductivity (R2 =0.91), IGp and stomatal conductivity (R2 =0.80). The predictive power of CWSIp was higher than Stomatal Conductivity Index (IGp). The experiment illustrated that Pp and temperature data, which are plant-based monitoring methods, have the potential to detect water stress in peppers.

Effect of Berry Heterogeneity in Organic and Conventional Vineyards on Grape Berry Characteristics

In a two-part experiment, the first parcel is certified organic vineyard and, consisting of Cabernet Sauvignon cv. vines grafted onto the 1103P rootstock. The second parcel is conventional vineyard, with cv. Cabernet Sauvignon vines grafted onto the 5BB rootstock. Using Split-Plot Design based on stress levels, the experiment is set up with three repetitions, with two main plots representing Organic and Conventional vineyard, each split into two sub-plots. Predawn leaf water potential values were measured, and vines with values below -0.8 MPa and above -0.8 MPa were grouped into Dryland-Shallow Soil and Bottomland-Deep Soil, respectively, based on soil type (six groups, namely Control, Stress 1, and Stress 2). Berry characteristics were studied during harvest, and berries were classified into four groups based on their diameter (10mm-12mm, 12mm-14mm, 14mm-16mm). The results showed that the 10mm-12mm berry size group had the desired berry characteristics, Dryland-Shallow Soil produced smaller berries, and Stress 2 increased berry skin area and berry skin area/berry volume values.

Evaluation of the yield of strawberry genotypes by morpho-physiological parameters under deficit irrigation in the Mediterranean environment

The most pressing concern of the century is food security, mostly supported by irrigated agriculture. In this respect, studies on water stress have drawn increased attention with a highlighting expectation foreseen via our breeding efforts documented in this study concerning the significant commercial strawberry cultivars ‘Rubygem’, ‘Sabrina’ and ‘Festival’ along with some selected superior bred lines (‘33’, ‘36’, ‘59’, ‘61’ and ‘112’). Plants cultivated in the Spanish-type high tunnel were exposed to both full (IR100) and deficit irrigation (IR50) in the Mediterranean part of Türkiye. Fruit yield as well as certain critical morphological and physiological parameters were examined throughout the active harvest period. This study found that the parameters relating to the vegetative components, as well as the fruit weight and yield, drastically dropped when plants were subjected to deficit irrigation. Therefore, depending on the limited irrigation, as a result of the closure of stomata, it was concluded that the amount of water and stomatal conductance of the plant is associated with a decrease. IR50 was found to have less impact on low-yield genotypes than on high-yield genotypes. Photosynthetic activity and stomatal conductivity were high in the ‘33’ bred line with a high yield. On the other hand, photosynthesis activity and leaf water potential (LWP) values were relatively low in the ‘36’ bred line with low yield. The study proved that variables like photosynthetic activity, stomatal conductance, and LWP could be used as markers for high yield genotype selection.

The hemiparasitic shrub Osyris lanceolata (Santalaceae) does not disturb the ecophysiology of its hosts

Osyris lanceolata is a hemiparasitic dioecious shrub species growing on stabilised dunes. This study aimed to determine the spatial structure of O. lanceolata and its hosts, to understand the ecophysiological mechanisms involved in water and nutrient transfer, and quantify the physiological stress on its hosts. In the Asperillo stabilised dunes (Doñana, Spain) we selected one mixed plot (50 m × 50 m) with Pinus pinea and Juniperus phoenicea in which the coordinates of every individual, the hosts and the hemiparasitic species, were recorded. Additionally, we selected two study areas in which O. lanceolata was well represented, one dominated by P. pinea and the other by J. phoenicea. We marked 60 plants: 20 O. lanceolata with their respective hosts (10 Pinus and 10 Juniperus) and 20 free host plants. In all the marked plants we measured: leaf water potential, gas exchange, photochemical efficiency, morpho-anatomical leaf traits, pigments, and proline content.Our results evidenced that O. lanceolata is spatially associated with its hosts. Midday leaf water potential values were always between 1.5 to 3 times more negative and transpiration rates were 6-fold higher for the hemiparasite than for the hosts. Additionally, O. lanceolata plants showed a high accumulation of proline in leaves and haustorium. Although the hemiparasitic species maintains an active photosynthetic canopy, its rates of CO2 assimilation were 35–48% lower than in the hosts, which caused a 10-fold lower instantaneous water use efficiency. Through these mechanisms, the hemiparasitic plant can absorb water and nutrients from the host species. Despite this parasitic relationship, there were no significant differences in the physiological performance of the hosts in comparison to the parasite-free plants.We conclude that O. lanceolata presents a specific strategy to absorb water in this dry ecosystem, without exerting negative effects on the plant community, which might indicate that there is an equilibrium in the tradeoffs between parasitism and mutualism in the interaction between species.

Responses of the Leaf Water Physiology and Yield of Grapevine via Different Irrigation Strategies in Extremely Arid Areas

The contradiction between water supply and demand has become increasingly prominent due to the large agricultural water consumption and low irrigation water use efficiency (IWUE) in the extremely arid area of Xinjiang, which needs to be solved by efficient irrigation. In this study, the effects of different irrigation levels (the lower and upper limits of irrigation (LULI) were 50–80%, 60–90%, and 70–100% of the field capacity (FC), respectively) under two irrigation methods (root zone irrigation (RZI) and furrow irrigation (FI)) on the photosynthetic physiology and yield of grape were analyzed to explore suitable irrigation schemes in extremely arid areas. The results show that the diurnal variation curve of the net photosynthetic rate (Pn) of grape leaves in the extreme arid region was not sensitive to the response of irrigation methods. However, RZI could improve the apparent quantum efficiency and maximum photosynthetic rate by 60.00% and 31.25%, respectively, reduce the light compensation point by 17.91%, and alleviate the photosynthetic lunch break phenomenon. Under FI, the physiological indexes of leaves increased with the increase in the LULI, while the Pn and SPAD values were the largest under RZI when the LULI was 60–90% of FC. The daily average Pn value of T2 in 2021 and 2022 ranged from 12.93 to 17.77 μmol·m−2·s−1. Compared with FI, RZI significantly improved the leaf water potential, Pn, and SPAD values by increasing the soil water content (SWC) of the 40–80 cm soil layer by 5.04–8.80%, which increased the yield by 6.86–18.67%. The results show that the yield and water use efficiency reached the peak when the LULI was 60–90% of FC under RZI, which could provide theoretical support for efficient irrigation of vineyards in extremely arid areas.

Water stress, yield, and grape quality in a hilly rainfed “Aglianico” vineyard grown in two different soils along a slope

Vineyards from hilly areas of the Mediterranean region are mostly grown in shallow soils that present low soil water holding capacity. These vineyards are prone to water stress conditions, which if well managed can raise the grape quality potential. This study aimed to investigate the water stress development in an “Aglianico” vineyard grown along a 90 m slope. The two-year (2011–2012) trial was conducted in two soils having different hydraulic properties, the Up-slope with lower soil water holding capacity than the Down-slope site. The results showed that grapevines were more stressed in the Up-slope soil than in the Down-slope soil, as reflected by the higher crop water stress index, lower leaf water potential and leaf gas exchanges values. Consequently, the yield was significantly lower by 40% in the Up-slope, which was determined by the lower weight and volume of berries. The smaller berries improved must quality parameters of total soluble solids, total polyphenols, total anthocyanins, and color intensity within a range of 4–25% higher in the Up-slope compared to the Down-slope site. Moreover, the pre-veraison stress experienced in 2012 reduced yield by 30% and depressed berry weight and volume, compared to 2011. The post-veraison stress induced the improvement of must quality, mainly in the Up-slope 2011. Interestingly, there was no significant difference in the pH and titratable acidity between both sites, which indicates the ability of Up-slope vines to make up for more stressful conditions, and, thus, their resilient behavior to maintain their high-quality wine. This study highlights that vineyards in hilly areas may benefit from a differentiated management between different viticulture zones to bring up their high-quality wine.

Assessment of drought stress responsive genes expression profiles and proline accumulation in a diverse set of grapevine rootstocks

In order to study plant responses to drought stress, it is important to have markers for such responses. This issue has been a challenge for decades and numerous traits have been used for this purpose. In the current study, the influence of drought stress on proline biosynthesis, leaf water potential, and also gene expression levels of 10 genes probably involved in drought stress response regulation pathways were investigated. Also, all experiments were performed in both root and leaf tissues of studied rootstocks to investigate the response of plant tissues which is more suitable for the assessment of possible markers. As a result of the study, the highest percentage of proline increase in leaf and root tissues was mostly observed in susceptible rootstocks. The leaf water potential (-MPa) measurements showed the most decrease in leaf water potential values in highly tolerant rootstocks, so the maximum differences between control and drought stress treated plants were determined in SO4, 140Ru, 1045, and 44-53M rootstocks, respectively. Gene expression levels of HAT5, RAP2-4, WRKY23, GRP, GDH, PRP2, GAS2, PD2, STPK, and genes were described in 18 different grapevine rootstocks and it was concluded that the root samples indicating more significant gene expression changes, could be more informative than leaf samples.

Efficacy of Exogenous Sodium Nitroprusside, Salicylic Acid and Moringa (Moringa oleifera) Leaf Extracts as Biostimulants on Growth and Physiological Attributes of Rubber (Hevea brasiliensis) under Sub-optimal Climatic Conditions

Stress phenomena that coincide, such as drought and heat, have been shown to affect the growth of rubber (Hevea brasiliensis) negatively under sub-optimal climatic conditions in nontraditional drier areas of Sri Lanka. Exogenous sodium nitroprusside (SNP), salicylic acid (SA), and moringa leaf extract (MLE) as bio-stimulants have been shown to improve the growth and physiology of crop plants under sub-optimal climatic conditions. Therefore, the present study aimed at exploring the effect of the above bio-stimulants on the growth and physiology of rubber under sub-optimal climatic conditions. Rubber plants of clone RRIC 121 cultivated in Hingurana, Ampara, Dry Zone (DZ) were spray treated with SNP at 100 and 200 µM, SA at 0.1 and 0.2 µM, and MLE at 5, 10% concentrations at monthly intervals for six months. Physiological parameters viz. chlorophyll content (cc), stomatal conductance (gs), and leaf water potential (Ψ) were recorded before and after three months from the commencement of treatments while growth measurements (girth and height) were recorded at three and ten months of treatments. Significantly higher girth values were recorded in plants treated with SNP, SA, and MLE at all concentrations compared to control and mock treatment after ten months from the commencement of treatments. Significantly higher chlorophyll values were recorded in plants treated with SNP at 100 µM (50.6±1.85), 200 µM (53.4±1.24), SA at 0.1 µM (49.5±1.49), MLE at 5% (50.1±1.98) and 10% (51.1±1.35) concentrations compared to control (41.9±1.15) and mock treatment (44.6±1.32) respectively after ten months from the commencement of treatments. Significantly higher leaf water potential values were recorded in plants treated with SNP, SA, and MLE at all concentrations compared to control and mock treatments after three months of the first treatment. Significantly lower stomatal conductance values were recorded in plants treated with SNP at 200 µM, SA at 0.1 and 0.2 µM, and MLE at 10% concentrations compared to control and mock treatments after three months from the first treatment. Improved growth and physiological attributes of rubber plants could be attributed to the beneficial effect of SNP, SA, and MLE as bio-stimulants. Therefore, exogenous application of the above bio-stimulants may be utilized for growth improvement in Hevea sp. under sub-optimal climatic conditions.
 Keywords: Bio-stimulants, Growth, Physiological parameters, Rubber, Sub-optimal climatic conditions

Spatial and seasonal patterns of water use in Mediterranean coastal dune vegetation

AimsThis paper examines the water dynamics of a coastal dune plant community, addressing spatial and seasonal variations. We aimed to detect the patterns of water use by plants at the community level according to their distribution across a coastal dune gradient from beach to inland.MethodsFive sites were established: upper beach, embryo-dune, slack, foredune, and inland. Eight perennial species were collected seasonally to analyse the isotopic composition and water potential. Soil water samples at 3 depths, groundwater, and atmosphere, were obtained to determine plant water sources.ResultsThe species from Inland and foredune plant communities, Retama, Juniperus, and Helichrysum, showed the most stable isotopic signal throughout the year. On the contrary, the species most abundant on the upper beach, embryo-dune, and slack (Ammophila, Achillea, and Polygonum) showed the highest variability. Water deficit decreased the dependence on shallow and mid-soil layers along the beach-inland gradient. Beach and embryo-dune sites showed less negative leaf water potential values than the other positions in the dune gradient.ConclusionsThree factors mark the proportion of water sources used for vegetation in coastal vegetation: community composition, distance to the sea, and seasonality. Coastal dune vegetation exhibited a species-specific response in water uptake that was modified by its location on the gradient. From upper beach to inland, the plant communities showed a slight progressive increase in the use of water from deeper layers. This pattern was similar and overlapped with the wet to dry seasonal pattern.

Carbon isotope discrimination and water use efficiency in interspecific Prunus hybrids subjected to drought stress

In C3 plants, carbon isotope composition (δ13C) is influenced by isotopic effects during diffusion from the atmosphere to the chloroplasts and carboxylation reactions. This work aimed to demonstrate if δ13C of leaf soluble carbohydrates (δ13Cleaves) and of dry matter from new-growth shoots (δ13Cshoots) of Prunus plants subjected to a period of water deficit was related to water use efficiency (WUE). For this purpose, three interspecific Prunus hybrids rootstocks (6–5, 7-7 and G × N) were gradually subjected to drought and then rewatered. Soil water content (SWC) decreased from 26.1 to 9.4% after 70 days of water shortage, when plants reached values of predawn leaf water potential (LWP) ranging from −3.12 to −4.00 MPa. Gas exchange, particularly net photosynthetic and transpiration rates, differed among the three hybrids, leading to different values of WUE. After 70 days of drought, a significant δ13C increase of 5.86, 4.28 and 4.99‰ was observed in 6–5, 7-7 and G × N, respectively. Significant correlations between δ13C and other parameters (substomatal CO2/atmospheric CO2 ratio, stomatal conductance and stem water potential) were found in all hybrids. The rewatering phase caused a recovery of the physiological status of the plants. The isotope composition of δ13Cshoots was correlated with the average WUE measured during the whole experiment. δ13Cleaves and δ13Cshoots were positively related (r = 0.87; p < 0.001). The isotopic signature was a reliable screening tool to identify Prunus genotypes tolerant to drought stress. The results suggest the possibility of using δ13C as an integrated indicator of level of drought stress in plants subjected to prolonged stress conditions.

Disentangling the link between leaf photosynthesis and turgor in fruit growth.

Despite the importance of understanding plant growth, the mechanisms underlying how plant and fruit growth declines during drought remain poorly understood. Specifically, it remains unresolved whether carbon or water factors are responsible for limiting growth as drought progresses. We examine questions regarding the relative importance of water and carbon to fruit growth depending on the water deficit level and the fruit growth stage by measuring fruit diameter, leaf photosynthesis, and a proxy of cell turgor in olive (Olea europaea). Flow cytometry was also applied to determine the fruit cell division stage. We found that photosynthesis and turgor were related to fruit growth; specifically, the relative importance of photosynthesis was higher during periods of more intense cell division, while turgor had higher relative importance in periods where cell division comes close to ceasing and fruit growth is dependent mainly on cell expansion. This pattern was found regardless of the water deficit level, although turgor and growth ceased at more similar values of leaf water potential than photosynthesis. Cell division occurred even when fruit growth seemed to stop under water deficit conditions, which likely helped fruits to grow disproportionately when trees were hydrated again, compensating for periods with low turgor. As a result, the final fruit size was not severely penalized. We conclude that carbon and water processes are able to explain fruit growth, with importance placed on the combination of cell division and expansion. However, the major limitation to growth is turgor, which adds evidence to the sink limitation hypothesis.

Effect of Soil Water Availability on Physiological Parameters, Yield, and Seed Quality in Four Quinoa Genotypes (Chenopodium quinoa Willd.)

Drought represents significant environmental stress, and improving agriculture water management and yield is a priority goal. The effect of diminishing soil water content in the grain filling (GF) stage, throughout physiological maturity (GM), on the yield and grain quality, leaf water potential (LWP), and maximum quantum yield (Fv/Fm) in four long photoperiod quinoa genotypes was evaluated in the South-Central zone of Chile, during the 2014–2015 and 2015–2016 seasons. Five irrigation treatments (T) were established. Irrigation was carried out when the available water (AW) of the root zone reached values of 100%, 70%, 40%, 20%, and 0%. The lowest LWP values were obtained by T20 and T0 (−1.95 MPa). The ‘Morado’ genotype reached the lowest LWP at both seasons, while the highest average LWP was achieved by the ‘AG 2010’ (2014–2015) and ‘Cahuil’ genotypes (2015–2016). A global trend of Fv/Fm values was observed from GF to GM: 0.74 toward 0.79 (2014/2015), and 0.74 toward 0.82 (2015/2016). Only during the second season, Fv/Fm showed differences among irrigation treatments. Total average grain yields in the second season (2.97 t ha−1) were greater than those in the first season (1.43 t ha−1). In both seasons, the ‘Cahuil’ genotype and T100 reached the highest yields. A significative decrease in yield was observed when AW diminished. A direct relationship between seed yield and leaf water potential (ΔY/ΔLWP) was found in all genotypes, varying between 5.53 (‘Cahuil’) and 2.86 t ha−1 MPa−1 (‘AG 2010’). Total proteins, albumins, and globulins varied between seasons, with almost no differences among irrigation treatments. Only the ‘Morado’ genotype showed a slight trend to obtain a higher content of total protein in both seasons. It is possible to grow quinoa under irrigation deficit conditions between GF throughout GM, maintaining yield parameters and nutritional quality.

Macro scale analysis of Syrah vineyards under winter growing cycles: Agronomical and ecophysiological responses

In Southeast Brazil, the change of grape harvest from wet summer to dry winter through double-pruning management has improved the quality of wines, currently denominated winter wines. In order to better understand the influences of soil, macroclimate, and vineyard management in winter wines, we investigated seven vineyards in the states of Minas Gerais (Três Corações – TC, Três Pontas – TP, Cordislândia – COR, São Sebastião do Paraíso – SSP and Andradas – AND) and São Paulo (Itobi – ITO and Espirito Santo do Pinhal – PIN) during three consecutive growing seasons. The vineyards are located in warm temperate zones and grouped in four soil types: Acrudox in TC, AND and SSP, Hapludox in TP; Hapludult in AND and PIN; Eutrudept in ITO. The high clay content (> 35 %) observed in all soil types, associated to low evapotranspiration demand, avoided the occurrence of severe water stress, as observed by the high values of leaf and stem water potential, stomatal conductance, photosynthesis, and transpiration. Differences in vigor were more related to vineyard management and did not affect grape composition. Among vineyards, parameters for berry quality from ITO, such as sugar and acidity, were more associated to high soil sand content and winter temperature. No significant differences were found in anthocyanins and total phenols of berries among vineyards, suggesting that the high thermal range and low precipitation during autumn-winter, historically observed in all municipalities, seemed to be the main factor for improvement of phenolic compounds.

Excessive Pruning Levels in Young Grapevines (Vitis vinifera L. cv. Sultan 7) Cause Water Loss in Seedless Cluster Berries

ABSTRACT Late-season dehydration is known as a type of berry shrivel and it is often associated with wine grapes. This study is different from other berry shrivel studies as it focuses on seedless grape cv. Sultan 7 (Vitis vinifera L.) and aims to determine the effects of different pruning levels (90, 150, 180 buds per vine), leaf removal (LR) (25%, 50% per shoot) treatments on vine yield, and the number of harvested clusters. Additionally, we aim to find the effects of treatments on the number of unhealthy clusters with shriveled (S) berries. Although treatments were conducted under the same irrigation practices and determined close leaf water potential values, S berries were not obtained from the vines with 90 buds per vine treatment. Thus, S berries were determined in the lower side of unhealthy clusters together with non-shriveled (NS) berries in treatments of 150 and 180 buds per vine. It was found that the total soluble solids content and titratable acidity of S berries were higher than NS. While high pruning levels per vine enabled to obtain more clusters, the expected yield was negatively affected due to the quantity of the unhealthy cluster. Significant polynomial regression was observed between the number of harvested and unhealthy clusters in 2016 (R2 = 0.69) and 2017 (R2 = 0.76). In this research, it was hypothesized that the water losses in S berries of unhealthy clusters in overloaded vines (150, 180 buds per vine) were caused by obtaining more harvested clusters compared to the 90 buds per vine treatment.

Asma Su Stresinin Hiperspektral Analizi

Viticulture is very sensitive to water stress, which is critical and influenced by all environmental factors, relating to the crop quality and productivity of vineyards. In this study, water stress was examined in veraison and harvest stages for nine different species with spectroradiometric measurements. Leaf water potential (LWP) values from field measurements and original spectra-based (OSB) and continuum removed spectra-based (CRSB) curves were analyzed with correlation and regression analysis to find the highest related wavelengths. The analysis was done for both specific dates of field measurements (i.e. 08.08.2012 and 06.09.2012) and also in aggregate i.e. all measured data. The specific date wavelength-based analysis revealed the “red edge region” as a major water stress indicator. The highest correlated wavelength was found to be 684 nm of CRSB curves with R=0.988. For the aggregate wavelength-based water stress analysis, the “violet and green regions” were identified as the best indicators. The highest correlated wavelength was found to be 410 nm of OSB curves with R=0.820. Furthermore, the Analysis of Variance (ANOVA) testing indicates that the results are significant at relatively high confidence levels. The spectral-based method performed in this study provides fast, flexible, and non-destructive water stress measurements of grapevines when compared to classical methods.