Deficit Irrigation Strategies Research Articles

A global meta-analysis of yield and water productivity responses of vegetables to deficit irrigation

Strategies promoting efficient water use and conserving irrigation water are needed to attain water security to meet growing food demands. This meta-analysis study evaluated the effect of deficit irrigation (DI) strategy on eight vegetables to provide a quantitative estimate of yield and water productivity (WP) responses under variable soil textures, climates, and production systems (open-field and greenhouse). This study analyzed 425 yield and 388 WP comparisons of different DI levels to full irrigation (FI), extracted from 185 published studies representing 30 countries. Moving from the highest (> 80%FI) to the lowest (< 35%FI) irrigation level, the overall yield decline was 6.9 to 51.1% compared to FI, respectively. The WP gains ranged from 8.1 to 30.1%, with 35–50%FI recording the highest benefits. Soil texture affected the yield significantly only under the least irrigation class (< 35%FI), wherein sandy clay and loam recorded the highest (82.1%) and the lowest (26.9%) yield decline, respectively. Among the climates, temperate climate was overall the most advantageous with the least yield penalty (21.9%) and the highest WP gain (21.78%) across various DI levels. The DI application under the greenhouse caused lesser yield reduction compared to the open-field. The WP gains due to DI were also higher for greenhouse (18.4%) than open-field (13.6%). Consideration of yield penalties and the cost of saved irrigation water is crucial while devising the reduced irrigation amounts to the crops. The yield reductions under low to moderate water deficits (> 65%FI) accompanied by gains in WP may be justifiable in the light of anticipated water restriction.

Effects of Deficit Irrigation Scheduling on Water Use, Gas Exchange, Yield, and Fruit Quality of Date Palm

Water scarcity is very common in the arid region due to the low yearly rainfall. The cost of water for agricultural usage is extremely high in dry locations. Date palm is a high water-demanding tree throughout the year in arid regions. Therefore, the application of deficit irrigation strategies for date palm cultivation may significantly contribute to conserving irrigation water. The present study aimed to assess the effects of controlled deficit irrigation using two modern micro-irrigation systems on water use efficiency (WUE), gas exchange, fruit yield, and quality of date palm (Khalas cv.). The irrigation systems included drip irrigation (DI) and subsurface irrigation (SI) systems. The study was conducted during the 2020 and 2021 seasons at the Date Palm Research Center of Excellence, King Faisal University, Saudi Arabia. The meteorological variables of the study area were real-time monitored using cloud-based IoT (Internet of Things) to calculate the evapotranspiration reference (ETo) and control the irrigation scheduling. Three irrigation treatments (50, 75, and 100% ETc) were applied using DI and SI systems compared with the traditional surface bubbler irrigation (Control). The actual applied water at the deficit irrigation treatments of 50, 75, and 100% ETc were 27.28 ± 0.06, 44.14 ± 1.07, and 55.55 ± 0.37 m3 palm−1, respectively. At all deficit irrigation treatments, the leaf chlorophyll and gas exchange were significantly higher in the SI compared to the DI system. The yield of date palms did not differ significantly between the control and SI systems at both the level of 100 and 75% ETc. The WUE under the SI (1.09 kg m−3) was significantly higher than the DI system (0.52 kg m−3) at the 50% level. There was no significant difference regarding the fruit quality parameters between SI at 50% ETc and control at 100% ETc. Therefore, adopting deficit irrigation strategies using the SI system at 50% ETc level throughout the year could be suggested for date palm irrigation to save water, improve WUE, and maintain fruit quality.

Responses of 'Syrah' grapevine to deficit irrigation in the Brazilian semi-arid region

Grapevine growing in areas with low rainfall as the Brazilian semi-arid requires irrigation to full fill plant water demand. The objective of this study was to evaluate the physiological and yield responses of grapevine to irrigation strategies in the Lower Middle São Francisco Valley, in Petrolina, State of Pernambuco, Brazil. The experiment was carried out over three consecutive growing seasons of drip irrigated 'Syrah' grapevine, grafted on 1103 Paulsen and planted in an Ultisol (Soil Taxonomy, USA). Full irrigation (FI), regulated deficit irrigation (RDI), and deficit irrigation (DI) treatments were designed in a randomized block with four replications. Mostly soil moisture depletion was observed until 0.6 m soil depth while higher moisture values and their small variation over the time were observed below 0.6 m and until 1.20 m depth as consequence of dense soil layers. RDI and DI promoted moderate water stress in plants (pre-dawn water potential from −0.2 to 0.4 MPa), reducing water consumption and gas exchange. Intrinsic water use efficiency was higher in RDI and DI (121 and 115 µmol CO2 mol H20−1, respectively). Tritratable acidity reduced to 5.81 and 6.28 g L−1 tartaric acid as water deficit increased, except in the third season. Soluble solids were influenced by treatments only in the second season, when it decreased in FI plants (22.6° brix). Weight of 100 berries was influenced by treatments in all seasons, with lower values for DI and RDI grapevines (less than 155 g). Number (15) and weight (2.2 kg) of cluster per grapevine and yield (7284 kg) were significantly higher in FI only in the third growing season, while average cluster weight was greater in FI in the first and third seasons (84 and 149 g, respectively). Irrigation water productivity did not differ among irrigation strategies. Deficit irrigation strategies allowed water saving.

Physiological responses of almond trees under regulated deficit irrigation using saline and desalinated reclaimed water

Regulated deficit irrigation (RDI) strategy using reclaimed water (RW) is becoming a common procedure in some Mediterranean regions. Full and regulated deficit irrigation were combined with desalinated (ECw 1 dS m−1) and saline (ECw 3 dS m−1) reclaimed water to irrigate young potted almond trees over a 3-year period. The full irrigation treatments received 130% of the crop evapotranspiration (ETc) and the RDI treatments received 80% of ETc during the kernel filling. Trunk diameter decreased in both RDI treatments at the end of the experimental period, although this response was more marked in the trees irrigated with saline RW. There were negative relationships between shoot growth and leaf Na+ and Cl+ contents in the saline treated trees, in which the accumulation of salts in leaves was associated with osmotic adjustment, which was responsible for maintaining midday leaf turgor. Plant water status, measured by the leaf and water potential, decreased in almond exposed to water deficit or irrigated with saline RW, indicating a slight dehydration in these plants due to the difficulty in water uptake from the substrate. Trees subjected to both deficit irrigation treatments showed lower stomatal conductance values than full irrigated treatments during the RDI period. However, at the end of experimental period, the lowest Pn values were found in plants irrigated with saline RW, especially in trees irrigated with saline RW combined with RDI strategy, verifying the relevance of duration of exposure to the stress. Saline and desalinated RW can be successfully used for irrigating almond trees, which might be of great economic and competitive significance for agriculture, but further research focused on a longer term should be carried out since detrimental effects might appear. Deficit irrigation combined with saline RW in P. dulcis is not recommended since it intensifies the negative effects of water and salt stress applied individually.

Mild water and salt stress improve water use efficiency by decreasing stomatal conductance via osmotic adjustment in field maize

Water and salt stress often occur simultaneously in heavily irrigated arid agricultural areas, yet they are usually studied in isolation. To understand the physiological bases of water use efficiency (WUE) of field-grown maize (Zea mays) at multi-scales under combined water and salt stress, we investigated the joint effects of water and salt stress on physiology, growth, yield, and WUE of two genotypes (XY335 and ZD958). We measured leaf stomatal conductance (gs), net photosynthesis rate (A) and hydraulic traits, whole-plant growth and water use (ET), and final biomass and grain yield. Leaf osmotic adjustment was a key trait of the physiological differences between XY335 and ZD958 under water and salt stress. Although the responses of the two genotypes were different, mild water and salt stress improved intrinsic water use efficiency (iWUE = A/gs) by (i) decreasing gsvia increasing osmotic adjustment and hydraulic resistance, and (ii) declining A via increasing stomatal limitations rather than reducing photosynthetic capacity. Joint water and salt stress had a synergistic effect on reproductive growth and grain formation of maize. Mild water and salt stress reduced ET, stabilized grain yield, and improved grain WUE via declining gs, maintaining photosynthetic capacity, and improving harvest index. Collectively, our study provides a novel insight into the physiological mechanisms of WUE and demonstrates an approach for the efficient management of water and salt by using a growth stage-based deficit irrigation strategy or/and selecting genotypes with strong osmotic adjustment capacity and high harvest index.

The Effects of Different Irrigation Scheduling Approaches on Seed Yield and Water Use Efficiencies of Cotton

This study was conducted in the Aegean region conditions of Turkey in 2020. It was carried out on May-505, a local cotton variety. The study examined the variation of seed yield, water use efficiency (WUE), and irrigation water use efficiency (IWUE) of cotton with different irrigation programs and water levels. The field trial, which was designed as two factors and three replications, was designed according to the randomized complete block trial design. Four different irrigation levels (IL) (100%, 67%, 33%, and 0%) and two different irrigation scheduling approaches (gravimetric and pan evaporation) were investigated in the study. Seasonal water use values in treatments varied between 215 (0%) and 746 (100% - Pan evaporation approach) mm during the production period. The average yield values obtained with irrigation levels, which have essential effects on cotton seed yield, are listed as follows; 2057 kg ha-1 (IL-0%), 3471 kg ha-1 (IL-33%), 3771 kg ha-1 (IL-67%), and 5083 kg ha-1 (IL-100%). It was determined pan evaporation applications performed higher yields than gravimetric applications. WUE values were between 0.63 – 1.04 kg m-3. The gravimetric method’s yield response factor (ky) was 0.73, and the pan evaporation method’s yield response factor (ky) was 0.89. These results show that cotton is tolerant of water stress. In conclusion, although the pan evaporation approach with 100% treatment is suggested for cotton production in the parts of the Aegean region within the semi-arid climate zone, while water resources are sufficient. When the results are evaluated in terms of seed cotton yield for a deficit irrigation strategy, IL-67% treatment with a gravimetric approach can be used.

Climate Change Adaptation Measures in the Irrigation of a Super-Intensive Olive Orchard in the South of Portugal

The south of Portugal is one of the regions that will be most affected by the impacts of climate change (CC), with an expected increase in water scarcity. Irrigated super-intensive olive orchards occupy a large area of the used agricultural surface in the Alentejo region, south of Portugal, making it necessary to adapt this crop to the effects of CC. This study assessed the impacts of CC and defined adaptation measures concerning irrigation management of the super-intensive olive orchard. To compute the crop irrigation requirement (CIR), the soil water balance model ISAREG was combined with climate data relative to the reference period 1971–2000 and to the representative concentration pathways RCP4.5 and RCP8.5 for the periods 2011–2040, 2041–2070, and 2071–2100. The growing degree-days (GDD) approach was used to estimate olive phenology for these CC scenarios. Unchanged irrigation management with an average CIR increase up to 16% in RCP4.5 and 31% in RCP8.5 is expected. By adopting higher levels of water deficit, water savings of up to 22% can be realized. The results showed that the anticipated CIR increase for the CC scenarios can be mitigated through regulated deficit irrigation strategies.

The Complexity of Modulating Anthocyanin Biosynthesis Pathway by Deficit Irrigation in Table Grapes.

Deficit irrigation (DI) is an irrigation scheduling technique that is used in grapes to improve red color development; however, results are not always satisfactory in table grapes. The red color in grapes is mainly due to the plant pigment anthocyanin. In the present study, the anthocyanin biosynthesis in Scarlet Royal grapes (Vitis vinifera L.) grown in the San Joaquin and Coachella Valleys, and subjected to two different DI strategies was investigated. The objective of this study was to identify potential regulatory factors that may lead to potential treatments to improve red color in table grapes, especially under warm climate conditions. In both locations, DI induced the expression of several genes involved in three major pathways that control the red color in table grapes: anthocyanin biosynthesis, hormone biosynthesis, and antioxidant system. DI at veraison induced anthocyanin accumulation and enhanced red color in berries at harvest time. However, anthocyanin accumulation was lower at the Coachella Valley compared to the San Joaquin Valley. The lower level of anthocyanin was associated with lower expression of critical genes involved in anthocyanin biosynthesis, such as flavonoid-3-O-glucosyltransferase (UFGT), myb-related regulatory gene (R2R3-MYB) (MYBA1), basic helix-loop-helix (bHLH) (MYCA1) and the tryptophan-aspartic acid repeat (WDR or WD40) proteins (WDR1). Further, gene expression analysis revealed the association of ABA biosynthesis gene 9-cis-epoxycarotenoid dioxygenase (NCED1), 1-aminocyclopropane-1-carboxylic acid oxidase (ACO3), and the gibberellic acid (GA) catabolic gene GA2 oxidase (GA2ox1) in the induction of anthocyanin biosynthesis. An increase in the chalcone synthase gene (CHS2) was observed in response to DI treatments in both sites. However, CHS2 expression was higher in Coachella Valley after ending the DI treatment, suggesting the involvement of environmental stress in elevating its transcripts. This data was also supported by the lower level of antioxidant gene expression and enzyme activities in the Coachella Valley compared to the San Joaquin Valley. The present data suggested that the lack of grape red coloration could partially be due to the lower level of antioxidant activities resulting in accelerated anthocyanin degradation and impaired anthocyanin biosynthesis. It seems that under challenging warmer conditions, several factors are required to optimize anthocyanin accumulation via DI, including an active antioxidant system, proper light perception, and hormonal balance.

Effects of growth‐stage‐based deficit irrigation management on physiological and biochemical characteristics and yield of winter wheat in Northwest China*

AbstractGrowth‐stage‐based deficit irrigation is an appropriate method when irrigation water is scarce. However, the effects of continuous deficit irrigation during the winter wheat growth period on crop physiological and biochemical processes need to be further evaluated. Five growth‐stage‐based deficit irrigation strategies were established and tested in winter wheat in the present study. The results showed that water stress resulted in a decrease in net photosynthetic rate (Pn) and transpiration rate, but led to an increase in catalase and peroxidase activities and an increase in malondialdehyde and proline contents. A high Pn could be sustained when the relative water content of the soil was maintained within the range of 60%–75%. Pn was negatively correlated with antioxidant enzyme activity. Based on the averaged data from 2017 to 2019, all water stress treatment groups showed varying degrees of yield reduction compared to the control (CK). Though the T1 treatment (i.e., irrigation from jointing stage to filling stage with 240 mm of water) had the highest water productivity (2.19 kg m−3), its grain yield was only 7.01% lower than the CK treatment. The present results suggest that the T1 treatment is the better irrigation model for saving water and achieving high grain yield in winter wheat in this region.

The Effect of Deficit Irrigation Strategies on the Efficiency From Plant to Essential Oil Production in Peppermint (Mentha piperita L.)

The effect of deficit irrigation on water productivity in the water supply and utilization chain has been computed, employing a systematic and quantitative approach. By applying such an investigation, weaknesses and strengths of deficit irrigation strategies could be revealed, and actions and measures could be implemented to improve water productivity as much as possible. The peppermint plants were subjected to regulated deficit irrigation (RDI) and partial root-zone drying (PRD). Peppermint was cultivated under full irrigation (FI, control) and RDI treatments including RDI85, RDI70, RDI55, and RDI40, receiving 85, 70, 55, and 40% of FI treatment, respectively; PRD techniques including PRD70, PRD55, and PRD40, receiving 70, 55, and 40% of FI treatment in one side of the root-zone at each irrigation event, respectively during two cutting seasons. There was no significant improvement in leaves weight and dried yield step by applying deficit irrigation treatments. Leaves and aerial parts from the whole plant and dried yield as the main source of essential oil had the weakest function, which should be optimized to adjust and gain more efficiency. In the essential oil yield step, as a final procedure, the highest improvements were observed in PRD55 treatment with 90% improvement in efficiency compared to control treatment. According to the results and calculating water productivity, PRD55 treatment improved water productivity by 179% compared to the control treatment. Two-way ANOVA analysis, between deficit volume and the deficit applying method, showed that total water productivity was affected (increased) significantly by the deficit applying method. This implies the contribution of the PRD technique to enhance more signals than RDI-based signals, which resulted in more improvements in secondary metabolism production in peppermint.

Monitoring of Emerging Water Stress Situations by Thermal and Vegetation Indices in Different Almond Cultivars

In recent years, the area dedicated to modern irrigated almond plantations has increased significantly in Spain. However, the legal irrigation allocations are lower than the maximum water requirements of the crop in most cases. Therefore, almond growers are forced to implement regulated deficit irrigation strategies on their farms, applying water stress in certain resistant phenological periods and avoiding it in sensitive periods. Given the need to monitor the water status of the crop, especially in the most sensitive periods to water stress, the objective of this work was to evaluate the sensitivity of two UAV-based crop water status indicators to detect early water stress conditions in four almond cultivars. The field trial was conducted during 2020 in an experimental almond orchard, where two irrigation strategies were established: full irrigation (FI), which received 100% of irrigation requirements (IR), and regulated deficit irrigation (RDI), which received 70% of IR during the whole irrigation period except during the kernel-filling stage when received 40% IR. The UAV flights were performed on four selected dates of the irrigation season. The Crop Water Status Index (CWSI) and the Normalized Difference Vegetation Index (NDVI) were derived from thermal and multispectral images, respectively, and compared to classical water status indicators, i.e., stem water potential (Ψstem), stomatal conductance (gs), and photosynthetic rate (AN). Of the four flights performed, three corresponded to mild water stress conditions and a single flight was performed under moderate water stress conditions. Under mild water stress, CWSI was not able to capture the differences between FI and RDI trees that were observed with Ψstem. Under moderate stress conditions, CWSI was sensitive to the water deficit reached in the trees and showed significant differences among both irrigation treatments. No differences were observed in the CWSI and NVDI response to water stress among cultivars. Although NDVI and CWSI were sensitive to water stress, the low signal intensity observed in NDVI makes this index less robust than CWSI to monitor crop water stress. It can be concluded that UAV-based CWSI measurements are reliable to monitor almond water status, although for early (mild) levels of water stress, Ψstem seems to be the preferred option.

Deficit Irrigation Strategies on Tree Physiological and Chemical Properties: Treatment Effects, Prediction Based Model Analyses and Inter-Correlations

Irrigation is a key factor for different physiological aspects of fruit trees. Therefore, such irrigation protocols that can save water consumption during irrigation and maintain fruit trees productivity are an essential goal especially under semiarid climate conditions. The aim of this 3-year apricot study was to investigate the effect of four deficit irrigation (DI) treatments (control, moderate regulated deficit irrigation: RDIm, severe RDI: RDIs and continuous DI: CDI) on 15 tree physiological properties (chilling requirement—CR, heat requirement—HR, days from end—dormancy until fruit harvest—DEDFH, sum of growing degree days—sGDD, total number of buds—TNB, number of flower buds—NFB, number of vegetative buds—NVB, starting date of flowering—SDF, number of opened flower buds—NOFB, flower bud abscission—FBA, fruit set—FS, seasonal vegetative growth—SVG, fruit number per tree—FNT, fruit weight—FW, fruit yield—FY), and on two tree chemical properties (total soluble carbohydrates—TSC and total proline content—TPC) on apricot cultivars ‘Ninfa’ and ‘Canino’ in Egypt. Results showed that both DI treatments and cultivars significantly influenced the values of CR, HR, TNB, SDF, NOFB, FS, SVG, FNT, FY, TSC, and TPC. Values of FBA were significantly affected by years and DI treatments, while sGDD by years and cultivars. Values of DEDFH, NFB, and FW were significantly influenced only by cultivars, while NVB only by DI treatments. The RDIm treatment gave the most acceptable values for most measured properties compared to the fully irrigated control treatment. Prediction based model analysis demonstrated that generalized linear models (GLMs) can be predictors for the measured tree properties in the DI treatments. The best goodness-of-fit of the predicted GLMs was reached for HR, NOFB, FS, SVG, FNT, TSC, and TPC. In all the four DI treatments, 22 pair-variables (TNB versus (vs.) NFB, TNB vs. NOFB, TNB vs. NOFB, NFB vs. NOFB, NFB vs. FNT, NFB vs. FY, NFB vs. FW, NOFB vs. SVG, NOFB vs. FNT, NOFB vs. FY, FS vs. FNT, FS vs. FY, SVG vs. FNT, SVG vs. FY, SVG vs. TSC, FNT vs. FY, FY vs. FW, CR vs. TSC, HR vs. TNB, HR vs. NFB, HR vs. FNT, HR vs. FY, and NOFB vs. FBA) correlated significantly in Pearson correlation and regression analyses. Principal component analyses explained 82% of the total variance and PC1, PC2, and PC3 explained 23, 21, and 15% of the total variance and correlated with the HR, TNB, FS, FNT and FY; FBA, SVG, TSC, and TPC; and NFB, NVB and NOFB, respectively, indicating strong connections among tree physiological and chemical properties. In conclusion, DI techniques using moderate water deficits can be managed successfully in apricot production under semiarid Mediterranean climate conditions such as the one in Egypt.

Effects of Water Stress on the Phenolic Compounds of ‘Merlot’ Grapes in a Semi-Arid Mediterranean Climate

Of all the abiotic stress types to which plants grown in fields are exposed, the most influential is water stress. It is well accepted that adopting controlled deficit irrigation strategies during the growing season has beneficial effects on the chemical compositions of grapes and red wines. However, there is a discrepancy in the timing, intensity and duration of deficit. This study aimed to evaluate the changes in phenolic composition of ‘merlot’ cultivar grapes when subjected to different levels of water stress in a semi-arid Mediterranean climate. Four treatments with different water stress levels were applied within two phenological intervals (flowering-veraison, veraison-maturity) to 128 grapevines for two consecutive years. The water stress levels for Treatments 1, 2, 3 and 4 were: no-light, light-moderate, moderate-intense and intense for the flowering-veraison and veraison-maturity intervals, respectively. Water stress distinctly affected the phenolic compounds in skin and seeds. The concentrations of flavan-3-ols and total polyphenols were much higher in seeds than in skin, and in both fractions, tannins are the major compounds.

Field and modelling study for deficit irrigation strategy on roots volume and water productivity of wheat

In many regions of the world, including Egypt, water shortages threaten food production. An irrigation deficient strategy in dry areas has been widely investigated as a valuable and sustainable approach to production. In this study, the dry matter and grain yield of wheat was decreased by reducing the amount of irrigation water as well as the volume of the root system. As a result of this, there was an increase the soil moisture stress. This negatively affected the absorption of water and nutrients in the root zone of wheat plants, which ultimately had an effect on the dry matter and grain yield of wheat. The values of dry matter and grain yield of wheat increased with the ʻSakha 94ʼ variety compared to the ʻSakha 93ʼ class. It is possible that this was due to the increase in the genetic characteristic of the root size with the ʻSakha 94ʼ variety compared to the ʻSakha 93ʼ class, as this increase led to the absorption of water and nutrients from a larger volume of root spread. Despite being able to increase the water productivity of wheat by decreasing the amount of added irrigation water, the two highest grain yield values were achieved when adding 100% and 80% of irrigation requirements ( IR) needed to irrigate the wheat and no signif-icant differences between the yield values at 100% and 80% of IR were found. Therefore, in accordance with this study, the recommended irrigation for wheat is at 80% IR which will provide 20% IR. When comparing the water productivity of two wheat varieties in study, it becomes clear that ʻSakha 94ʼ was superior to ʻSakha 93ʼ when adding the same amount of irrigation water, and this resulted in increased wheat productivity for ʻSakha 94ʼ. The SALTMED results confirmed good accuracy (R2: 0.92 to 0.98) in simulating soil moisture, roots volume, water application efficiency, dry matter, and grain yield for two varieties of wheat under deficit irrigation conditions. Whilst using sprinkler irrigation system under sandy soils in Egypt.

Can Sustained Deficit Irrigation Save Water and Meet the Quality Characteristics of Mango?

Mango is one of the most cultivated tropical fruits worldwide and one of few drought-tolerant plants. Thus, in this study the effect of a sustained deficit irrigation (SDI) strategy on mango yield and quality was assessed with the aim of reducing irrigation water in mango crop. A randomized block design with four treatments was developed: (i) full irrigation (FI), assuring the crop’s water needs, and three levels of SDI receiving 75%, 50%, and 33% of irrigation water (SDI75, SDI50, and SDI33). Yield, morphology, color, titratable acidity (TA), total soluble solids (TSS), organic acids (OA), sugars, minerals, fiber, antioxidant activity (AA), and total phenolic content (TPC) were analyzed. The yield was reduced in SDI conditions (8%, 11%, and 20% for SDI75, SDI50, and SDI33, respectively), but the irrigation water productivity was higher in all SDI regimes. SDI significantly reduced the mango size, with SDI33 generating the smallest mangoes. Peel color significantly changed after 13 days of ripening, with SDI75 being the least ripe. The TA, AA, and citric acid were higher in SDI75, while the TPC and fiber increased in all SDI levels. Consequently, SDI reduced the mango size but increased the functionality of samples, without a severe detrimental effect on the yield.

An adequate regulated deficit irrigation strategy improves wine astringency perception by altering proanthocyanidin composition in Cabernet Sauvignon grapes

Regulated deficit irrigation (RDI) is an agricultural practice that can enhance grapevine berry and wine quality. However, the effects of water deficit on concentration and composition of proanthocyanidins (PAs) and wine astringency are often limited and contrasting. Therefore, the profiles of PAs were investigated in Cabernet Sauvignon grown at 60% (RDI-1), 70% (RDI-2), 80% (RDI-3), and 100% (conventional irrigation, CI) of estimated evapotranspiration in 2016 and 2017. The treatments, replicated three times, were laid out in a randomized block design where any border effects were avoided. Our results showed that compared with CI, grapes grown under RDI had greater total concentrations of phenolic compounds. Skin PAs content increased in response to the RDI, especially in RDI-1 and RDI-2, while the seed PAs content was relatively insensitive to RDI. Hierarchical cluster analysis indicated that higher percentage of galloylation, molecular mass, mean degree of polymerization and the special extension subunits, such as percentage of (–)-epicatechin-3-O-gallate (%ECG) and percentage of (–)-epicatechin (%EC), led to greater astringency intensity in the wine. However, RDI-1 decreased perceived astringency due to the decreased %ECG and %EC of PAs extension subunits, and increased %ECG of PAs terminal subunits. Our study suggests that the irrigation levels at RDI-2 and RDI-3 can significantly influence the PAs compositions and improve wine astringency perception.

RESPOSTA DA CULTURA DO RABANETE SOB CULTIVO ORGÂNICO AOS FATORES DE PRODUÇÃO ÁGUA E COBERTURA DO SOLO

RESPOSTA DA CULTURA DO RABANETE SOB CULTIVO ORGÂNICO AOS FATORES DE PRODUÇÃO ÁGUA E COBERTURA DO SOLO ANTONIO VANKLANE DE ALMEIDA1; ALEXSANDRO OLIVEIRA DA SILVA1; JENYFFER DA SILVA GOMES SANTOS2; JANIQUELLE DA SILVA RABELO3; VALSERGIO BARROS DA SILVA1 E ALFREDO MENDONÇA DE SOUSA1 1 Departamento de Engenharia Agrícola, Universidade Federal do Ceará, UFC, Av. Mr. Hull, s/n, Pici, CEP:60356-001, bloco 804, Fortaleza, Ceará, Brasil. E-mail: vanklaneprece@hotmail.com, alexsandro@ufc.br, valsergiobarros@hotmail.com, alfredomendonca121@gmail.com 2 Faculdade de Engenharia Agrícola, Universidade Estadual de Campinas, UNICAMP, Av. Cândido Rondon, 501 - Cidade Universitária, CEP: 13083-875, Campinas, São Paulo, Brasil. E-mail: jnfgomes@gmail.com 3 Departamento de Fitotecnia, Universidade Federal do Ceará, UFC, Av. Mr. Hull, s/n, Pici, CEP:60356-001, bloco 805, Fortaleza, Ceará, Brasil. E-mail: janekellyrabelo@hotmail.com 1 RESUMO Em regiões com limitações de recursos hídricos, como semiárido cearense, o uso eficiente da água torna-se a cada dia imprescindível para a produção de hortaliças irrigadas nestas regiões. Neste sentido, a presente pesquisa teve como objetivo a avaliação técnica e econômica do efeito dos fatores de produção água e níveis de cobertura do solo da bagana de carnaúba sobre a produtividade da cultura do rabanete. A pesquisa foi conduzida no período de junho a agosto de 2018 em dois ciclos de produção em área pertencente ao Prece (Programa de Educação em Células Cooperativas), localizado no município de Pentecoste-CE. O experimento foi conduzido em um delineamento em blocos casualizados com quatro repetições. Os tratamentos foram constituídos por cinco lâminas de irrigação (50%; 75%; 100%; 125% e 150% da evapotranspiração das culturas localizada, ETcloc) e cinco diferentes níveis de cobertura morta constituída de bagana de carnaúba: 25%; 50%; 75% e 100% além da testemunha com o solo sem cobertura 0%, totalizando 100 parcelas experimentais. Os resultados permitiram concluir que a bagana de carnaúba apresentou potencial para utilização como cobertura morta no cultivo de rabanete, proporcionando incremento no rendimento da cultura em condições de estratégia de irrigação com déficit para o uso de 16 t ha-1 de cobertura morta. A cultura rabanete responde de forma crescente às diferentes lâminas de irrigação até a ETcloc de 100%, podendo-se obter ganhos econômicos quando associadas à utilização de cobertura morta no solo. Palavras-chave: Cobertura do solo. Manejo da irrigação. Função de produção. Raphanus sativus L. ALMEIDA, A. V.; SILVA, A. O.; SANTOS, J. S. G.; RABELO, J. R.; SILVA, V. B.; SOUSA, A. M. RESPONSE OF RABANET CULTURE UNDER ORGANIC CULTIVATION TO PRODUCTION FACTORS WATER AND SOIL COVERAGE 2 ABSTRACT In regions with limited water resources, such as the semi-arid region of Ceará, the efficient use of water becomes indispensable every day for the production of irrigated vegetables in this region. In this sense, this research had as objective the technical and economic evaluation of the effect of the factors of production water and levels of the cover of the soil of the bagana on the productivity of the radish culture. The research was conducted in the period from June to August 2018 in two production cycles in area belonging to Prece (Cooperative Cell Education Program), located in the municipality of Pentecoste-CE. The experiment was conducted in a randomized block design with four replicates. The treatments consisted of five irrigation depth (50%, 75%, 100%, 125% and 150% of crop localized evapotranspiration, ET cloc) and five levels of ground cover consisting of carnauba bagana: 25%; 50%; 75% and 100% beyond the control with the soil without 0% coverage, totalizing 100 experimental units. The results allowed to conclude that the carnauba bagana presented potential for use as ground cover in the cultivation of radish, providing an increase in the yield of the crop under conditions of deficit irrigation strategy to use 16 t ha-1 of ground cover. The radish crop significantly responds to the different irrigation depth, up to 100% ET cloc, and economics gains can be obtained when associated with the use of ground cover in soil. Keywords: Soil cover. Irrigation management. Production function. Raphanus sativus L.

Mango fruit quality improvements in response to water stress: implications for adaptation under environmental constraints

Mediterranean farming is facing increasing periods of water shortage and, in the coming decades, the water reduction is expected to exert the most adverse impact upon growth and productivity. This study was performed to assess the response of the physico-biochemical quality parameters of mango fruits to different doses of irrigation in a Mediterranean subtropical area in Spain. During two-monitoring seasons, trees were subjected to deficit-irrigation strategies receiving 33, 50, and 75% of a crop evapotranspiration (ETC), and a control at 100% ETC. According to the findings and respect to control, the yield was reduced in 8, 11, and 20% for the water-stressed trees at 75, 50, and 33% ETC, respectively, producing smaller fruits in line with the amount of applied irrigation. However, the water-stressed fruits significantly enhanced their quality, in particular at 33% ETC, with regards to the content of the health-promoting phytochemicals (total soluble solids, vitamin C, and β-carotenoids). Thus, sustainable water management without a detrimental effect on the yield could be possible, and farmers should be encouraged to adapt to the environmental constraints, producing improved quality fruits.

Effect of regulated deficit irrigation on pomegranate fruit quality at harvest and during cold storage

The effect of regulated deficit irrigation (RDI) strategies on fruit yield and quality at harvest and during cold storage at 5 °C of Wonderful pomegranates was studied. Three irrigation strategies were tested: control strategy (C) using farm irrigation with 100% of crop evaporation (ETc), and two RDI strategies where 25% of ETc was applied during flowering and fruit set (RDI 1) and during the final phase of fruit growth and ripening (RDI 2). The RDI 1 approach reduced the pomegranate yield. Conversely, the RDI 2 allowed a similar pomegranate yield to C treatment. Fruit morphological characteristics were not affected by RDI at harvest and during cold storage. Both RDI strategies resulted in fruits with higher aril percentages. Physicochemical parameters of fruits at harvest and during cold storage were not affected by irrigation strategies, except the total soluble solids content that was higher in fruits from RDI 2 than in those from C and RDI 1. During storage, a reduction of the fruit weight and size was observed, particularly in the first 15 days of storage. The total soluble solids content and titratable acidity decrease, while pH increases with storage. At harvest and during cold storage, the total phenolic content and antioxidant activity evaluated by ABTS+ assay did not differ among irrigation treatments, whereas using a FRAP assay fruits from RDI trended to have higher antioxidant activity than those from C treatment. Total phenolic content and ABTS+ values were lower at the final of storage time than on the first day. Present results showed that RDI strategies applied in a final phase of fruit growth and ripening could be a convenient irrigation strategy for commercial Wonderful orchards in the south of Portugal, allowing improve the fruit quality with a water saving of 14.6%.

Simulated efficient growth-stage-based deficit irrigation strategies for maximizing cotton yield, crop water productivity and net returns

Declining water levels in the southern Ogallala Aquifer and associated reduction in irrigation capacities and increasing pumping costs necessitate adoption of deficit/limited irrigation practices for sustaining cotton production in the Texas High Plains (THP) region. The overall goal of this study was to evaluate the response of cotton crop to water stress in different growth stages and suggest efficient growth-stage-based deficit (GSBD) irrigation schedules for maximizing yield, crop water productivity (CWP) and economic returns under contrasting weather conditions using the CROPGRO-Cotton model. Five growth stages including seedling emergence/germination, squaring, early bloom/flower initiation, peak bloom, and boll opening/late bloom were considered. A combination of five irrigation scenarios (S1 through S5 with seasonal irrigation amounts of 240, 300, 360, 420 and 480 mm) and six irrigation treatments (T1 through T5: no irrigation in one of the five growth stages, and T6: irrigation applied in all five growth stages) were then simulated with a center pivot irrigation system. Skipping irrigation during the peak bloom growth stage (T4 treatment) resulted in the lowest yield, CWP and net returns under all weather conditions. The T1 irrigation treatment in which irrigation was skipped during the seedling emergence/germination stage was identified as the most efficient irrigation strategy for maximizing yield, CWP and net returns among all irrigation scenarios. Application of more than 360, 420 and 480 mm of irrigation water in wet, normal and dry years, respectively, did not significantly improve yield or net returns, and resulted in a decrease in CWP. These results imply that cotton responses to water deficit vary by growth stages, and adoption of appropriate GSBD irrigation strategies could optimize the use of limited water resources and extend the life of the southern Ogallala Aquifer.