Continuous Deficit Irrigation Research Articles

How far can the interactive effects of continuous deficit irrigation and foliar iron fertilization improve the physiological and agronomic status of soybeans grown in calcareous soils under arid climate conditions?

Water and iron are crucial elements for soybean growth and development, particularly in calcareous soils and arid climatic conditions. The aim of this study was to improve iron and water use efficiency and enhance soybean resilience to water scarcity and iron deficiency. So, the effect of 16 treatments; 4 deficit irrigation water regimes (25, 50, 75 and 100 % crop water requirements (CWR)) combined to 4 foliar iron gradual concentrations (F0=0, F1=1, F2=3 and F3=5 g/L of FeSO4) applied at 3–4 leaves, at the beginning of flowering and at the end of flowering; was investigated in this split plot experiment with 4 replicates. Our results showed that supplying iron and water to plants can improve chlorophyll florescence a, chlorophyll content, stomatal conductance, yield, iron uptake, and protein content. Determining the optimal combination of deficit irrigation treatment and gradual iron sulfate concentrations for soybean is an alternative to save water and improve growth parameters. In our manuscript, we can conclude that 75 % CWR × F2 is the best combination of the two factors that led to the same biological yield as 100 % CWR. Consequently, we can say that applying F2 as a foliar iron concentration led to an economy of 25 % of the soybean crop water requirement by ensuring an adequate supply of soluble iron, facilitating root uptake, promoting protein synthesis, enhancing chlorophyll formation, and supporting overall nutrient uptake and metabolism.

Bioactive compounds and quality attributes of pomegranate fruit as affected by continuous deficit irrigation

Bioactive compounds and quality attributes of pomegranate fruit as affected by continuous deficit irrigation

The impact of “continuous” deficit irrigation on carrot crop development in the Saïs plain, Morocco

In the Maghreb, as in many arid and semi-arid zones, water resources are vulnerable to climatic variations, for which reason various scientific studies are being conducted in an attempt to face these changes while maintaining the yield potential of crops. The aim of the following paper is to evaluate the impact of continuous deficit irrigation (CDI) on the carrot (Daucus Carota L.) crop. A complete randomized block design (CRBD) involving five treatments and four repetitions was adopted for this experimental design. The studied treatments are: T1(125% ETc), T2(100% ETc), T3(85% ETc), T4 (75% ETc) and T5 (66% ETc). Vegetative, biochemical, and yield parameters were measured to identify carrot response and provide optimal water management for deficit irrigation on carrot. Irrigation at 125% ETc achieved the highest yield (59 tons/ha). However, in terms of yield, treatment (T1) was not significantly different from (T2) nor (T3). Meanwhile, the 66% ETc water deficit treatment (T5) showed remarkable decreases in yield. This means that even when providing more water it does not increase the yield meaning that the plant does not use the given water but instead, it is lost and on the other hand a 15% water deficit did not significantly impact the yield.

Effects of regulated, precision and continuous deficit irrigation on the growth and productivity of a young super high-density olive orchard

Water is the main limiting factor for olive cultivation in rainfed conditions. In irrigated orchards, water availability is scarce mainly during drought periods. Thus, increasing irrigation efficiency is a key issue to improve water management, especially in semiarid conditions. The objective of this study was to assess different irrigation strategies on tree growth and production components during three years in a young super high-density olive orchard (Arbequina cv.) located in northeast Spain. Four deficit irrigation strategies were compared to a control strategy based on replenishing crop evapotranspiration. The four strategies were as follows: Continuous Deficit Irrigation (CDI), two Regulated Deficit Irrigation strategies (Moderate, MRDI, and Severe, SRDI), and a precision Irrigation strategy based on daily trunk growth (Precision). In the Precision strategy, olive oil production increased by 7% and the vegetative variables did not show significant reductions, resulting in an average yearly water savings of 31% compared to the control strategy. The Regulated Deficit Irrigation strategies also produced promising results based on the high average yearly water-saving rates of 19% and 29%. However, the SRDI strategy exhibited significant reductions in tree height, lateral branches growth, olive yield, and oil yield compared to the control. On the other hand, the MRDI strategy did not differ significantly in oil yield, tree height, and lateral branches growth compared to the control or Precision strategies. Similarly, the CDI strategy resulted in significantly lower tree height, lateral branches growth, and production compared to the control. Although the observed reduced growth in both SRDI and CDI strategies presents an interesting opportunity for managing excessive vigor in super high-density olive orchards, it is important to consider that this approach may compromise production in successive seasons.

Validation of DNA marker-assisted selection for forage biomass productivity under deficit irrigation in alfalfa.

Drought and limited irrigation resources threaten agricultural sustainability in many regions of the world. Application of genomic-based breeding strategies may benefit crop variety development for these environments. Here, we provide a first report on the effect of deploying DNA marker-assisted selection (MAS) for the drought resilience quantitative trait in alfalfa (Medicago sativa L.). The goals of this study were to validate the effect of several quantitative trait loci (QTL) associated with alfalfa forage and crown-root (CR) biomass during drought and to determine their potential to improve forage yield of elite germplasm under water-limited conditions. Marker assisted selection was employed to introgress favorable or unfavorable DNA marker alleles affiliated with 10 biomass QTL into three elite backgrounds. Thirty-two populations were developed and evaluated for forage productivity over 3 yr under continuous deficit irrigation management in New Mexico, USA. Significant yield differences (ranging from -13 to 26%) were detected among some MAS-derived populations in all three elite backgrounds. Application of QTL MAS generally resulted in expected phenotypic responses within an elite genetic background that was similar to that in which the QTL were originally identified. However, relative performance of the populations varied substantially across the three genetic backgrounds. These outcomes indicate that QTL MAS can significantly affect forage productivity of elite alfalfa germplasm in drought-stressed environments. However, if biomass QTL are detected in donor germplasm that is genetically dissimilar to targeted elite populations, characterization of donor alleles may be warranted within elite backgrounds of interest to confirm their phenotypic effects prior to implementing MAS-based breeding.

Investigation of the Response of onion (Allium Cepa L.) to continuous deficit irrigation as smart approaches to crop irrigation under Mediterranean conditions

Water is a crucial resource for food production and its scarcity associated with frequent droughts has increased the need for a more efficient use of it along with new irrigation management technologies. This study addressed onion crop responses to continuous deficit irrigation with trigging thresholds of readily available water content. The experiment was conducted on an experimental plot in open field in Morocco. Three water regimes were applied T1 control (100%), T2 (75%) and T3 (50%) of crop evapotranspiration ETc combined with two trigging thresholds (10% and 5%). This is a complete random block device with four repetitions. The measurements concerned the monitoring of vegetative, Eco physiological and yield parameters. The results obtained show that: (i) 100% ETc irrigation at a threshold of 5% of RAW recorded the maximum bulb diameter and weight, thus achieving the best marketable bulb yields. However, in terms of yields, this treatment is not significantly different from the other irrigation regimes with the exception of the irrigated treatment at 50% daily ETc and at a threshold of 10% RAW. The latter recorded the lowest values in terms of production parameters. (ii) For the ecophysiological parameters, significant effects of irrigation dose were observed for proline content, stomatal conductance and leaf temperature, and the effect of the trigging threshold was clearly observed for the moisture content of the leaves. (iii) Water restrictions have minimized the rate of premature run and population density of Thrips tabaci in the onion. (iv) Finally, the best agronomic efficiencies in the use of irrigation water were recorded in treatments with a water restriction of 50%.

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.

Identification of water stress conditions in olive trees through frequencies of trunk growth rate

Continuous monitoring of the tree water status will enhance irrigation performance, particularly when applying deficit schedules. The olive tree is a highly drought-resistant species and management of the water stress could increase water savings. Trunk diameter fluctuations can be displayed as daily curves representing the shrinkage and swelling, and can provide information about tree water status. In olive trees, trunk growth rate (TGR) is the most useful indicator, but the daily variability reduced the commercial applications. Recently, weekly frequencies of TGR values were associated to the water status in one seasonal experiment. The aim of this work is to study the seasonal pattern and the interannual variations of these parameters in order to integrate them in an irrigation scheduling tool. The experiment was performed during two consecutive seasons (2018 and 2019) in a superhigh density mature olive orchard at Carmona (Seville, Spain). Three different irrigation scheduling treatments were considered in a randomized complete block design. The control treatment was fully irrigated with 150–175% crop evapotranspiration (ETc) in order to ensure an optimum water status. Regulated deficit irrigation-1 (RDI-1) was scheduled using only TGR data provided through the continuous measurements from a dendrometer. In this treatment, water stress conditions were controlled during the pit hardening period. RDI-2 was similar to RDI-1, but with a more severe water stress conditions during pit hardening and a maximum seasonal amount of water that limited rehydration. Water stress was greater during the 2019 season than the 2018 season, according to the midday stem water potential (SWP). Weekly frequencies of TGR values lower than −0.3 mm day−1 (Severe FR) and values between −0.1 and 0.3 mm day−1 (Good FR) described the water status pattern in the three treatments for both seasons. Only under severe water stress conditions (SWP more negative than −4 MPa) the values of these frequencies did not identify accurately the water status. However, the use of weekly frequencies of values greater than 0.3 mm day−1 (Alert FR) and the pattern of these Severe FR and Good FR themselves identified such conditions. The use of these three weekly frequencies (Severe, Good and Alert (SGA) approach) are suggested for continuous deficit irrigation scheduling in olive trees.

The Response of Braeburn Apple to Regulated Deficit Irrigation

Regulated deficit irrigation (RDI) is one of deficit irrigation (DI) techniques and it is developed to minimize irrigation inputs in fruit production, especially in areas where water resources are limited, is recommended for saving irrigation water in agriculture. This study was conducted to determine the effects of deficit irrigation treatments applied in different growth periods on plant water consumption, water yield relations, stomatal conductance and yield of Braeburn apple variety (grafted on M9 rootstock). Experiments were conducted in the years 2010, 2011, and 2012 at Fruit Research Institute, Eğirdir, Isparta, Turkey. Six different irrigation treatments were applied as I1; non-deficit irrigation program, I2; continuous deficit irrigation program (CDI), I3; deficit irrigation program between the 40th and 70th days after full bloom (DAFB), I4; deficit irrigation program between the 70th and 100th DAFB, I5; deficit irrigation program between the 100th and 130th DAFB and I6; deficit irrigation program between the 130th and 160th DAFB. The highest yield (55.2, 54.1 and 63.8 t ha-1 in 2010, 2011 and 2012 respectively) and water use efficiency (WUE) (0.130, 0.129 and 0.137 t ha-1 mm-1 in 2010, 2011 and 2012) values were obtained from I3 treatment in all short-term deficit irrigation treatments. The stomatal conductance values decreased during the short-term deficit irrigation treatments, but the values increased following the deficit irrigation periods. The results revealed that apple trees grafted on M9 rootstock were influenced by short-term water stress, but they were able to cope with stress after the deficit periods. In all deficit irrigation treatments, yield response factor (Ky) ranged from 0.77 to 2.11 Apple tree yield was less sensitive to water deficit in I3 compared to other treatments. Therefore I3 treatment was found to be applicable in case of scarce water resources since it ensured water saving.

Fruit Yield and Quality of ‘Valencia’ Orange Trees under Long-Term Partial Rootzone Drying

Climate, soil and tree water status, fruit yields and quality of ‘Valencia’ orange trees were monitored over five consecutive seasons (2007–2012) to study the effects of irrigation placement or volume. Three irrigation treatments were imposed: conventional irrigation (CI, 100% of crop evapotranspiration on both sides of the rootzone), partial rootzone drying (PRD, 50% of CI water only on one alternated side of the rootzone) and continuous deficit irrigation (DI, 50% of CI water on both sides of the rootzone). Yield parameters were generally not affected by PRD, and only yield per tree was lower in DI than CI trees. Fruit size and juice content were also reduced by DI, and not by PRD. Both PRD and DI increased juice soluble solids and acidity, vitamin C and carotenoid concentrations, as well as fruit, juice and sugar productivity per unit of irrigation water. Overall, the straight reduction of irrigation volumes by ~55% (DI) induced an average of 4.4% leaf dehydration, which caused significant fruit size reductions and a 3.4% reduction in juice yield, corresponding to a loss of about 2.6 tons of juice and 261 kg of sugars per hectare and year. On the other hand, water savings of about 2 mega liters per hectare and year with PRD caused a mild 2.3% leaf dehydration and mainly fruit quality improvements, indicating that PRD is a sustainable irrigation strategy for ‘Valencia’ orange.

Effects of deficit irrigation on the yield and irrigation water use efficiency of drip-irrigated sweet pepper (Capsicum annuum L.) under Mediterranean conditions

Water scarcity is seriously affecting agricultural production, especially in arid and semi-arid areas. Therefore, there is increasing interest in improving water productivity in agriculture. This research aims to study the effects of deficit irrigation on the productive response of sweet pepper plants. Nine deficit irrigation strategies were assayed during two seasons (2017 and 2018) in a randomised complete block design with three replicates. These irrigation strategies consisted of applying 100%, 75% and 50% of the irrigation water requirement (IWR) during the entire growing period (continued deficit irrigation) or applying 75% or 50% of the IWR during one of the following stages (regulated deficit irrigation): vegetative growth, fruit setting, and harvesting. Pepper plants cultivated under deficit irrigation reduced fruit biomass and indicators of plant water status. Applying water deficits during the vegetative growth and fruit-setting stages had minimal effects on the marketable yield but with minimal water savings. Irrigating pepper plants with 75% or 50% of the IWR during the entire crop cycle or with 50% of the IWR during harvesting resulted in a high incidence of fruits affected by blossom end rot, which in turn, led to a drastic reduction of the marketable yield in relation to fully irrigated plants (− 36%, − 55% and − 44%, respectively). These strategies also recorded the highest soluble solid and phenolic contents. Reducing the water applied to 75% of the IWR at harvesting led to a yield reduction (− 19%) but with important water savings (21%) and acceptable levels of soluble fruit solids and phenolic compounds.

Controlled deficit irrigation as a water-saving strategy for processing tomato

In a complex scenario characterized by climate change and increasing population demand, it is necessary to adopt production strategies involving a lower use of water. For this purpose, controlled deficit irrigation, CDI, strategies with an initial full irrigation covering 100 % crop evapotranspiration (ETc) followed by mild (50 %ETc) and moderate (75 %ETc) irrigation restrictions after the fruit set stage were evaluated. The study was performed during two years in two growing areas of processing tomato in Spain, using conventional and high-lycopene cultivars. With moderate levels of CDI an average saving of water of 26.1 % was achieved, but productivity was reduced on average by 10.7 %. It should be considered though, that the effect was dependent on the environment and genotype, and high-yield cultivars seemed to be more sensitive to the negative effects of moderate CDI on productivity. In contrast, mild CDI levels did not affect productivity and still entailed a water saving of 13 %. Moderate CDI levels increased soluble solids content, but this increase was not due to a higher accumulation of taste-related compounds, such as sugars and acids. Indeed, irrigation dose had no significant effect on the levels of fructose, glucose, citric and glutamic acid nor on derived variables related to tomato acceptability and CDI decreased the levels of malic acid. Considering previous results, mild CDI strategies would be preferred to continuous deficit irrigation strategies as the former contribute to reduce the use of water, an increasingly scarce resource, avoiding negative impacts on productivity, a key parameter to promote farmer adoption of CDI strategies.

Deficit Irrigation as a Sustainable Practice in Improving Irrigation Water Use Efficiency in Cauliflower under Mediterranean Conditions

Water shortage is one of the major constraints in vegetable production. Deficit irrigation is a sustainable technique that improves irrigation water use efficiency. Field studies were conducted during two growing seasons to evaluate the effects of deficit irrigation on plant growth, plant water status, productive response (curd yield and quality), irrigation water use efficiency (IWUE), and crop profitability of cauliflower. Nine irrigation treatments were used, applying 100%, 75% (moderate), or 50% (severe) of the irrigation water requirements (IWR) during the entire growing season (Continued Deficit Irrigation, CDI), or 75% and 50% of IWR during one of the following stages (Regulated Deficit Irrigation, RDI): Juvenility, curd induction, and curd growth. Severe deficit irrigation applied during juvenility and curd induction reduced the plant size, but it only led to a significant reduction of marketable yield (22%), and average curd size and weight if it was maintained throughout the crop cycle, supposing the highest IWUE (43.6 kg m−3). Moderate CDI or severe RDI during juvenility did not reduce significantly the curd yield compared to fully irrigated plants (4.4 kg m−2), thereby obtaining similar gross revenues (16,859 € ha−1) with important water savings (up to 24.3%), improving IWUE (up to 34.2 kg m−3).

Water-Related Variables for Predicting Yield of Apple under Deficit Irrigation

Predicting apple yield in relation to tree water use is important for irrigation planning and evaluation. The aim of the present study was to identify measurable variables related to tree water use that could predict final fruit yield of apple trees under different strategies of deficit irrigation. Adult ‘Gala’ and ‘Fuji’ apple trees were exposed to conventional irrigation (CI), delivering 100% of crop evapotranspiration; partial root zone drying (PRD), delivering 50% of CI water only on one alternated side of the root-zone; and continuous deficit irrigation (CDI), delivering 50% of CI water on both sides of the root-zone. Integrals of soil (SWDint) and leaf (LWSDint) water deficit along with growth and stomatal conductance (Gsint) were calculated across each season and used to estimate total conductance (GStree) and transpiration (Trtree) per tree, transpiration efficiency on a fruit (GRfruit/Tr) or tree (GRtrunk/Tr) growth basis, and transpiration productivity (Yield/Trtree). ‘Fuji’ trees had higher Yield/Trtree, but had lower GRtrunk/Tr and similar GRfruit/Tr compared to ‘Gala’ trees. In ‘Fuji’, CDI reduced yield, trunk growth, leaf hydration, and gas exchange, while in ‘Gala’, it did not reduce yield and gas exchange. In ‘Fuji’, a linear combination of GRtrunk/Tr, GRfruit/Tr, and Gstree contributed to predicting yield, with GRfruit/Tr explaining nearly 78% of the model variability. In ‘Gala’, a linear combination of LWSDint and Gstree contributed to predicting yield, with Gstree explaining over 79% of the model variability. These results indicate that measuring tree water status or water use may help predict final apple yields only in those cultivars like ‘Gala’ that cannot limit dehydration by closing stomates because of carbon starvation. In more vigorous cultivars like ‘Fuji’, transpiration efficiency based on fruit growth can be a powerful predictor of final yields.

Applicability of time-of-flight-based ground and multispectral aerial imaging for grapevine canopy vigour monitoring under direct root-zone deficit irrigation

ABSTRACTThis study investigates the applicability of ground-based 3D time-of-flight (ToF) imaging and small unmanned aerial system (UAS) integrated multispectral imaging as a rapid grapevine canopy vigour mapping tool for decision support during crop production management. Direct root-zone deficit irrigation was applied to grapevines with continuous and pulse irrigation techniques at 15%, 30%, and 60% rates as that of standard irrigation rate (100%) established by the grower in a commercial production. The control block was irrigated continuously at 100% standard irrigation rate. Field plots were imaged using ground platform integrated with 3D ToF imaging sensor and small UAS-integrated multispectral camera at 128 and 65 days before the harvest to estimate the canopy vigour variability associated with irrigation treatments. Customized as well as standard methods (convex hull and voxel grid) were utilized to extract canopy attributes (e.g. volume) from the 3D ToF imaging sensor data. The multispectral images were processed to extract normalized and green normalized difference vegetation index images. Resulting data were used to estimate canopy area ratio i.e. the ratio between the grapevine canopy area with respect to the total area in selected region of interest. A significant correlation (r = 0.34) between canopy volume estimated by customized algorithm and aerial canopy area ratio was observed. Custom canopy volume estimates were also highly correlated (r = 0.79) with voxel grid derived canopy volume data. Overall, 60% continuous direct root zone deficit irrigation appeared to produce canopy volume/vigour comparable with those under control treatment. Results also suggest that grower can utilize either or both (ground and aerial) grapevine canopy mapping techniques for effective management.

Impact of Deficit Irrigation on Yield and Fruit Quality of Orange Trees (Citrus Sinensis, L. Osbeck, CV. Meski Maltaise) in Southern Tunisia

AbstractAn experiment on deficit irrigation of orange trees (Citrus sinensis, L. Osbeck, cv. Meski Maltaise) with saline water (1.5 g l‐1) was conducted in the arid region of Medenine, Tunisia. Four irrigation treatments were applied: full irrigation (FI), irrigated at 100% of the crop evapotranspiration; deficit irrigation (DI75) and (DI50), which received respectively 25 and 50% less water than FI; and the farmer's method (FM). Soil water content and salinity were monitored during the orange active period. Yield and fruit quality were measured at harvest and used to analyse water productivity (WP) and net income. Results show a decrease in soil salinity between the spring and winter seasons with maximum values observed for the DI50 treatment. Maximum yield levels were obtained under the FI treatment (26.6 t ha−1). Applying continuous deficit irrigation resulted in 24 and 45% yield reduction respectively for DI75 and DI50, compared to FI. Fruit‐quality parameters showed significant differences, with higher levels of total soluble solids for DI50 and better fruit weight for FI and FM. For total water supplies between 415 and 786 mm, WP was in the range 2.9–3.6 kg m‐3, with the highest values observed for the DI50 treatment and the lowest for FM. The soil water balance‐based irrigation method (FI) generated the greatest net income and the lowest soil salinization. Reduction in water supply produced an equivalent reduction in yield but a much stronger decrease in the economic return: using the DI75 strategy resulted in 25% water saving, 24% reduction in yield and 40% reduction in net income. Copyright © 2020 John Wiley & Sons, Ltd.

Response of Sugar Beet to Continuous Deficit Irrigation and Foliar Application of some Micronutrients under Sandy Soil Conditions.

Response of Sugar Beet to Continuous Deficit Irrigation and Foliar Application of some Micronutrients under Sandy Soil Conditions.

Growth and water relations of field-grown ‘Valencia’ orange trees under long-term partial rootzone drying

Climate, soil water potential (SWP), leaf relative water content (RWC), stem water potential (WPstem), stomatal conductance (g s), trunk, shoot and fruit growth of ‘Valencia’ orange trees were monitored during five consecutive seasons (2007–2012) to study water status and growth responses to irrigation placement or volume. 48 adult trees were exposed to conventional irrigation (CI, 100% of crop evapotranspiration on both sides of the rootzone), partial rootzone drying (PRD, 50% of CI water only on one alternated side of the rootzone) and continuous deficit irrigation (DI, 50% of CI water on both sides of the rootzone). Reducing irrigation volumes by 55% (DI) over CI increased leaf water deficit by 27% and reduced ‘Valencia’ fruit growth by 15% but not shoot or trunk growth. Similar water savings by PRD did not induce significant growth reductions. Differences in fruit growth rates determined 17% yield reduction in DI but not PRD trees. If we consider integrals of data across each season, PRD induced milder soil and leaf water deficit than DI but similar stomatal conductance. Tree daily water consumption (E tree) estimated from daily leaf transpiration was significantly lower in PRD and DI than in CI. Fruit growth efficiency (growth rate per unit E tree) was similar in all irrigation treatments, while shoot growth efficiency was higher in PRD than in CI. In PRD, an increased shoot growth efficiency rather than fruit growth efficiency is most likely due to water and assimilates being diverted from fruit to shoot growth under high VPD conditions. Although these results show good evidence of an irrigation placement effect inducing an advantage of the PRD strategy in ‘Valencia’ orange in terms of milder soil and leaf water deficit and more sustainable fruit growth compared to DI, PRD did not induce any significant advantage in terms of final yield over a simple reduction of irrigation volumes.

Deficit irrigation and maturation stage influence quality and flavonoid composition of 'Valencia' orange fruit.

Effects of continuous deficit irrigation (DI) and partial rootzone drying (PRD) treatments (50% ETc) in comparison with full irrigation (CI, 100% ETc) were investigated during 'Valencia' orange fruit maturation. Ultra-high-performance liquid chromatography/high-resolution mass spectrometry was used to quantify hesperidin, narirutin, tangeritin, nobiletin, didymin and neoeriocitrin in the fruit juice and peel. No significant effect of irrigation was found on yield, juice soluble solids or acidity. Juice color was not influenced by irrigation or harvest date, whereas peel color increased during maturation and was more pronounced in CI and PRD fruits. Juice acidity reached a peak in May, while soluble solids increased linearly throughout maturation. Hesperidin was the major flavanone detected during maturation, with concentrations 200-fold higher in the fruit peel than in the juice. In the peel, narirutin, didymin and neoeriocitrin decreased while hesperidin, nobiletin and tangeritin increased with maturation. Narirutin synthesis in the orange fruit was insensitive to irrigation strategy. In fruit peels, PRD and DI induced the decline of hesperidin, nobiletin and tangeritin only in June, whereas in the juice, deficit irrigation treatments induced an increase in hesperidin and didymin. These results suggest that deficit irrigation, in particular the conditions imposed with PRD, may cause a significant accumulation shift of total flavonoids from the fruit peel into the juice, with a positive impact on juice quality and nutritional value. Fruit compositional changes during maturation also suggest that late harvest can improve fruit palatability and nutritional quality under the cultural and environmental conditions of this study. © 2016 Society of Chemical Industry.

Improvement of Continuous Deficit Irrigation Efficiency on Young Plum Tree Using Arbuscular Mycorrhizal Fungi

Improvement of Continuous Deficit Irrigation Efficiency on Young Plum Tree Using Arbuscular Mycorrhizal Fungi