Deficit Irrigation Strategies Research Articles

Phytoprostanes and Phytofurans-Oxidative Stress and Bioactive Compounds-in Almonds are Affected by Deficit Irrigation in Almond Trees.

Almonds have gained consumers' attention due to their health benefits (they are rich in bioactive compounds) and sensory properties. Nevertheless, information about phytoprostanes (PhytoPs) and phytofurans (PhytoFs) (new plant markers of oxidative stress and compounds with biological properties for human health) in almonds under deficit irrigation is scarce or does not exist. These compounds are plant oxylipins synthesized by the oxidation of α-linolenic acid (ALA). Besides, they are biomarkers of plant oxidative degradation and biologically active molecules involved in several plant defense mechanisms. hydroSOStainable or hydroSOS mean plant foods made from from plants under controlled water stress. Almonds are a good source of polyunsaturated fatty (PUFAs) acids, including a high content of ALA. This paper aimed to describe the influence of diverse irrigation treatments on in vitro anti-oxidant activity (AAc) and total phenolic content (TPC), as well as on the level of ALA, PhytoP, and PhytoF in "Vairo" almonds. The AAc and TPC were not affected by the irrigation strategy, while the in vivo oxidative stress makers, PhytoPs and PhytoFs, exhibited significant differences in response to water shortage. The total PhytoP and PhytoF contents ranged from 4551 to 8151 ng/100 g dry weight (dw) and from 33 to 56 ng/100 g dw, respectively. The PhytoP and PhytoF profiles identified in almonds showed significant differences among treatments. Individual PhytoPs and PhytoFs were present above the limit of detection only in almonds obtained from trees maintained under deficit irrigation (DI) conditions (regulated deficit irrigation, RDI, and sustained deficit irrigation, SDI) but not in control almonds obtained from fully irrigated trees. Therefore, these results confirm PhytoPs and PhytoFs as valuable biomarkers to detect whether an almond-based product is hydroSOStainable. As a final conclusion, it can be stated that almond quality and functionality can be improved and water irrigation consumption can be reduced if controlled DI strategies are applied in almond orchards.

Soil water extraction pattern and water use efficiency of spring canola under growth-stage-based irrigation management

The rapid depletion rate of the Ogallala aquifer threatens agriculture sustainability in the U.S. Southern Great Plains (SGP). Adoption of drought tolerant crop with suitable irrigation strategy is critical to improve water use efficiency and sustain crop production in the region. The objective of the study was to assess soil water extraction pattern and water use efficiency of spring canola (Brassica napus L.) under deficit irrigation strategy (DI). Three diverse canola cultivars (‘H930’, ‘H955’ and ‘L140’) were grown under four different irrigation treatments; full-season irrigation (FI), no irrigation at the vegetative stage (VS), no irrigation at the reproductive stage (RS) and dryland (DL). Treatment VS extracted similar amount (20 mm) of total water from planting to harvest as FI in wetter year of 2015. However, VS extracted 10 mm of extra water from soil depth down to 1.6 m until harvest compared to FI in drier year of 2016. As water extraction during reproductive stage in 2016 was almost similar (70 and 67 mm in FI and VS, respectively) in VS and FI, most of the extra water extracted was utilized during vegetative stage when irrigation was skipped in VS. Canola sustained vegetative growth utilizing soil water extraction and efficiently utilized irrigation received during reproductive stage to reduce seasonal evapotranspiration (ET) in VS compared to FI. Treatment RS and DL also reduced seasonal ET, but they reduced average 11 and 13 % oil content compared to FI in 2015 and 2016, respectively. The VS had similar oil content as FI and optimized water use efficiency for biomass (WUEpb), and seed (WUEsy) and oil (WUEoy) yields. Among cultivars, L140 consistently had the greatest WUEpb in both experimental years and 34 and 36 % greater WUEsy and WUEoy in 2016 compared to both H930 and H955, respectively. Adopting spring canola cultivar L140 and skipping irrigation during vegetative stage could maximize water productivity in water deficit conditions of the SGP.

Assessing the Water-Stress Baselines by Thermal Imaging for Irrigation Management in Almond Plantations under Water Scarcity Conditions

This work examines the use of thermal imaging to determine the crop water status in young almond trees under sustained deficit irrigation strategies (SDIs). The research was carried out during two seasons (2018–2019) in three cultivars (Prunus dulcis Mill., cvs. Guara, Lauranne, and Marta) subjected to three irrigation treatments: a full irrigation treatment (FI) at 100% of irrigation requirements (IR), and two SDIs that received 75% and 65% of the IR, respectively. Crop water monitoring was done by measurements of canopy temperature, leaf water potential (Ψleaf), and stomatal conductance. Thermal readings were used to define the non-water-stress baselines (NWSB) and water-stress baselines (WSB) for each treatment and cultivar. According to our findings, Ψleaf was the most responsive parameter to reflect differences in almond water status. In addition, NWSB and WSB allowed the determination of the crop water-stress index (CWSI) and the increment of canopy temperature (ITC) for each SDI treatment, obtaining threshold values of CWSI (0.12–0.15) and ITC (~1 °C) that would ensure maximum water savings by minimizing the effects on yield. The findings highlight the importance of determining the different NWSB and WSB for different almond cultivars and its potential use for proper irrigation scheduling.

Optimizing precision irrigation of a vineyard to improve water use efficiency and profitability by using a decision-oriented vine water consumption model

While the agronomic and economic benefits of regulated deficit irrigation (RDI) strategies have long been established in red wine grape varieties, spatial variability in water requirements across a vineyard limits their practical application. This study aims to evaluate the performance of an integrated methodology—based on a vine water consumption model and remote sensing data—to optimize the precision irrigation (PI) of a 100-ha commercial vineyard during two consecutive growing seasons. In addition, a cost-benefit analysis (CBA) was conducted of the tested strategy. Using an NDVI generated map, a vineyard with 52 irrigation sectors and the varieties Tempranillo, Cabernet and Syrah was classified in three categories (Low, Medium and High). The proposed methodology allowed viticulturists to adopt a precise RDI strategy, and, despite differences in water requirement between irrigation sectors, pre-defined stem water potential thresholds were not exceeded. In both years, the difference between maximum and minimum water applied in the different irrigation sectors varied by as much as 25.6%. Annual transpiration simulations showed ranges of 240.1–340.8 mm for 2016 and 298.6–366.9 mm for 2017. According to the CBA, total savings of 7090.00 € (2016) and 9960.00 € (2017) were obtained in the 100-ha vineyard with the PI strategy compared to not PI. After factoring in PI technology and labor costs of 5090 €, the net benefit was 20.0 € ha−1 in 2016 and 48.7 € ha−1 in 2017. The water consumption model adopted here to optimize PI is shown to enhance vineyard profitability, water use efficiency and yield.

Automatic Irrigation Scheduling on a Hedgerow Olive Orchard Using an Algorithm of Water Balance Readjusted with Soil Moisture Sensors

Recent technological advances have made possible automated irrigation scheduling using decision-support tools. These tools help farmers to make better decisions in the management of their irrigation system, thus increasing yields while preserving water resources. The aim of this study is to evaluate in a commercial plot an automated irrigation system combined with remote-sensing techniques and soil mapping that allows the establishment of regulated deficit irrigation (RDI) strategies. The study was carried out over 3 years (2015–2017) in a commercial hedgerow olive orchard of the variety ‘Arbequina’ located in Alvarado (Extremadura, Spain). An apparent electrical conductivity (ECa) map and a normalized difference vegetation index (NDVI) map were generated to characterize the spatial variability of the plot and classify the zones in homogeneous areas. Then, reference points were selected to monitor the different irrigation sectors. In 2015, the plot was irrigated according to the farmer’s technical criteria throughout the plot. In 2016 and 2017, two different areas of the plot were irrigated applying an RDI strategy, one under expert supervision and the other automatically. The results show that in a heterogeneous plot the use of new technologies can be useful to establish the ideal location for an automatic irrigation system. Furthermore, automatic irrigation scheduling made it possible to establish an RDI strategy recommended by an expert, resulting in the homogenization of production throughout the plot without the need for human intervention.

EFFECTS OF UV–C ON BIOACTIVE COMPOUNDS AND QUALITY CHANGES DURING SHELF LIFE OF SWEET CHERRY GROWN UNDER CONVENTIONAL OR REGULATED DEFICIT IRRIGATION

The effect of a UV–C postharvest treatment (4 kJ m–2) on physicochemical quality, phenolic contents and total antioxidant capacity of ‘Prime Giant’ sweet cherry throughout 20 d at 2 °C (simulated cold storage during transportation period) plus 5 d at 15 °C (additional shelf life period) was studied. Furthermore, the effect of two regulated deficit irrigation strategies, with 36–39 % water savings, was also studied on such quality parameters. In general, physicochemical quality at harvest (soluble solids content: 16–18 %; titratable acidity: 11.2–12.4 g L–1) was unaffected throughout the storage periods, independently on storage time, regulated deficit irrigation or postharvest treatments. As observed from the darker red colour, cherry skin showed ≈ 9–10–fold higher phenolic contents and total antioxidant capacity than cherry flesh. Cyanidin–3–rutinoside was the major anthocyanin. Generally, phenolic compounds of cherry skin decreased during storage. However, UV–C treatment lowered such reductions, even increasing total phenolic content by 21–36 % after shelf life in fruit grown under regulated deficit irrigation. Conclusively, a UV–C pre–treatment can be considered as an excellent postharvest tool to increase sweet cherry phenolic compounds. Furthermore, a UV–C pre–treatment can be even combined with regulated deficit irrigation strategies to reduce natural resources consumption without affecting fruit quality, which is particularly interesting in Regions with scarce water availability.

Effect of Deficit Irrigation on Yield and Water Use Efficiency of Maize at Selekleka District, Ethiopia

Irrigation water availability is diminishing in many areas of the Ethiopian regions, which require many irrigators to consider deficit-irrigation strategy. This study investigated the response of maize (Zea mays L.) to moisture deficit under conventional, alternate and fixed furrow irrigation systems combined with three irrigation amounts over a two years period. The field experiment was conducted at Selekleka Agricultural Research Farm of Shire-Maitsebri Agricultural Research Center. A randomized complete block design (RCBD) with three replications was used. Irrigation depth was monitored using a calibrated 2-inch throat Parshall flume. The effects of the treatments were evaluated in terms of grain yield, dry above-ground biomass, plant height, cob length and water use efficiency. The two years combined result indicated that net irrigation water applied in alternate furrow irrigation with full amount irrigation depth (100% ETc AFI) treatments was half (3773.5 m3/ha) than that of applied to the conventional furrow with full irrigation amount (CFI with 100% ETc) treatments (7546.9 m3/ha). Despite the very significant reduction in irrigation water used with alternate furrow irrigation (AFI), there was insignificant grain yield reduction in maize(8.31%) as compared to control treatment (CFI with100% ETc). In addition, we also obtained significantly (p<0.001) higher crop water use efficiency of 1.889 kg/m3 in alternate furrow irrigation (AFI), than that was obtained as 0.988 kg/m3 in conventional furrow irrigation (CFI). In view of the results, alternate furrow irrigation method (AFI) is taken as promising for conservation of water (3773.5 m3/ha), time (23:22'50" hours/ha), labor (217.36 USD/ha) and fuel (303.79 USD/ha) for users diverting water from the source to their fields using pump without significant trade-off in yield.

Capability of a solar energy-driven crop model for simulating water consumption and yield of maize and its comparison with a water-driven crop model

As water scarcity becomes more acute in many parts of the world, crop modeling tools that effectively simulating crop response to deficit irrigation strategies to help investigate management improvement are needed. Identifying the strengths and weaknesses of the crop models with different growth-engines are therefore of great importance. The objective of this study was to investigate the capability and improvements of the new version of a solar energy-driven crop model (DSSAT-CERES-Maize, v4.7.5.0) in simulating water consumption and yield of hybrid seed maize under different soil water conditions, and its comparison with a water-driven crop model (AquaCrop, v4.0). Data obtained from a 4-year (2012–2015) field trial on maize grown under different irrigation treatments at Wuwei, Northwest China, was used for this assessment. These models were calibrated and validated using measured daily evapotranspiration (ET), leaf area index (LAI), aboveground biomass, yield (Y), harvest index (HI) and soil water content (SWC). Daily ET was measured using a combination of an eddy covariance (EC) system, sap flow sensors, and micro-lysimeter cylinders. The ability of DSSAT-CERES-Maize using the two different ET options, i.e., Priestley-Taylor/Ritchie (PT) and FAO-56 Penman-Monteith (PM) was analyzed. The results showed that DSSAT-CERES-Maize with the PT approach had fair agreement with measured daily ET of maize under non-water stress condition (R2=0.85; NRMSE=26.7%), but poor agreement with ET under water stress conditions (R2=0.51; NRMSE=43.8%). DSSAT-CERES-Maize with the PM approach systematically underestimated ET by up to 13% under non-water stress condition, which was mainly attributed to that the maximum static CERES-Maize crop coefficient (EORATIO) was currently hard coded to 1.0. Using the PT or FAO-56 PM approach as ET input in DSSAT-CERES-Maize showed no different effect on final biomass (B) and Y simulation for full irrigation. But for water stress conditions, DSSAT-CERES-Maize with the FAO-56 PM approach simulated B and Y with higher overestimation to the measured data than those simulated using the PT approach. The simulated LAI, biomass and SWC by DSSAT-CERES-Maize using the PT approach generally well followed the trend of the measured values for most irrigation treatments. The model with the PT approach showed acceptable prediction for B and Y of different irrigation treatments across years, with NRMSE of 15.5% and 26.2%, respectively, but the accuracy decreased with an aggravation of water stress. Furthermore, the strengths and weaknesses of DSSAT-CERES-Maize and AquaCrop, and their different cores of growth-engines, i.e. RUE and normalized water productivity (WP*) were carefully discussed. It was concluded that DSSAT-CERES-Maize was a superior estimate of maize yield than was AquaCrop, especially when the climate varied dramatically between years. But DSSAT-CERES-Maize, for the simulation of maize water consumption in an arid region where drought often occurs, was inferior to AquaCrop. These results contribute to recommend the appropriate crop model for specific modeling goals.

Evaluation of different deficit irrigation strategies in the late-maturing Japanese plum cultivar 'Angeleno'

In stone fruits, the pit hardening period is usually one of slow fruit growth that is considered relatively insensitive to an imposed moderate water stress. For this reason, this period is commonly employed for a first phase of reduced water input in regulated deficit irrigation (RDI) strategies. However, in previous studies with the Japanese plum cv. 'Angeleno', the identification of a period of slow growth just before harvest suggested the need to reconsider the most suitable RDI strategy for this cultivar. In this 3-year study (2014, 2015 and 2016) three irrigation strategies were compared: Control (CON) designed to meet tree water requirements throughout the season; Regulated Deficit Irrigation (RDI) with two separate periods of water deficit, one preharvest with no irrigation inputs during an intermediate period of fruit growth (pit hardening period), and the other postharvest with a 30 % reduction of the CON inputs; and Preharvest + Regulated Deficit Irrigation (RDP) with a single period of deficit irrigation initiated before harvesting and extended until the end of the irrigation campaign. Both deficit irrigation treatments were found to be effective at controlling tree vigor, with lower trunk cross-sectional area growth and pruned wood weight than in the CON treatment. Average water savings with the RDI and RDP strategies over the three years of the study were 24 % and 18 %, respectively, compared to CON, with no impact on yield and no carry-over effect. Fruit size in the RDP treatment was similar to the CON. The differences in fruit firmness, soluble solids concentration (SSC), acidity, lightness (L), hue (ho) and chroma (C*) of the skin were only slight or inconsistent over the three years. Our results confirm the suitability of moderate pre- and postharvest water stress (RDP strategy) in this cultivar, with greater water productivity than the traditional RDI strategy.

Improving the crop productivity in rainfed areas with water harvesting structures and deficit irrigation strategies

Watershed management practices aim at improving the agricultural productivity in rainfed agricultural areas by conserving rainwater for an extended period. The stored rainwater in the harvesting structures is used for meeting crop water demand. The water use efficiencies of these structures can be further enhanced through adoption of deficit irrigation management strategies. In this study, deficit irrigation scheduling is formulated using a simulation-optimization framework for a rainfed agricultural area with supplemental irrigation from a check dam in Kondepi IWMP area, near Kondepi Mandal, Prakasam district, Andhra Pradesh, India. The results from the study indicate that the adoption of irrigation management strategies have the potential to improve the productivity and bring more area under irrigation with an increase of 20% and 140% for yield and irrigated area respectively. The outcomes of this study indicate that the proposed method can be suggested for developing optimum irrigation strategies under water deficit in rainfed agriculture having water harvesting structures for an efficient utilization of stored rainwater.

The Productive, Economic, and Social Efficiency of Vineyards Using Combined Drought-Tolerant Rootstocks and Efficient Low Water Volume Deficit Irrigation Techniques under Mediterranean Semiarid Conditions

In many areas of southern Europe, the scarcity of water due to climate change will increase, making its availability for irrigation an even more limiting factor for agriculture. One of the main necessary measures of adaptation of the vineyards in these areas will be the implementation of water-saving irrigation strategies and technologies to improve WUE (water use efficiency). The objective of the present study was to evaluate the long-term economic viability/profitability of different deficit irrigation techniques such as regulated deficit irrigation (RDI) and partial root-zone irrigation (PRI) with low water volume/fertilizer applied in a Monastrell vineyard in southeastern Spain to plants grafted on different rootstocks, and to assess the productive, social, and economic efficiency in these semiarid conditions. Through a cost/benefit analysis, socio-economic and environmental criteria for the selection of optimal deficit irrigation strategies and tolerant/water use efficient rootstocks for the vineyards in arid environments are proposed. Our analysis shows a clear conflict between productivity and quality in wine grape production. Productive and economic indices, such as yield, productive WUE (kg m−3), economic efficiency (€ m−3), break-even point (kg ha−1), and water productivity (€ m−3), were inversely related with berry quality. Besides, high berry quality was closely related with higher production costs. Under the current market of low-priced grapes, if the grower is not rewarded for the quality of the grapes (considering technological, phenolic, and nutraceutical quality), the productivity vision will continue and the cost-effective option will be to produce a lot of grapes, even if at the expense of the berry and wine quality. In this situation, it will be difficult to implement optimized deficit irrigation strategies and sustainable irrigation water use, and the pressure on water resources will increase in semiarid areas. Public policies should encourage vine growers to invest in producing high-quality grapes as a differentiating character, as well as to develop agronomic practices that are environmentally and socially sustainable, by the grapes more adjusted to their real quality and production costs. Only in this way we can implement agronomic measures such as optimized low-input DI (deficit irrigation) techniques and the use of efficient rootstocks to improve WUE and grape quality in semiarid regions in a context of climate change and water-limiting conditions.

PERFORMANCE EVALUATION OF IRRIGATION SCHEMES IN RUGERAMIGOZI MARSHLAND, RWANDA

Evaluating irrigation schemes contributes to the identification of performance gaps and this may lead to implementation of necessary improvements for enhancing agricultural productivity. In Rwanda, despite significant investments in irrigated agriculture, most of the irrigation schemes are performing far below their planned capacity. This study aimed at benchmarking the performance of Rugeramigozi 1 and Rugeramigozi 2 irrigation schemes located in Rugeramigozi marshland, Rwanda using irrigation indicators developed by the International Water Management Institute (IWMI). The study showed that land productivity for both the two irrigation schemes was generally low. Rugeramigozi 2 irrigation scheme had superior performance than Rugeramigozi 1 in terms of water productivity due to adoption of deficit irrigation strategies that promoted water conservation. The performance indicators for water service delivery showed that water use was more sufficient in Rugeramigozi 1 compared to Rugeramigozi 2 irrigation scheme. The water delivery capacity performance for both schemes revealed that the existing irrigation canals were sufficient to meet the irrigation water requirements at peak demand. The analysis of financial performance in both schemes indicated that the collected irrigation fees were inadequate to cover the operation and maintenance costs. Similarly, the gross returns on investment were low in both irrigation schemes due to low crop yields that generated low revenue for farmers. Overall, the performance indicators showed that both Rugeramigozi 1 and Rugeramigozi 2 irrigation schemes were in need of intensive management and infrastructural improvements in order to increase productivity and enhance sustainability of the schemes.

Deficit irrigation strategies inVitis viniferaL. ‘Crimson Seedless’ table grape: physiological responses, growth, yield and fruit quality

Deficit irrigation strategies in<i>Vitis vinifera</i>L. ‘Crimson Seedless’ table grape: physiological responses, growth, yield and fruit quality

Growth Response of Cassava to Deficit Irrigation and Potassium Fertigation during the Early Growth Phase

Cassava (Manihot esculenta Crantz) experiences intermittent water deficit and suffers from potassium (K) deficiency that seriously constrains its yield in the tropics. Currently, the interaction effect between deficit irrigation and K fertigation on growth and yield of cassava is unknown, especially during the early growth phase. Therefore, pot experiments were conducted under controlled greenhouse conditions using cassava cuttings. Treatments initiated at 30 days after planting included three irrigation doses (30%, 60%, 100% pot capacity) and five K (0.01, 1, 4, 16, and 32 mM) concentrations. The plants were harvested 90 days after planting. Decreasing irrigation dose to 30% together with 16 mM K lowered the leaf water potential by 69%, leaf osmotic potential by 41%, photosynthesis by 35%, stomatal conductance by 41%, water usage by 50%, leaf area by 17%, and whole-plant dry mass by 41%, compared with full-irrigated plants. Lowering the K concentration below 16 mM reduced the values further. Notably, growth and yield were decreased the least compared with optimal, when irrigation dose was decreased to 60% together with 16 mM K. The results demonstrate that deficit irrigation strategies could be utilized to develop management practices to improve cassava productivity by means of K fertigation under low moisture conditions.

A Decision Support System for Irrigation Management: Analysis and Implementation of Different Learning Techniques

Automatic irrigation scheduling systems are highly demanded in the agricultural sector due to their ability to both save water and manage deficit irrigation strategies. Elaborating a functional and efficient automatic irrigation system is a very complex task due to the high number of factors that the technician considers when managing irrigation in an optimal way. Automatic learning systems propose an alternative to traditional irrigation management by means of the automatic elaboration of predictions based on the learning of an agronomist (DSS). The aim of this paper is the study of several learning techniques in order to determine the goodness and error relative to expert decision. Nine orchards were tested during 2018 using linear regression (LR), random forest regression (RFR), and support vector regression (SVR) methods as engines of the irrigation decision support system (IDSS) proposed. The results obtained by the learning methods in three of these orchards have been compared with the decisions made by the agronomist over an entire year. The prediction model errors determined the best fitting regression model. The results obtained lead to the conclusion that these methods are valid engines to develop automatic irrigation scheduling systems.

Effects of irrigation level and timing on profile soil water use by grain sorghum

Although deficit irrigation (DI) may have the potential to optimize crop yields in water limited environments, the success of such strategies may depend on the ability to manage variability in profile stored soil water during periods of drought. Understanding variability in stored soil water and crop rooting depth is an important component of successfully managing a deficit irrigation strategy. Traditionally, DI is applied at a fraction of the full irrigation (FI) requirement, but managed deficit irrigation (MDI) may optimize yield and irrigation by coordinating irrigation timing with the crop’s reproductive stages through the management of soil water depletion and water stress. The depth of the soil water use by grain sorghum [Sorghum bicolor (L.) Moench] was evaluated in the High Plains of Texas, USA under FI, DI, and MDI strategies: during the 2010–2012 growing seasons. Crop water use during critical growth stages was year specific due to variable precipitation and antecedent soil moisture even though irrigation strategies were maintained as planned in all years. In 2010, soil water contents within the rooting zone (0–1.6 m) were > 50 % of the potential plant available water (PPAW) in the soil at emergence under all treatments, and soil water contents remained > 50 % PPAW at half-bloom for FI and MDI. Soil water contents were < 50 % PPAW at half-bloom for both DI and MDI in 2011 and 2012. In 2011, water contents only remained> 50 % PPAW under FI from 0- to 0.6-m through the growing season. Due to variability in the depth of the stored soil water, irrigation scheduling based on managed allowed depletion below PPAW may need to be modified to account for greater sparse root densities deeper in the profile.

Volatile, Sensory and Functional Properties of HydroSOS Pistachios

Climate change, the increase in world population, and the intensification of urban and industrial activities, will cause a shortage of water for agriculture. This situation requires conscientious studies to manage water deficits without affecting the quality of the crops. In this study, regulated deficit irrigation (RDI) strategies and three rootstocks (P. atlantica, P. integerrima, and P. terebinthus) were applied to pistachio cultivation to study the quality of fruits obtained based on the morphological, functional, aroma, and their sensory properties. The results obtained demonstrated that RDI T1 (during phenological phase II of cultivation the stem water potential was maintained around −1.5 MPa) led to pistachios with same morphological properties, total polyphenol content, antioxidant activity, volatile composition, sensory properties, better profile of fatty acids, and being the favorite ones for international consumers, as compared to pistachios obtained under full irrigation treatments. On the other hand, when P. integerrima was used, pistachios obtained had the highest weight, the lowest content of sucrose and the best functional properties.

Effects of Dynamic and Static New Deficit Irrigation Strategies on the Yield and Water Productivity of Two Field Grown Corn Cultivars

Effects of Dynamic and Static New Deficit Irrigation Strategies on the Yield and Water Productivity of Two Field Grown Corn Cultivars

Assessing the Climate Change Impacts on Grain Sorghum Yield and Irrigation Water Use under Full and Deficit Irrigation Strategies

HighlightsIrrigated grain sorghum yield and irrigation water use decreased under climate change.Increase in growing season temperature beyond 26°C resulted in a sharp decline in grain sorghum yield.Irrigating during early reproductive stages resulted in the most efficient use of limited water.Irrigating to replenish soil water to 80% of field capacity was found suitable for both current and future climates. Groundwater overdraft from the Ogallala Aquifer for irrigation use and anticipated climate change impacts pose major threats to the sustainability of agriculture in the Texas High Plains (THP) region. In this study, the DSSAT-CSM-CERES-Sorghum model was used to simulate climate change impacts on grain sorghum production under full and deficit irrigation strategies and suggest optimal deficit irrigation strategies. Two irrigation strategies were designed based on (1) crop growth stage and (2) soil water deficit. For the first strategy, seven deficit irrigation scenarios and one full irrigation scenario were simulated: three scenarios with a single 100 mm irrigation scheduled between panicle initiation and boot (T1), between boot and early grain filling (T2), and between early and late grain filling (T3) growth stages; three 200 mm irrigation treatments with combinations of T1 and T2 (T4), T1 and T3 (T5), and T2 and T3 (T6); one 300 mm irrigation scenario (T7) that was a combination of T1, T2, and T3; and a full irrigation scenario (T8) in which irrigation was applied throughout the growing season to maintain at least 50% of plant-available water in the top 30 cm soil profile. For the second strategy, the irrigation schedule obtained from auto-irrigation (T8) was mimicked to create a full irrigation scenario (I100) and six deficit irrigation scenarios. In the deficit irrigation scenarios, water was applied on the same dates as scenario I100; however, the irrigation amounts of scenario I100 were reduced by 10%, 20%, 30%, 40%, 50%, and 60% to create deficit irrigation scenarios I90, I80, I70, I60, I50, and I40, respectively. Projected climate forcings were drawn from nine global climate models (GCMs) and two representative concentration pathways (RCP 4.5 and RCP 8.5). Climate change analysis indicated that grain sorghum yield under full irrigation was expected to be reduced by 5% by mid-century (2036 to 2065) and by 15% by late-century (2066 to 2095) under RCP 8.5 compared to the baseline period (1976 to 2005). Simulated future irrigation water demand of grain sorghum was reduced due to the shorter growing season and improved dry matter- and yield-transpiration productivity, likely due to CO2 fertilization. Based on the simulated grain sorghum yield and irrigation water use efficiency, the most efficient use of limited irrigation was achieved by applying irrigation during the early reproductive stages of grain sorghum (panicle initiation through early grain filling). A 20% deficit irrigation scenario was found to be optimal for current and future conditions because it was more water use efficient than full irrigation with a minor yield reduction of &amp;lt;11%. In summary, these results indicated that strategic planning of when and how much to irrigate could help in getting the most out of limited irrigation. Keywords: CERES-Sorghum, Critical growth stages, Crop yield, Global climate model, Irrigation demand, Soil water depletion.

Irrigation Water Use Efficiency and Water Productivity of Commercial Sugarcane Hybrids under Water-Limited Conditions

HighlightsSugarcane hybrids with improved IWUE have greater scope in sugarcane agriculture as irrigation water is getting scarce.Among sugarcane hybrids, Co 8371 registered high mean water productivity of 4.18 kg m-3, followed by Co 85019 (3.92 kg m-3), while in I2, six hybrids had significantly higher water productivity (Co 85019, Co 0212, Co 86249, Co 10026, Co 0218 and Co V92102) above 4 kg m-3.Deficit irrigation scheduling (irrigation at recommended interval, with 50% crop evapotranspiration replacement) appears to be far more useful than reducing frequency as well as quantity of irrigation water alone. Hybrid mean water productivity was 3.2, 2.7, and 2.1 kg m-3 in I0, I1, and I2, respectively.ABSTRACT. The escalating deficit rainfall scenario in India indicates that drought is a recurrent phenomenon associated with tropical sugarcane farming, and the availability of irrigation water for sugarcane cultivation will be much less in coming years. To meet the challenge of limited and costly water supply, tropical sugarcane growers will have to find ways of increasing the efficiency of irrigation to maintain high cane yields. More efficient irrigation systems, accurate irrigation scheduling, and the right choice of sugarcane hybrids are potential means of increasing irrigation water use efficiency (IWUE), water productivity (WP), and global water security. With the objective of optimizing irrigation water use, a field experiment evaluating the physiological efficiency of commercial sugarcane hybrids for WP in a sandy clay soil under water-limited conditions was conducted during 2016-2017 at the ICAR-Sugarcane Breeding Institute in Coimbatore, India. The replicated field experiment was laid out in split-plot design with three irrigation levels as the main plot and 33 sugarcane hybrids as subplots. The prevailing climatic conditions during the experiment represented a tropical wet and dry climate, with the wet season lasting from October to December due to the northeast monsoon. The results showed that full irrigation at recommended intervals with 100% crop evapotranspiration (ET) replacement (I0) produced significantly higher cane yield than deficit irrigation at recommended intervals with 50% crop ET replacement (I1) and skipping alternate irrigations with 50% crop ET replacement (I2). The deficit irrigation treatments (I1 and I2) had declines in cane yield of 41.2% and 56.4%, respectively. IWUE was similar in I0 and I1, while I2 had reduced IWUE by 23%. WP was significantly influenced by irrigation level; reduction in irrigation water reduced WP by 17.5% and 36.3% in I1 and I2 compared to I0. Among sugarcane hybrids, Co 85019, Co 13006, Co 10026, Co 99004, CoLk 8102, Co 86249, Co 8371, Co 94008, and Co 95020 yielded higher than the genotypic mean under both deficit irrigation treatments, suggesting their usefulness in deficit irrigation strategies. Sugarcane hybrids with high WP can play a pivotal role in sustaining sugarcane productivity and can reduce the large volumes of irrigation water consumed in water-scarce tropical India. Thus, considering water security, the implications of the results are of paramount importance in promoting the coordinated development and management of water, land, and related resources to maximize economic benefits and social welfare in an equitable manner without compromising the sustainability of vital ecosystems at local as well as national levels. Keywords: Cane yield, Global water security, Sugarcane, Water-limited condition.