Deficit Irrigation Research Articles

Evaluation of Physiological Changes in Important Dried Apricot Varieties Under Drought Stress

Nearly all of the apricot varieties grown in Malatya are dried apricots and the plantation areas in this region are expanding daily. Due to the impact of climate change, producers are growing apricots mostly under limited irrigation or even dry conditions. Therefore, it is essential to determine the drought resistance characteristics of the varieties commonly cultivated in this region. In this study, different irrigation levels of 100%, 75%, 50% and 25% of available water were applied to Hacıhalioğlu, Kabaaşı, Çataloğlu, Hasanbey and Soğancı apricot varieties. To evaluate the resistance of the varieties to drought stress and its relationship with physiological changes, chlorophyll a and b, carotenoids, total sugar, total starch and abscisic acid contents in the leaves were analyzed. A decrease in chlorophyll a and b, carotenoids, total starch values and an increase in total sugar and ABA values were determined due to the decrease in irrigation rates. In Kabaasi and Hasanbey varieties, which were observed as the most resistant to water shortage, chlorophyll a and b, carotenoids, total starch values were higher and total sugar content was lower at decreased irrigation levels. No difference was detected between varieties in ABA values. As a result of the observations in the drought resistance tests and physiological analyses, it was concluded that the most resistant varieties were Kabaasi and Hasanbey. Unfortunately, the most sensitive variety was the most widespread Hacihaliloglu. In addition, analyzing and evaluating the physiological changes occurring in apricot under drought stress will be useful in developing the most appropriate irrigation strategies for each variety and increasing water use efficiency. It may also be useful in cross-breeding studies to develop new drought-resistant varieties.

Combined Effects of Deficit Irrigation and Biostimulation on Water Productivity in Table Grapes

Biostimulation and precision irrigation are strategies that increase the sustainability of agriculture, and both have been widely studied in table grapes, but their interaction is a new approach for viticulture. The objective of this field trial was to assess the physiological effects of water deficit on table grapes pretreated for two consecutive years with five different biostimulation programs. Therefore, during the first year, vines were preconditioned with biostimulants composed of microorganisms, seaweed, and plant extracts and compared to an untreated control. During the second year, the same biostimulation treatments were evaluated under two different irrigation schedules: (i) farmer irrigation (FI), according to a farmer’s criteria; and (ii) a deficit irrigation program, precision irrigation (PI), in which irrigation water was reduced from the post-veraison period to harvest, setting a threshold for allowable soil water depletion of 10% with respect to field capacity in order to minimize water leaching. The water inputs in the treatments under PI were reduced by 30% with respect to the FI treatment. While the deficit irrigation treatment clearly affected the plant water status indicators, biostimulation enhanced the root colonization by mycorrhizae and showed a trend of increased new root density. The combined effect of biostimulation and PI was shown to be an efficient strategy for optimizing the available resources, promoting the yield precocity.

Evaluating farmer-driven weed management approaches and their impact on paddy yields in Mahaweli system B

Mahaweli System B in Polonnaruwa, Sri Lanka, lies in the dry zone’s DL1b agro-ecological region and receives an average annual rainfall of 900 mm. Paddy cultivation is the primary livelihood, supported for over 30 years by supplemental irrigation from the Maduru Oya reservoir. Roughly 35,000 farmers grow paddy across 25,000 hectares during both Yala and Maha seasons, contributing 4.2% of the national paddy production each season, with an average yield of 5.1 tons per hectare, surpassing the national average of 3.7 tons per hectare. To improve yields, Mahaweli System B leverages irrigation infrastructure, skilled extension services, collaboration with agricultural organizations, and strong farmer networks. Awareness programs emphasize high-quality seed selection, optimized land preparation, nutrient-specific fertilization, and safe agrochemical use. Despite comprehensive weed control practices, weeds remain a major challenge, reducing yields by 28-89% and impacting harvest quality. This study aims to identify weed management practices adopted by farmers in Mahaweli System B and to evaluate their effectiveness in enhancing paddy yield, providing insights to strengthen regional production outcomes.

Malt Barley Yield and Quality Response to Crop Water Stress Index

Malt barley is a crucial irrigated crop in the semi-arid Western United States, where the states of Idaho, Colorado, Wyoming, and Utah account for 92% of the irrigated production acreage and 30% of total U.S. production. In this region, spring malt barley’s seasonal evapotranspiration ranges from 400 to 650 mm, and competition for limited water supplies, coupled with drought, is straining regional water resources. This study aimed to investigate the use of canopy temperature for deficit irrigation scheduling of malt barley. Specifically, the objectives were to use data-driven models to estimate well-watered (TLL) and non-transpiring (TUL) canopy temperatures, correlate the crop water stress index (CWSI) with malt barley yield and quality measures, and assess the applicability of CWSI for malt barley irrigation scheduling in a semi-arid climate. A 3-year field study was conducted with five irrigation treatments relative to estimated crop evapotranspiration (full, 75%, 50%, 25%, and no irrigation) and four replicates each. Continuous canopy temperature measurements and meteorological data were collected, and a feedforward neural network model was used to predict TLL, while a physical model was used to estimate TUL. The neural network model accurately predicted TLL, with a strong correlation (R2 = 0.99), a root mean square error of 0.89 °C, and a mean absolute error of 0.70 °C. Significant differences in calculated season-average CWSI were observed between the irrigation treatments, and relative evapotranspiration, malt barley relative yield, test weight, and plump kernels were negatively correlated with the season-average CWSI, while seed protein was positively correlated. The relationship between daily CWSI and fraction of available soil water was well described by an exponential decay function (R2 = 0.72). These results demonstrate the applicability of data-driven models for computing CWSI of irrigated spring malt barley in a semi-arid environment and their ability to assess plant water stress and predict crop yield and quality response from CWSI.

Effect of stage‐wise deficit irrigation on crop water productivity of different varieties of teff (Eragrostis tef)

AbstractThe increasing demand for water for various purposes is causing the availability of water for irrigation to decrease daily. Consequently, it is necessary to implement deficit irrigation. Research on the different teff crop varieties and the level of deficit irrigation with crop growth stages at semi‐arid agroecological zones remains inadequate. Therefore, the objective of this research was to evaluate the effect of stage‐wise deficit irrigation and crop variety on crop water productivity for the teff crop. Two varieties of teff and three irrigation levels were selected and applied for each growth stage. Crop water productivity was determined by using crop water consumed with their yield production and analyzed using Statistix 10.0 software. The results showed that crop varieties had a significant effect on crop water productivity. The maximum crop water use efficiency (0.92 kg m−3) and field water use efficiency (1.387 kg m−3) were obtained for a 30% deficit at the ripening growth stage for the Tseday teff variety. Contrarily, the minimum CWUE and FWUE of 0.617 kg m−3 and 0.959 kg m−3 were obtained to 30% deficit irrigation at the yield formation growth stage of the Quncho teff variety. Therefore, deficit irrigation during the yield formation growth stage was not recommended, but it was possible to apply deficit irrigation during the ripening growth stage to improve crop water productivity in areas of water scarcity.

Building Ethiopia’s food security resilience to climate and hydrological change

Abstract Historically Ethiopia’s food security has been sensitive to climatic variability, but changes in future weather and climate could lead to overall reductions and increased variability in agricultural production, without further adaptation. We present an integrated modelling assessment framework which combines climate, crop, and hydrological modelling to quantify future risks to Ethiopia’s food security. We explore the impacts of 2°C and higher climate change scenarios on water availability and crop yields and simulate how future climate shocks may impact Ethiopia’s food. We consider three adaptations to agricultural management practices (improved seed varieties, increased use of nitrogen fertilizer and supplementary irrigation) and quantify their effectiveness in enhancing the resilience of Ethiopia’s food system to climate and hydrological change by 2050. Results show that, without policy intervention, climate change creates a risk of declining Meher season crop yields across Ethiopia. Under the worst climate change scenario, Teff (-12.0%), barley (-6.7%), and wheat (-4.4%) are projected to have the largest decline in average yields, whilst maize (-0.1%) and sorghum (+0.9%) yields are less impacted thanks to more favourable growing conditions. However, the results also indicate that the adaptation options have a bigger beneficial effect than the climate impact. Of the policies evaluated, improved seeds have a relatively greater effect than increased fertilizer use. Supplementary irrigation could help to mitigate increases in crop water requirements under warmer climate conditions and is most effective in drought prone basins and for drought-vulnerable crops. Overall, the results show that locally relevant agricultural policies are necessary to build Ethiopia’s food system resilience to climate and hydrological change by the mid-century.

Towards sustainable agricultural water management in Poland – How to meet water demand for supplemental irrigation?

The global challenge of water scarcity, particularly in agriculture, demands urgent attention due to the overexploitation of water resources and the escalating impacts of climate change. This study focuses on the unique challenges faced by Poland, experiencing increasing concerns related to droughts. It explores the utilization of supplemental irrigation, specifically in the context of Central Europe, where a distinctive approach known as supplemental irrigation is employed. The study emphasizes the need for sustainable water management practices and investigates the potential of small water retention measures (SWRMs), such as ponds and drainage water management, as solutions to enhance water availability in agriculture. A macro-scale water balance study is conducted using the Soil and Water Assessment Tool (SWAT) to estimate spatio-temporal variability of water demand for supplemental irrigation in Poland. The highest demand, approximately 2.5 billion m3 (for arable lands) and 1.3 billion m3 (for grasslands), occurred during the exceptionally dry year of 2015, characterized by severe agricultural drought effects. The study also assesses the efficiency of SWRMs in meeting irrigation demands at national level. The results highlight a paradox in their effectiveness during critical periods, specifically in dry years when water demands are the highest. The outcomes of the model experiment underscored concerns about the insufficiency of meeting the water needs of irrigated agriculture solely through the construction of small retention facilities during very dry years. The outcomes of this research contribute to a better understanding of irrigation water demands in temperate climate region, support evidence-based practices for sustainable water management, and inform policymakers and stakeholders involved in water governance.

Leaf Orientation Method as a Proxy for Sensing Nitrogen and Water Deficit in Tomato Plants

Precision field management and modeling crop growth requires precise, efficient, timely, nondestructive, and cost-effective measurements of structural component including leaf area index (LAI) and leaf orientation based on the foliage mean tilt angle (MTA), which is defined as the average leaf inclination angle of a canopy. Two experiments were carried out to investigate 1) the influence of different nitrogen (N) fertigation levels and 2) cycles of water deficit on leaf orientation (specifically, MTA) of young tomato (Solanum lycopersicum cv. Florida 47). N rates were 10, 50, 100, 200, and 300 mg·L−1 (mg N per liter of water) and irrigation treatments were well-watered and deficit irrigation. MTA was measured using the LAI-2200C Plant Canopy Analyzer. Across the experimental period, low N supply to leaves reduced the angle between leaf petiole and stem (high MTA) and produced plants with more erect leaves compared with N-sufficient plants. The MTA for the 10 mg·L−1–N treatment ranged from 54.3° to 73.6° and higher levels of N (50 to 300 mg·L−1–N) had MTA between 36.4° and 51.9°. Compared with lower N level (10 mg·L−1), LAI of tomato plants fertigated with a nutrient solution containing 300 mg·L−1–N increased by 3.6- to 4.9-fold across the study period. Similarly, canopy normalized difference vegetation index (NDVI) and leaf N% values at 300 mg·L−1–N were 2- to 3-fold higher than at 10 mg·L−1–N. However, MTA did not consistently differ across the 100 to 300 mg·L−1–N rates. In terms of water treatments, MTA of well-watered plants ranged from 32.3° to 40.5° whereas the same plants at water-deficit level had MTA between 45.7° and 51.8°. Although the relationship between MTA and canopy LAI, NDVI as well as leaf N was inconsistent or not significant under well-watered and water-deficit conditions, leaf gas exchange components (photosynthesis, stomatal conductance, and transpiration) showed a significant negative relationship (R2, 0.39–0.81, P < 0.001) with MTA. Overall, leaf orientation, specifically MTA, was modulated by N levels (highest at 10 mg·L−1; lowest at 300 mg·L−1–N) and cycles of water deficit and therefore, MTA determination hold promise as a nondestructive method to assess N and water deficit in young tomato plants.

Optimizing irrigation and planting strategies to prevent non-point source pollution in the Hetao Irrigation District using SWAT-MODFLOW-RT3D model

Non-point source (NPS) pollution is a significant issue in the Hetao Irrigation District (HID), affecting local water environment and ecological safety. To explore solutions for managing NPS pollution in the HID, this study establishes the SWAT-MODFLOW-RT3D (SMFR) model based on data from recent years. The results show that the determination coefficient (R2) of monthly drainage simulation for both the calibration and validation periods are >0.6, the Nash-Sutcliffe efficiency (NSE) values are >0.7, and the percent bias (PBIAS) values are <10 %. For pollutant transport simulation (total nitrogen and total phosphorus), the R2 values for both calibration and validation periods exceed 0.6, the NSEs are >0.75, and the PBIAS values are below 20 %. The model demonstrates good performance in simulating hydrology and pollutant transport in the study area, indicating strong applicability. Building on this, the spatial and temporal distribution characteristics of nitrogen and phosphorus losses in the HID were analyzed, and the impacts of different agricultural management practices, such as irrigation and fertilization regimes, drip irrigation under film (DIUF), and crop structure adjustments, on NPS pollution were assessed. Extensive scenario testing indicates that deficit irrigation and DIUF reduce total nitrogen (TN) in agricultural NPS pollution by 7.74 % and 9.34 %, respectively, and total phosphorus (TP) by 35.12 % and 40.99 %, respectively. In contrast, crop structure adjustments have a relatively moderate reduction effect on TN and TP, ranging from 2.66 % to 6.80 %. Additionally, the study examines the NPS pollution control effects of various combined scenarios. Through economic benefit evaluation, it was found that the scenario combining deficit irrigation with crop structure adjustments has a lower cost-effectiveness (CE) ratio and a higher cost-benefit (CB) ratio, making it a more favorable measure for controlling NPS pollution in the HID.

A Cradle-to-Retailer Environmental Profile of Yellow Lentils (Lens culinaris ssp. Orientalis) as Such or Malted

This study evaluated the environmental impact of malted, decorticated, and split yellow lentils, specifically Moroccan (ML) and Onano (OL) varieties, cultivated in Morocco and Italy, using a cradle-to-retailer Life Cycle Assessment (LCA) approach. An analysis through SimaPro 9.5.0.0 software and the Product Environmental Footprint method revealed carbon footprints of approximately 4.5 and 3.3 kg CO2e per kg for malted, dehulled, and split MLs and OLs, respectively, representing increases of 50% and 52% compared to their untreated dry seed counterparts. The Product Environmental Footprints also rose significantly, by 50% for MLs and 55% for OLs, reflecting the higher water and energy demands, as well as additional waste generation, associated with the malting process. This study emphasizes the importance of focusing mitigation efforts on improving the agricultural phase, particularly in land and water use efficiency. While supplemental irrigation can boost yields, especially in water-limited regions, it significantly increases the environmental footprint, underscoring a trade-off between yield gains and sustainability. Consequently, the optimal environmental strategy may not involve increasing irrigation, but rather developing drought-resistant lentil varieties, which could reduce the overall environmental impact.

Physiological and agronomic effects of regulated-deficit irrigation on soybean grown under arid climatic conditions

Physiological and agronomic effects of regulated-deficit irrigation on soybean grown under arid climatic conditions

Vegetative Growth, Enzymatic Activities, Fruit Yield, and Quality of ‘Balady’ Mandarins (Citrus reticulata) in Response to Deficit Irrigation Levels

Vegetative Growth, Enzymatic Activities, Fruit Yield, and Quality of ‘Balady’ Mandarins (Citrus reticulata) in Response to Deficit Irrigation Levels

Unraveling the influence of sowing dates, deficit irrigation levels and osmoregulators on dicoccum wheat: A regression approach to relate yield and associated parameters

Unraveling the influence of sowing dates, deficit irrigation levels and osmoregulators on dicoccum wheat: A regression approach to relate yield and associated parameters

Midsummer Deficit Irrigation of Alfalfa for Water Conservation in the San Joaquin Valley of California

Midsummer Deficit Irrigation of Alfalfa for Water Conservation in the San Joaquin Valley of California

Optimization of deficit irrigation level and phosphorus fertilizer rate for soybean production in Jimma, Southwest Ethiopia

Optimization of deficit irrigation level and phosphorus fertilizer rate for soybean production in Jimma, Southwest Ethiopia

Effects of rhizobacteria producing deaminase enzymes for aminocyclopropane‐1‐carboxylate on drought tolerance and post‐stress recovery in creeping bentgrass under field conditions

AbstractSome endophytic rhizobacteria, including species producing deaminase enzymes for 1‐aminocyclopropane‐1‐carboxylic acid (ACC) suppressing ethylene production (ACCd), form symbiosis with plant roots to enhance plant growth and stress tolerance. The objectives of this study were to determine growth‐promoting effects and effective rates of inoculation with ACCd‐producing Paraburkholderia aspalathi (WSF23 and WSF14) on creeping bentgrass (Agrostis stolonifera L.) performance under deficit irrigation in field conditions and effectiveness on post‐stress recovery during re‐watering. Turf field plots established with ‘L‐93’ creeping bentgrass were inoculated with P. aspalathi strains (WSF23 and WSF14) through soil drenching either as a single strain or as a combination of both strains. After inoculation, plots were subjected to drought stress with deficit irrigation to replace 60% of the daily evapotranspiration rate, followed by re‐watering for post‐stress recovery. Three inoculant rates of 1.0, 1.5, and 2.0 × 107 colony‐forming units (CFUs) were evaluated to determine the most effective dosage to apply under field conditions. Inoculation of plants with the consortium of the two strains at 1.5 × 107 CFUs was most effective in enhancing turf quality, percent green cover, normalized difference vegetation index, and dark green color index during drought stress and recovery periods. These results suggest that creeping bentgrass tolerance to drought stress and improved post‐stress recovery could benefit from inoculation with P. aspalathi strains under field conditions and also ACC deaminase‐producing rhizobacteria could be incorporated into turf management programs to maintain creeping bentgrass during abiotic stress conditions.

Effect of different deficit irrigation regimens on soil moisture, production parameters of mango (Mangifera indica L.), and spectral vegetation indices in the Mediterranean region of Southern Spain

Mediterranean region is facing a severe water resource crisis, exacerbated by climate change. In recent decades, the region has experienced increased anthropogenic pressure due to population growth, tourism, and urban and agricultural expansion, intensifying competition for water among economic sectors. The agri-food sector is one of the most affected by water scarcity. This presents significant challenges for the sustainability of irrigated crops and underscores the need for efficient irrigation strategies and adaptive mechanisms. Among innovative strategies is deficit irrigation. In this context, to ensure effective water management, it is essential to constantly monitor soil moisture and adapt water conditions to the specific requirements of each crop. Precision agriculture, supported by technologies such as remote sensing and UAVs, plays a fundamental role in this context, enabling detailed crop monitoring and facilitating more efficient irrigation management. This study aims to evaluate the impact of using three different irrigation treatments on mango cultivation, a subtropical crop of growing importance in the Mediterranean region. Specifically, Treatment 1 is based on conventional surface drip irrigation without restrictions; Treatment 2 involves conventional surface drip irrigation with a 65% water reduction; and Treatment 3 uses deep subsurface drip irrigation (20 cm), with a similar water restriction as the previous treatment. The effect on mango cultivation has been evaluated based on: (i) soil moisture, (ii) production data collected during the 2022–2023 growing season on the experimental plot; and (iii) two vegetation indices (NDVI and NDRE) derived from multispectral data collected via two UAV flights at different phenological stages. The results indicate that surface drip irrigation has shown better outcomes in terms of production, yield, and crop quality compared to other treatments involving significant water reductions or subsurface irrigation. Deep deficit irrigation has obtained the worst results in the evaluation of plant production, and yield.

Stem characteristics and yield of wheat is regulated to improve planting efficiency and reduce lodging risk by fertilizer rate and irrigation stage

Optimizing fertilizer and water application and using standardized and clean production methods are important for achieving green and sustainable agricultural development. The study was conducted from 2018 to 2021, arranged in a split-plot experimental design. Three fertilization levels (main plots) and four supplementary irrigation treatments (secondary plots) were set through three consecutive years of field positioning experiments. Chemical compound fertilizer application levels were 750 kg ha−1 (F1), 600 kg ha−1 (F2), 450 kg ha−1 (F3). Irrigation levels were as follows: no irrigation during the whole growth period after emergence (W0), irrigation only at jointing stage (W1), irrigation at jointing and anthesis stage (W2), irrigation at greening, jointing and anthesis stage (W3). The results indicated that the stem length of the base increased with the increase of irrigation and water and fertilizer, especially on the base stem node. There was a significant interaction between different fertilizer and water treatments. Correlation analysis revealed a significant negative correlation between stem strength and the stem lodging index. After anthesis, the lodging index was significantly lower in the F2 treatment than that in the F1 treatment. Moreover, the contribution of dry matter accumulation to the grain before anthesis was significantly higher under the W2 treatment than that under the W3 treatment but was significantly lower than that under the W0 treatment. Furthermore, the W2 treatment exhibited significantly greater fertilizer and water effects than those under the W3 treatment, irrigation benefit increased by 10.39 kg ha−1 mm−1, whereas the F2 treatment exhibited significantly greater effects than those of the F1 treatment. In terms of yield, grain yield of F2W2 treatment was significantly higher than that of F3W1 treatment. The maximum yield of F2W2 treatment over three years was 9900.05 kg ha−1. Therefore, reducing the amount of fertilizer and adjusting the irrigation regimes can enhance wheat growth and yield and mitigate the risk of lodging in the field.

Optimizing water use efficiency in maize (Zea mays L.) production through deficit irrigation in Gazhen-Fuafuat Kebele, Northwest Ethiopia

Ethiopia's dominant maize production relies on rain, but growing water scarcity challenges dry season irrigation efforts. This necessitates smarter irrigation techniques to maximize water use efficiency. This study optimizes water use efficiency in maize production through deficit irrigation in Gazhen-Fuafuat kebele, Fogera woreda, Ethiopia. A field experiment was conducted during the 2019/20 dry season, comparing four irrigation levels: 55%, 70%, 85%, and 100% of crop water requirements (ETc). Findings revealed that while higher irrigation levels generally enhanced plant growth and grain yield, irrigation water use efficiency was optimized at 70% ETc. Deficit irrigation at 55% ETc proved to be suboptimal, leading to significant reductions in crop growth and grain production. Conversely, applying 70% ETc resulted in a 30% reduction in irrigation water use without compromising yield. Compared to full irrigation, deficit irrigation at 85% ETc, 70% ETc, and 55% ETc resulted in yield reductions of 8%, 13.5%, and 33.1%, respectively. However, these reductions were accompanied by water savings of 15%, 30%, and 45%, respectively, leading to corresponding increases in water use efficiency of 8%, 23.4%, and 21.9%. These results suggest that deficit irrigation practices can be effectively employed to improve water use efficiency in maize production, especially in the study area facing water scarcity. This study provides valuable insights into the potential of deficit irrigation to improve maize production in Ethiopia while conserving water resources. Therefore, by implementing deficit irrigation strategies and supporting farmers with appropriate training and resources, Ethiopia can enhance its agricultural productivity and ensure food security in the face of increasing water scarcity.

Enhancing ‘Mirlo Rojo’ Apricot (Prunus armeniaca L.) Quality Through Regulated Deficit Irrigation: Effects on Antioxidant Activity, Fatty Acid Profile, and Volatile Compounds

Water scarcity is a significant global risk affecting health, food security, economic development, social stability, environmental sustainability, and climate change adaptation. Implementing deficit irrigation strategies can improve water efficiency and agricultural resilience. Spain, particularly the Region of Murcia, has pioneered apricot cultivation, with the ‘Mirlo Rojo’ variety known for its high productivity, Sharka virus resistance, and exceptional organoleptic qualities. This study evaluates the effects of regulated deficit irrigation (RDI) on the quality, antioxidant activity, fatty acid profile, and volatile compounds of ‘Mirlo Rojo’ apricots. Four irrigation treatments (100% ETc, 60% ETc, 33% ETc, and 0% ETc) were tested during the final growth stages in May 2023. Results showed no adverse effects on the evaluated parameters. RDI treatments increased total soluble solids, glucose, and fructose content, improving maturity and sweetness indices. RDI also enhanced phenolic content and antioxidant activity, optimizing water use without compromising fruit quality and bioactive compounds.