Deficit Irrigation Research Articles

Comprehensive analysis of drought tolerance in pure lines derived from half-diallel crosses of upland cotton (Gossypium hirsutum L.)

Drought has a significant impact on plants, affecting their growth, development and survival. This study focuses on evaluating the impact of drought stress, a significant abiotic factor, on the agronomic and fiber parameters of potential cotton (Gossypium hirsutum L.) lines with the aim of developing drought-tolerant varieties. The experiment involved two irrigation regimes—well-watered (100% field capacity) and deficit irrigation (50% field capacity)—conducted on F9–F10 generations. Key fiber parameters, including fiber length, boll weight, fiber strength, and lint percentage, were identified as crucial selection criteria under both well-watered and deficit irrigation conditions. Notably, boll number emerged as the decisive parameter in both F9 and F10 generations. The study employed univariate and multivariate analyses, such as PCA, heat map cluster, correlation analysis, and decision tree, which consistently highlighted fiber length, boll weight, fiber strength and lint (ginning) percentage the key factor. In the F10 generation, the integration of decision tree and heat map cluster results led to the identification of 8 promising lines. These selected genotypes have potential for inclusion in future cotton breeding programmes, offering the opportunity to increase drought tolerance and improve cotton yield and productivity. Their resilience to environmental stresses makes them promising candidates for improving overall cotton performance under challenging conditions.

Dry Matter Accumulation, Water Productivity and Quality of Potato in Response to Regulated Deficit Irrigation in a Desert Oasis Region.

As one of the most important food crops, the potato is widely planted in the oasis agricultural region of Northwest China. To ascertain the impact of regulated deficit irrigation (RDI) on various facets including dry matter accumulation, tuber yield, quality and water use efficiency (WUE) of potato plants, a two-growth season field experiment under mulched drip irrigation was conducted in the desert oasis region of Northwest China. Water deficits, applied at the seedling, tuber formation, tuber expansion and starch accumulation stages, encompassed two distinctive levels: mild (55-65% of field capacity, FC) and moderate (45-55% FC) deficit, with full irrigation (65-75% FC) throughout the growing season as the control (CK). The results showed that water deficit significantly reduced (p < 0.05) above-ground dry matter, water consumption and tuber yield compared to CK, and the reduction increased with the increasing water deficit. A mild water deficit at the tuber formation stage, without significantly reducing (p > 0.05) yield, could significantly increase WUE and irrigation water use efficiency (IWUE), with two-year average increases of 25.55% and 32.33%, respectively, compared to CK. Water deficit at the tuber formation stage increased starch content, whereas water deficit at tuber expansion stage significantly reduced starch, protein and reducing sugar content. Additionally, a comprehensive evaluation showed that a mild water deficit at the tuber formation stage is the optimal RDI strategy for potato production, providing a good balance between yield, quality and WUE. The results of this study can provide theoretical support for efficient and sustainable potato production in the desert oasis regions of Northwest China.

Water and fertilizer decision model for synergistic optimization of yield, quality and efficiency of cherry tomato based on combination evaluation

The scientific nutrient supply under deficit irrigation can ensure the yield and quality of crops, and balance water and fertilizer benefits. The model of the combination of water and fertilizer was constructed based on the analysis of the effects of irrigation, K2O and MgO application on yield, quality and water and fertilizer use efficiency of cherry tomato over two growing seasons. Deficit irrigation contributed to quality accumulation, while full irrigation resulted in higher yields. The optimal irrigation water use efficiency (IWUE) was attained with a moderate level of potassium and magnesium. An evaluation system of cherry tomato was established containing totally 6 indicators from 3 categories of yield, quality and efficiency based on correlation analysis, and yield obtained the highest weight of 0.402 and 0.373 in the two study seasons, respectively. The overall differential combination model was adopted to comprehensively evaluated combination of water and fertilizer factors by integrating three single models of TOPSIS, Membership function analysis and Grey relational analysis, and the correlation coefficient of any two single model was greater than 0.614. The response of comprehensive score for cherry tomato to each single factor of irrigation, K2O and MgO followed a downward-opening parabola. The analytical model revealed that the coupling of potassium and magnesium has a mutually reinforcing effect when they were both at medium level, while an inhibitory effect was observed at higher or lower level. The model verification showed that 7 out of the total 10 indicators reached more than 80 % of maximum value of the corresponding single indicator under the condition of the water and fertilizer with highest comprehensive score. Considering yield, quality and efficiency, the optimal combination of irrigation, K2O, and MgO was 80.6 ∼ 83.2 % Evaporation (Ep), 161.40 ∼ 171.27 kg/ha, and 19.59 ∼ 20.17 kg/ha in 2021S. The corresponding combination for 2021F was 75.4 ∼ 77.9 % Ep, 133.41 ∼ 140.45 kg/ha, and 13.99 ∼ 14.80 kg/ha. This strategy can maintain yield, improve quality, save irrigation amount, and increase fertilizer efficiency, which guides the production of deficient irrigation in northwest China.

Effects of Drip Irrigation Flow Rate and Layout Designs on Soil Salt Leaching and Cotton Growth under Limited Irrigation

Optimal drip irrigation management in shallow groundwater areas needs to clarify the effects of flow rate and layout designs on the soil moisture, salt distribution, cotton root length density, plant height, leaf area, and yield. In this study, a one-year field experiment was conducted from April to October 2018 in the fifth company of the 16th Regiment in Alar City, Xinjiang, to investigate the effects of various drip flow rates and layout designs of cotton growth. Two drip flow rates (2.8 and 5.6 L·h−1) and two layout designs (one film, two drip tapes, and six rows; one film, three drip tapes, and six rows) were applied to explore the optimal combination, resulting in a total of four treatments that were irrigated three times in the whole growth period. Soil moisture, salt distribution, cotton root length density, plant height, and leaf area were measured. The main results were as follows: (1) Under the same layout designs, the soil moisture content was higher and the soil salinity was lower when the drip flow rate was 5.6 L·h−1, and the cotton root length density, plant height, leaf area, and yield were significantly higher than that of 2.8 L·h−1. (2) Under the same drip flow rate, the soil desalination rate, cotton growth indexes, and yield under the three-tapes treatment were significantly higher than the values of the two-tapes treatment. The actual yield of treatment D was 21.56%, 19.23%, and 11.71% higher than that of treatments A, B, and C, respectively. (3) The crop evapotranspiration of cotton during the two irrigation cycles showed an increasing trend, and the groundwater contribution showed a smaller and then increasing trend. Overall, the combination of three tapes and a drip flow rate of 5.6 L·h−1 had the highest cotton yield and net income, which were 6211.36 kg·hm−2 and 4820.21 kg·hm−2 for the theoretical and actual yields. The results of this study can provide a reference for the management of limited irrigation leaching soil salinity and cotton cultivation in shallow groundwater areas.

Effect of Growth Stage-based Water Stress on Yield and Water Use Efficiency of Tomatoes (Solanum lycopersicon L.) in Semi-arid Regions of Tigray, Ethiopia

Water availability is a major concern in regions with limited water resources. Implementation of best irrigation water management methods can maximize crop yields and irrigation water use efficiency. An experiment was conducted in Laelay Koraro district, Tigray, Ethiopia for two consecutive years (2018 and 2019 off seasons) to investigate the effect of growth stage-based deficit irrigation on tomato yield, yield characteristics and water usage efficiency. The experiment used a randomized complete block design (RCBD) with three replications. The treatments were three irrigation levels (100%, 50%, and 25% of crop irrigation requirement) and four FAO-defined tomato growth stages (initial, developmental, mid, and late seasons). Data on agronomic parameters and irrigation water were collected and analyzed statistically. The results revealed that reducing irrigation amount by up to 75% during the development growth stage significantly decreased marketable yield by up to 66.5%. However, the highest water use efficiency (9.2kgm-3) was achieved by reducing irrigation amount by 75% at the end-growth stage of tomato. Treatments with the lowest water use efficiency (3.5kgm-3) were those receiving 75% less irrigation amount than the full requirement during the development growth stage. Irrigation deficit up to 75% of the full requirement during tomato development stages greatly affect marketable yield and water use efficiency. Therefore, the tomato crop is highly susceptible to water stress when receiving more than a 50% reduction in full irrigation requirement during its developmental growth stage.

Deficit irrigation of reclaimed water relieves oat drought stress while controlling the risk of PAEs pollution in microplastics-polluted soil

Reclaimed water irrigation has emerged as a critical alternative in agricultural regions facing water scarcity. However, soil pollution with microplastics (MPs) greatly increases the exposure risk and toxic effects of reclaimed water contaminations, such as phthalate esters (PAEs). A field experiment consisting of soil column pots evaluated the feasibility of using PAEs-contaminated water to irrigate oats (Avena sativa L.) in drought seasons. Three irrigation regimens based on soil matric potential thresholds (−10 kPa, −30 kPa, −50 kPa) explored the impact of PAE-contaminated water on oat physiology and environmental pollution in soil with and without MPs contamination. The results showed that treating oats at the SMP of −30 kPa boosted shoot biomass by 3.1%–14.0% compared to the drought condition at −50 kPa, and the root biomass of oats was significantly increased. The physiological metrics of oats indicated that irrigation at −50 kPa induced drought stress and oxidative damage in oats, particularly during the milk stage. Different irrigation treatments influenced the accumulation of PAEs in plants, soil, and leachate. The ratios of leachate to irrigation water in −10 kPa treatment with and without MPs addition were 1.18% and 4.48%, respectively, which aggravated the accumulation of pollutants in deep soil layers and may cause groundwater pollution. MPs pollution in soil increased the content of PAEs in the harvested oats and reduced the transport and accumulation of PAEs in deep soil layers (20–50 cm) and leachate. The coupling of PAEs in irrigation water with soil MPs pollution may exacerbate plant damage. However, the damage can be minimized under the scheduled irrigation at −30 kPa which could balance crop yield and potential risks.

Integrating UV/persulfate and deficit irrigation of recycled water: Strategy to minimize crop accumulation of trace organic contaminants and enhance crop yield

This study investigated the combination of UV persulfate (UV/PS) treatment of recycled water and deficit irrigation to minimize pharmaceutical and personal care products (PPCPs) accumulation and improve crop quality. Lettuce, carrot, and tomato, commonly consumed raw, were cultivated in a greenhouse using PPCPs spiked recycled water, UV/PS treated recycled water, and tap water control, under irrigation rates at 60 %, 80 % and 100 % of crop evapotranspiration (ETC) rates. UV/PS removed ≥ 99 % of carbamazepine, diclofenac, and fluoxetine from spiked recycled water. Post-treatment, carbamazepine accumulation in harvested lettuce, carrot, and tomato was reduced by 96–99 %, 35–70 % and 72–93 %, respectively. Minimal accumulation of diclofenac and fluoxetine occurred in edible crops due to their existence as dissociated ions. Three edible crops exhibited distinct trends of PPCPs accumulation in response to irrigation rates. Lettuce exhibited a decreasing PPCPs accumulation with a reduced irrigation rate, which was attributed to slower transpiration. In contrast, carrot and tomato exhibited increased PPCP accumulation due to osmotic adjustment. Lettuce and carrot exhibited higher irrigation water utilization efficiency at deficit irrigation, while the opposite was observed for tomato. This study highlights the beneficial integration of UV/PS with deficit irrigation to conserve water, maintain crop yield, and minimize PPCPs accumulation.

Interactive effects of mycorrhizal, Azospirillum and nitrogen+phosphorus with limited irrigation on yield and morpho-physiological traits of evening primrose (Oenothera biennis L.) in arid and semi-arid regions

Evening primrose (Oenothera biennis L.) is a valuable medicinal plant known for its oil, which is rich in gamma-linolenic acid. However, the productivity and quality of evening primrose can be significantly affected by drought stress, a common challenge in arid and semi-arid regions. Water deficit stress not only limits plant growth and development but also affects physiological and biochemical processes. To mitigate the adverse effects of drought, the use of chemical and biological fertilizers has been explored. Mycorrhizal fungi and Azospirillum are known for their ability to enhance plant resilience to abiotic stresses, including drought, by improving nutrient uptake and promoting plant growth. Nitrogen and phosphorus (N+P) are essential nutrients that play crucial roles in plant metabolism and stress tolerance. This study aimed to assess the impact of mycorrhizal fungi, Azospirillum, and N+P on evening primrose under drought conditions. One experiment was conducted in two locations, Tehran (semi-arid) and Varamin (arid) in 2014 and 2015, using a greenhouse for growing plants and through field transplantation. Using a split factorial design within a randomized complete block layout, three irrigation regimes (50 %, 40 %, and 30 % of field capacity) constituted the main plots, while the subplots included three chemical fertilizer treatments (none, 50 %, and 100 % of N+P) and four biological fertilizer treatments (non-inoculated and inoculated with mycorrhizal fungi and Azospirillum) in factorial combinations. The study revealed that drought, both moderate and severe, resulted in reduced plant height, shoot dry weight, leaf area index, seed yield, harvest index, phosphorus content, relative water content, and oil yield. Notably, the highest water use efficiency occurred under moderate water deficit stress. Severe water deficit stress, however, led to the highest root dry weight, root ratio to shoot dry weight, and catalase activity. The application of chemical and biological fertilizers alleviated the negative effects of water deficit stress on plant growth and yield. Evening primrose water use efficiency increased under moderate water deficit stress, particularly when coupled with the application of chemical (N+P) and biological (mycorrhizal fungi and Azospirillum) fertilizers. The study emphasized the positive impact of mycorrhizal and Azospirillum inoculation on enhancing evening primrose growth under water deficit stress.

Carbon and water vapor exchanges coupling for different irrigated and rainfed conditions on Andean potato agroecosystems

The fundamental exchange of water for carbon lays the groundwork for understanding the interplay between carbon and water cycles in terrestrial ecosystems, providing valuable insights into global water and carbon balances and vegetation growth. Inherent water use efficiency (IWUE) was used as a study framework of the diurnal patterns and degree of coupling of carbon and water exchange to investigate the net ecosystem carbon exchange (NEE) responses of three water regime potato cropping systems [full-irrigation (FI), deficit-irrigation (DI), and rainfed (RF)] in Cundinamarca, Colombia. The eddy covariance method was used to determine CO2 and water fluxes, surface resistances, and the omega decoupling factor (Ω). Additionally, leaf area index (LAI), and specific leaf area (SLA) were assessed to determine the canopy influence on carbon and water exchange. The highest carbon sink activity (NEE = -311.96 ± 12.82 g C m−2) at FI, is primarily attributed to a larger canopy with high autotrophic activity and low internal resistance. This supported a highly coupled and synchronized exchange between evapotranspiration (ET) and gross primary production (GPP), as reflected in the highest IWUE (4.7 mg C kPa s−1 kg−1 H2O). In contrast, the lower sink capacity at DI (NEE = − 17.3 ± 4.6 g C m−2) and the net carbon source activity from RF (NEE = 187.21 ± 3.84 g C m−2) were related to a smaller leaf area available for water and carbon exchange, resulting in lower IWUE (2.3 and 1.01 mg C kPa s−1 kg−1 H2O, respectively) and a decoupled and desynchronized gas exchange caused by unbalanced restrictions on ET and GPP fluxes. These results provide new information on carbon–water interactions in potatoes and improve the understanding of carbon sequestration and drought effects on potato sink activity.

Understanding Florida Residents’ Perceptions of and Experiences with Landscape Irrigation Restrictions: Insights for Water Conservation Experts as Well as Extension Educators

Understanding Florida Residents’ Perceptions of and Experiences with Landscape Irrigation Restrictions: Insights for Water Conservation Experts as Well as Extension Educators

Effect of Phenological Basis Deficit Irrigation on Yield and Water Use Efficiency of Tomato (Solanum lycopersicon L.)

The availability of water is a major concern in regions with limited water resources. In such regions, the focus of irrigation management shifted from producing per unit area to producing per unit of water consumed, water productivity. An experiment was carried out, for two consecutive years( 2020 and 2021) at the research farm of Shire-Maitsebri Agricultural Research Center, Tselemty district, Tigray, Ethiopia to exmine the response of tomato to deficit irrigation at various growth stages. A randomized complete block design with three replications was used. Combination of three irrigation regimes (100%, 50%, and 25% of full irrigation requirement) and four FAO-defined tomato growth stages (initial, developmental, mid, and late seasons) were considered to form a total of nine treatments. Data on agronomy and irrigation water were collected and analyzed statistically. The results revealed that reducing irrigation amount up to 75% during the development growth stage significantly decreased marketable yield by 66.5%. However, the highest water use efficiency (9.2 kg/m3) was achieved by reducing irrigation amount by 75% during the end-growth stage of tomatoes. Treatments with the lowest water use efficiency (3.5 kg/m3) were those receiving 75% less irrigation amount than the full requirement during the development growth stage. Reducing irrigation to less than 75% of the full requirement during tomato development stages can greatly impact marketable yield and water use efficiency. Therefore, the tomato crop is highly susceptible to water stress when receiving more than 50% of the full irrigation requirement during its developmental growth stage.

Deficit Irrigation of Forage Cactus (Opuntia stricta) with Brackish Water: Impacts on Growth, Productivity, and Economic Viability under Evapotranspiration-Based Management

Climate change significantly impacts agriculture and forage production, requiring the implementation of strategies toward increased water and energy use efficiency. So, this study investigated the yield of forage cactus (Opuntia stricta (Haw.) Haw) under different irrigation depths using brackish groundwater (1.7 dS m−1), whose management was based on reference evapotranspiration (ETo) estimated by the Hargreave–Samani (HS) and Penman–Monteith (PM) equations. The research was conducted in Independência, Ceará, Brazil, under the tropical semi-arid climate. A randomized block design in a 2 × 5 factorial scheme was employed, varying the ET0 estimation equations (HS and PM) and irrigation levels (0; 20; 40; 70; and 100% of total required irrigation—TRI). Growth, productivity, and water use efficiency variables were evaluated at 6, 12, and 18 months after treatment initiation. The economic analysis focused on added value, farmer income, and social reproduction level. The results showed no isolated effect of the equations or their interaction with irrigation depths on the analyzed variables, suggesting that irrigation management can be effectively performed using the simpler HS equation. Furthermore, there was no statistical difference between the means of 100% and 70% TRI as well as between 70% and 40% TRI for most variables. This indicates satisfactory crop yield under deficit irrigation. Dry matter productivity and farmer income at 12 months resulting from complementary irrigation with depths between 40% and 70% of TRI were significantly higher than under rainfed conditions. The 70% depth resulted in yields equivalent to those at 100% TRI, with the social reproduction level being achieved on 0.65 hectares in the second year.

Phenological and yield response of primed carrot (Daucus carota L) seeds under deficit irrigation

Seedling emergence and stand establishment of carrot seeds are often slow and erratic which results in low productivity. Poor seed quality together with lack of pre-sowing seed treatments and improper irrigation management can be mentioned as the major factors that influence the yield and productivity of carrot. The present study was carried out with the objective to evaluate the effects of different seed priming techniques on early seedling establishment, growth and yield of carrot (Daucus carota L. cultivated variety Nantes) exposed to different irrigation intervals, under field conditions at Gerado, South Wollo, Ethiopia. Four seed priming treatments (no priming, hydro priming, halo priming and hormonal priming) and three irrigation intervals (4, 7 and 10 days) were combined as factorial RCBD in split plot arrangement with three replications. The irrigation intervals were assigned to main plots and the seed priming techniques to sub plots. Result indicated that the interaction effects of priming techniques and irrigation intervals significantly affected the phenological and yield parameters. Distilled water treatment in seven and ten days irrigation interval recorded the highest marketable carrot root yields of 33.73 t h-1 and 30.63 t h-1, respectively. Hence, hydro priming and seven days irrigation interval can be recommended for the production of carrot in the study area and similar agro-ecologies. Given the promising results obtained, further repetitions of the study are recommended to validate the use of these techniques in further locations and in different seasons.

Physiological and agronomic response of young ‘Verna’ lemon trees to the application of partial root irrigation compared to conventional deficit irrigation under conditions of high evaporative demand

Physiological and agronomic response of young ‘Verna’ lemon trees to the application of partial root irrigation compared to conventional deficit irrigation under conditions of high evaporative demand

Artificial Neural Network Modeling for Investigation on the Effect of Deficit Irrigation and Nitrogen Levels on Yield and Quality of Hay Remaining After Seed Harvest of Sorghum Sudangrass Hybrid

ABSTRACT This study aims to develop an Artificial Neural Network (ANN) modeling to be trained to forecast the effects of different irrigation water levels and fertilizer doses on the hay yield and some quality traits of herbal parts of Sorghum × Sudan grass hybrid (Sorghum sudanense vs. Sorghum bicolor). The ANN model was developed on the limited field experiments implemented in Bilecik, Turkey, for 2 years in 2021 and 2022. Experiments were conducted in split-plot design with three replications. In the study, three irrigation levels (I100, I60, and I30) were placed in the main parcels, and four fertilizer levels (N0, N50, N100 and N150 kg ha−1) were placed in the sub-parcels. Irrigations were made in three critical periods according to the amount of cumulative evaporation occurring in the Class A Pan. The results showed that irrigation and fertilization are important in terms of yield and quality characteristics. The yield increased depending on the irrigation and fertilization dose, and the highest value was obtained from the I100 × N150 interaction (28.10 t ha−1). The highest protein yield was determined from the I60 × N150 (2.37 t ha−1) interaction, and the Relative Feed Value (RFV) value was determined from the I30 × N150 (92.17) interaction. Irrigation Water Use Efficiency (IWUE) and Water Use Efficiency (WUE) values increased with decreasing irrigation amount, and the highest IWUE was determined from I30 and the highest WUE was determined from I60 irrigation subjects. According to the field experiments and ANN model, the I80 irrigation with 100 kg ha−1 nitrogen doses would suit the feed yield and quality of Sorghum × Sudan grass hybrid.

Effect of deficit irrigation and partial rootzone drying on the water consumptive use, growth and yield of faba bean (vicia faba L.) in a gypsiferous soil

Iraq’s farming sector is under increasing pressure to improve water use productivity as a result of the recent drought, environmental concerns regarding sustainable river ecosystems, and government policies on water metering and allocations. To cope with scarce supplies, deficit irrigation, and partial rootzone drying, defined as the application of water below full crop-water requirements, is an important tool to achieve the goal of reducing irrigation water use. It is necessary to develop new irrigation scheduling approaches, not necessarily based on full crop water requirement, but ones designed to ensure the optimal use of allocated water. These two methods of irrigation are one way of maximizing water use efficiency (WUE) for higher yields per unit of irrigation water applied: the crop is exposed to a certain level of water stress either during a particular period or throughout the whole growing season. The expectation is that any yield reduction will be insignificant compared with the benefits gained through diverting the saved water to irrigate other crops. This paper reviews the yield response of the faba bean (Vicia faba L.). The deficit of irrigation on gypsiferous soils is not known. A field experiment was carried out to study the effect of deficit irrigation and partial drying of the root system on the growth and yield of the bean Randomized Complete Blocks (RCBD) design in gypsiferous soil in the fields of the College of Agriculture- Tikrit University, which is located on Latitude 49° 40ʹ 34˝ North and Longitude 40° 38ʹ 43˝ East At an altitude of 129 m above sea level. The study included seven treatments of full irrigation, deficit irrigation, 25, 50 %, and fixed, alternating partial drying. The seeds of the Barcelona variety were sown for the season on 16/10/2021 and harvested on 2/4/2022. The results showed that the full irrigation treatment gave the highest water consumption use of 635 mm, while the alternative partial root drying decreasing 50% gave the lowest water consumption use of 245 mm and gave the highest crop water use efficiency of 2.0 kg m-3. Treatment full irrigation gave the highest seed yield of 5186.3 kg.ha-1, While the 50% deficit irrigation treatment gave the highest dry weight of the root system, which was 25.6 gm.plant-1.

Physiological adaptations of lucerne under a limited irrigation system

A field study was conducted to identify the physiological tolerance mechanism of lucerne to limited irrigations. Lucerne needs irrigation once in 10 days. So, limited irrigation treatment was imposed once every 25 days. In the initial part of the experiment, accessions collected from the western part of India were screened for biomass potential under limited irrigation in an augmented RBD design. Accessions that performed well under these conditions were grown under temporal isolation, and seeds were collected. In the second part, a field experiment was conducted at SRRS, ICAR-IGFRI, Dharwad, from December 2018 to March 2020 to screen lucerne accessions under limited irrigation to identify the physiological and morphological characters that are required to impart tolerance in lucerne under the cut and carry limited irrigation system. An RBD design was adopted to screen 12 lucerne accessions under limited and full irrigated conditions. Accessions that maintained good persistence under limited irrigation also performed significantly (Acc38/2010, Acc23/2010, A2) regarding yield. Persistence during the juvenile phase depended on conductance, osmotic adjustment and antioxidant capacity. Accessions showed a constant increase in the number of branches after each harvest under limited irrigation was promising in yield performance. Specific-leaf weight (SLW), crude protein, conductance, increased number of branches, and persistence were significantly and positively correlated with yield.

Water-Nutrient Coupling Strategies That Improve the Carbon, Nitrogen Metabolism, and Yield of Cucumber under Sandy Cultivated Land

The purpose of this study was to explore the carbon and nitrogen metabolism mechanisms of sand-cultivated cucumbers under different deficit irrigation–nitrogen management strategies and provide a theoretical basis for their greenhouse management. This study set up two factors, the deficit irrigation level and the nitrogen application rate, and conducted an experiment on deficit irrigation–nitrogen coupling of sand-cultivated cucumbers using a quadratic saturation D–optimal design. Seven treatments were set up in the experiment, to measure the soluble sugar and protein contents, as well as the activity of key enzymes for carbon and nitrogen metabolism at five different growth stages. The results indicate that the 80% irrigation with 623 kg N hm−2 (IN4) treatment significantly improved the soluble sugar, protein, and actual leaf nitrogen contents of cucumber at the five different growth stages and, as a result, achieved higher sucrose synthase (SS) and sucrose phosphate synthase (SPS) activities in the cucumber leaves. Furthermore, such improvements were due to the reduction in oxidative damage of sand–cultivated cucumber at various growth stages. The IN4 and 89% irrigation with 1250 kg N hm−2 (IN5) treatments significantly increased the activities of RuBisCO, catalase (CAT), peroxidise (POD), and superoxide dismutase (SOD) at various growth stages of sand-cultivated cucumber. The higher activities of glutamate dehydrogenase (GLDH), glutamate synthase (GOGAT), nitrate reductase (NR), glutamine synthase (GS), acid invertase enzyme (AIE), neutral invertase enzyme (NIE), and better antioxidative enzyme activities were recorded under the IN4 treatments at various growth stages, which effectively improve (69.6%) cucumber yield. The soil properties, carbon and nitrogen metabolism, and antioxidant metabolism were positively correlated with sand-cultivated cucumber yield in a greenhouse. We concluded that the IN4 treatment was the better deficit irrigation–nitrogen management strategy because it considerably improves carbon and nitrogen metabolism, antioxidant enzyme activities, and sand–cultivated cucumber yield in a greenhouse.

Response of Malt Barley (&amp;lt;i&amp;gt;Hordeum distichum L.&amp;lt;/i&amp;gt;) to Different Phosphorus Fertilizer Rates and Irrigation Levels Under Furrow Irrigation Methods in South Eastern Ethiopia

Nutrient availability to crops is a function of soil type, moisture condition, environment, crop type, and management and their interaction affects nutrient use efficiencies and crop growth conditions. The objective of this study was to determine the optimum P rate and deficit irrigation level, as well as to identify the interactive effect of nutrient and moisture levels on yield and yield quality malt barley under irrigation in Ormiya region Tiyo district. The experiment was conducted at small plot level for three consecutive years from 2020/21 to 2022/23 G.C. This experiment was conducted at Kulumsa Agricultural Research Center On-Station arranged by split-plot layout with RCBD design by three replications. Irrigation amounts (100%, 75% and 50%) were assigned the main plot and phosphorus fertilizer rates (0, 10, 20, 30 and 40 kg) corresponded to the subplot. The combined effect of irrigation levels and phosphorus fertilizer rate had a significant effect (p &amp;lt; 0.05) on malt barely grain yield, above-ground biomass, thousand kernel weight and water productivity but not on plant height, seeds per spike and protein content. The highest grain yield and above-ground biomass were 3.16 t/ha and 6.77 t/ha obtained from the application of 100% ETc with 30 kg of phosphorus fertilizer. The maximum water productivity (0.97 kg/m&amp;lt;sup&amp;gt;3&amp;lt;/sup&amp;gt;) was observeat the application of 75% ETc with 30 kg of Phosphorus fertilizer while more profitable practice was found at 100% ETc with 30 kg of phosphorus application. The highest protein content (15.57%) was observed at the application of 50% deficit irrigation and the lowest (14.66%) was observed at 100% ETc irrigation application. Applying the optimum amount of irrigation with 30 Kg phosphorus fertilizer gives high grain and above biomass yield and is economically profitable in Tiyo district and agroecologies similar to Tiyo.

Impact of Deficit Irrigation on Bell Pepper (Capsicum annuum var. Grossum) Cultivation

The purpose of this study is to determine the effect of deficit irrigation application on the growth of bell pepper plants and to assess the efficiency of irrigation water application for bell pepper plants. The design used in this research is a Completely Randomized Design with 4 levels of deficit irrigation treatments and six replications. The procedures involved in this study include analysis of soil moisture to determine field capacity and permanent wilting point, treatment conditioning, planting, plant maintenance, observations, and finally, harvesting. The data obtained were tested for homogeneity of variances using the F-test, and if there were differences among treatments, further analysis was conducted using the Least Significant Difference test at the 5% level. The results of the data analysis are presented in tables, graphs, and diagrams. Deficit irrigation treatments significantly affected the plant height and leaf number parameters. The plant response to irrigation was limited under deficit irrigation based on total fruit weight, where bell pepper plants produced the best fruit under the 80% deficit irrigation treatment, with an average total fruit weight of 242.17 grams. Meanwhile, in the ID4 treatment, the plant results were less favorable due to stress. The response of the results to water (Ky) indicates that the Ky value (Ky &lt;1) for bell pepper plants in the ID2, ID3, and ID4 treatments shows values less than 1, meaning that these treatments are tolerant to water stress. Keywords: Bell Pepper, Deficit irrigation, Irrigation, Yield response