Deficit Irrigation Research Articles

Response of Durum Wheat to Deficit Irrigation

Deficit irrigation trial has been conducted to see the response of durum wheat to the extent of deficit irrigation at Debre Zeit research center for three successive seasons from 2016 to 2018. Establishment irrigations were given for all plots after swing and irrigation water application events were monitored using long term meteorological data and soil moisture readings. Irrigation water application depths (amount of water applied) were calculated from cumulative crop evapotranspiration (ETc) values in a given period and plots were irrigated with depths that was replenish 100 %, 75%, and 50 % of the cumulative ETc as per the treatment to be applied. Measured amount of irrigation water applied to every plot measured by using 3 inch Parshall flume. Results indicated those grain yields significantly affected by deficit irrigation levels and furrow irrigation methods. The highest mean grain yield of 5.8 t/ha attained from 75% ETc irrigation level with alternate furrow irrigation method while the lowest mean yield of 3.989 t/ha was obtained from treatment irrigated with 50% ETc and conventional furrow irrigation method. Therefore, based on the current findings, the highest grain yield was obtained at 75% ETc with alternate furrow irrigation system while the highest WUE was recorded at irrigating 100% ETc with alternate furrow system.

Enhancing drought-salinity stress tolerance in lettuce: Synergistic effects of salicylic acid and melatonin

Salicylic acid (SA) and melatonin (MEL) are affordable and effective phytohormones that help mitigate environmental stress. However, the combined benefits of SA and MEL in managing salt and drought stress in lettuce have not been evaluated. Therefore, this study was designed to evaluate the effectiveness of foliar spraying with 1.0 mM SA and 100 µM MEL, either alone or in combination, to enhance lettuce yield, growth, photosynthetic pigments, mineral status, quality, and antioxidant response under four different irrigation regimes. The irrigation practices used were: full irrigation (FI, irrigated with 0.18 dS m−1 at 100 % field capacity [FC]), deficit irrigation (DI, irrigated with 0.18 dS m−1 at 75 % FC), saline irrigation (SW, irrigated with 2.5 dS m−1 at 100 % FC), and deficit saline irrigation (DSW, irrigated with 2.5 dS m−1 at 75 % FC). Additionally, a control treatment (CK) was carried out with foliar application of distilled water and irrigation at 0.18 dS m−1. Compared to the CK, the application of SA, MEL, and SA+MEL increased evapotranspiration by 4.3 %, 8.6 %, and 15.1 %, and yield by 10.2 %, 16.4 %, and 23.8 %, respectively, under FI conditions. Furthermore, the joint application of SA and MEL at FI showed 25.3 % and 20.2 % higher K+/Na+ and Ca2+/Na+ ratios, respectively, compared to the CK. Additionally, the co-application of SA+MEL improved chlorophyll a, b, and carotenoid levels by 19.2 %, 17.2 %, and 20.4 %, respectively, under FI conditions, compared to the CK. Exogenous application of SA, MEL, and SA+MEL also improved total soluble solids by 17.3 %, 18.5 %, and 11.1 % and reduced nitrate content by 9.7 %, 10.4 %, and 13.5 % in lettuce under FI conditions, compared to the CK. The application of SA+MEL together resulted in a more pronounced increase in vitamin C content compared to supplying SA and MEL individually. Moreover, under DSW conditions, exogenous application of SA, MEL, and SA+MEL decreased the membrane stability index by 13.7 %, 9.4 %, and 6.3 %, increased malondialdehyde by 65.4 %, 40.8 %, and 36.6 %, and increased proline content by 68.4 %, 65.4 %, and 96.4 %, respectively, compared to the CK. Moreover, exogenous SA+MEL significantly increased the activities of superoxide dismutase, catalase, peroxidase enzymes under both SW and DSW conditions compared to the SA or MEL. Conversely, the activity of ascorbate peroxidase enzyme showed a gradual decrease in DI, SW, and DSW conditions, relative to the FI conditions. In conclusion, the integrated application of SA+MEL is an optimal strategy to enhance yield, morpho-physiological traits, nutrient homeostasis, antioxidant capacity, and quality in lettuce and mitigate the adverse effects of drought, salinity, and drought-salinity stress.

Experimental study to understand the effects of deficit irrigation in maize

ABSTRACT Given the challenges posed by climate change and the scarcity of water, it is essential to adopt sustainable irrigation practices that do not compromise crop yields. Research studies are crucial to determine the optimal deficit soil moisture levels to be maintained for cultivation in different soil types. This study examines the response of maize grown on loamy sand soil under different water deficit moisture contents by monitoring the variation of the crop growth in terms of the leaf area index, biomass weight, root depth and yield. The daily soil moisture is measured to understand the actual evapotranspiration from the study plots. From the experiments, the optimal moisture content identified is 13%, and the plot maintained at this moisture content has shown the highest evapotranspiration, yield and biomass. The yield response factor of the maize grown in water deficit conditions is also observed to be very close to the value reported by FAO. As expected, the yield response factor is found to be sensitive to water stress. The deficit irrigation at the optimal moisture content of 13% could be recommended for maize cultivation in loamy sand soil in North Indian climatic conditions. Such considerations will be vital for achieving sustainable irrigation goals.

Cross‐Generational Effect of Water Deficit Priming on Physiology of Peanut Plants Under Water Stress

ABSTRACTWater deficit priming through regulated deficit irrigation has been shown to be beneficial for peanut cultivation, leading to improved water‐use efficiency during the crop cycle and enhanced stress acclimation. The effects of priming using water deficit can be heritable, but little is known about stress priming effects on the physiology and growth of successive generations undergoing water stress. Two experiments were conducted to assess cross‐generational priming by determining physiological and growth responses of offspring of primed and non‐primed peanut plants of two genotypes, COC‐041 and New Mexico Valencia C (NMV‐C), both previously found to be strongly responsive to priming. Seeds were collected from parental plants subjected to mild water stress by regulated deficit irrigation (primed) or adequate irrigation (non‐primed). These seeds were then planted, and the offspring were monitored for physiological and growth responses to water stress, including on a whole‐plant basis using a high‐throughput physiological phenotyping platform and on individual leaves by periodic single‐leaf measurements. Measurements included whole‐plant transpiration (plant‐Tr), root water uptake, leaf transpiration, stomatal conductance and net CO2 assimilation (leaf‐Tr, leaf‐gs, and leaf‐A), leaf water and osmotic potential (leaf‐Ψw and leaf‐Ψo), leaf osmotic adjustment, leaf relative water content (leaf‐RWC) and cumulative plant‐Tr. Offspring of both genotypes from primed parent plants had faster early establishment, with more uniform germination, and more rapid initial seedling growth compared to offspring from non‐primed parent plants. Although offspring of both non‐primed and primed plants of both genotypes exhibited a significant reduction of plant‐Tr, gas exchange, leaf‐Ψw, leaf‐Ψo, and leaf‐RWC when exposed to water stress, offspring of primed plants showed increased water use efficiency through reduced leaf‐gs, leaf‐Tr and plant‐Tr while maintaining leaf‐A under water stress. Despite offspring of both primed and non‐primed plants being susceptible to severe water stress, offspring of primed plants exhibited overall enhanced water use efficiency, leading to greater dry biomass production per gram of transpired water and a trend of less growth reduction due to water stress compared to offspring of non‐primed plants, especially for the genotype COC‐041. This study shows the potential of water deficit priming to promote cross‐generational changes in physiological function under limited water availability, by enhancing crop stress acclimation in the next plant generation.

Comprehensive analysis on investigating water-saving potentials of irrigated cotton in semi-arid area in China

Deficit irrigation is a common strategy to reduce water use and improve the sustainability of cotton production. However, the effects of water deficits on crop productivity and quality are subject to genotype by management by environmental interactions. This study investigated effects of water deficits and frequency of irrigation on cotton performance grown in semi-arid region, Xinjiang, the main cotton-growing area in China. Two field trials (2020 and 2021) with split experimental design, including main factors of three irrigation levels (moderate-deficit, mild-deficit and full-irrigation) and split factors of three irrigation frequencies (4, 8 and 12 days) were conducted. Results from two trials both showed little negative influence of irrigation levels on yield, and higher irrigation frequency improved yield under same irrigation level. Significant effects of irrigation levels on yield components were found in 2021, with a 22 % increase in boll number and an 18 % reduction in boll weight under moderate-deficit irrigation compared with those under full-irrigation. Interactions between irrigation levels and frequencies significantly affected harvest index (HI), showing that reduced irrigation might be beneficial for improving HI. However, decreased fibre length while increased fibre micronaire were found under deficit irrigation. A strong association between radiation use efficiency (RUE) and boll growth rate was observed, suggesting that RUE might be the driving force of yield formation. A tight correlation between both biomass and transpiration efficiency versus delta temperature between air and canopy (ΔTair-canopy) was observed, suggesting ΔTair-canopy could be used as an efficient tool to assess plant production under deficit irrigation. This study provided an improved understanding of the physiological basis of cotton yield formation and further identified a high-throughput and instantaneous method to monitor effects of deficit irrigation on crop productivity.

Deficit Irrigation as an Effective Way to Increase Potato Water Use Efficiency in Northern China: A Meta-Analysis

Water scarcity poses a significant threat to the sustainable production of crops in Northern China. Despite this, the effect of water management practices, such as deficit irrigation, on the yield and WUE of potatoes has been rarely explored. Based on the meta-analysis of field experiment data, this study evaluated the influence of deficit irrigation on potato yield, evapotranspiration (ET), water use efficiency (WUE) and irrigation water use efficiency (IWUE) under variable soil types, water-saving ratio, irrigation methods, soil organic carbon (SOC) content, and fertilizer rate in Northern China. Here, we determined that potato WUE and IWUE were significantly increased by 10.0 and 31.6%, respectively, under deficit irrigation, while ET was significantly decreased by 26.3% compared to full irrigation. Conclusively, deficit irrigation significantly reduced potato yields by 16.4% compared to full irrigation. Furthermore, SOC content played a vital role in improving the WUE and alleviating potato yield losses under deficit irrigation. Our study suggested that maximum WUE with lower potato yield losses under deficit irrigation can be achieved in the Central Plains region of China or in yellow loam soil, brown soil, and meadow soil under alternate root-zone irrigation when the water-saving ratio was less than 45% and fertilizer application rates were 300 kg N ha−1, >240 kg P2O5 ha−1, and 181–300 kg K2O ha−1. Overall, these findings highlight the need for a comprehensive understanding of various agricultural management practices and local environmental conditions to optimize the benefits of deficit irrigation in potato-growing regions across Northern China.

Responses of Soil Water, Temperature, and Yield of Apple Orchard to Straw Mulching and Supplemental Irrigation on China’s Loess Plateau

The combination effect of straw mulching and supplemental irrigation on the soil water and heat, and the growth and productivity of mature apple trees on the Loess Plateau of China remains unclear. Field experiments were conducted in 2022 and 2023 to evaluate the combined effect of straw mulching and supplemental irrigation (two irrigation types, ring and double-row drip irrigation, and three irrigation levels: high, medium, and low irrigation level) on the soil water and temperature, growth, yield, and water productivity (WP) of a mature apple orchard. Local rainfed cultivation was used as the control (CK). The results showed that straw mulching increased soil moisture by 2.4–6.5% compared to the CK treatment. Supplemental irrigation significantly increased soil moisture in the 0–60 cm layer by 3.0–8.1%, and its effect increased with an increasing irrigation level. Straw mulching significantly reduced soil temperature by 7.8% compared to the CK treatment. Supplemental irrigation significantly increased the new shoot length and stem thickness of apple trees. Under straw mulching, a medium supplemental irrigation level significantly increased both apple yield and WP compared to the CK treatment. In this study area, it is recommended to choose a combination of straw mulching and a medium supplemental irrigation level.

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.