Deficit Irrigation Practices Research Articles

Improving Water Productivity in Irrigated Agriculture: A Review of Techniques and Water Conservation Methods in Ethiopia

Water is a scarce resource and the competition for it is increasing from time to time due to population growth and economic status change. The population growth leads to high expectations to produce more food from irrigated agriculture which could not be satisfied by rain-fed conditions. As irrigated agriculture is by far the largest water consumer in an inefficient way, improving water productivity has paramount importance both for the production of more food and for wise utilization of scarce water. Beyond these, studies suggest that improving water productivity in Ethiopia contributes to an increase in the irrigated area, reduced competition, and conflict between users, increased profitability due to reduced labor cost, water pumping and working time, and generally increased food production. Different water productivity improvement techniques and water conservation methods have been tested in different parts of the country. These include improving the performance of irrigation schemes, regulated deficit irrigation practice, partial root zone drying, application of irrigation on selected crop growth stages, supplementary irrigation, drip irrigation, surge and cutback irrigation, and water conservation methods like mulching and integrating irrigation with conservation agriculture. The level of water productivity improvement varies considerably for different methods, study areas, crop types, and seasons. Generally, more studies concentrated on deficit irrigation and irrigation application at different crop growth stages. Water conservation and integration of cultivation practices with efficient irrigation led to an improvement in water productivity. Despite few studies, scheme-level study results suggest that the level of deficit irrigation should be selected based on the available irrigation water and cultivable land area for maximizing the benefit of the scheme. According to the economic profitability, crop types and crop varieties also should be selected for production with site-specific conditions. Despite different types and levels of reduced irrigation leading to lower crop yield, the inclusion of the economic importance is essential as most crops showed higher water productivity at lower irrigation levels. On the other hand, studies on the integration of different water productivity enhancement techniques and crop planting patterns are minimal in the country, though current studies revealed better water productivity. Moreover, basin-level water productivity improvement studies could contribute to alleviating water competition and increasing irrigated areas. Therefore, studies on the optimization of these different methods could be done at the basin level for better water resource utilization. Government policies should also focus on water productivity improvement for the implementation of research findings.

Adaptation of Almond Cultivars in Majorca Island: Agronomical, Productive, and Fruit Quality Characteristics

Almond cultivation has a long-standing tradition on the island of Majorca, traditionally practiced under rainfed conditions. Currently, new plantations are established with irrigation; however, due to present conditions and the impacts of climate change, water availability is limited. The Government of the Balearic Islands permits a maximum water supply of 3000 m3 ha−1 per year for almond cultivation. In this study, a 6-year field trial was conducted to investigate the adaptation of fourteen almond cultivars obtained from different research centers under deficit irrigation practices in the soil and climatic conditions of Majorca Island. The cultivars had a significant effect on trunk cross-sectional area TCSA, cumulative almond in-shell yield, cumulative kernel yield, yield efficiency, and shelling percentage. The ‘Marta’ and ‘Tarraco’ cultivars exhibited the highest TCSA values. Regarding cumulative almond in-shell yield, ‘Glorieta’ and ‘Constantí’ produced the highest yields, whereas the lowest yields were observed in ‘Mardía’ and ‘Tarraco’. In terms of shelling percentage, ‘Ferragnès’ exhibited the highest value. Kernel quality parameters were cultivar-specific. Additionally, oleic acid content was strongly negatively correlated with linoleic acid content. All cultivars exhibited an unsaturated fatty acid content exceeding 90%, with ‘Masbovera’ showing the highest value.

Laboratory Evaluation of Soil Moisture Sensors for Precision Irrigation in Agriculture

Water is essential for agricultural production and food security, making efficient water use critical. Accurate measurement of soil moisture is vital for scheduling irrigation, ensuring that crops receive the right amount of water at the right time. This prevents both under- and over-irrigation, conserving water and maximizing crop production. Currently, digital soil moisture sensors are used for their accuracy and instant measurement capabilities. The soil moisture sensor's functionality was evaluated through observations of four Capacitive soil moisture sensors 1.2 (SMS A, B, C, D) at various moisture levels, with gravimetric method verification. The calibrated linear equations demonstrated a strong linear relationship for each sensor. The coefficient of determination (R2) were also found to be 0.92, 0.93, 0.91 and 0.93 respectively. These R² values indicate a strong linear relationship for each sensor. An automated drip irrigation module was developed by integrating these soil moisture sensors with the Arduino platform. The system activates the irrigation motor when soil moisture content falls below the field capacity or a desired set value, and turns it off once the required moisture level is reached. This sensor-based automated drip irrigation module enables farmers to irrigate their fields precisely and efficiently, delivering the right quantity of water at the right time. The system is also suitable for deficit irrigation practices, improving crop yield and water use efficiency.

Effect of Deficit Irrigation on Growth Parameters of the Salvia splendens L. Plant

This study aims to investigate alterations in the developmental parameters of Salvia splendens L., a commonly utilized seasonal flower associated with excessive water consumption in urban green spaces, through the implementation of deficit irrigation practices. Four distinct irrigation treatments, which entailed maintaining the evaporation pot’s water level at 100% (control), 75%, 50%, and 25% of the pot’s water-holding capacity, were established. This study scrutinized 18 growth parameters to assess the impact of varying water application levels. The findings of this research revealed that Salvia splendens L. plants exhibited more substantial improvements in 17 out of 18 assessed parameters when subjected to 75% water application (representing a 25% reduction in water supply) in comparison to 100% water application (with no reduction). Notably, the only parameter negatively affected by reduced water availability in Salvia splendens L. was the diameter of the flowers. Thus, it is recommended to reduce water application by 25% when cultivating Salvia splendens L. in urban areas. Such a measure is expected to yield substantial water conservation benefits in urban landscaping. Consequently, it is advisable to promote the frequent utilization of Salvia splendens L. plants in urban green spaces, given their robust development even under conditions of water scarcity.

Irrigation Water and Nitrogen Fertilizer Management in Potato (Solanum tuberosum L.): A Review

Intensive irrigation and nutrient management practices in agriculture have given rise to serious issues in aquifer water depletion and groundwater quality. This review discusses the effects of irrigation and nitrogen management practices on potato growth, yield, and quality, and their impacts on water and nitrogen use efficiencies. This review also highlights the economics and consequences of applying deficit irrigation strategies in potato production. Many researchers have demonstrated that excessive irrigation and nitrogen application rates negatively impact potato tuber yield and quality while also increasing nitrate leaching, energy consumption, and the overall costs of production. An application of light-to-moderate deficit irrigation (10–30% of full irrigation) together with reduced nitrogen rates (60–170 kg/ha) has a great potential to improve water and nitrogen use efficiencies while obtaining optimum yield and quality in potato production, depending on the climate, variety, soil type, and water availability. There is an opportunity to reduce N application rates in potato production through deficit irrigation practices by minimizing nitrate leaching beyond the crop root zone. The best irrigation and nitrogen management techniques for potato production, as discussed in this review, include using sprinkle and drip irrigation techniques, irrigation scheduling based on local crop coefficients, soil moisture content, and crop modeling techniques, applying slow-release nitrogenous fertilizers, split nitrogen application, and applying water and nitrogenous fertilizers in accordance with crop growth stage requirements.

Mechanical Fruit-Zone Leaf Removal and Deficit Irrigation Practices Interact to Affect Yield and Fruit Quality of Cabernet Sauvignon Grown in a Hot Climate

Mechanical Fruit-Zone Leaf Removal and Deficit Irrigation Practices Interact to Affect Yield and Fruit Quality of Cabernet Sauvignon Grown in a Hot Climate

Effect of deficit irrigation practices on greenhouse gas emissions in drip irrigation

One of the most important sources of greenhouse gas emissions resulting from human activities is agricultural activities. Many factors such as tillage, fertilizer use, irrigation, soil properties, etc. can affect greenhouse gas emissions. However, their effects on greenhouse gas emissions are still among the important research topics today. In this study, the effects of different irrigation levels on CO2, CH4, N2O emission in soil were investigated in silage maize irrigated with drip irrigation system. The study was carried out for two years, 4 different irrigation levels (S1:100%, S2:70%, S3:40%, S4:0) were applied. ADA 9516 silage mazie variety was used as the test plant. Static cylinders were used in each plot for greenhouse gas measurements. Greenhouse gas Cylinders (cells) consisting of 2 pieces made of PVC placed on trial plots were used in the research. Gas samples were analyzed with gas chromatograph (Agilent GC 7890A) and gas emission values of CO2, CH4 and N2O were calculated. In the study, the highest cumulative CO2 emission values by years were obtained for S1 with 1470.4 and 1129.6 kg ha−1, respectively (p<0.01) and the CO2 emission values measured after irrigation were found to be higher than the pre-irrigation emission values. The highest cumulative N2O emission values were obtained for S1 with 0.54 and 0.50 kg ha−1, respectively, over the years (p<0.001), N2O emission values were higher after irrigation. In CH4 analyzes, it was determined that the trial area soil behaved as a CH4 sink. The highest cumulative CH4 uptake in both years of the study occurred in S1 with -1.79 and -3.17 kg ha−1, respectively (p<0.01). Similarity was observed in CH4 flux values before and after irrigation. In the research, it was determined that irrigation practices increased greenhouse gas emission statistically. On the other hand, it has been determined that producing with irrigation using less agricultural land can help reduce greenhouse gas emissions.

Review of cool‐season turfgrass water use and requirements: I. Evapotranspiration and responses to deficit irrigation

AbstractKnowledge of water use rates and responses to deficit irrigation practices in cool‐season turfgrasses is important, particularly in climates where irrigation is required to maintain turf quality. This is Part I of two companion papers reviewing cool‐season turfgrass water use and requirements. Part I presents the history of early water conservation and quantification methods in turfgrass and summarizes research on cool‐season turfgrass evapotranspiration (ET) and deficit irrigation. Part II summarizes research on cool‐season turfgrass drought resistance completed since 1980. Summaries of research from &gt; 60 experiments related to ET include: measured ET rates in various climates; comparisons of actual ET to estimated ET; crop coefficients; deficit irrigation; and how plant characteristics and management practices influence ET. Summarized daily evapotranspiration (ETc) rates for Agrostis L. spp., fine fescues (Festuca L. spp.), tall fescue (Festuca arundinacea Schreb.), Lolium spp., and Poa spp. were a weighted average ETc and coefficient of variation (CV) of 6.12 (19.0%), 5.52 (16.8%), 7.79 (14.5%), 5.90 (19.9%), and 5.35 (30.2%) mm d–1, respectively, with an overall ETc of 6.25 mm d–1 (26.9%). Average crop coefficients have ranged from 0.85 to 0.95 (0.91 weighted average across species) and vary slightly during growing months. Minimum deficit irrigation replacement levels for acceptable turf quality have ranged from 59 to 74% of ET under different irrigation intervals. Further study is warranted to investigate differences in crop coefficients among cultivars within species, cultural influences, deficit irrigation replacement levels, and to standardize measurement protocol to improve consistency in crop coefficients across future turfgrass experiments.

Effect of Partial Root Drying and Deficit Irrigation on Yield and Water Use Efficiency of Tomato Grown Under Greenhouse

Water conservation strategies are becoming increasingly important as a result of the shortage of water and climate change. The purpose of this study is to address water-saving irrigation strategies by evaluating the effect of partial root drying irrigation (PRD) and Deficit Irrigation (DI) practice on the yield and water use efficiency of tomatoes (Shivam variety). The treatments were partial root drying (PRD) at 75% and 50% crop evapotranspiration, ETc (PRD25 and PRD50, respectively), and deficit irrigation (DI) at 75% and 50% of ETc (DI25 and DI50, respectively). The PRD practice requires wetting one half of the root zone and keeping the other half dry, consequently using less amount of irrigation water that was applied. In the successive irrigations, the wet and dry sides were alternated. Over a growing season after transplanting, the highest fruit yield was obtained under FULL irrigation (225 t ha-1). In comparison to deficit irrigation that received the same quantity of water, the PRD treatments produced an increased yield of 5–10%. PRD and DI irrigation improved WUE considerably, and that was 30.35% and 25.71% respectively higher than FI. Results suggest that PRD treatment may be an option in a water shortage.

Deficit irrigation with wastewater in direct sowed silage maize reduces CO2 emissions from soil by providing carbon savings

Abstract Direct sowing and deficit irrigation practices can reduce the effect of wastewater on CO2 emissions from soil by providing carbon savings. Therefore, the effect of domestic recycled wastewater uses at different levels in irrigation under conventional tillage and direct sowing practices on the CO2 emission from soil at the end of the vegetation period of silage maize was investigated by comparing it with full irrigation of fresh water. Both organic carbon and CO2 emissions in the second year in fully irrigated treatments were higher than those in the first year. The CO2 emission in the full irrigation with wastewater (0.263 g m−2 h−1), compared to full irrigation with fresh water and 33 and 67% deficit irrigations with wastewater, was higher at 23.4, 25.0, and 59.3%, respectively. Direct sowing practice also (0.193 g m−2 h−1) resulted in 17.0% less CO2 emissions compared to conventional tillage. The positive linear relationships of H2O emission and the soil moisture content at different depths (5, 10, and 20 cm) with CO2 emission were significant, and the negative relationships with the soil temperatures were also found. It has been concluded that deficit irrigation and direct sowing applications can be practical for reducing CO2 emissions from soil in wastewater irrigation conditions.

Evaluation of Aqua-Crop Model using Onion Crop under Deficit Irrigation and Mulch in Semi-arid Nigeria

The Aqua-Crop simulation model has been playing a crucial role in assessing the performance of the existing strategies for the management of irrigation schemes for improving agricultural water use efficiency. This study evaluated the Aqua-Crop model using Onion crops under deficit irrigation and mulch practices in semi-arid Nigeria. Measurements were taken from the experimental plots which consisted of irrigation and mulch each at 4 levels were used to evaluate the Aqua-Crop model using canopy cover, biomass, yield, actual crop ET, and water productivity of Onion during the 2021 irrigation season. The simulated results from the Aqua-Crop model were evaluated and statistically compared with the experimental results. The model simulated canopy cover with the highest degree of correlation coefficient (0.74 ≤ r ≤ 0.94). The model perfectly predicted Onion yield and biomass under full irrigation irrespective of the mulching. However, the model underestimated Onion yield and biomass at deficit irrigation. The model has perfectly estimated the seasonal actual crop evapotranspiration at different irrigation levels and mulch materials while underestimating water productivity in most of the treatments except at 100% irrigation under white synthetic mulch. However, both model and experimental water productivity were better at white synthetic mulch plots. Therefore, the Aqua-Crop model has proven to be a good Onion crop growth and yield predictor under different irrigation levels and mulch materials which can help improve Onion productivity in water-stressed areas like semi-arid Nigeria.

CO2 emission from soil in silage maize irrigated with wastewater under deficit irrigation in direct sowing practice

It is necessary to understand and measure the impact of tillage and irrigation practices on CO2 emissions from the soil with an environmental sensitivity, while wastewater irrigation increases crop biomass yield. The main objective of the present study was to investigate the changes and reasons in CO2 emissions from soil conventional and conservative tillage under different levels of wastewater irrigation. The CO2 emission from tillage-sowing to harvest over the regular measurements with a EGM-5 infrared gas analyzer device was investigated with three replicates in three deficit irrigation levels (0%, 33%, and 67%) of domestic recycled wastewater in conventional tillage and direct sowing practices. Binary relationships of CO2 emissions with H2O emission, air temperature, and the soil temperature and moisture measured at three different depths (5 cm, 10 cm, 20 cm) were also investigated and strong (p < 0.01) positive linear correlations were determined. Wastewater irrigation and conventional tillage significantly increased CO2 emissions compared to freshwater irrigation and direct sowing practice, while deficit irrigation practice decreased it. The direct sowing reduced seasonal CO2 emissions 25.1% and 26.1% for per unit area (1 ha) of silage maize and per unit of fresh silage yield (1 kg), respectively, compared to conventional tillage. The lowest CO2 emission per unit area and yield was determined in full irrigation treatment with freshwater in direct-sowing, while, in wastewater applications, it was determined in irrigation levels 33% per unit area and 67% per unit yield, under direct sowing. Thirty-three percent and 67% treatments in direct sowing resulted in less seasonal CO2 emissions as 38.7% per unit area and 13.8% per unit fresh silage yield, respectively compared to full irrigation treatment with freshwater in conventional tillage. Mean CO2 emissions in these treatments were found lower 17.9% per unit area and higher 17.8% per unit fresh silage yield compared to the full irrigation treatment with freshwater in direct-sowing. It was concluded that CO2 emissions per unit yield could be decreased with 33% water saving under wastewater irrigation conditions, and could be achieved environmental additional benefits from more decreasing CO2 emission by direct sowing also.

The Essentials of Deficit Irrigation for Crop and Water Productivity in Ethiopia: A Review

Improving irrigation water management and enhancing crop and water productivity (WP) are required to address future water scarcity in Ethiopia. Increasing WP through exposing the crop to a positive level of water stress the use of deficit irrigation (DI) is taken into consideration a promising strategy. To espouse deficit irrigation strategies, a shred of complete proof regarding DI for distinctive crops is required. The objective of this critical review is to collect adequate information about the indicators on the essential of DI to crop and water productivity. Just a study on the role of deficit irrigation indicates improve crop yield and water productivity. The end result confirmed that DI appreciably improved WP in comparison to complete irrigation. Despite better WP, the decreased yield became acquired in a number of the studied DI practices in comparison to complete irrigation. It was additionally observed that yield reduction can be low in comparison to the advantages won through diverting the saved water to irrigate extra arable land. The advantages of water-saving techniques which include alternate furrow and deficit irrigation want to be explored to make sure meals safety for the ever-growing populace in the context of declining availability of irrigation water. Consequently, reviewer concluded that deficit irrigation is doubtlessly important to enhance sustainable crop and water productiveness in Ethiopian agriculture.

The Essentials of Deficit Irrigation for Crop and Water Productivity in Ethiopia: A Review

Improving irrigation water management and enhancing crop and water productivity (WP) are required to address future water scarcity in Ethiopia. Increasing WP through exposing the crop to a positive level of water stress the use of deficit irrigation (DI) is taken into consideration a promising strategy. To espouse deficit irrigation strategies, a shred of complete proof regarding DI for distinctive crops is required. The objective of this critical review is to collect adequate information about the indicators on the essential of DI to crop and water productivity. Just a study on the role of deficit irrigation indicates improve crop yield and water productivity. The end result confirmed that DI appreciably improved WP in comparison to complete irrigation. Despite better WP, the decreased yield became acquired in a number of the studied DI practices in comparison to complete irrigation. It was additionally observed that yield reduction can be low in comparison to the advantages won through diverting the saved water to irrigate extra arable land. The advantages of water-saving techniques which include alternate furrow and deficit irrigation want to be explored to make sure meals safety for the ever-growing populace in the context of declining availability of irrigation water. Consequently, reviewer concluded that deficit irrigation is doubtlessly important to enhance sustainable crop and water productiveness in Ethiopian agriculture.

Effect of Rhizobacteria and Microalgae Treatments on Development and Physically Parameters of Fenugreek (Trigonella foenum-graecum L.) Grown Under Deficit Water Conditions

In this study, the effects of deficit water (DW) (normal=control, ½ reduced and 3/4 reduced) and some beneficial rhizobacteria (Azospirillum lipoferum, Bacillus megaterium) and microalgae (Chlorella saccharophilia) on some growth and physiological parameters of fenugreek (Trigonella foenum-graecum L.) were investigated. The experiment was carried out in a fully controlled climate cabinet with 3 replications in factorial order according to the Random Plots Trial Design. Fenugreek (Trigonella foenum-graecum L.) plant was used as material. The study aims to investigate the effects of different deficit water treatments (normal=control, ½ reducedand 3/4 reduced) and some rhizobacteria (Control=R0, Azospirillum lipoferum=R1, Bacillus megaterium=R2) and microalgae (Chlorella saccharophilia=R3) on the growth and development of fenugreek. The effects of deficit irrigation practices on stem length, root fresh and dry weight, stem fresh and dry weight, and leaf area were found to be statistically significant. As the deficit irrigation doses increased, all growth parameters decreased. Root length, root age and stem weight were statistically significantly affected in rhizobacteria and microalgae applications. The highest stem length (19.32 cm) and root wet (1.34 g) and dry (0.18 g) weight were obtained from Bacillus megaterium applications.

Effect of Deficit Irrigation Practice on Nitrogen Mineralization and Nitrate Nitrogen Leaching under Semi-Arid Conditions

Agricultural sector acts as a major consumer of water which accounts for 70 percent of global freshwater use. Water scarcity acts as an imminent threat to agriculture, there is a need to use those irrigation and management practices that could overcome this overwhelming situation of water scarcity. Lab incubation study was designed to evaluate the effect of different moisture levels (50%, 60%, 70%, 80%, 90%, and 100% FC) on nitrogen mineralization rate. Net nitrogen mineralization was shown at 60% and 80% FC levels. Two optimized irrigation levels (I0.6 and I0.8) along with four levels of dairy manure (10, 15, 20, and 25 Mg ha-1) were used in a lysimetric trial. Nitrate-nitrogen was measured at four depths (D1: 30 cm, D2: 60 cm, D3: 90 cm, and D4: 120 cm). Results showed strong interaction of irrigation and dairy manure at all depths. Mean maximum nitrate-nitrogen concentration was shown under full irrigation at 120 cm soil depth with the application of DM ® 25 Mg ha-1. Under two levels of deficit irrigation, I0.8 has shown maximum nitrate-nitrogen concentration at 90 cm soil depth with the application of DM25, however, deficit irrigation level I0.6 restricted nitrate-nitrogen movement up to 60 cm soil depth, and high concentration was found at 30 cm soil depth. We concluded that deficit irrigation practice along with dairy manure resulted in more nitrate-nitrogen in the upper 60 cm layer of soil where it can be more available for the crops.

Establishing a Reference Baseline for Midday Stem Water Potential in Olive and Its Use for Plant-Based Irrigation Management.

Midday stem water potential (SWP) is rapidly becoming adopted as a standard tool for plant-based irrigation management in many woody perennial crops. A reference or “baseline” SWP has been used in some crops (almond, prune, grape, and walnut) to account for the climatic influence of air vapor pressure deficit (VPD) on SWP under non-limiting soil moisture conditions. The baseline can be determined empirically for field trees maintained under such non-limiting conditions, but such conditions are difficult to achieve for an entire season. We present the results of an alternative survey-based approach, using a large set of SWP and VPD data collected over multiple years, from irrigation experiments in olive orchards located in multiple countries [Spain, United States (California), Italy, and Argentina]. The relation of SWP to midday VPD across the entire data set was consistent with an upper limit SWP which declined with VPD, with the upper limit being similar to that found in Prunus. A best fit linear regression estimate for this upper limit (baseline) was found by selecting the maximum R2 and minimum probability for various upper fractions of the SWP/VPD relation. In addition to being surprisingly similar to the Prunus baseline, the olive baseline was also similar (within 0.1 MPa) to a recently published mechanistic olive soil-plant-atmosphere-continuum (SPAC) model for “super high density” orchard systems. Despite similarities in the baseline, the overall physiological range of SWP exhibited by olive extends to about −8 MPa, compared to about −4 MPa for economically producing almond. This may indicate that, despite species differences in physiological responses to low water availability (drought), there may be convergent adaptations/acclimations across species to high levels of water availability. Similar to its use in other crops, the olive baseline will enable more accurate and reproducible plant-based irrigation management for both full and deficit irrigation practices, and we present tentative SWP guidelines for this purpose.

Influence of Drought Stress and Post-Drought Rewatering on Phytoremediation Effect of Arabidopsis thaliana.

Globally, plants face large amounts of environmental stresses, which can inhibit their growth rate and element uptake capacity. Droughts are a critical limitation to plant growth in arid and semi-arid areas. Effects of drought stress and post-drought rewatering on the compensatory growth and Cd phytoremediation efficiency of Arabidopsis thaliana were estimated using slight and moderate drought conditions. Results showed compensatory growth can be induced by post-drought rewatering, as manifested by the increased dry weight and photosynthetic efficiency of the species under drought stress (particularly slight stress) as compared to those of the control. Slight stress increased concentrations of Cd in roots and leaves of A. thaliana by elevating its transpiration rate, whereas moderate stress induced the opposite effect. When the species was subjected to slight stress, Cd concentrations in plant tissues surpassed those in the control after rewatering, indicating that post-drought rewatering can compensate for the detrimental impacts caused by slight drought in A. thaliana. At the end of the experiment, slight and moderate drought stresses increased the Cd extraction ability of the species by 48.9% and 12.7%, respectively, compared to the control. This study demonstrates compensatory effects of post-drought rewatering on the Cd phytoextraction capacity of A. thaliana and suggests that suitable water deficit irrigation practices can enhance soil remediation efficiency and simultaneously save water in the field.

Effects of deficit irrigation on ‘Koroneiki’ olive tree growth, physiology and olive oil quality at different harvest dates

Agricultural water demand in the Mediterranean region is expected to increase due to climate change. The application of deficit irrigation practices may improve the efficiency of water use in orchards, by accounting for changes in environmental conditions and in the tree growth. The main goal of this study was to improve our understanding on the effect of deficit irrigation on physiology, morphology, yield, and oil quality of ‘Koroneiki’ olive trees. The effect of two deficit irrigation treatments and three harvest dates on olive yield and oil quality were investigated in a 17-year old, low-density ‘Koroneiki’ orchard in Cyprus, during a high crop load year. For the sustained deficit irrigation (SDI) treatment 70% ETc was applied over the irrigated period, while the regulated deficit irrigation (RDI) consisted of 70% ETc during water-stress sensitive growth stages (shoot growth, flowering, bud initiation) and 35% ETc during water-stress tolerant growth stages (pit hardening, oil accumulation). Environmental conditions and volumetric soil water content of the 70-cm rootzone were monitored. A Kc of 0.37 was derived for the irrigated period from daily water balance computations, excluding rain days. No significant effects of the two irrigation treatments were found on morphology, physiology, fruit yield and oil quality. Midday stem water potential reached − 4 MPa in September as a result of increasing fruit load. Leaf conductance ranged between 65 and 228 mmol m-2s-1, with highest values obtained under high soil water conditions and a vapour pressure deficit of 3.6kPa. Yields were approximately 9tonsha-1 in both irrigation treatments while water productivity was 1.4 and 1.0 kg oil m-3 irrigation water in SDI and RDI, respectively. Maximum phenolic content was found in early December, reaching on average 202 mg kg-1 oil in both irrigation treatments. Overall, irrigation water use in RDI was 32% less than in SDI, whereas oil quality was only affected by the harvest date.

Evaluation of Deficit Irrigation Effect on Water Use Efficiency and Yield Response for Onion and Potato at Ketar Scheme

In the situation of improving water productivity, there is increasing interest in deficit irrigation practice whereby water supply is reduced below maximum levels and mild stress is allowed with minimal effects on yield. For this authorize, the study was conducted during the dry season for three years from December 2017 to May 2019 to study the effect of deficit on application efficacy, storage efficiency, distribution uniformity and irrigation water use efficiency of potato and onion. The deficit water level used were 75 and 50% CWR lined with full irrigation 100%. From the result, average of application efficiency (Ea), storage efficiency (Es) and distribution uniformity (DU) of the three water levels (100%, 75% and 50%) were 60.97%, 70.27%, 75.4%, 55.45%, 62.84%, 88.68%, 88.24%, 87.61% and 89.89% for potato and 60.06%, 70.81%, 85.64%, 65.03%, 60.24%, 66.02%, 88.49%, 87.89% and 86.24% for onion respectively. The highest Ky of 0.98 and 0.85 was attained at 50% CWR for potato and onion respectively and the lowest was 100% CWR for both crops. This show the highest yield reduction was registered under 50% CWR. The application efficiency, storage efficiency, distribution uniformity and yield response of 75% CWR is slightly low from full irrigation water level. So it is recommended to use 75% CWR for both crops in saving water as it has low yield reduction. Therefore, to implement deficit irrigation on farm participatory training should be given for application of right amount of water.