Effect Of Different Irrigation Strategies Research Articles

Water-Yield Relationships of Green Pepper (Capsicum annuum) Cultivated at Different Irrigation Levels

A field experiment was carried out in Bursa ecological conditions to determine the effects of different irrigation strategies on water-yield relationships of green pepper cultivation. In the study, where the amount of water evaporated from the class A pan (E) was taken as reference, different pan-crop coefficients (kpc: 0.25, 0.50, 0.75, and 1.00) were used for four irrigation treatments (S25: E×0.25, S50: E×0.50, S75: E×0.75, and S100: E×1.00) was created. While statistically significant (p

Evaluation of long-term spatio-temporal characteristics of water and nitrogen in the vadose zone and potential threats to groundwater under different irrigation strategies

Groundwater contamination by nitrate-nitrogen (NO3–N) under intensive agriculture is increasingly receiving worldwide attention. However, knowledge of the potential effects of different irrigation strategies coupled with nitrogen applications on groundwater under intensive agricultural practices remains a critical issue and a grand challenge due to the long transit time for NO3–N across the thick vadose zone. To close this knowledge gap, the calibrated RZWQM2 model was used to investigate long-term (1970–2070) water and NO3–N dynamics in the vadose zone and the potential threat of NO3–N pollution on groundwater under different irrigation strategies (35% of total available water-triggered, 100% filled irrigation (I35% TAW), 90-mm irrigation (I90 mm), and 150-mm irrigation (I150 mm)) and nitrogen applications (optimal and conventional high rates) for the maize-wheat rotation system in the Jinghui Canal irrigation area of the Guanzhong Plain in China. Results showed that mean groundwater recharge values were 43, 65, and 271 mm yr−1 under the I35% TAW, I90 mm, and I150 mm scenarios, respectively, with no significant effect on crop yields. Accumulated NO3–N was concentrated at the 10-m depth over the past 50 years and would be deeply transported to the 15-m and 20-m depths under the I35% TAW and I90 mm strategies, respectively, in the future 50 years. Accumulated NO3–N was concentrated uniformly at the 30-m depth for the I150 mm scenario, with NO3–N amounts of 85.8 and 26.9 kg ha−1 yr−1 leached into the groundwater (30 m) under the conventional and optimal nitrogen applications. Although groundwater at 8–10 m faced the risk of NO3–N pollution during the past 50 years, and groundwater at the deeper depths of 15–20 m could be threatened in the next 50 years under the I35% TAW and I90 mm strategies, the annual amount of NO3–N leaching into groundwater could be significantly reduced from 68.9 to 71.8 kg ha−1 to 10.3–12.7 kg ha−1 by applying more optimal amounts of nitrogen. The results of this study provide a straightforward understanding of long-term spatial and temporal characteristics of water and NO3–N in the vadose zone, and provide insight into possible methods for controlling irrigation application amounts that would prevent groundwater pollution from NO3–N in irrigated areas.

Farklı Sulama Aralıkları ve Düzeylerinin Salçalık Domatesin Verim ve Kalite Bileşenlerine Etkileri ve Ekonomik Analizi

This study was carried out to determine the effects of different irrigation intervals (II) and irrigation levels (IL) on yield, quality and net income values of processing tomato cultivation in a sub-humid climatic zone in 2019. A split-plot randomized complete block design with three replicates was used for the field experiments. The II4-days (A) and 8-days (B) were determined as main-plot factor and different IL were established according to 100% (T1), 80% (T2) and 60% (T3) of the cumulative evaporation occurring in the Class A pan were determined as the sub-plot factor. Seasonal crop evapotranspiration (ET) values varied between 419 and 527 mm. The effects of different irrigation strategies on fruit yield, average fruit weight, brix and water productivity values of processing tomato were significant at the p<0.01 level. The greatest fruit yield was obtained in AT1 treatment with 111.65 t ha-1. The highest water and irrigation water productivity values were obtained from AT2 as 22.4 kg m-3 and 31.4 kg m-3 and the lowest values from BT3 treatment as 16.1 kg m-3 and 26.0 kg m-3 respectively. The yield response factor (ky) was determined as 1.7 for the growing season. The net income values of different treatments ranged from 213.49 to 5557.54 $ ha-1 and the net income increased with the augmentation inthe irrigation water applied. Based on the study results, AT1 treatment was recommended to obtain maximum fruit yield and net income. However, in locations with limited water resources, AT2 treatment which provides a reasonable balance between quality components and water requirements can also be evaluated.

Post-anthesis supplementary irrigation improves grain yield and nutritional quality of drip-irrigated rice (Oryza sativa L.).

Approximately 50% of irrigation water is saved during drip-irrigation of rice, which has tremendous potential for water-saving agriculture, particularly in areas where water resources are scarce. However, the grain yield and quality of drip-irrigated rice are adversely affected. In this study, we investigated the effects of different irrigation strategies on the grain yield and quality of drip-irrigated rice using field experiments. Four irrigation treatments were studied: whole growing season flooding (FI), whole growing season normal drip irrigation (DI, soil relative moisture (RSM) was maintained in the range of 90-100%), pre-anthesis drip irrigation and post-anthesis water stress (SAF, the RSM was maintained in the range of 80-90% after anthesis), pre-anthesis drip irrigation, and post-anthesis flooding (FAF). The results showed that grain yield, harvest index, seed setting rate and 1000 grain weight in DI and SAF were significantly lower than in FI and FAF. These parameters were not significantly different between FI and FAF but were significantly greater in DI than in SAF. Compared with FI and FAF, the source capacity, source activity time, and sink activity of DI and SAF decreased, and the sink-source difference increased. The sink-source difference had a significant negative correlation with rice yield and 1000 grain weight. The activities of ADP-glucose pyrophosphorylase, starch branching enzyme, and amylopectin content in grains in the middle panicles of FAF were significantly higher than those of DI and SAF. SAF resulted in increased amylose/amylopectin ratio and total protein content in grains but decreased proportion of glutenin in total protein. Irrigation after anthesis of drip-irrigated rice narrowed the difference between sink sources in rice plants, increased the grain yield and harvest index by 29.2% and 11%, respectively, compared to DI, increased water productivity by 19% compared to FI, and improved the grain quality of drip-irrigated rice. This study highlights that post-anthesis sufficient irrigation of drip-irrigated rice plays a positive role in maintaining the source-sink balance. This study serves as a foundation for the development of more effective rice farming methods that conserve water, while increasing the grain yield and quality of drip-irrigated rice.

Crop yield estimation and irrigation scheduling optimization using a root-weighted soil water availability based water production function

The crop-water production function (CWPF) is widely used to quantitatively describe relationships between crop water deficit and yield, and evaluate the effects of different irrigation strategies in agro-hydrological models. In order to reasonably and reliably estimate crop yield and optimize irrigation scheduling , a novel CWPF was proposed by combining the plant water deficit index (PWDI), estimated based on root-weighted soil water availability, with a daily water sensitivity index derived from a sigmoidal cumulative function. Parameterized using data from a two-year winter wheat field lysimetric experiment conducted in the North China Plain and from a previously published two-year spring maize field drip irrigation experiment in Inner Mongolia, China, the CWPFs provided reasonable estimation of different crop yields with different water stress response characteristics under different field environments. Through coupling the genetic algorithm with the integrated simulations of soil water dynamics, PWDI and CWPF in the soil-wheat system, an optimization procedure was developed to determine PWDI threshold combinations to timely trigger irrigation according to pre-designed crop water deficit status. Crop yield and water use efficiency (WUE) of winter wheat were estimated and compared under different optimized constant and variable PWDI threshold combinations. In addition, the effects of climate change on the optimized variable PWDI threshold combinations were investigated using 38 years of historic meteorological data . The results showed that regulated deficit irrigation (RDI) with a variable threshold combination, in which the sensitivity characteristics to water deficit were considered for the crop at different growth stages, was superior to a constant threshold in enhancing crop yield and WUE. Irrespective of the number of irrigation events (1, 2, 3 or 4) during the growing season, the coefficients of variation (CV) of optimized PWDI thresholds for different combinations of irrigation sequence and events were not very large under the same kind of hydrological year (wet, normal or dry), with CV < 0.39 and a median of 0.21. When the mean (MN) of the optimized PWDI threshold combinations for different irrigation sequence and events was used to schedule RDI of winter wheat in terms of various hydrological years, up to 91% of the estimated relative yield was found to be higher than 90% of the corresponding maximum values. Therefore, the MN can be valuable in formulating rational irrigation management strategies of winter wheat to achieve relatively high yields with limited water under changing climatic conditions.

Optimizing drip irrigation with alternate use of fresh and brackish waters by analyzing salt stress: The experimental and simulation approaches

Drip irrigation with alternate use of fresh and brackish waters is an excellent irrigation strategy to overcome salt stress problems induced by brackish water. Understanding salt stresses in the soil profile and their relationship with crop growth is critical when optimizing irrigation strategies with alternate use of fresh and brackish waters. The HYDRUS (2D/3D) model was calibrated and validated using experimental data collected in 2019 and 2020, respectively. The calibrated model was then used to evaluate the effects of different irrigation strategies involving the use of only freshwater (FW) or brackish water (BW), or the alternative use of brackish and fresh waters (1B1F, one irrigation with brackish water and one with fresh water; 2B1F, two irrigations with brackish water and one with fresh water; and 3B1F, three irrigations with brackish water and one with fresh water) on the soil electrical conductivity (ECsw), salt stress, crop growth, and yield. In general, the model performed well, with the average RMSE, M RE , and R2 for ECsw of 0.12 dS m−1, 6.85%, and 0.97, respectively. The average ECsw in the 0–40 cm soil layer (the main root zone) showed large differences between different alternate irrigation strategies, increasing by 55.9% between FW and BW. There was a strong linear relationship between salt stress (ECsw of 3.4–11.8 dS m−1, SS) in the main corn root zone and salts introduced by irrigation water. The SS duration and area increased with the frequency of irrigations with brackish water, while the opposite was observed for the average desalination rate (DR) after irrigation during the entire growth stage. The SS duration was 90, 111, 115, 121, and 121 days for FW, 1B1F, 2B1F, 3B1F, and BW, respectively, while the corresponding values for the duration of high salt stress (ECsw of 7.6–11.8 dS m−1, HSS) were 4, 24, 32, 37, and 46 days, respectively, and the average DRs were 4.3%, 2.4%, 1.9%, 1.7%, and 0.8%, respectively. Average fractions of the SS and HSS areas to the main root zone area for BW increased by 5.3% and 26.6% compared with FW, respectively. When the HSS duration increased by 42 days from the FW to BW scenarios, corn yield, plant height, stem diameter, and leaf area index decreased by 8.8%, 10.4%, 17.7%, and 19.6%, respectively. Additionally, the quantitative relationship between SS and corn yield, i.e., a sensitivity function of the crop yield to soil water and salt stresses, was proposed based on HYDRUS (2D/3D) simulations. The 2B1F scenario can be recommended as the optimal strategy for the studied region, using most brackish water with only a 4% decrease in the corn yield.

Effects of Irrigation Strategy and Plastic Film Mulching on Soil N2O Emissions and Fruit Yields of Greenhouse Tomato

Agriculture is a major source of global greenhouse gas emissions. Approximately 1/3 of vegetables in China are produced in greenhouses. However, the effects of different irrigation strategies and plastic film (PF) mulching combinations on N2O emissions and tomato fruit yields in greenhouses are unclear. The aims of this study were to explore the effects of micro-sprinkler irrigation under plastic film (MSPF), drip irrigation under plastic film (DIPF) and micro-sprinkler irrigation (MSI) on the soil nutrients, enzyme activity, nirS-type denitrifying bacterial community, N2O emissions and fruit yields of tomato. The results showed that MSPF could improve the uniformity of soil water distribution and surface (0–40 cm) soil water content. Film mulching could increase soil temperature at depths of 5–25 cm. Both MSPF and DIPF increased microbial nitrogen, promoted the activity of rhizosphere soil urease and leucine aminopeptidase, changed the community of denitrifying bacteria, accelerated the turnover of soil nutrients and improved yield and water use efficiency. PF mulching had a greater impact on the nirS-type denitrifying bacterial community when compared to irrigation strategy. We conclude that MSPF can be used to configure commercially available installation and operation. The comprehensive benefit of MSPF treatment is that it is more profitable than that of DIPF.

Winter wheat root distribution with irrigation, planting methods, and nitrogen application

Soil water uptake is a function of root growth and distribution. Therefore, restrictions on root system growth may reduce water and nutrient uptake, which results in slower plant growth. The objective of this study was to determine the effects of different irrigation strategies, nitrogen application rates, and planting methods on the winter wheat root growth. The experimental factors included two irrigation strategies (variable alternate furrow irrigation defined as partial root-zone irrigation and ordinary furrow irrigation), two planting methods (in-furrow planting and on-ridge planting), and three nitrogen (N) application rates (0, 150, and 300 kg N ha−1) in 2015–2016 and 2016–2017 growing seasons. Results indicated that the in-furrow planting decreased mean root length density and root mass density (8% and 10%, respectively, in the fertilized treatments) compared to that obtained in the on-ridge planting. The partial root-zone irrigation reduced root length density by about 5% and 7% in the fertilized treatments compared to that obtained in full irrigation in the first and second year, respectively; however, these reductions were not statistically significant. Furthermore, the results implied that nitrogen fertilizer application increased root length density by 48% and 24% in the first and second year, respectively. Likely, root mass density increased by 32% and 5% in the first and second year, respectively. The exponential decaying relationship between root length density and soil depth indicated that the in-furrow planting with 300 kg N ha −1 produced the highest root density at the soil surface layer and reduced deep root penetration compared to the on-ridge planting and the other N treatments. Further analysis revealed that grain yield linearly correlated with root length density and root mass density in the first year. However, a polynomial (quadratic) relationship was obtained in the second year. Consequently, increasing the main root traits, including root length and root mass, enhanced winter wheat grain yield until it reached a threshold value. Higher values negatively affected grain yield, which might be due to allocating carbon to roots instead of grains.

Response and Modeling of Hybrid Maize Seed Vigor to Water Deficit at Different Growth Stages

Research is imperative to predict seed vigor of hybrid maize production under water deficit in arid areas. Field experiments were conducted in 2018 and 2019 in arid areas of northwestern China to investigate the effects of different irrigation strategies at various growth stages with drip irrigation under film mulching on grain yield, kernel weight, seed protein content, and seed vigor of hybrid maize (Zea mays L.). Water deficit at vegetative, flowering, and grain-filling stages was considered and a total of 16 irrigation treatments was applied. A total of 12 indices of germination percentage, germination index (GI), shoot length (SL), and root length (RL) under different germination conditions (standard germination and accelerated aging); electrical conductivity (EC) of the leachate; and activities of peroxidase, catalase, and superoxide dismutase in seeds were measured and analyzed using the combinational evaluation method (CEM). Furthermore, five water production functions (Blank, Stewart, Rao, Jensen, and Minhas) were used to predict seed vigor evaluated by CEM under water deficit. The results showed that leachate EC was higher under water deficit than that under sufficient irrigation. The SL, RL, and GI of different germination conditions increased under water deficit at the flowering stage. The Rao model was considered the best fitted model to predict the vigor of hybrid maize seeds under water deficit, and an appropriate water deficit at the flowering stage is recommended to ensure high seed vigor of hybrid maize production with drip irrigation under film mulching. Our findings would be useful for reducing crop water use while ensuring seed vigor for hybrid maize production in arid areas.

Soil drainage water and nutrient leaching in winter wheat field lysimeters under different management practices

The objective of this study was to investigate the effects of different irrigation strategies, planting methods and various nitrogen application rates on water and solutes transport under the root zone. Furthermore, Hydrus-1D model was used to simulate the drainage water and soil nutrient (N, K) leaching by the drainage water in the experimental treatments. Results indicated that variable alternate furrow irrigation (VAFI) decreased drainage water by a mean value of 30% compared with that obtained in full irrigation (OFI); whereas, precipitation played a significant role in increasing drainage water. About 60% and 80% of drainage water occurred due to rainfall in the full irrigation strategy in the first and second year, respectively, and most of the drainage water in VAFI strategy occurred due to precipitation as 90% for both years. Additionally, precipitation during the low growth stages of winter wheat (fall and winter) had noticeable influence on solute transport. On average, 75%, and 65% of leached nitrate, and potassium, respectively, occurred due to rainfall in OFI method; however, about 85% of leached nitrate, and potassium in VAFI strategy occurred due to rainfall events. Application of 150 kg N ha−1 decreased about 40% nitrate leaching below the root zone in comparison with that obtained in 300 kg N ha−1 without significant difference in crop yield. Hydrus-1D model reasonably simulated solute transport especially nitrate and potassium. Therefore, Hydrus-1D could be a successful tool for predicting N, and K transport and making proper management decisions to improving environmental problems.

Effect of Irrigation Strategies on Yield of Drip Irrigated Sunflower Oil and Fatty Acid Composition and its Economic Returns

A field trial was conducted to observe the effects of different irrigation strategies on the yield and the water use, oil content and marginal return of sunflower which was irrigated by means of a drip system during 2010 and 2011 under Cukurova condition of Turkey. The irrigation strategies include three irrigation intervals (A1: 25 mm; A2: 50 mm; A3: 75 mm of cumulative pan evaporation) and six water levels (WL) based upon the percentages of cumulative pan evaporation (WL1= 0.50, WL2= 0.75, WL3= 1.00 and WL4= 1.25). In addition, WL5= PRD50 and WL6= PRD75 treatments were evaluated. They obtained water from alternative laterals 50% and 75% of the WL3 treatment. Additionally, a nonirrigated treatment (NI) was included as control plot in the experiment. In each of the experimental years, the largest and the smallest average yields were acquired from the A2WL4 and NI treatments, respectively. The oil content and fatty acid composition were significantly affected by irrigation strategies. The oil content increased with the increasing amount of irrigation. Among all irrigation intervals, PRD-50 (WL5) treatment provided the largest water use efficiency (WUE) and irrigation water use efficiency (IWUE) values in both growing seasons. In order to attain higher yields and a generated the marginal return, A2WL4 irrigation regime is suggested for sunflower production in the Mediterranean region. A2WL3 water strategy is proposed for an acceptable marginal return in case of water shortage.

Assessing AquaCrop model to simulate soil water contents under semi arid climate of Central Tunisia

The objective of the present study was to preliminary calibrate and validate AquaCrop model based on crop conservative parameters from the literature for plant growth and water stress thresholds. In addition, physical soil characteristics, root growth, duration of plant stages and atmospheric demands were introduced according to field measurements. Based on this preliminary calibration, simulated water contents were compared to a measured data set of water contents retrieved from deficit and full irrigation treatments on a potato cropped field during an experimental year of 2015. Statistical indexes were computed and finally this performance in simulating water contents were validated under independent measurements carried out during an experiments campaign on the same field on 2014. Moreover, the paper presents the experimental protocol followed for soil characterization, considered as a milestone component for this soil water contents prediction. Results showed, that under the followed preliminary calibration, the model was able to simulate water contents (0v). In general, values of Root Mean Square Error were lower than 0.03 cm3.cm-3 representing the magnitude of error of the time domain reflectometry probe. Moreover values of Nash coffecients were close to 1 confirming the goodness of fit between measured and estimated water contents. Once assessed, the model could be used to study effects of different irrigation strategies on dynamic of water contents aiming to increase water use efficiency.

Effects of different irrigation strategies on the evolution of peat hydraulic properties during cultivation

The combined effects of root development and irrigation strategies on the physical and hydraulic properties of peat substrates were studied within a culture of Rosa × hybrida ‘Radrazz’ during five months when watering was managed in three different ways: (1) water potential always maintained at container capacity, (2) irrigation triggered when water potential reached -10 kPa or (3) -30 kPa. Root volume, total volume, air and water retention properties, saturated hydraulic conductivity, relative gas diffusivity, and wettability were measured at the beginning and then at the end of the experiment. The study showed important changes over time, mainly due to the hydric history, and the irrigation strategies leading to large modifications of pore size distribution and connectivity. Furthermore, the intensity of drying amplified the degradation of peat wettability, and altered the physical qualities of peat. However, positive effects of the root system were shown by limiting the decrease in wettability.

Effects of Different Irrigation Strategies on Soil Water, Salt, and Nitrate Nitrogen Transport

Abstract Intermittent irrigation has attracted much attention as a water-saving technology in arid and semi-arid regions. For understanding the effect of intermittent irrigation on water and solute storage varied from irrigation amount per time (IRA), irrigation application frequency (IRAF), irrigation intervals (IRI) and even soil texture (ST), intermittent irrigation experiment was carried out in 33 micro-plots in Inner Mongolia, China. The experiment results were used for the calibration and validation of HYDRUS-1D software. Then 3 ST (silty clay loam, silty loam, and silty clay), 5 IRA (2, 4, 6, 8, and 10 cm), 4 IRAF (2, 3, 4, and 5 times) and 4 IRI (1, 2, 3, and 4 days) were combined and total 240 scenarios were simulated by HYDRUS-1D. Analysis of variance (ANVOA) of simulated results indicated that ST, IRA, and IRAF had significant effect on salt and nitrate nitrogen (NO3 −-N) storage of 0-40 cm depth soil in intermittent irrigation while only ST affected soil water storage obviously. Furthermore, salt leaching percentage (SLP) and water use efficiency (WUE) of 0-40 cm depth were calculated and statistical prediction models for SLP were established based on the ANOVA using multiple regression analysis in each soil texture. Then constraint conditions of soil water storage (around field capacity), salt storage (smaller than 168 mg·cm−2), WUE (as large as possible) in 0-40 cm depth and total irrigation water amount (less than 25 cm) were proposed to find out the optimal intermittent irrigation strategies. Before sowing, the optimal irrigation strategy for silty clay loam soil was 6 cm IRA, 3 times IRAF, and 2 days IRI respectively. For silty loam and silty clay soils, IRA, IRAF, and IRI were 8 cm, 3 times, and 2 days respectively.

Quantifying the impact of irrigation on groundwater reserve and crop production – A case study in the North China Plain

The North China Plain (NCP) is one of the main grain production regions in China. However, the annual double cropping system of winter wheat and maize consumed a large amount of groundwater, has led to decline in groundwater table. For conservation of groundwater resource, deficit irrigation is promoted to reduce irrigation water use in recent years. This study combined process-based modeling and experimental data together to evaluate the effects of different irrigation strategies on crop production and groundwater table change for the past three decades in NCP. Data from a six year field trial (2006–2012) under four irrigation schedules and 28 year (1984–2012) field experiment under full irrigation was used to test the agricultural production systems simulator (APSIM) to simulate the responses of winter wheat and maize to different irrigation management. The results showed that APSIM model could well simulate the grain yield and water consumption of the double cropping system under the changing climate and management practices. Simulation results with four irrigation scenarios (critical stage irrigation (CI), minimum irrigation (MI), rainfed (RF) and full irrigation (FI)) from 1984 to 2012 showed that irrigation water use efficiency (IWUE) was highest under CI, although changing from FI would lead to reduction in average annual grain yield by 19.5%, 33.7%, and 58.8% under CI, MI and RF, respectively. Even the minimum irrigation strategy (MI—one irrigation for each crop) will result in continuous decline in the groundwater table, implying an inevitable future shift to alternative cropping systems like dryland wheat-maize system, single wheat or maize. Such change will likely result in lower crop productivity and increased inter-annual variability in crop yields, which will demand improved risk management strategies to minimize loss in bad year while maximize return in good years.

Effects of different irrigation methods on pepper yield and soilborne diseases incidence

In this study, the effect of different irrigation strategies and irrigation methods on yields and the incidence of wilt (Fusarium oxysporum) and root rot (Fusarium solani and Macrophomina phaseolina) diseases causing significant yield losses on field grown processing red pepper is determined. Experiments were carried out at Topcu Station of the Soil and Water Resources Research Institute of Tarsus in 2010 and 2011. Karaisali processing pepper (Capsicum annuum L.) was used in the experiments. Three furrows and five drip irrigation treatments were used in the study. The disease incidence rates were found 8.0-18.2% in furrow irrigation plots and 4.5-10.0% in drip irrigation plots in 2010, while it was 3.4-9.7% in furrow irrigation plots and 2.2-4.5% in drip irrigation plots in 2011. Pepper yields ranged from 3 416 to 4 417 kg da-1 and 3 376 to 4 779 kg da-1 in drip irrigated plots in 2010 and 2011, respectively. However, yields varied between 3 172-3 559 kg da-1 and 2 932-4 150 kg da-1 in furrow irrigated plots in 2010 and 2011 growing seasons.

Effect of different irrigation strategies on vine physiology, yield, grape composition and sensory profile of Sauvignon Blanc (&lt;em&gt;Vitis vinifera&lt;/em&gt; L.) in a cool climate area

&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Aim&lt;/strong&gt;: The impacts of partial root zone drying (PRD) and regulated deficit irrigation (RDI) on soil moisture, vine water status, yield components, fruit composition and wine sensory profile of Sauvignon blanc were studied in a cool climate region.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Methods and results&lt;/strong&gt;: Field experiments were conducted in a commercial Sauvignon blanc block in Ontario, Canada between 2006 and 2008. Treatments were: non-irrigated control, PRD, full irrigation [100% of crop evapotranspiration (ET&lt;sub&gt;c&lt;/sub&gt;)] and one level of RDI (25% ET&lt;sub&gt;c&lt;/sub&gt;). Treatments began immediately after fruit set and continued until the beginning of September. Reference evapotranspiration (ET&lt;sub&gt;o&lt;/sub&gt;) was calculated using the Penman–Monteith equation. Soil moisture and vine water status (leaf water potential and transpiration rate) in the PRD treatments were generally less than in 100% ET&lt;sub&gt;c&lt;/sub&gt; but higher than in non-irrigated and 25% ET&lt;sub&gt;c&lt;/sub&gt; treatments. Almost all treatments were different than non-irrigated vines in fruit composition and wine sensory attributes. RDI strategies were more consistent across vintages than the PRD treatments in their effect on vine water status, grape composition and sensory profiles.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Conclusions&lt;/strong&gt;: Use of RDI or PRD in cool climates during dry and warm years can improve grape composition. In very dry and hot seasons, like that of 2007, irrigation improved grape composition and wine aroma typicity. RDI enhanced fruity aroma attributes, which suggests that this could be a viable strategy to improve grape and wine quality in cool areas. However, due to high climatic variation over the period studied, no consistent pattern of irrigation effects was found for berry composition, suggesting that plant water status was not the only factor that controlled fruit and wine quality.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Significance and impact of the study&lt;/strong&gt;: To the best of our knowledge, this study is the first evaluation of PRD in a cool, humid climate, and highlights the potential value of both RDI and PRD irrigation techniques in cool climate regions, particularly during dry growing seasons.&lt;/p&gt;

Effect of different irrigation regimes on the quality attributes of monovarietal virgin olive oil from cv. “Cobrançosa”

The aim of this study was to assess the effect of different irrigation strategies in virgin olive oil (VOO) composition and quality of cv. Cobrancosa, integrated in a protected denomination of origin of “Azeite de Tras-os-Montes” in the Northeast of Portugal. Three irrigation treatments were applied: T2-full irrigation that received a seasonal water equivalent to 100% of estimated crop evapotranspiration (ET c ), T1-continuous deficit irrigation (30% ET c ) and T0- rainfed treatment. Data were collected from two consecutive crop years (2005-2006). Irrigation regimes had a minor effect on standard quality indices (free fatty acids, peroxide value, K 232 and K 270 ) of VOO and in fatty acid composition. Total polyphenols decreased up to treatment T2, and were strongly related to the water stress integral, suggesting that the effect of irrigation on this variable occurs along the crop season and not just during the oil accumulation phase. A strategy of continuous deficit irrigation with only 30% of maximum ETc may have an advantageous effect, as it increased oil yield to more than double that of rainfed conditions while VOO quality was similar.

Sensory analysis and volatile compounds of olive oil (cv. Cobrançosa) from different irrigation regimes

The aim of this study was to assess the effect of different irrigation strategies on the sensory quality of virgin olive oil (VOO) from the cv. “cobrancosa” integrated into a protected denomination of origin of “Azeite de Tras-os-Montes” in the Northeast of Portugal. Three irrigation treatments were applied: (T2)-full irrigation, which received a seasonal water equivalent of 100% of the estimated crop evapotranspiration (ET c ), (T1)-continuous deficit irrigation (30% ET c ) and (T0)- rainfed treatment. Data were collected from two consecutive crop years (2005-2006). Olive oil samples were analyzed for volatiles by GC-MS and the results compared with sensory evaluation data. Total volatile compounds tended to decrease with the amount of water applied. The characteristics pungent and bitter were more pronounced in olive oils from T0 and T1, which had higher polyphenolic concentrations, with a strong positive relationship with this variable and the bitter attribute. The Principal Components Analysis clearly separates the three olive oils from 2005, the driest year, and aggregates into a single group the three samples from 2006, suggesting no effect of irrigation on volatile compounds in years with a rainy spring and a marked effect in years with severe drought, suggesting that the effect of the trees’ water status on these variables occurs throughout the crop season and not just during the oil accumulation phase. In general, olive oil from the cv. Cobrancosa is more bitter than pungent and has a typical nutty sensory attribute shown by a strong positive relationship between benzaldehyde and the sensory notes of almonds and nuts.

Carbon retention in the soil–plant system under different irrigation regimes

Carbon (C) sequestration through irrigation management is a potential strategy to reduce C emissions from agriculture. Two experiments (Exps. I and II) were conducted to investigate the effects of different irrigation strategies on C retention in the soil–plant system in order to evaluate their environmental impacts. Tomato plants (Lycopersicon esculentum L., var. Cedrico) were grown in split-root pots in a climate-controlled glasshouse and were subjected to full irrigation (FI), deficit irrigation (DI) and alternate partial root-zone irrigation (PRI) at early fruiting stage. In Exp. I, each plant received 2.0 g chemical nitrogen (N), while in Exp. II, 1.6 g chemical N and maize residue containing 0.4 g organic N were applied into the pot. The results showed that, in both experiments, the concentration and the amount of total C in the soil were lower in FI and PRI as compared to DI, presumably due to a greater microbial activity in the two treatments; particularly the PRI induced drying and wetting cycles of the soils may cause an increase of microbial activities and respiration rate, which could lead to more C losses from the soil. However, in both experiments the total C concentration in the PRI plants was the highest as compared with the FI and DI plants, and this was seemingly due to improved plant N nutrition under the PRI treatment. Consequently, the total amount of C retained in the soil–plant system was highest in the FI and was similar, but lower, for the PRI and DI. The different N input in the two experiments might have affected the C retention in the soil and in the plant biomass. Nevertheless, with a same degree of water saving, PRI was superior to DI in terms of enhancing C concentration in the plant biomass, which might have contributed to a better fruit quality in tomatoes as reported by Zegbe et al., 2004, Zegbe et al., 2006.