Complete Irrigation Research Articles

Effects of Enhanced UV-B Radiation and Drought Stress on Photosynthetic Performance of Lettuce (Lactuca sativa L. Romaine) Plants

Aims: The aim of the present study was to investigate some biochemical changes in field grown lettuce (Lactuca sativa L. cv Romaine) plants in terms of importance of the accumulation of anthocyanins, flavonoids and photosynthetic pigments as well as photosynthetic limitations which changed during exposure of plants to drought stress and UV-B radiation in order to circumvent the deleterious effects of these Stresses. Place and Duration of Study: The experiment was conducted under filed conditions from November 2012 to January 2013, at the Agricultural Research Center, KAU. Methodology: The experimental design was a factorial arrangement in randomized complete blocks with four replicates. The first factor was UV-B (300 nm). The second factor was irrigation regime (complete irrigation to field capacity and limited irrigation. Gas exchange measurements were carried out using a LI-6200 portable IRGA. Chlorophyll fluorescence of Fv/Fm was measured by PAM 2000 fluorometer. Biochemical analyses and antioxidant enzymes assays were performed according to the appropriate methods. Results: Exposure of lettuce plants to enhanced UV-B radiation and drought stresses (DS) negatively and significantly affected the process of photosynthesis including CO2 assimilation (PN), stomatal conductance to water vapour (gs) and transpiration rate (E). However, the amplitude of the effects of both stressors was dependent on the interactions. This resulted in alleviation of the negative effect of drought on photosynthesis and transpiration by UV-B radiation as the water stress intensified. Intercellular CO2 (Ci) concentration was only reduced due to water stress compared to control plants. The maximum efficiency of photosystem II (Fv/Fm) was not affected by UV-B radiation stress but reduced by drought. There was an increase in the activities of some antioxidant due to both stresses when applied singly and in combination UV-B irradiation increased the contents of the UV-B absorbing compounds (carotenoids, soluble phenols, anthocyanins), while drought stress caused a notable increase in free proline content. Increase in content of Proline may be the drought-induced factor which plays a protective role in response to UV-B. Conclusion: UV-B radiation provoked in general more severe damage, evaluated as changes in the amounts of stress markers, than DS, when applied separately. Under multiple stress conditions, each of the stress factors seems to bring out some adaptive effects to reduce the damage experienced by plants caused by the other one. DS can induce accumulation of UV-B absorbing compounds (flavonoids, carotenoids and soluble phenols), which is likely to offer some increased protection from UV-B.

Regulated Deficit Irrigation based upon optimum water status improves phenolic composition in Monastrell grapes and wines

The effects of three deficit irrigation strategies pre and post-véraison, on soil–plant water status and their influence on leaf area, cluster microclimate, fruit growth, yield and berry and wine quality were evaluated for three years (2009–2011) in field-grown Monastrell grapevines under semiarid conditions in South-Eastern (SE) Spain. Three treatments were applied: a Sustained Deficit Irrigated treatment (SDI) was irrigated at 40% of the Crop Evapotranspiration (ETc) throughout the orchard cycle, 211mmyear−1; a Regulated Deficit Irrigation treatment 1 (RDI-1threholds) received 30% ETc (2009 and 2010) or 20% ETc (2011) from budburst to fruit set. From fruit set to harvest the irrigation was established by maintaining an average mid-day stem water potential (Ψs) within the range −1.2>Ψs≥−1.3MPa and from véraison to harvest within the range −1.3>Ψs>−1.4MPa, 106mmyear−1); And a Regulated Deficit Irrigation treatment 2 (RDI-2cutoff-thresholds) received 20% ETc (2009 and 2010) or 10% ETc (2011) from budburst to fruit set and from fruit set to véraison an irrigation cut-off was applied. Then, from véraison to harvest, an irrigation recovery was applied based on maintaining mid-day Ψs within the range of Ψs proposed: −1.3>Ψs>−1.4MPa (similar to RDI-1), 76mmyear−1). A recovery of irrigation at 40% ETc was used in all treatments from harvest to leaf fall. The RDI-1thresholds strategy, which applied moderate water stress during pre and post-véraison, saved water, reduced vine vigor and vegetative development, controlled yield, improved cluster microclimate, maintained similar or even higher sugar content in the berries and improved the phenolic composition of Monastrell grapes and wines compared to the SDI and RDI-2 strategies. RDI-1thresholds vines increased color intensity, sugar and total anthocyanins in the berries, and color intensity, alcohol content, concentration of polyphenols and total anthocyanins and flavonols in the wines. In contrast, in the RDI-2cutoff-thresholds strategy, which had complete irrigation cut-off during the pre-véraison period (from fruit set to véraison) substantially decreased lateral shoot and berry growth at véraison, and also excessively reduced photosynthetic activity, water status pre-véraison and the resilience of photosynthesis during véraison- early ripening period, which was not beneficial from a physiological and agronomical point of view for Monastrell grapevines in SE Spain.

Efficacy of irrigation systems on penetration of sodium hypochlorite to working length and to simulated uninstrumented areas in oval shaped root canals

To assess the ability of sodium hypochlorite (NaOCl) to penetrate simulated lateral canals and to reach working length (WL) when using the self-adjusting file (SAF). Seventy single-rooted teeth with oval-shaped canals were used. Upon access, presence of a single canal was confirmed by direct visualization under a dental-operating microscope. Canal length and patency were obtained using a size 10 K-file and root length standardized to 18 mm. Pre-enlargement was restricted to the coronal one-third. The apical size of each canal was gauged at WL and samples larger than size 30 were excluded. Canals were instrumented for 5 min using the SAF system while delivering a total of 20 mL of 5.25% NaOCl and 5 mL of 17% EDTA. Then, the apical diameters were standardized to size 35 using hand files. Four hundred and twenty simulated lateral canals were then created during the clearing process and roots coated with wax to create a closed system. All samples were then cleared and randomly assigned to four experimental groups: 1 (n = 15) positive pressure; 2 (n = 15) SAF without pecking motion; 3 (n = 15) SAF with pecking motion; 4 (n = 15) apical negative pressure (ANP) irrigation and (n = 10) control groups. Samples were scored on the basis of the ability of the contrast solution to reach WL and permeate into the simulated lateral canals to at least 50% of the total length. The Kruskal-Wallis test was used to analyse irrigant penetration and the Tukey test to determine statistical differences between groups (P < 0.05). All samples irrigated with ANP were associated with irrigant penetration to WL (Table 1). The differences between group 4 (ANP) and all other groups were significant in penetration to WL (P < 0.05). The pecking motion allowed for further penetration of the irrigant when using the SAF system but failed to irrigate at WL. None of the experimental groups demonstrated predictable irrigation of simulated lateral canals. In this laboratory model, ANP was the only delivery system capable of irrigating consistently to full WL. None of the systems tested produced complete irrigation in artificial lateral canals.

English

In order to evaluate drought tolerance indices of lentil cultivars in the Ardabil region, a factorial experiment based on randomized complete block design with three replications was arranged at the Agricultural Research Station of Islamic Azad University, Ardabil branch, Ardabil, Iran, in 2010. The factors included two conditions of planting levels (irrigation and non-irrigation) and five lentil cultivars (ILL 1180, ILL 1324, ILL 1251, ILL1237, and native cultivars). Irrigation included complete irrigation from planting until maturity and non-irrigation from seed emergence until harvesting. &nbsp;The results showed that the length of vegetative and reproductive periods, total number of pod and seed per plant, 100-seed weight, seed yield and harvest index were of higher rates under irrigation than the stress (non-irrigation). Also, it was found that ILL 1180 and ILL 1324 cultivars possessed the highest and lowest values for all traits, respectively. Yield loss of the ILL 1180 under stress, was about 308.22 kg/ha (23.31%) than the normal conditions. This value for the ILL 1324 was approximately 448.53 kg/ha (35.51%). Also, ILL 1180 showed the lowest tolerance against stress (TOL) and stress susceptibility index (SSI) and the highest mean productivity (MP), geometric mean productivity (GMP) and stress tolerance index (STI) indices. ILL 1324 possessed the highest TOL, SSI and STI and ILL1237 showed the lowest MP and GMP indices. So, ILL1180 and ILL1251 were the superior cultivars under both conditions in terms of high yield and tolerance against drought stress. ILL1237 was distinguished as the most susceptible cultivar as well. &nbsp; Key words:&nbsp;Lentil, yield, normal and stress conditions, drought tolerance index.

Effect of UV Radiation and Evaluated CO2 on Morphological Traits, Yield and Yield Components of Canola (Brassica napus L.) Grown under Water Deficit Stress

In this study, we studied the combined effects of UV radiation, CO2 and water stress on the morphological traits, yield and yield components of canola (Brassica napus cv. ‘Okapi’ and ‘Talaye’) under twelve growth conditions: complete irrigation with ambient CO2 with UV-A (control), complete irrigation with ambient CO2 with UV-B, complete irrigation with ambient CO2 with UV-C, limited irrigation with ambient CO2 with UV-A, limited irrigation with ambient CO2 with UV-B, limited irrigation with ambient CO2 with UV-C, complete irrigation with elevated CO2 with UV-A, complete irrigation with elevated CO2 with UV-B, complete irrigation with elevated CO2 with UV-C, limited irrigation with elevated CO2 with UV-A, limited irrigation with elevated CO2 with UV-B and limited irrigation with elevated CO2 with UV-C. The results showed that water stress significantly decreased all of traits except for the oil percentage. Additionally, an elevated level of CO2 significantly increased the final yield, 1000-seed weight, oil yield, plant height, specific leaf area and number of branches per plant, whereas UV radiation decreased all of the traits in this experiment. Elevated CO2 ameliorated the adverse effects of UV radiation in the final yield, seed weight, oil percentage, oil yield, plant height, specific leaf area and number of branches per plant. This study showed that elevated CO2 can partially ameliorate some of the adverse effects of UV radiation in canola plants. Furthermore, in this study, we observed that the increase in the yield was due to the increase in the seed weight and number of branches caused by elevated CO2 in canola plants. In addition, the maximum yield was obtained from the ‘Talaye’ cultivar under conditions of sunlight, full irrigation and elevated CO2.

EFFECTS OF PLANTING DATE AND IRRIGATION DATE ON QUALITATIVE AND QUANTITATIVE CHARACTERISTICS OF CUMIN (CUMINUM CYMINUM L.)

Cumin is one of the most important drug plants that has many uses in food and drug technology. In order to investigate its drought resistance and determine the best date of planting, this experiment has been conducted in the form of split plot RCB design with 3 replications. Treatments were date of planting (main plot) at 4 levels (25 th Nov. D1, 27 th Dec. D2, 19 th Feb. D3 and 19 th Mar. D4) and date of irrigation (sub plot) at 4 levels (complete irrigation 11, twice irrigation (seed germination and stem elongation) I2, twice irrigation (seed germination and flowering) I3 and twice irrigation (seed germination and seed formation) I4) in 2007-2008. Traits under study were percent of essential oil, 1000 seed weight, no. of umbels per plant, seed no. per umbels, lateral shoots, final height, biological yield, seed yield and harvest index. Date of planting had significant effect on essential oil percent, 1000 seeds weight, no of seed per umbels, no of umbels per plant and final height at 1 % level. Also, irrigation date had significant effect on no. umbels per plant, no. of lateral shoots, biological yield and seed yield at 5% level. Interaction of planting date and irrigation date were significant for no. of lateral shoots, biological yield, seed yield and biomass at 5% level. Mean comparison had been done by Duncan's test that showed there were significant differences among means of traits at different planting date treatments, except harvest index at 5% level. Also, there were significant differences among means of traits at different date of irrigation treatments for essence percent, 1000 seeds weight, no. of umbels per plant, final height and harvest index. Also, there were significant differences among interaction of date of planting and date of irrigation for all traits at 5% level. The highest essential oil percent was related to D2I2 treatment equal to 1.8%. Also, the highest seed yield and biological yield occurred at D2I1 treatment. Then the best treatment was 27 th December planting date with complete irrigation.

Effect of Zeolite and Foliar Application of Selenium on Growth, Yield and Yield Component of Three Canola Cultivar under Conditions of Late Season Drought Stress

AbstractIn order to study effect of zeolite soil application and selenium foliar application on growth, yield and yield components of three canola cultivar under conditions of late season drought stress an experiment was conducted in two growing season in 2006 and 2007. Site study was field of Seed and Plant Improvement Institute, Karaj, Iran. The experimental design was a Randomized Complete Block arrangement in factorial split plot with three replications. Irrigation factors were chosen at two levels, included complete irrigation and irrigation holding at stem elongation stage. Zeolite was used at two levels, non application and 10 ton per hectare. Also selenium was sprayed at three concentrations, 0, 15 and 30 gr per liter from sodium selenate. These treatments were randomized in main plots while three canola cultivars (‘Zarfam’, ‘Okapi’ and ‘Sarigol’) were randomized in sub plots. The results showed that, main effects of different irrigation levels have significant effect on all traits and drought stress decreased significantly all traits. Foliar application of selenium had significant and additive effect on plant height, number of pods in plant, number of seeds in pod, seed yield, biological yield, harvest index and oil yield. There was significant difference between zeolite application and non application on all traits except oil percent and harvest index. It was shown that canola cultivars were different in all of studied traits. Comparison of means showed that, four critical traits that is seed yield, biological yield, harvest index and oil yield were affected by experimental treatments. Different cultivars have different responses under unlike conditions inside upon traits. Under different treatment conditions especially drought stress, zeolite and selenium application have positive and significant effect on traits related to yield. In finally, zeolite and selenium application in dry lands that are exposure to late season drought stress can be helpful for yield improvement and prevent of decreasing yield.

Possible utilization of high-salinity waters and application of low amounts of water for production of the halophyte Kochia scoparia as alternative fodder in saline agroecosystems

Production of halophytes using saline waters and soils and feeding them to livestock is one of the most sustainable methods of conservation in desert ecosystems, in addition to accomplishing food production for the people living in these areas. Therefore, to study the possibility of irrigating Kochia ( Kochia scoparia L. Schrad) with minimum quantities of highly saline water for use as a fodder crop in arid environments stretching across saline waters, two experiments were carried out in the Research Farm of the Ferdowsi University of Mashhad, Iran. In the salinity experiments, two populations of Kochia, including the Sabzevar and Indian genotypes, were irrigated with ground water having electrical conductivity (EC) of 5, 15, and 20 dS m −1 . In the irrigation-treatment experiments, two local populations of Kochia, including Sabzevar and Borujerd, were subjected to four irrigation regimes as follows: complete irrigation (100%), 80%, 60%, and 40% of the water requirements using a saline ground water with EC = 5 dS m −1 . Because, the Indian genotype is preferred as an ornamental plant , it is not suitable for increased dry-matter production under high-salinity irrigation water compared to the local genotype (Sabzevar), which is suitable for forage. The Sabzevar genotype produced a large amount of dry matter (7530 kg ha −1 ), even when irrigated with 20 dS m −1 saline water. The best time for harvesting Kochia for fresh feeding is at the end of flowering (88 days after sowing or DAS), when the biomass is relatively high (6500 kg ha −1 ) and the leaf-to-shoot ratio, as a quality index, is approximately 50%. The highest green-area index was observed at 15 dS m −1 and decreased at high levels of salinity. Photosynthesis and transpiration rate did not decline significantly with increasing external salinity four weeks after salinization , but increased in both genotypes at 15 dS m −1 , indicating that the salinity-tolerance threshold of Kochia for both photosynthesis and transpiration reduction is above this salinity level. The Indian genotype also showed a very low seed yield (210 kg ha −1 ) at low levels of salinity, whereas Sabzevar produced 1120 kg ha −1 seed under the same conditions. Different irrigation regimes had a significant effect on the biomass and seed production of Kochia. The highest forage yield was obtained from complete irrigation, with 11.1 Mg ha −1 dry material. Sabzevar local population represented a better performance in terms of all characteristics, except accumulation of inflorescence dry matter, and no significant effects were recorded. In conclusion, Kochia's high foliage production capacity in the presence of salinity and limited irrigation make this plant suitable for use as an alternative forage crop in harsh environmental conditions. There is a wide range of intraspecific variation in K. scoparia, but more investigation is needed to introduce it as a cash crop.

Economic analysis of navel orange cv. ‘Lane late’ grown on two different drought-tolerant rootstocks under deficit irrigation in South-eastern Spain

Abstract During a three-year period, we evaluated the profitability of a deficit-irrigation (DI) treatment in mature ‘Lane late’ navel orange (Citrus sinensis (L.) Osb.) trees grafted on two different drought-tolerant rootstocks, ‘Cleopatra’ mandarin (Citrus reshni Hort. ex Tanaka) and ‘Carrizo’ citrange (C. sinensis (L.) Osb. × Poncirus trifoliata L. Raf.). The irrigation strategies for each rootstock were a control treatment, irrigated at 100% crop evapotranspiration (ETc) during the entire season, and a DI, irrigated at 100% ETc except during phase I (fruit set) and phase III (fruit maturation) of fruit growth, when complete irrigation cut-off was applied. The main difference found was between rootstocks, orchards of ‘Carrizo’ being 39% more profitable than those of ‘Cleopatra’ due to the greater yield and fruit size and higher price (0.02 € kg−1) for trees on ‘Carrizo’. The application of the DI treatment increased the profit for ‘Carrizo’ since the decrease in pruning costs was greater than the reduction of incomes. The profit of ‘Cleopatra’ under DI decreased due to yield reduction. The variable and fixed operating costs during the growth cycle were decreased by the DI treatment, with a reduction of fertiliser (40%), water applied (30%) and electricity consumed (30%) compared with the control. In addition, in ‘Carrizo’, DI decreased the pruning (16%), machinery (11%) and phytosanitary products (9%) costs as a result of the reduction of the canopy growth. From these results, we conclude that, with similar crop management, orchards of ‘Lane late’ navel orange on ‘Carrizo’ rootstock were more profitable than those on ‘Cleopatra’ under deficit-irrigation conditions.

Effect of Preharvest Deficit Irrigation on Second Crop Watermelon Grown in an Extremely Hot Climate

As a second crop, watermelons (Citrullus vulgaris, Crimson sweet) were grown in 2003 and 2004 in the Sanliurfa-Harran Plain in southeastern Turkey to determine the effect of preharvest water stress on fruit yield, quality (i.e., soluble solids contents and fruit size), leaf temperature, and some other physiological parameters. Preharvest drip irrigation treatments included (1) complete irrigation cutoff, dry (D); (2) full irrigation based on replenishment of soil water depleted from 0 to 90 cm soil profile (C); (3) 75% full irrigation (IR1); (4) 50% full irrigation (IR2); and (5) 25% full irrigation (IR3) with 3-day irrigation interval. Treatment plots received the same level of irrigation water until the fruit formation stage, except for Treatment D. Then, different water stress levels were imposed on treatment plots. Irrigation water applied to the five respective treatments were 636, 511, 395, 245, and 120 mm in 2003 and 648, 516, 403, 252, and 127 mm in 2004. Results indicated that fruit yield was sig...

Dual Irrigation Technology (DIT) Under Surface Irrigation System

In the dual irrigation technology (DIT), irrigation process is divided into two stages. In the first stage saline water is added as a part of irrigation water requirements , then good quality irrigation water is supplied in the second stage to complete irrigation water requirements. Piston flow may accurse in the soil because the time interval between two stages as short as possible , so the water content is greater than field capacity . Piston flow leaches the saline water that used in the firs stage of (DIT) under the root zone depth, so it is minimize the salinity effects of that water. Drainage water of 6 ds/m and Euphrates river water (1ds/m) are used to irrigate corn under furrow irrigation system with (DIT) at Ramady city in Iraq. Advance face in the furrow completes from drainage water , then second stage of (DIT) using river water . The experiment results summarized in the high relative yield (more than 95%) and saving about third quantity of fresh irrigation water. No significant differences in the salinity effects at the upper two thirds of the root zone depth compared with some furrows irrigated by river water only . Salinity effects at the lower third decrease as the distance from the upstream of the furrow increase, logarithmic relation between salinity effect and furrow length is proposed Key words: Dual Irrigation , saline irrigation water , water quality

Response of sweet orange cv ‘Lane late’ to deficit irrigation in two rootstocks. I: water relations, leaf gas exchange and vegetative growth

The influence of a deficit-irrigation (DI) strategy on soil–plant water relations and gas exchange activity was analysed during a 3-year period in mature ‘Lane late’ (Citrus sinensis (L.) Osb.) citrus trees grafted on two different rootstocks, ‘Cleopatra’ mandarin (Citrus reshni Hort. ex Tanaka ) and ‘Carrizo’ citrange (C. sinensis L., Osbeck × Poncirus trifoliata L.). Two treatments were applied for each rootstock: a control treatment, irrigated at 100% ETc (crop evapotranspiration) during the entire season, and a DI treatment, irrigated at 100% ETc, except during Phase I (cell division) and Phase III (ripening and harvest) of fruit growth, when complete irrigation cut-off was applied. Under soil water deficit, the seasonal variations of soil water content suggested that ‘Cleopatra’ mandarin had a better root efficiency for soil water extraction than ‘Carrizo’ citrange. Moreover, in all years, trees on ‘Cleopatra’ reached a lower water-stress level (midday xylem water potential values (Ψmd) > −2 MPa), maintaining a better plant water status during the water-stress periods than trees on ‘Carrizo’ (Ψmd < −2 MPa). Similarly, net CO2 assimilation rate (A) was higher in trees on ‘Cleopatra’ during the water-stress periods. In addition, the better plant water status in trees on ‘Cleopatra’ under DI conditions stimulated a greater vegetative growth compared to trees on ‘Carrizo’. From a physiological point of view, ‘Cleopatra’ mandarin was more tolerant of severe water stress (applied in Phases I and III of fruit growth) than ‘Carrizo’ citrange.

An oxygen embolism after hydrogen peroxide scalp infiltration

Complications due to the application of hydrogen peroxide to semiclosed spaces are well known. We present the first report of gas embolism following unnoticed H2O2 infiltration of the scalp. A 7-month-old girl with a medical history of uncontrolled gelastic seizures was scheduled for subfrontal resection of a giant hypothalamic hamartoma. Preoperative laboratory data, chest x-ray films, and electrocardiograms revealed nothing abnormal. Intraoperative monitoring included an electrocardiogram, invasive blood pressure, central venous pressure, pulse oximetry, capnography, and urine output. Anesthesia was induced with fentanyl and propofol and maintained with 60% nitrous oxide and 0.5% isoflurane in O2. The patient was placed supine and a bicoronal incision was marked. Following subcutaneous infiltration and before the skin incision was accomplished, the patient became hemodynamically unstable. Endtidal CO2 tension dropped to 20 mm Hg followed by a sudden decrease in systolic arterial blood pressure to 50 mm Hg. The heart rate decreased to 80 bpm and the O2 saturation fell from 99 to 85%. This situation required intensive cardiovascular support, including intravenous epinephrine and ventilation with 100% O2. The anesthetic equipment was checked and no malfunction was found. An air embolism was suspected on a clinical basis. Five ml of air was aspirated through the central line. The patient’s condition gradually improved but the surgical procedure was not continued. In that moment, the nurse assistant realized that she had filled the infiltration syringe with H2O2 instead of normal saline. An emergency computerized tomography (CT) scan was obtained to rule out any intracranial complication. The CT scan verified the presence of air in the subcutaneous tissue (Fig. 1). The patient recovered with no deficit and the surgery was successful 2 weeks later. Hydrogen peroxide is known to decompose in water and O2 on contact with organic tissue when abundant catalase is present. Some authors believe that liberated O2 mechanically removes contaminants, has a germicidal effect, and causes vasoconstriction, thus facilitating hemostasis;4 however, no convincing evidence in the literature supports this statement. The germicidal effect of H2O2 is frequently overrated, and its chief value is probably limited to cleansing wounds in which the effervescence caused by O2 release may remove tissue debris from inaccessible regions.3 The amount of suddenly liberated O2 can be large enough to cause serious hemodynamic consequences because 1 ml of 3% H2O2 can release 10 ml of O2.2 There are sporadic reports of O2 embolism following irrigation of the surgical field with H2O2 during neurosurgical procedures such as cervical spine surgery and lumbar discectomy.1,4 Infiltration of a closed space can be particularly hazardous because the pressure gradient generated may be immense. Therefore, it has been suggested that the use of H2O2 be strictly limited to clearly open wounds for which no possibility of gas entrapment can occur.5 In our patient, complete skin opening and profuse irrigation with saline would have probably helped to control O2 embolism by decreasing the pressure gradient and clearing out the H2O2.

Behavior of arthroscopic irrigation systems

In the literature, no consensus exists about optimal irrigation of joints during arthroscopic operations. The goal of this paper is to study the behavior of irrigation systems resulting in the proposal of guidelines for optimal irrigation. To this end, optimal irrigation is defined as the steady state of irrigation of a joint in which a sufficient positive intra-articular pressure and a sufficient flow are maintained. A model of the complete irrigation system was created to schematically elucidate the behavior of pump systems. Additionally, clinical experiments were performed during arthroscopic knee operations in which the pressure at different locations and the irrigation flow were measured. The combination of model prediction and clinical results could well be used to derive guidelines, since the clinical results, which showed considerable variation, were used to verify the model, and the model could be used to explain the typical trends. The main findings are twofold the set pressure is always higher than the intra-articular pressure, and the scope-sheath combination has a significant influence on irrigation control, because of its large restriction. Based on the results, we advice to increase the set pressure during active suction, and to include the sheath-scope combination in the control loop.

Fertigation guidelines for furrow irrigation

A mathematical model was developed to simulate the application efficiency and uniformity of water-soluble fertilizers through furrow irrigation. The model simulates solute mass balance and transport for one-dimensional unsteady flow during the advance and post-advance phases of a furrow irrigation event. The model was programmed to determine the best timing and duration of fertilizer injection using two performance indices: solute application efficiency and solute application uniformity. The results from the model were compared with two sets of field data and were found to be in close agreement in terms of advance trajectories and surface water solute concentrations. Nearly 50,000 simulations were performed with the model and the results were analyzed in terms of best injection start and end times for fertilizer application efficiency and uniformity. It was found that the best injection duration time was from 5 to 15% of the time of cutoff for a complete irrigation. Most of the cases showed that the injection should take place in a relatively short time span, and at a relatively high injection rate.

Optimization model for automated surge irrigation

A surge flow model has been developed after extensive experimentation in TNAU campus with different practical combinations of furrow size, length and gradients coupled with non-erosive as well as non-silting ranges of furrow inflow discharges for selected surge cycle ratios and number of surges to complete irrigation to predict the water front advance time under automated surge flow. The model was validated in respect of water front advance times and water distribution efficiencies in order to optimize the dimensional combinations of long furrow layouts coupled with automatic surge mode of irrigation. A user friendly computer software also was developed based on the model for interactive use by the customer.

Use of the modified atmometer to estimate reference evapotranspiration in Mediterranean environments

Reference crop evapotranspiration (ET 0) estimates on the basis of FAO recommended methodology require the knowledge of several meteorological data. An alternative approach is the use of the modified atmometer which reduces the work and the complexity associated with ET-based irrigation scheduling. To establish relationships between Penman Monteith (PM), atmometer and Class ‘A’ pan ET 0 in Mediterranean environments, field tests were carried out during five irrigation seasons in different east and west coast sites of southern Italy. In all sites, high values of the correlation coefficient were found when comparing daily estimates of atmometer versus PM ET 0. Scattering of experimental data was the result of atmometer readings taken manually. Linear regression models yielded intercept coefficients which did not differ from zero, in any of the sites. A unique relationship could be established between atmometer and PM when data from all sites were pooled, providing a slope coefficient of 1.034. When comparing with a high resolution weighing lysimeter across a complete irrigation season, a slope not different from unity was found. Comparisons with Class ‘A’ mean weekly ET 0 during two consecutive irrigation season, indicated a slight underestimation of pan ET 0 by the atmometer. On the basis of experimental evidence, atmometer may be used for reliable ET 0 estimates under Mediterranean conditions, at both the farm and the extension level, whenever standard meteorological data are not available.

Effects of preharvest drip-irrigation scheduling on strawberry yield, quality and growth

Strawberry (Fragaria × ananassa Duch) cultivars, Oso Grande and Camarosa were grown in the field from July 1999 to May 2000 in order to investigate the effectiveness of preharvest drip-irrigation management on fruit yield, quality (i.e. soluble dry matter, fruit size), leaf macro-nutrient composition and normal growth parameters. All plots were irrigated uniformly until 2 weeks before harvest. Differential treatments were then imposed ranging from a complete cut-off of irrigation to full irrigation through the harvest period. Preharvest drip-irrigation management treatments were (i) complete irrigation cut-off, dry (D), (ii) normal irrigation based on class A pan and percentage cover (C), (iii) 75% of normal irrigation, C (IR1), (iv) 50% of normal irrigation, C (IR2), and (v) 25% of normal irrigation, C (IR3). Normal irrigation (control, C) was created by irrigating plants once every 2 days at 100% A pan (Epan) evaporation. No irrigation (D) and IR3 treatments caused reductions in most parameters measured, except water-soluble dry matter concentrations (SDM) in fruit compared with other treatments. There were no significant differences between C, IR1, and IR2 treatments in normal growth parameters or leaf nutrient composition. Fruit size and SDM were both significantly affected by late-season irrigation management; individual fruit weight was significantly reduced and SDM increased even in the IR2 and IR3 treatments compared with control values. Fruit yield was not affected significantly by reduced water application except in the D treatment. These results clearly indicate that reduced preharvest irrigation was partially detrimental; a small reduction in irrigation (IR1) had little or no effect but 50% or less of normal irrigation, while not reducing overall fruit yield, resulted in smaller fruits.

A computer model for design and evaluation of surge flow furrow irrigation systems

Successful performance of Surge irrigation system depends chiefly on the design of Surge Cycle Timing parameters and prediction of the net Waterfront Advance times to reach the furrow tailends within the stipulated duration of irrigation. Extensive expermentation with different practical combinations of furrow inflow rates, furrow sizes, length and gradients for selected Surge Cycle Ratios and Numebr of Surges to complete irrigation has resulted in the development of a comprehensive computer model entitled as Surgemode. Validation of the model surgemode has also revealed that the predicted and the observed values of net waterfront advance times to reach furrow tailends lie in an acceptable range of Sto10% deviation while those of the soil moisture distribution efficiency lic in a range of 3108%, making the developed model reliable for design and pre-evaluation of surge irrigation systems to suit the conditions prescribed in the text

Discussion and Closure: Complete Hydrodynamic Border-Strip Irrigation Model

Discussion and Closure: Complete Hydrodynamic Border-Strip Irrigation Model