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1.
One-year-old carob (Ceratonia siliqua L.) rootstock was grown in fertilised substrate to evaluate the effects of NaCl salinity stress. The experiment consisted of seven treatments with different concentrations of NaCl in the irrigation water: 0 (control), 15, 30, 40, 80, 120 and 240 (mmol L−1), equivalent to electrical conductivities of 0.0, 1.5, 2.9, 3.9, 7.5, 10.9 and 20.6 dS m−1, respectively. Several growth parameters were measured throughout the experimental period. At the end of the experiment, pH, extractable P and K, and the electrical conductivity of the substrate were assessed in each salinity level. On the same date, the mineral composition of the leaves was compared. The carob rootstock tolerated 13.4 dS m−1 for a period of 30 days but after 60 days the limit of tolerance was only 6.8 dS m−1. Salt tolerance indexes were 12.8 and 4.5 for 30 and 60 days, respectively. This tolerance to salinity resulted from the ability to function with concentrations of Cl and Na+ in leaves up to 24.0 and 8.5 g kg−1, respectively. Biomass allocation to shoots and roots was similar in all treatments, but after 40 days the number of leaves was reduced, particularly at the larger concentrations (120 and 240 mmol NaCl L−1). Leaves of plants irrigated with 240 mmol NaCl L−1 became chlorotic after 30 days exposure. However, concentrations of N, P, Mg and Zn in leaves were not affected significantly (P > 0.05) by salinity. Apparently, K+ and Ca2+ were the key nutrients affected in the response of carob rootstocks to salinity. Plants grown with 80 and 120 mmol L−1 of NaCl contained the greatest K+ concentration. Na+/K+ increased with salinity, due to an elevated Na+ content but K+ uptake was also enhanced, which alleviated some Na+ stress. Ca2+ concentration in leaves was not reduced under salinity. Salinization of irrigation water and subsequent impacts on agricultural soils are now common problems in the Mediterranean region. Under such conditions, carob seems to be a salt as well as a drought tolerant species.  相似文献   

2.
In the spring-summer season of 2005 and 2006, we explored the influence of three fertigation strategies (A-C) on the water and nitrogen use efficiency of semi-closed rockwool culture of greenhouse tomato conducted using saline water (NaCl concentration of 9.5 mol m−3). The strategies under comparison were the following: (A) crop water uptake was compensated by refilling the mixing tank with nutrient solution at full strength (with the concentrations of macronutrients equal or close to the corresponding mean uptake concentrations as determined in previous studies) and the recirculating nutrient solution was flushed out whenever its electrical conductivity (EC) surpassed 4.5 dS m−1 due to the accumulation of NaCl; (B) the refill nutrient solution had a variable EC in order to maintain a target value of 3.0 dS m−1; due to the progressive accumulation of NaCl, the EC and macronutrient concentrations of the refill nutrient solution tended to decrease with time, thus resulting in a progressive nutrient depletion in the recycling water till N-NO3 content dropped below 1.0 mol m−3, when the nutrient solution was replaced; (C) likewise Strategy A, but when EC reached 4.5 dS m−1, crop water uptake was compensated with fresh water only in order to reduce N-NO3 concentration below 1.0 mol m−3 before discharge. In 2005 an open (free-drain) system (Strategy D), where the plants were irrigated with full-strength nutrient solution without drainage water recycling, was also tested in order to verify the possible influence of NaCl accumulation and/or nutrient depletion in the root zone on crop performance. In the semi-closed systems conducted following strategies A, B or C, the nutrient solution was replaced, respectively, 10, 14 and 7 times in 2005, and in 19, 24 and 14 times in 2006, when the cultivation lasted 167 days instead of 84 days in 2005. In both years, there were no important differences in fruit yield and quality among the strategies under investigation. Strategy C produced the best results in terms of water use and drainage, while Strategy B was the most efficient procedure with regard to nitrogen use. In contrast to strategies A and D, the application of strategies B and C minimized nitrogen emissions and also resulted in N-NO3 concentrations in the effluents that were invariably lower than the limit (approximately 1.42 mol m−3) imposed to the N-NO3 concentration of wastewater discharged into surface water by the current legislation associated to the implementation of European Nitrate Directive in Italy.  相似文献   

3.
A long-term greenhouse experiment was conducted to study the effects of irrigation frequency and salinity on pepper fruit yield and quality in crops growing in coconut coir. Two salinity levels (4 mM NaCl, 2.6 dS m−1 and 24 mM NaCl, 4.6 dS m−1) were combined with four irrigation treatments (one irrigation event every two days (0.5), one irrigation event per day (1), four irrigation events per day (4), and eight irrigation events per day (8)) in a 2 × 4 factorial combination. The effect on fruit quality was evaluated at the early and late harvest seasons, corresponding with two different periods of fruit production (May and July). We found that above-ground total biomass and marketable fruit yield decreased in the salinized treatments. When salinized (24 mM NaCl) nutrient solution (NS) was applied, increasing the number of irrigation events to eight per day resulted in a decrease in the incidence of blossom-end rot and a corresponding increase in the marketable fruit yield. When control (4 mM NaCl) NS was applied, one irrigation event per day yielded as much marketable fruit as was produced with the highest irrigation frequency, and therefore increased water use efficiency, expressed as marketable fruit weight per L of NS applied. When NS containing 24 mM NaCl was used, there was an increase of Cl but not Na+ in the leaf tissue, with this increase reaching its maximum in the treatment involving eight irrigation events per day. Salinity decreased the Ca2+ concentration of the fruit only in the early harvest season of production. However, increasing irrigation frequency consistently resulted in higher Ca2+ concentration in the fruit. The effects of salinity on the morphological and organoleptic properties of the fruit were more pronounced in the late harvest season.  相似文献   

4.
Water demand for irrigation is increasing in olive orchards due to enhanced yields and profits. Because olive trees are considered moderately tolerant to salinity, irrigation water with salt concentrations that can be harmful for many of fruit tree crops is often used without considering the possible negative effects on olive tree growth and yield. We studied salt effects in mature olive trees in a long term field experiment (1998-2006). Eighteen-year-old olive trees (Olea europaea L.) cv. Picual were cultivated under drip irrigation with saline water composed of a mixture of NaCl and CaCl2. Three irrigation regimes (i. no irrigation; ii. water application considering soil water reserves, short irrigation; iii. water application without considering soil water reserves and adding a 20% more as a leaching fraction, long irrigation) and three salt concentrations (0.5, 5 or 10 dS m−1) were applied. Treatments were the result of the combination of three salt concentrations with two irrigation regimes, plus the non-irrigated treatment. Growth parameters, leaf and fruit nutrition, yield, oil content and fruit characteristics were annually studied. Annual leaf nutrient analyses indicate that all nutrients were within the adequate levels. After 8 years of treatment, salinity did not affect any growth measurement and leaf Na+ and Cl concentration were always below the toxicity threshold of 0.2 and 0.5%, respectively. Annual and accumulated yield, fruit size and pulp:stone ratio were also not affected by salts. However, oil content increased linearly with salinity, in most of the years studied. Soil salinity measurements showed that there was no accumulation of salts in the upper 30 cm of the soil (where most of the roots are present) because of leaching by rainfall at the end of the irrigation period. Results suggest that a proper management of saline water, supplying Ca2+ to the irrigation water, using drip irrigation until winter rest and seasonal rainfall typical of the Mediterranean climate leach the salts from the first 0-60 cm depth, and growing a tolerant cultivar, can allow using high saline irrigation water (up to 10 dS m−1) for a long time without affecting growth and yield in olive trees.  相似文献   

5.
Wetting plant foliage with saline irrigation increases the uptake of toxic ions Na+ and Cl. Over three consecutive seasons, Colombard vines grafted on Ramsey rootstock were irrigated with saline water (EC 3.5 dS/m) by over-canopy sprinklers during any one of the first three of the four annual growth stages: bud burst to full bloom (treatment BB-FB), full bloom to veraison (treatment FB-V), and veraison to harvest (treatment V-H). At other times, vines received non-saline water (EC 0.5 dS/m) as did the control. Seasonal average soil salinities remained relatively constant over the trial. In contrast, the concentrations of Na+ and Cl in one-year old wood and grape juice more than doubled. In treatments FB-V and V-H the average yield over the three seasons was reduced by up to 15%. Results were compared with those obtained in an earlier study which was undertaken in the same vineyard with the same treatments applied via dripper. With drippers, the maximum reduction in the average yield over three seasons was 2%. Saline sprinkling caused rises in Na+ and Cl concentrations of fruit, leaf lamina and one-year-old wood that were at least 7-fold, 5-fold and 2-fold greater, respectively, than the rises caused by application of the same treatments with drip. Progressive seasonal rises in the concentrations of Na+ and Cl in these tissues were due in part to carryover of salt added in previous seasons; with saline sprinkling the magnitude of these carryovers was 4-fold greater than those with saline drip irrigation. With saline water, vignerons can reduce losses by using irrigation systems which do not wet the foliage.  相似文献   

6.
Salinization and nitrate leaching are two of the leading threats to the environment of the European Mediterranean regions. Inefficient use of water and fertilizers has led to a nitrate increase in the aquifers and reduction in crop yields caused by salts. In this study, a triple emitter source irrigation system delivers water, salt (Na+), and fertilizer (N) applications to maize (Zea mays L.). The objective of the study was to evaluate the combined effect of saline water and nitrogen application on crop yields in two different textured soils of Alentejo (Portugal) and to assess if increasing salinity levels of the irrigation water can be compensated by application of nitrogen while still obtaining acceptable crop yield. Maximum yield was obtained from both soils with an application of 13 g m−2 of nitrogen. Yield response to Na+ application was different in the two studied soils and depended on the total amount of Na+ or irrigation water applied. No significant interaction was found between nitrogen and sodium, but a positive effect on maize yield was observed in the medium textured soil for amounts of Na+ less than 905 g m−2 when applied in the irrigation water.  相似文献   

7.
Free-drainage or “open” substrate system used for vegetable production in greenhouses is associated with appreciable NO3 leaching losses and drainage volumes. Simulation models of crop N uptake, N leaching, water use and drainage of crops in these systems will be useful for crop and water resource management, and environmental assessment. This work (i) modified the TOMGRO model to simulate N uptake for tomato grown in greenhouses in SE Spain, (ii) modified the PrHo model to simulate transpiration of tomato grown in substrate and (iii) developed an aggregated model combining TOMGRO and PrHo to calculate N uptake concentrations and drainage NO3 concentration. The component models simulate NO3-N leached by subtracting simulated N uptake from measured applied N, and drainage by subtracting simulated transpiration from measured irrigation. Three tomato crops grown sequentially in free-draining rock wool in a plastic greenhouse were used for calibration and validation. Measured daily transpiration was determined by the water balance method from daily measurements of irrigation and drainage. Measured N uptake was determined by N balance, using data of volumes and of concentrations of NO3 and NH4+ in applied nutrient solution and drainage. Accuracy of the two modified component models and aggregated model was assessed by comparing simulated to measured values using linear regression analysis, comparison of slope and intercept values of regression equations, and root mean squared error (RMSE) values. For the three crops, the modified TOMGRO provided accurate simulations of cumulative crop N uptake, (RMSE = 6.4, 1.9 and 2.6% of total N uptake) and NO3-N leached (RMSE = 11.0, 10.3, and 6.1% of total NO3-N leached). The modified PrHo provided accurate simulation of cumulative transpiration (RMSE = 4.3, 1.7 and 2.4% of total transpiration) and cumulative drainage (RMSE = 13.8, 6.9, 7.4% of total drainage). For the four cumulative parameters, slopes and intercepts of the linear regressions were mostly not statistically significant (P < 0.05) from one and zero, respectively, and coefficient of determination (r2) values were 0.96-0.98. Simulated values of total drainage volumes for the three crops were +21, +1 and −13% of measured total drainage volumes. The aggregated TOMGRO-PrHo model generally provided accurate simulation of crop N uptake concentration after 30-40 days of transplanting, with an average RMSE of approximately 2 mmol L−1. Simulated values of average NO3 concentration in drainage, obtained with the aggregated model, were −7, +18 and +31% of measured values.  相似文献   

8.
In this paper, we discuss the effect of elevated CO2 concentration, irrigation and nitrogenous fertilizer application on the growth and yield of spring wheat in semi-arid areas. A field experiment was conducted at the Dingxi Agricultural Experiment Station during 2000–2002. According to the experimental design, the CO2 concentration increased to 14.5, 40 and 54.5 μmol mol−1, respectively, by NH4HCO3 (involving CO2) application, direct application of CO2 gas and combination of fertilizer NH4HCO3 plus CO2 application, which are equal to CO2 concentration of the Earth's atmosphere in the next 5, 15 and 20 years. The fertilizer application was divided into three levels: application of NH3NO3 (250 kg h m−2), NH4HCO3 (500 kg h m−2) and no fertilizer. Irrigation was divided into two levels: with 90 mm irrigation in the growth period and without irrigation. They can be combined as eight treatments. Each treatment was replicated three times. The results showed that elevated CO2 concentration owing to CO2 application leads to remarkable increase in leaf area index (LAI) and shoot biomass, and also generates the higher value of leaf area duration (LAD) that can benefit the photosynthesis in the growth stage and yield increase in crop compared than the no CO2 application treatment. When CO2 concentration elevated by 14.5, 40 and 54.5 μmol mol−1 with irrigation and fertilization, correspondingly, the grain yield increased by 6.3, 13.1 and 19.8%, respectively, whereas without irrigation and fertilization, the grain yield increased by only 4.2% when CO2 concentration increased to 40 μmol mol−1. Meanwhile, irrigation and fertilization can result in larger and deeper root system and have significantly positive influences on higher value of root/shoot (R/S) and water use efficiency. The grain yields in irrigation, irrigation plus NH3NO3 application and irrigation plus application of NH4HCO3 treatments are 73.4, 148.0 and 163.6% higher than that of no-irrigated and no-fertilized treatment, suggesting that both irrigation and fertilizer application contribute to remarkable increase of crop yield. In all treatments, the highest water use efficiency (WUE, 7.24 kg h m−2 mm−1) and grain yield (3286 kg h m−2) consistently occurred in the treatment with 90 mm irrigation plus fertilizer NH4HCO3 and elevated CO2 concentration (54.5 μmol mol−1), suggesting that this combination has an integrated beneficial effect on improving WUE and grain yield of spring wheat. These results may offer help to maintain and increase the crop yields in semi-arid areas.  相似文献   

9.
This work assesses the seasonal dynamics of the substrate oxygen content and the response to nutrient solution oxygen enrichment (oxyfertigation) of an autumn-spring tomato crop grown on rockwool slabs and irrigated with treated wastewater of very low dissolved oxygen (DO) content under Mediterranean greenhouse conditions. DO values in the nutrient solution were clearly higher for the oxygen-enriched (14.6 mg L−1) tomato crop than for the non-enriched one (4.5 mg L−1). However, DO values in the substrate solution were similar for both oxygen treatments (mean seasonal values of 5.1 and 4.8 mg L−1 for the enriched and the non-enriched one, respectively), except for a short crop period at the end of the cycle when they were significantly higher for the oxygen-enriched crop. For both treatments, substrate DO values were highest for the winter period and decreased progressively during the spring period, reaching minimum values of around or below 3 mg L−1 at the end of the spring. The oxygen enrichment of the nutrient solution did not affect any of the irrigation and fertigation parameters evaluated in the tomato crop: water uptake, volumetric water content of the substrate, electrical conductivity (EC) or nutrient concentration in the leached nutrient solution. Moreover, the oxygen enrichment of the nutrient solution did not affect the aboveground biomass and the biomass partitioning, the fresh weight of total and marketable tomato fruits or the tomato fruit quality parameters. Overall, it appears that oxygen deficiency conditions did not occur as the substrate DO values were higher than, or about, 3 mg L−1 throughout most of the tomato crop cycle for both treatments and the rockwool slabs maintained good aeration conditions throughout the whole cycle.  相似文献   

10.
A research has been carried out to determine the effects of nutrition systems and irrigation programs on soilless grown tomato plants under polyethylene covered unheated greenhouse conditions. Two nutrition systems (open and closed) and three irrigation programs (high, medium and low) based on integrated indoor solar radiation triggering thresholds (1 MJ m−2 [0.4 mm], 2 MJ m−2 [0.8 mm] and 4 MJ m−2 [1.6 mm]) in both nutrition systems have been tested. Applied and discharged nutrient solution, evapotranspiration, total and marketable yield have been measured and water use efficiency has been calculated. The highest total yield has been obtained from the open system with respectively 11% and 7.2% increases in autumn and spring. Applied nutrient solution volume and seasonal ET have been modified between 47.8-180.4 l plant−1 and 41.7-145.5 l plant−1 respectively during both growing seasons. As average of two growing seasons, respectively 826.5 and 330.6 m3 ha−1 nutrient solutions have been discharged from the greenhouse in the open and closed systems. WUE of treatments varied between 33-55 kg m−3 in autumn and 26-35 kg m−3 in spring. Highest WUE values have been determined in 4 MJ m−2 and in the closed system in both growing seasons. Results showed that the closed system and infrequent irrigations increased water use efficiency while decreasing yield and discharged nutrient solution.  相似文献   

11.
Expected yield losses as a function of quality and quantity of water applied for irrigation are required to formulate guidelines for the effective utilisation of marginal quality waters. In an experiment conducted during 2004-2006, double-line source sprinklers were used to determine the separate and interactive effects of saline and alkali irrigation waters on wheat (Triticum aestivum L.). The study included three water qualities: groundwater (GW; electrical conductivity of water, ECw 3.5 dS m−1; sodium adsorption ratio, SAR 9.8 mmol L−1; residual sodium carbonate, RSC, nil) available at the site, and two synthesized waters, saline (SW; ECw 9.4 dS m−1, SAR 10.3 mmol L−1; RSC nil) and alkali (AW; ECw 3.7 dS m−1, SAR 15.1 mmol L−1; RSC 9.6 meq. L−1). The depths of applied SW, AW, and GW per irrigation ranged from 0.7 to 3.5 cm; the depths of applied mixtures of GW with either SW (MSW) or AW (MAW) ranged from 3.2 to 5 cm. Thereby, the water applied for post-plant irrigations using either of GW, SW or AW ranged between 15.2 and 34.6 cm and 17.1 and 48.1 cm during 2004-2005 and 2005-2006, respectively and the range was 32.1-37.0 and 53.1-60.0 cm for MSW or MAW. Grain yields, when averaged for two years, ranged between 3.08 and 4.36 Mg ha−1, 2.57 and 3.70 Mg ha−1 and 2.73 and 3.74 Mg ha−1 with various quantities of water applied using GW, SW and AW, respectively, and between 3.47 and 3.75 Mg ha−1 and 3.63 and 3.77 Mg ha−1 for MSW and MAW, respectively. The water production functions developed for the two sets of water quality treatments could be represented as: RY = 0.528 + 0.843(WA/OPE) − 0.359(WA/OPE)2 − 0.027ECw + 0.44 × 10−2(WA/OPE) × ECw for SW (R2 = 0.63); RY = 0.446 + 0.816(OPE/WA) − 0.326(WA/OPE)2 − 0.0124RSC − 0.55 × 10−4(WA/OPE) × RSC for AW (R2 = 0.56). Here, RY, WA and OPE are the relative yields in reference to the maximum yield obtained with GW, water applied for pre- and post-plant irrigations (cm), and open pan evaporation, respectively. Crop yield increased with increasing amount of applied water for all of the irrigation waters but the maximum yields as obtained with GW, could not be attained even with increased quantities of SW and AW. Increased frequency of irrigation with sprinklers reduced the rate of yield decline with increasing salinity in irrigation water. The sodium contents of plants increased with salinity/alkalinity of sprinkled waters as also with their quantities. Simultaneous decrease in potassium contents resulted in remarkable increase in Na:K ratio.  相似文献   

12.
Studies on irrigation scheduling for soybean have demonstrated that avoiding irrigation during the vegetative growth stages could result in yields as high as those obtained if the crop was fully irrigated during the entire growing season. This could ultimately also lead to an improvement of the irrigation water use efficiency. The objective of this study was to determine the effect of different irrigation regimes (IRs) on growth and yield of four soybean genotypes and to determine their irrigation water use efficiency. A field experiment consisting of three IR using a lateral move sprinkler system and four soybean genotypes was conducted at the Bledsoe Research Farm of The University of Georgia, USA. The irrigation treatments consisted of full season irrigated (FSI), start irrigation at flowering (SIF), and rainfed (RFD); the soybean genotypes represented maturity groups (MGs) V, VI, VII, and VIII. A completely randomized block design in a split-plot array with four replicates was used with IR as the main treatment and the soybean MGs as the sub-treatment. Weather variables and soil moisture were recorded with an automatic weather station located nearby, while rainfall and irrigation amounts were recorded with rain gauges located in the experimental field. Samplings for growth analysis of the plant and its components as well as leaf area index (LAI) and canopy height were obtained every 12 days. The irrigation water use efficiency (IWUE) or ratio of the difference between irrigated and rainfed yield to the amount of irrigation water applied was estimated. The results showed significant differences (P < 0.05) between IR for dry matter of the plant and its components, canopy height, and maximum leaf area index as well as significant differences (P < 0.05) between MGs due to IR. Differences for the interaction between IR and MG were significant (P < 0.05) only for dry matter of pods and seed yield. In general, seed yield increased at a rate of 7.20 kg for each mm of total water received (rainfall + irrigation) by the crop. Within IR, significant differences (P < 0.05) on IWUE were found between maturity groups with values as low as 0.55 kg m−3 for MG V and as high as 1.14 kg m−3 for MG VI for the FSI treatment and values as low as 0.48 kg m−3 for maturity group V and as high as 1.02 kg m−3 for maturity group VI for the SIF treatment. We also found that there were genotypic differences with respect to their efficiency to use water, stressing the importance of cultivar selection as a key strategy for achieving optimum yields with reduced use of water in supplemental irrigation.  相似文献   

13.
Rapid urbanization and industrialization have increased the pressure on limited existing fresh water to meet the growing needs for food production. Two immediate responses to this challenge are the efficient use of irrigation technology and the use of alternative sources of water. Drip irrigation methods may play an important role in efficient use of water but there is still limited information on their use on sugar beet crops in arid countries such as Iran. An experiment was conducted to evaluate the effects of irrigation method and water quality on sugar beet yield, percentage of sugar content and irrigation water use efficiency (IWUE). The irrigation methods investigated were subsurface drip, surface drip and furrow irrigation. The two waters used were treated municipal effluent (EC = 1.52 dS m−1) and fresh water (EC = 0.509 dS m−1). The experiments used a split plot design and were undertaken over two consecutive growing seasons in Southern Iran. Statistical testing indicated that the irrigation method and water quality had a significant effect (at the 1% level) on sugar beet root yield, sugar yield, and IWUE. The highest root yield (79.7 Mg ha−1) was obtained using surface drip irrigation and effluent and the lowest root yield (41.4 Mg ha−1) was obtained using furrow irrigation and fresh water. The highest IWUE in root yield production (9 kg m−3) was obtained using surface drip irrigation with effluent and the lowest value (3.8 kg m−3) was obtained using furrow irrigation with fresh water. The highest IWUE of 1.26 kg m−3 for sugar was obtained using surface drip irrigation. The corresponding efficiency using effluent was 1.14 kg m−3. Irrigation with effluent led to an increase in the net sugar yield due to an increase in the sugar beet root yield. However, there was a slight reduction in the percentage sugar content in the plants. This study also showed that soil water and root depth monitoring can be used in irrigation scheduling to avoid water stress. Such monitoring techniques can also save considerable volumes of irrigation water and can increase yield.  相似文献   

14.
A great challenge for the agricultural sector is to produce more food from less water, particularly in arid and semi-arid regions which suffer from water scarcity. A study was conducted to evaluate the effect of three irrigation methods, using effluent versus fresh water, on water savings, yields and irrigation water use efficiency (IWUE). The irrigation scheduling was based on soil moisture and rooting depth monitoring. The experimental design was a split plot with three main treatments, namely subsurface drip (SSD), surface drip (SD) and furrow irrigation (FI) and two sub-treatments effluent and fresh water, which were applied with three replications. The experiment was conducted at the Marvdasht city (Southern Iran) wastewater treatment plant during 2005 and 2006. The experimental results indicated that the average water applied in the irrigation treatments with monitoring was much less than that using the conventional irrigation method (using furrows but based on a constant irrigation interval, without moisture monitoring). The maximum water saving was obtained using SSD with 5907 m3 ha−1 water applied, and the minimum water saving was obtained using FI with 6822 m3 ha−1. The predicted irrigation water requirements using the Penman-Monteith equation (considering 85% irrigation efficiency for the FI method) was 10,743 m3 ha−1. The pressure irrigation systems (SSD and SD) led to a greater yield compared to the surface method (FI). The highest yield (12.11 × 103 kg ha−1) was obtained with SSD and the lowest was obtained with the FI method (9.75 × 103 kg ha−1). The irrigation methods indicated a highly significant difference in irrigation water use efficiency. The maximum IWUE was obtained with the SSD (2.12 kg m−3) and the minimum was obtained with the FI method (1.43 kg m−3). Irrigation with effluent led to a greater IWUE compared to fresh water, but the difference was not statistically significant.  相似文献   

15.
Excessive amounts of irrigation water and fertilizers are often utilized for early potato cultivation in the Mediterranean basin. Given that water is expensive and limited in the semi-arid areas and that fertilizers above a threshold level often prove inefficacious for production purposes but still risk nitrate and phosphorous pollution of groundwater, it is crucial to provide an adequate irrigation and fertilization management. With the aim of achieving an appropriate combination of irrigation water and nutrient application in cultivation management of a potato crop in a Mediterranean environment, a 2-year experiment was conducted in Sicily (South Italy). The combined effects of 3 levels of irrigation (irrigation only at plant emergence, 50% and 100% of the maximum evapotranspiration - ETM) and 3 levels of mineral fertilization (low: 50, 25 and 75 kg ha−1, medium: 100, 50 and 150 kg ha−1 and high: 300, 100 and 450 kg ha−1 of N, P2O5 and K2O) were studied on the tuber yield and yield components, on both water irrigation and fertilizer productivity and on the plant source/sink (canopy/tubers dry weight) ratio. The results show a marked interaction between level of irrigation and level of fertilization on tuber yield, on Irrigation Water Productivity and on fertilizer productivity of the potato crop. We found that the treatments based on 50% ETM and a medium level of fertilization represent a valid compromise in early potato cultivation management. Compared to the high combination levels of irrigation and fertilization, this treatment entails a negligible reduction in tuber yield to save 90 mm ha−1 year−1 of irrigation water and 200, 50 and 300 kg ha−1 year−1 of N, P2O5 and K2O, respectively, with notable economic savings for farmers compared to the spendings that are usually made.  相似文献   

16.
Early planting of rice crop during the period of peak evaporative demand results in substantial mining of ground water and threats the sustainability of rice production in Punjab, northwest India. In order to increase yield and water productivity, arrest the mining of ground water, and achieve sustainability of rice production, there is need to adopt water-saving management practices. The present investigation in the Indian Punjab was aimed at investigating the effect of date of transplanting in four rice cultivars varying in growth duration (short-duration RH-257 and PR-115, and medium-duration PR-113 and PAU-201) on yield and water productivity. Delaying in transplanting from 15 June to 25 June or 5 July resulted in reduction in mean grain yield of the four cultivars by 7.2% and 15.9%, respectively. PAU-201, a photoperiod-sensitive cultivar, had higher mean grain yield (7.8 t ha−1) by 14.1%, 12.8% and 11.5% over the photoperiod-insensitive cultivars, PR-113, PR-115 and RH-257, respectively. Irrespective of transplanting dates, short-duration cultivars, RH-257 and PR-115, respectively, resulted in 18.9% and 16.6% saving of water, as compared to medium-duration cultivar PR-113. With delayed transplanting after 15 June, both yield and water productivity decreased for all photoperiod insensitive cultivars, but yields remained statistically similar and water productivity greater for a photoperiod sensitive cultivar. Mean irrigation water productivity (WPI) was highest for 15 June transplanting (0.66 kg m−3) and lowest for 5 July transplanting (0.57 kg m−3), and was highest for RH-257 (0.68 kg m−3) and lowest for PR-113 (0.50 kg m−3). Total water productivity (WPI+R; irrigation plus rainfall) decreased by 9.1% for 5 July transplanting compared with 15 June transplanting, and was highest for RH-257 (0.49 kg m−3) and lowest for PR-113 (0.38 kg m−3). Real crop water productivity (WPET) of the photoperiod insensitive cultivars decreased (1.10-1.40 kg m−3), but that of a photoperiod sensitive cultivar increased (1.63 kg m−3), with delayed transplanting. We conclude that substantial amount of water can be saved and yield increased by transplanting short-duration cultivars during the period of peak evaporative demand, or water saved and yield maintained by transplanting a photoperiod-sensitive cultivar late in the season when the evaporative demand is low.  相似文献   

17.
The development of different tools to evaluate the performance of Water Users Associations (WUAs) is an important practice for improving water and energy management, together with other production costs. One of these tools is the Benchmarking technique, which is based on the comparison between different WUAs to determine the best practices in each of them.In this paper, a Benchmarking process is applied to seven WUAs located in Castilla-La Mancha (Spain) during three irrigation seasons (2006-2008). The performance indicators developed by the International Programme for Technology and Research in Irrigation and Drainage (IPTRID) are used, while new indicators dealing with production and energy are proposed. The goals of this paper are to group WUAs with the same characteristics, using performance and energy indicators, and to reduce the set of indicators using statistical methods. The most important indicators, easy to obtain and yielding result in maximum information are retained for further use.Three proposals reducing the initial number of indicators were proposed, with an aim of being useful for future applications based on characterizing WUAs. Indicators results highlighted that irrigable areas can be grouped based on the application of drip irrigation systems and those with sprinkler irrigation systems. When using groundwater resources, no significant differences were observed for energy consumption between these irrigation systems. This can be explained by the indicator energy load index (ICE, m), which had similar values in all WUAs analyzed. According to annual irrigation water supply per unit irrigated area (VTSr, m3 ha−1), the highest values (between 5200 m3 ha−1 and 6800 m3 ha−1) were obtained in WUAs with sprinkler irrigation systems, which contained crops characterized by high water requirements, compared to the VTSr (less than 1800 m3 ha−1) of WUAs with drip irrigation systems, with crops that required less volume of irrigation water. Regarding production efficiency indicators, in drip irrigation systems the high presence of vineyards, almond and olive trees, crops with low water requirements, explained high values of gross margin per unit irrigation delivery (MBVs, € m−3)(close to 0.82 € m−3) in comparison with sprinkler irrigation systems (close to 0.36 € m−3).  相似文献   

18.
Olive tree (Olea europaea L.) is commonly grown under environmental conditions characterised by water deficit, high temperatures and irradiance levels typical of Mediterranean semi-arid regions. Measurement of gas exchange, chlorophyll content, chlorophyll fluorescence and photoinhibition was carried out on two-year-old olive trees (cv. ‘Coratina’) subjected to a 21-day period of water deficit followed by 23 days of rewatering. At the beginning of the experiment, plants were divided in to two groups and subjected to different light regimes: exposed plants (EP) under a mean photosynthetically active radiation (PAR) at mid-day of 1800 μmol m−2 s−1 and shaded plants (SP) under a mean PAR of 1200 μmol m−2 s−1. The effect of drought and high irradiance levels caused a reduction of gas exchange and photosystem 2 (PSII) efficiency, in terms of quantum yield of PSII (ΦPSII) both in EP and SP. Shading conditions allowed plants to maintain a high photosynthetic activity at low values of stomatal conductance, whereas in EP the reductions in photosynthetic efficiency and intrinsic water efficiency were due to non-stomatal components of photosynthesis. The decrease in photosynthetic activity and the increase of photoinhibition under drought were more marked in EP than in SP. Full sunlight caused in EP a higher non-photochemical quenching, whereas SP showed a better photochemical efficiency. The information here obtained can be important to understand the mechanisms by which olive plants can minimize photoinhibition when subjected to simultaneous abiotic stresses.  相似文献   

19.
Irrigation performance assessments are required for hydrological planning and as a first step to improve water management. The objective of this work was to assess seasonal on-farm irrigation performance in the Ebro basin of Spain (0.8 million ha of irrigated land). The study was designed to address the differences between crops and irrigation systems using irrigation district data. Information was only available in districts located in large irrigation projects, accounting for 58% of the irrigated area in the basin. A total of 1617 records of plot water application (covering 10,475 ha) were obtained in the basin. Average net irrigation requirements (IRn) ranged from 2683 m3 ha−1 in regulated deficit irrigation (RDI) vineyards to 9517 m3 ha−1 in rice. Average irrigation water application ranged from 1491 m3 ha−1 in vineyards to 11,404 m3 ha−1 in rice. The annual relative irrigation supply index (ARIS) showed an overall average of 1.08. Variability in ARIS was large, with an overall standard deviation of 0.40. Crop ARIS ranged between 0.46 and 1.30. Regarding irrigation systems, surface, solid-set sprinkler and drip irrigated plots presented average ARIS values of 1.41, 1.16 and 0.65, respectively. Technical and economic water productivities were determined for the main crops and irrigation systems in the Aragón region. Rice and sunflower showed the lowest productivities. Under the local technological and economic constraints, farmers use water cautiously and obtain reasonable (yet very variable) productivities.  相似文献   

20.
Water is the most important limiting factor of wheat (Triticum aestivum L.) and maize (Zea mays L.) double cropping systems in the North China Plain (NCP). A two-year experiment with four irrigation levels based on crop growth stages was used to calibrate and validate RZWQM2, a hybrid model that combines the Root Zone Water Quality Model (RZWQM) and DSSAT4.0. The calibrated model was then used to investigate various irrigation strategies for high yield and water use efficiency (WUE) using weather data from 1961 to 1999. The model simulated soil moisture, crop yield, above-ground biomass and WUE in responses to irrigation schedules well, with root mean square errors (RMSEs) of 0.029 cm3 cm−3, 0.59 Mg ha−1, 2.05 Mg ha−1, and 0.19 kg m−3, respectively, for wheat; and 0.027 cm3 cm−3, 0.71 Mg ha−1, 1.51 Mg ha−1 and 0.35 kg m−3, respectively, for maize. WUE increased with the amount of irrigation applied during the dry growing season of 2001-2002, but was less sensitive to irrigation during the wet season of 2002-2003. Long-term simulation using weather data from 1961 to 1999 showed that initial soil water at planting was adequate (at 82% of crop available water) for wheat establishment due to the high rainfall during the previous maize season. Preseason irrigation for wheat commonly practiced by local farmers should be postponed to the most sensitive growth stage (stem extension) for higher yield and WUE in the area. Preseason irrigation for maize is needed in 40% of the years. With limited irrigation available (100, 150, 200, or 250 mm per year), 80% of the water allocated to the critical wheat growth stages and 20% applied at maize planting achieved the highest WUE and the least water drainage overall for the two crops.  相似文献   

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