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1.
不同冲洗措施下迷宫流道灌水器泥沙运行分布机理研究   总被引：2，自引：0，他引：2  
评估了3种冲洗流速（0.25、0.50、0.75m/s）和5种冲洗频率（2d冲洗1次、4d冲洗1次、7d冲洗1次、10d冲洗1次和无冲洗对照组）对内嵌式齿形迷宫流道灌水器抗堵塞性能的影响,利用激光粒度仪对水源泥沙、滴头排出泥沙、滴头内滞留泥沙进行级配对比和粒径分析,并对不同冲洗处理下灌水器的相对流量和灌水均匀度进行拟合。结果表明：冲洗处理对齿形迷宫流道灌水器抗堵塞性能有显著影响,12种冲洗处理提高了内嵌式齿形迷宫流道灌水器的输沙能力,使滴头使用年限平均提高了39.58%;在冲洗作用下,泥沙凝聚沉降的机会降低,流道内小颗粒泥沙及时排出,没有形成体积较大的团聚体,滴头堵塞形成缓慢,灌水均匀度和流量系数下降缓慢;冲洗处理能有效减少毛管内泥沙堆积,降低大颗粒泥沙进入迷宫流道的机率,从而提高了齿形迷宫流道灌水器的抗堵塞性能。  相似文献   

2.
基于模拟降雨的北京褐土坡地土壤团粒流失特征试验   总被引：2，自引：0，他引：2  
选取20°北京典型褐土坡面径流小区为试验对象,基于野外人工模拟降雨试验和有无雨滴打击作用对坡面侵蚀的影响,研究了坡面土壤团粒组成及其变化特征,揭示了坡面侵蚀过程中泥沙团粒的分离和输移规律。试验处理包括3种代表性降雨强度(35、65、100 mm/h)和3种植被盖度(0%、30%、80%)。结果表明,消除雨滴打击作用后,坡面侵蚀特征变化明显,坡面含沙量和土壤分离率分别减少25.91%~31.15%和35.10%~41.20%,坡面侵蚀泥沙团粒中值粒径均小于雨滴击溅坡面。通过侵蚀泥沙有效粒径分布和最终粒径分布的比值(E/U)分析泥沙团粒的粒径分选特征,发现产流初始阶段粗砂、细砂、细粉粒和粘粒多以团聚体形式存在,而粗粉砂以初级粒子形式存在;随着降雨历时延长,侵蚀泥沙各粒级的分离程度增加,泥沙颗粒逐步分解为初级粒子。坡面侵蚀泥沙分离规律表明,泥沙团粒结构变化与坡面水动力学特征密切相关,土壤团聚体分形维数(D)与时间(T)呈幂函数关系。坡面产流前雨滴击溅对土壤分离有重要作用,其对土壤分离贡献率为28.09%,而无雨滴打击坡面土壤团聚体分形维数增量是有雨滴打击增量的48.43%。在该区坡地泥沙颗粒输移过程中,稳定性较差的砂粒被分解为细小颗粒,粗粉砂多以初级粒子形式存在,对坡面侵蚀泥沙颗粒分离过程具有重要影响,而粘粒在侵蚀坡面则逐渐富集。  相似文献   

3.
为探明半透膜微润管对细小泥沙抗堵塞性能的影响,采用有压连续灌水方式对微润管3种粒径组成小于0.100 mm的泥沙颗粒进行了不同质量分数浑水灌溉堵塞试验.分析了泥沙粒径、含沙量以及压力水头对灌水器堵塞的影响,同时探讨了灌水器发生堵塞时的敏感粒径范围和含沙量质量分数值.试验结果表明:随着浑水含沙量的增大堵塞越严重,呈正相关关系;粒径在0.061 0 mm~0.100 0 mm对微润管的堵塞影响最大;相同水质条件下,随着压力水头的增大微润管堵塞程度会降低.研究结果为进一步利用半透膜微润灌溉技术提供了相关的理论基础.  相似文献   

4.
浑水特性与水温对滴头抗堵塞性能的影响   总被引：9，自引：0，他引：9  
为探明迷宫流道滴头发生物理堵塞的成因及过程,采用分段粒径浑水周期间歇滴灌的试验方法,分别对含沙量、泥沙颗粒粒径和水温对滴头堵塞发生过程的影响进行研究。结果表明:对于泥沙颗粒粒径小于0.1 mm的浑水滴灌而言,粒径越小越易造成滴头堵塞,且其堵塞程度随浑水含沙量的升高而急剧升高;存在造成滴头堵塞的敏感粒径范围,在夏季灌溉时小于0.031 mm的粒径为易堵塞粒径;水温是影响滴头堵塞的重要因素,水温越高滴头的抗物理堵塞性能越好。  相似文献   

5.
The evolution of drip emitter clogging with labyrinth channel was investigated experimentally to study the fine particle size and concentration effects in the irrigation water. Short-term clogging tests were performed using muddy water containing particles with 8 different sizes (all less than 0.1 mm). The particles used in this study were composed of fine sands, slit and clay. Afterwards, verification tests were conducted to prove the results obtained from short-term clogging tests. The impacts of particle size and particle concentration in muddy water on emitter clogging were analyzed by means of calculating the mean discharge and the Christiansen uniformity coefficient. The results showed that for particles that were smaller than 0.1 mm in diameter, sediment concentration significantly affected clogging. The clogging level of emitters increased with raising the concentration. Especially when the sediment concentration was higher than 1.25 g/L, the impacts became remarkable. On the other hand, the sensitive sediment particle range that could get emitters clogged easily was found. In this study, the sensitive particle range were D6 (0.038–0.034 mm) and D7 (0.034–0.031 mm) The results aim to help in improving drip irrigation methods using water with high sediment concentration and providing experimental data for optimization design of emitter channel.  相似文献   

6.
滴灌毛管泥沙分布与灌水器堵塞试验研究   总被引：3，自引：0，他引：3  
为探明滴灌毛管泥沙分布及灌水器堵塞规律,通过对8种粒径的泥沙进行短周期浑水试验和堵塞试验,研究了泥沙在不同毛管分布和灌水器堵塞规律。结果表明:泥沙在不同毛管中淤积量的不均匀程度可以通过毛管淤积分布系数来衡量;泥沙在支管中的运动状态对进入毛管中的泥沙量影响很大,通过计算支管泥沙悬浮指数,可确定泥沙在不同毛管中的淤积状况,悬浮指数越大,泥沙在各毛管淤积量越不均匀,突变发生在悬浮指数等于0.325处;大颗粒泥沙在毛管底部以推移质形式运动,是造成灌水器突然堵塞的直接原因,且主要出现在第1、2条毛管中,而细小颗粒的絮凝作用是造成灌水器逐渐堵塞的主要原因。  相似文献   

7.
The effects of deficit irrigation (DI) and partial rootzone drying (PRD) on apple (Malus domestica Borkh. Cv. ‘Fuji’) yield, fruit size, and quality were evaluated from 2001 to 2003 in the semi-arid climate of Washington State. PRD and DI were applied from about 40 days after full bloom until just before (2001, 2002) or after (2003) harvest and compared to a control irrigation (CI). Irrigation was applied once a week using two micro-sprinklers per tree. Soil-water content in CI was maintained above 80% of field capacity using micro-sprinklers on both sides of a tree. The DI and PRD were irrigated at about 50% (2001–2002) and 60% (2003) of the CI, but differed in placement of irrigation. For DI both micro-sprinklers were operated whereas PRD was irrigated using only one micro-sprinkler wetting half the rootzone compared to CI and DI. Wetting/drying sides of PRD trees were alternated every 2–4 weeks (2001, 2002) or when soil-water content on the drying side had reached a threshold value (2003). Seasonal (1 May–31 October) potential evapotranspiration (ET0) was 967, 1002, and 1005 mm for 2001, 2002, and 2003, and rainfall totaled 58, 39, and 21 mm, respectively. Irrigation amounts applied were 596, 839, and 685 mm in the CI; 374, 763, and 575 mm in the DI; and 337, 684, and 513 mm in the PRD for the 2001, 2002, and 2003 seasons. Higher irrigation volumes in 2002 were due to excessive (177–324 mm) irrigations after harvest. No significant differences were found in yield and fruit size among treatments in 2001 and 2003. In 2002, DI had significantly lower yield than CI, while the yield of PRD did not differ from CI and DI. Fruit from DI and PRD were firmer and had higher concentrations of soluble solids than fruit from CI, both at harvest and following short-term storage at 20°C, but differences to CI were significant in 2002 only. Treatment effects on fruit titratable acidity were inconsistent. Additional water was preserved in the soil profile under PRD compared to DI in 2001 and 2003, but no statistical differences were found between PRD and DI in 2002. Approximately 45–50% of irrigation water was saved by implementing newly developed DI and PRD irrigation strategies without any significant impact on fruit yield and size with PRD. However, apple yield was reduced by DI compared to CI in the second year.  相似文献   

8.
【目的】探索灌渠泥沙迁移特性及泥沙级配的沿程变化规律,找出减少渠道泥沙淤积的方法,保障灌区正常运行。【方法】通过对尊村灌区典型干渠高含沙水流实时监测采样,分析了悬移质泥沙沿程含沙量变化及级配特征,并根据实测数据带入4个典型挟沙力公式,筛选出适合尊村灌区的挟沙力公式,进一步改进得到尊村灌区渠道挟沙力计算公式.同时,通过一干渠改造段实测数据,推求出一干渠冲淤平衡比降计算公式。【结果】不同粒径泥沙的输移特性不同,总干渠悬移质含沙量随来水含沙量的增加而增加,渠道淤积主要与粉粒和砂粒量有关,其中砂粒对来水含沙量的变化表现得最为敏感,而黏粒更多的被水流带走,渠道由非平衡输沙经冲刷、淤积达到冲淤平衡输沙的过程比较缓慢。同时沉沙池能有效地减小引水中砂粒量。二干渠末清淤修缮段依旧存在泥沙淤积问题,一干渠剩余未改造部分,在条件允许的情况下,建议增大比降。【结论】含沙量在2 kg/m3内时,一级站来水量在8 m3/s左右,渠道基本实现冲淤平衡。  相似文献   

9.
The effect of gypsum, ground to varying degrees of fineness, on the properties of two soils having exchangeable sodium percentages of 35 and 80, respectively, was studied in the laboratory. Two types of gypsum were used, one having both upper and lower size limits of the grades defined (2.0-1.0, 1.0-0.6, 0.6-0.25, 0.25-0.125 and < 0.125 mm) and the other having only the upper size limit defined (2.0, 1.0, 0.6, 0.25 and 0.125 mm). After mixing with gypsum, the soils were leached with distilled water under a constant water head.Treatments with the finest gypsum had the highest initial hydraulic conductivity which decreased sharply with time. Treatments with coarser particles had a lower initial hydraulic conductivity that was maintained or increased with time. The reason for this was higher solubility of finer particles followed by a sharp decrease in electrolyte concentration due to precipitation of dissolved calcium in the first case, and dissolution of coarser particles and little precipitation in the latter case. Inactivation of gypsum particles due to formation of CaCO3 coatings over their surfaces has also been indicated in the case of the finer grades. These studies suggest that gypsum passed through a 2-mm sieve, having a wide particle size distribution, is likely to be more efficient for the reclamation of sodic soils with appreciable quantities of Na2CO3 in the soil solution.  相似文献   

10.
为了探究引黄灌溉枢纽挟沙水流沿程含沙量变化规律和悬移质泥沙的垂向分布规律,推求首部枢纽有害泥沙悬浮的临界不淤流速,阐明减少有害泥沙引入的措施与方法,以提高输配水利用效率.以山西尊村灌区为主要研究对象,通过对一级站首部枢纽2019年5—7月取黄河水样及工况、断面流速、水深、水面宽度数据监测,分析了泥沙含量、沉起流速,采用...  相似文献   

11.
Limited precipitation restricts yield of winter wheat (Triticum aestivum L.) grown in the North China Plain. Water stress effects on yield can be avoided or minimized by application of irrigation. We examined the multiseasonal irrigation experiments in four locations of the piedmont and lowland in the region, and developed crop water-stress sensitivity index, relationship between seasonal evapotranspiration (ET) and yield, and crop water production functions. By relating relative yield to relative ET deficit, we found that the crop was more sensitive to water stress from stem elongation to heading and from heading to milking. For limited irrigation, irrigation is recommended during the stages sensitive to water stress. Grain yield was 258–322 g m−2 in the piedmont and 260–280 g m−2 in the lowland under rainfed conditions. The corresponding seasonal ET was 242–264 mm in the piedmont and 247–281 mm in the lowland. Irrigation significantly increased seasonal ET and therefore grain yield as a result of increased kernel numbers per m−2 and kernels per ear. On average, one irrigation increased grain yield by 21–43% and two to four irrigations by 60–100%. Grain yield was linearly related to seasonal ET with a slope of 1.15 kg m−3 in the lowland and 1.73 kg m−3 in the piedmont. Water-use efficiency was 0.98–1.22 kg m−3 for rainfed wheat and 1.20–1.40 kg m−3 for the wheat irrigated 2–4 times. Grain yield response to the amount of irrigation (IRR) was developed using a quadratic function and used to analyze different irrigation scenarios. To achieve the maximum grain yield, IRR was 240 mm in the piedmont and 290 mm in the lowland. When the maximum net profit was achieved, IRR was 195 mm and 250 mm in the piedmont and lowland, respectively. The yield response curve to IRR showed a plateau over a large range of IRR, indicating a great potential in saving IRR while maintaining reasonable high levels of grain yield.  相似文献   

12.
Seasonal partitioning of evapotranspiration (ET) between transpiration by grapevines (Vitis vinifera) (T gp) and by cover crops of a ryegrass/clover mixture (T cc), and soil evaporation (E s) was performed for a furrow-irrigated vineyard during the 1994/1995 and 1995/1996 growing seasons in south-eastern Australia. ET, determined with a water balance approach, averaged 622 mm. The ET rate averaged over the two seasons increased from 2 mm day–1 in spring (September to November), when it was dominated by T cc, to peak rates of around 5 mm d–1 in summer (December to February) when it was dominated by E s. T gp, determined with either heat-pulse sensors or the Penman-Monteith equation, attained peak rates of 0.75 and 0.98 mm d–1, or 6.2 and 8.1 l vine–1 day–1 in the first and second seasons, respectively. Total seasonal T gp of 109.1 mm (900 l vine–1) in 1994/1995 and 118.8 mm (980 l vine–1) in 1995/1996 constituted just 18 – 19% of total ET. T cc totalled 214 mm (34% of ET) in the first season, when pasture cover was sparse and present for 5 months of the growing season (September to February), and 196 mm (30% of ET) in the second season when pasture cover was heavy but present for only 3 months (September to November). E s averaged 49% of total ET over both seasons. At least 30% of water used for ET was contributed by antecedent soil water in both seasons. The crop factor (K c) was largely constant throughout the season with an average value of 0.48. The depletion pattern of soil water indicated that the vine explored the soil profile well beyond 1.0 mm depth and almost evenly up to a distance of 1.5 m from the trunk. Water use efficiencies for fresh fruit yield (WUE), i. e., the ratio of fruit weight to total water use at harvest,were 13.3 and 40.5 kg ha–1 mm–1 when based on ET in 1994/1995 and 1995/1996, respectively, and 84.0 and 211.1 kg ha–1 mm–1, respectively, when based on T gp. The T gp data were used to verify three models of vine transpiration developed in an earlier study. Models based on the green area index or on fraction of incident radiation intercepted by the vine canopy produced good agreement with T gp. The model based on canopy resistance performed poorly, indicating the difficulty of extrapolating the stomatal response to environmental variables from one set of experimental conditions to another. Received: 23 September 1996  相似文献   

13.
为探究含沙水磁化处理对悬浮泥沙在滴灌管网中沉降的影响,揭示含沙水磁化处理对滴头堵塞的减缓机理,以内镶贴片式迷宫流道滴头为研究对象,设置4种磁化强度(0、0.2、0.4、0.6 T)和4种粒径级配(0～0.100 mm、0.075～0.100 mm、0.038～0.075 mm、0～0.038 mm)的泥沙,泥沙质量浓度...  相似文献   

14.
Seasonal evapotranspiration (ET) was determined for Sultana grapevines grown on their own roots (Own-rooted) or grafted onto Ramsey rootstock (Grafted), and irrigated with water of three salinity levels – low (0.4 dS m–1), medium (1.8 dS m–1) and high (3.6 dS m–1) – during the 1994/1995 growing season in south-eastern Australia. Transpiration (T) was determined from sap flux, soil evaporation (E s) with a model, and soil water (S) with a neutron probe. Total ET for the season was similar for both Own-rooted and Grafted, averaging 382 mm. However, Grafted partitioned a mean of 193.5 mm (50.8%) of the ET through T compared to 146.7 mm (38.4%) by Own-rooted. Daily rates of T were generally low and attained peaks of 1.2 mm (9.9 l per vine) for Grafted and 0.9 mm (7.5 l) for Own-rooted in late November, and changed very little until after harvest in February. In contrast to T, the E s rate was consistently higher for Own-rooted than for Grafted from November onwards, and at the end of the season totalled 237 mm for Own-rooted compared to 187 mm for Grafted. Differences between Own-rooted and Grafted in their partitioning of ET into T and E s were associated with their canopy development. Grafted had a higher rate of canopy development than Own-rooted, and in mid-season, the former intercepted about 50% more incident radiation than Own-rooted. The crop factors, i. e. ratio of water use to evaporative demand, based on ET were similar for both vine types with an average seasonal value of 0.25, but when based on T were 0.12 for Grafted and 0.10 for Own-rooted. The ratio of fresh fruit weight to total water used at harvest, i. e. crop water use efficiency (CWUE), based on ET, had a mean of 86 kg mm–1 ha–1 for Grafted and 43 kg mm–1 ha–1 for Own-rooted, and when based on T, was 165 and 115 kg mm–1 ha–1, respectively; however, supplementary data obtained during the 1993/1994 season, indicated a CWUE based on T of 294 and 266 kg mm–1 ha–1 for Grafted and Own-rooted, respectively. Salinity did not have significant effects on canopy development and water use for most of the 1994/1995 growing season. The study shows ET and crop factors for the drip-irrigated grapevines to be much lower than previously reported for this district. Received: 6 May 1996  相似文献   

15.
浑水质量分数对石英砂滤料过滤性能的影响   总被引：1，自引：0，他引：1  
为了正确评价泥沙颗粒对微灌系统堵塞的影响,试验配置了4种质量分数分别为0.3‰,0.5‰,0.8‰和1‰的浑水,通过微灌用砂过滤器模型,研究了滤后水的浊度、粒径变化以及泥沙颗粒质量浓度随时间的变化规律.结果表明:浑水质量分数影响滤后水浊度和颗粒质量浓度,浑水质量分数大,则滤后水浊度和颗粒质量浓度高;不同质量分数浑水过滤10 min后,滤后水浊度均逐渐下降,而当浑水质量分数增大到0.8‰时,过滤10 min时滤后水浊度极不稳定,滤层截留较多的粒径大于0.1 mm颗粒,也有2%~3%的大粒径颗粒穿过了滤层.当浑水质量分数小于0.5‰时,滤后水中粒径小于0.1 mm颗粒的质量分数增大较少,粒径大于0.1 mm颗粒的质量分数不到1%.随着浑水质量分数的增大,平均浊度滤除率和颗粒质量浓度减少率均呈负二次曲线变化,当浑水质量分数为0.8‰时,分别达到56.69%和57.61%.大质量分数的浑水具有较大的浊度滤除率和颗粒质量浓度减少率,但易于造成砂滤层的堵塞,降低其过滤效果、缩短过滤时间.  相似文献   

16.
为了分析鄂尔多斯市准格尔旗不同粒径砒砂岩的力学性能,进行不同干湿循环次数试验,得到了砒砂岩收缩变形和强度特性的变化规律.结果表明:<2.00 mm(原状砒砂岩)试样在3次干湿循环后收缩变化最大;0.50~1.00 mm试样一直缓慢收缩沉积;0.25~0.50 mm和<0.25 mm试样在第3次循环后土体的密实度达到最强.在此基础上,利用直剪仪测定其抗剪强度.在相同的垂直荷载下,发现<2.00 mm试样随着循环次数的增大,1~3次循环的过程中抗剪强度增加最大,之后小幅度增加;0.50~1.00 mm试样随循环次数的增加呈现出缓慢增长的趋势;0.25~0.50 mm和<0.25 mm试样随着循环次数的增加而先略有降低,之后稍有增加并逐渐保持稳定.砒砂岩内摩擦角变化,<2.00 mm和0.50~1.00 mm粒径随干湿循环次数增加而递增;而0.25~0.50 mm和<0.25 mm粒径内摩擦角几乎不变化.黏聚力变化,<2.00 mm 和0.50~1.00 mm试样呈现出先增大逐渐平缓的趋势;0.25~0.50 mm和<0.25 mm试样呈现先减小随后小幅度增大的趋势.  相似文献   

17.
Odour nuisance arising from piggery slurry can be prevented by aeration. The stability of aerobically treated slurry, which is free of offensive odours, increases as the dry matter of the slurry decreases. This paper investigates the performance of a decanting centrifuge as one means of achieving a lower dry matter in piggery slurry.Slurry was centrifuged to show the effects of various operating conditions; 61% of the total solids were removed from slurry of 8% dry matter content wet basis (d.m.) in the form of fibrous solids of 27% d.m. and 43% of the total solids were removed from slurry of 2% d.m. as fibrous solids of 30% d.m. When the raw slurry had 8% d.m., centrifuging reduced the volume needed for liquid storage by 17%. A particle size analysis of the solids which remained in the centrifuged liquid showed that 98% were less than 0·020 mm diameter. This agrees with the predicted maximum size of particle left in the centrifuged liquid. Centrifuged liquid from the dilute slurry contained only 4% of particles greater than the predicted maximum diameter of 0·012 mm.  相似文献   

18.
【目的】分析砾石量及粒径对土壤蒸发的定量影响。【方法】以辽西低山丘陵区坡地非砾石土壤为对照(CK),通过设置4种粒径和6种砾石量的含砾石土壤,采用室内恒温蒸发模拟研究砾石量和粒径对土壤水分蒸发的影响。【结果】2～5 mm粒级砾石量在30%范围内均能减少蒸发,当粒径大于2～5 mm时,较低的砾石量并不能减少土壤累积蒸发量,甚至增大土壤累积蒸发量,当砾石量大于15%时土壤累积蒸发量随砾石量的增大显著减小;当砾石量较小时,小粒径的土壤累积蒸发量较小,随土壤中砾石量的增加,土壤累积蒸发量随着砾石粒径的增大而减小;含砾石土壤平均蒸发速率均小于非砾石土壤,初始蒸发速率表现为含砾石土壤大于非砾石土壤,且随砾石量的增大表现为增大趋势。【结论】砾石能够显著的降低土壤蒸发量。  相似文献   

19.
为了解决引黄灌区浑水管道输水灌溉工程中泥沙淤堵问题,合理确定临界不淤流速,用试验沙样和清水配制了6组不同含沙量的浑水水样,在4种规格管径的管道中进行了浑水管道输水临界不淤流速试验．分析了浑水含沙量、输水管径、泥沙密度和颗粒粒径对临界不淤流速的影响．结果表明:当管径和泥沙密度不变时,临界不淤流速随含沙量的增大而增大;当含沙量和泥沙密度不变时,临界不淤流速随管径的增大而增大;泥沙密度和粒径对临界不淤流速影响也很明显,特别是泥沙颗粒的上限粒径(d90或d95),一般最先沉降到管底的是粒径比较大的泥沙颗粒．同时,基于泥沙悬浮效率系数和悬浮泥沙能量耗损的角度,建立了临界不淤流速计算公式;利用试验数据,确定了泥沙悬浮效率系数计算方法;经试验并比较了临界不淤流速的实测值与计算值,两者之间的最大误差为2958％．  相似文献   

20.
Food production and water use are closely linked processes and, as competition for water intensifies, water must be used more efficiently in food production worldwide. A field experiment with wither wheat (Triticum Aestivum L.), involving six irrigation treatments (from rain-fed to 5 irrigation applications), was maintained in the North China Plain (NCP) for 6 years. The results revealed that dry matter production, grain yield and water use efficiency (WUE) were each curvilinearly related to evapotranspiration (ET). Maximum dry matter at maturity was achieved by irrigating to 94% and maximum grain yield to 84% of seasonal full ET. A positive relationship was found between harvest index (HI) and dry matter mobilization efficiency (DMME) during grain filling. Moderate water deficit during grain filling increased mobilization of assimilate stored in vegetative tissues to grains, resulting in greater grain yield and WUE. Generally, high WUE corresponded with low ET, being highest at about half potential ET. At this location in NCP, highest WUE and grain yield was obtained at seasonal water consumption in the range 250–420 mm. For that, with average seasonal rainfall of 132 mm, irrigation requirements was in the range of 120–300 mm and due to the deep root system of winter wheat and high water-holding capacity of the soil profile, soil moisture depletion of 100–150 mm constituted the greater part of the ET under limited water supply. The results reveal that WUE was maximized when around 35% ET was obtained from soil moisture depletion. For that, seasonal irrigation was around 60–140 mm in an average season.  相似文献   

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