Yield and Quality Response of Cucumber to Irrigation and Nitrogen Fertilization Under Subsurface Drip Irrigation in Solar Greenhouse

The aims of this research were to compare subsurface drip irrigation scheduling and nitrogen fertilization rates in cucumber, and evaluate yield and quality of cucumber fruit, water （WUE）, irrigation water （IWUE）, and nitrogen use （NUE） efficiencies in the solar greenhouse in Southwest China. The irrigation water amounts were determined based on the 20 cm diameter pan （Ep） placed over the crop canopy, and cucumber plant was subjected to three irrigation water levels （I1, 0.6 Ep; I2, 0.8 Ep; and I3, 1.0 Ep） in interaction with three nitrogen fertilization levels （N1, 300 kg ha-1; N2, 450 kg ha-1; and N3, 600 kg ha-1）. The results showed that the cucumber fruit yield increased with the improvement of irrigation water. Irrigation water increased yields by increasing the mean weight of the fruits, and also by increasing fruit number. But the highest values of IWUE and WUE were obtained from I2 treatment. NUE significantly decreased with the improvement of N application, but increased by irrigating more water. The quality of cucumber fruit decreased with the improvement irrigation water and nitrogen fertilization. In conclusion, the optimum irrigation level and nitrogen fertilizer application level for cucunber under subsurface drip irrigation in the solar greenhouse in Southwest China were 0.8 Ep and 450 and 600 kg ha-1, respectively.

Tomato Root Response to Subsurface Drip Irrigation

Four depth treatments of subsurface drip irrigation pipes were designated as 1) at 20,2) 30 and 3) 40 cm depths all with a drip-proof flumes underneath,and 4) at 30 cm without a drip-proof flume to investigate the responses of a tomato root system to different technical parameters of subsurface drip irrigation in a glass greenhouse,to evaluate tomato growth as affected by subsurface drip irrigation,and to develop an integrated subsurface drip irrigation method for optimal tomato yield and water use in a glass greenhouse. Tomato seedlings were planted above the subsurface drip irrigation pipe. Most of the tomato roots in treatment 1 were found in the top 0-20 cm soil depth with weak root activity but with yield and water use efficiency (WUE) significantly less (P ---- 0.05) than treatment 2; root activity and tomato yield were significantly higher (P = 0.05) with treatment 3 compared to treatment 1; and with treatment 2 the tomato roots and shoots grew harmoniously with root activity,nutrient uptake,tomato yield and WUE significantly higher (P= 0.05) or as high as the other treatments. These findings suggested that subsurface drip irrigation with pipes at 30 cm depth with a drip-proof flume placed underneath was best for tomato production in greenhouses. In addition,the irrigation interval should be about 7-8 days and the irrigation rate should be set to 225 m3 ha-1 per event.

The Potential Contribution of Subsurface Drip Irrigation to Water-Saving Agriculture in the Western USA

Water shortages within the western USA are resulting in the adoption of water-saving agricultural practices within this region. Among the many possible methods for saving water in agriculture, the adoption of subsurface drip irrigation （SDI） provides a potential solution to the problem of low water use efficiency. Other advantages of SDI include reduced NO3 leaching compared to surface irrigation, higher yields, a dry soil surface for improved weed control, better crop health, and harvest flexibility for many specialty crops. The use of SDI also allows the virtual elimination of crop water stress, the ability to apply water and nutrients to the most active part of the root zone, protection of drip lines from damage due to cultivation and tillage, and the ability to irrigate with wastewater while preventing human contact. Yet, SDI is used only on a minority of cropland in the arid western USA. Reasons for the limited adoption of SDI include the high initial capital investment required, the need for intensive management, and the urbanization that is rapidly consuming farmland in parts of the western USA. The contributions of SDI to increasing yield, quality, and water use efficiency have been demonstrated. The two major barriers to SDI sustainability in arid regions are economics （i.e., paying for the SDI system）, including the high cost of installation; and salt accumulation, which requires periodic leaching, specialized tillage methods, or transplanting of seedlings rather than direct-seeding. We will review advances in irrigation management with SDI.

Modeling of Different Irrigation Methods for Maize Using AquaCrop Model: Case Study

Modeling of irrigation methods is one of the most important techniques that contribute to the future of modern agriculture. This will conserve water as water scarcity is a major threat for agriculture. In this study, AquaCrop model was used to model different irrigation methods of maize in field trails in Al-Yousifya, 15 km Southwest of Baghdad. Field experiments were conducted for two seasons during 2016 and 2017 using five irrigation methods including furrow, surface drip and subsurface drip with three patterns of emitter depth (10, 20 and 30 cm) irrigation. AquaCrop simulations of biomass, grain yield, harvest index and water productivity were validated using different statistical parameters under the natural conditions obtained in the study area. For 2016 and 2017 seasons, results of R2 were 0.98 and 0.99, 0.99 and 0.99, 0.99 and 0.97, and 0.8 and 0.73 for biomass, grain yield, harvest index and water productivity, respectively. The study has conducted that simulation using AquaCrop is considered very efficient tool for modeling of different irrigation applications for maize production under the existing conditions in the central region of Iraq.

Experimental study on calculation model of labyrinth emitter discharge under subsurface drip irrigation

For different texture of soils,the grain composition is different with significant changes.Since the emitter of subsurface drip irrigation(SDI)is buried in the soil,emitter discharge is influenced by soil properties.An experiment was conducted to investigate the relationship between the soil properties with emitter working pressure and emitter discharge of SDI.Selecting three different grain composition soils,and emitter working pressure,as well as soil clay content,soil bulk density and initial soil moisture content respectively as influence factors of emitter discharge of SDI,the experimental scheme was gained by uniform design.A calculation model for determination of the SDI emitter discharge was established by regression analysis with the first two kinds of soil test data,and its reliability was verified by the third kind of soil test data.The model is simple with high accuracy,easy to use,and lays the foundation to study hydraulic elements of SDI field network,especially taking the soil clay content as an influencing factor has widened the scope of application of the model.The achievement is of great significance for design and management of SDI.

Effects of topdressing ratio and frequency on the dry matter, yield, and quality of tomato and celery under a small amount of continuous subsurface drip irrigation

Compared with conventional full irrigation,the existing water-saving irrigation method achieves the purpose of water saving by actively controlling soil moisture.High-frequency irrigation can make the ideal conditions for soil water movement and root absorption of water and nutrients.This research used a plot experiment in a greenhouse and set up different fertilization amounts and frequencies during the growth stage to study the effects of small-amount and continuous subsurface drip irrigation on the dry matter,yield,and quality of tomato and celery.The results showed that the frequency of topdressing had a great influence on the dry matter accumulation of tomatoes,and the amount of topdressing had little effect on the fresh weight of the upper part of a tomato plant.The application of high-frequency fertilizer increased the dry matter accumulation in the underground part of the tomato.Under the premise given amount of total fertilization,the growth rate and yield of tomatoes were positively correlated with the amount of topdressing.The optimum fertilization frequency was 1 time during the first fruit stage,3 times for the second fruit stage,and 5 times for the third fruit stage,the yield during the fourth stage was increased with higher frequency,and the topdressing was started ahead of the fourth fruit stage when the diameter of fruit was 40 mm.The lower fertilization frequency during the early stage and higher fertilization frequency during the later stage can increase the yield of celery.The higher ratio of topdressing,the higher frequency during the early growth stage,and the lower frequency during the later stage can achieve the best quality of celery.

紫花苜蓿地下滴灌灌水均匀性与适宜灌溉定额研究

研究主要探究不同灌溉方式紫花苜蓿地下滴灌灌水均匀性差距,并提出适宜的灌水定额。采用田间试验,设3个地下滴灌灌水定额(20、25、30 mm),2个埋设深度(10、20 cm)和2个滴头流量(1.38、2.0 L/h),研究了滴灌带流量、埋深在不同紫花苜蓿生育期内的灌水均匀度差异,同时进一步探究了不同灌水处理对紫花苜蓿株高、产量等参数的影响。滴灌带滴头流量对滴灌灌水均匀性的影响相对较大。在相同的滴灌带滴头流量下,滴灌带埋设深度10 cm与20 cm对滴灌灌水均匀系数影响不显著。当耗水量为456.69 mm时,紫花苜蓿干草产量最大,为12847.78 kg/hm-2。基于节水效果、产量和高效等多生产因素的综合考虑,建议鄂尔多斯鄂托克前旗地区紫花苜蓿地下滴灌灌水定额为25 mm,灌水12~14次。

中国北方地区不同滴灌方式节水增产效应的Meta分析

为了探明中国北方地区地下滴灌(subsurface drip irrigation,SSDI)与地表滴灌(surface drip irrigation,SDI)节水增产效应的差异,该研究以SDI作为对照,采用Meta分析定量分析了不同条件下SSDI对作物产量和水分利用效率的影响。结果表明,与SDI相比,SSDI可使作物总体增产6.66%(P<0.05),水分利用效率提高9.34%(P<0.05),净效益增加6.94%(P<0.05);SSDI在西北和华北地区均能提高作物产量和水分利用效率;当年均降雨量不大于400 mm时,SSDI能显著提高作物产量;当土壤容重大于1.5 g/cm^(3),灌水施肥频率大于6次,滴灌带埋深为>15~25 cm,滴头流量介于>1.5~<2.5 L/h时,更有利于发挥SSDI优势,节水增产效果显著。研究可为中国北方地区SSDI的推广应用提供理论参考。

地下滴灌关键技术参数对砂土地区苜蓿根系与产量的影响

为研究地下滴灌条件下,适宜于紫花苜蓿根系生长和高产的滴头流量、滴灌带埋深以及灌水定额,采用田间试验,设3个滴灌带滴头流量(1.38、2.00、3.00 L/h),3个滴灌带埋深(10、20、30 cm)和3个地下滴灌灌水定额(15.0、22.5、30.0 mm),研究了不同地下滴灌关键技术参数对苜蓿根系与产量的单因素影响。结果表明:滴头流量为2.00 L/h时更有利于苜蓿根系的生长,滴灌带埋深对苜蓿侧根的影响显著;灌水定额对苜蓿的根系比表面积、根尖数、侧根发生数、侧根位置影响显著;小滴头流量处理的苜蓿产量总体上高于大滴头流量处理;滴灌带埋深对苜蓿产量的影响不显著;在一定范围内,随着灌水定额的增大,苜蓿产量增加。综合节水与产量因素,建议鄂尔多斯市鄂托克前旗地区紫花苜蓿地下滴灌关键技术参数:滴头流量为2.00 L/h、滴灌带埋深为20 cm、灌水定额为22.5 mm。

水氮耦合对地下滴灌冬小麦和夏玉米水氮利用效率影响研究

【目的】探索冬小麦、夏玉米地下滴灌条件下最佳灌水施氮制度。【方法】采用田间试验方法,分别设置4个灌水水平,冬小麦:W1:2580 m^(3)/hm^(2)、W2:2240 m^(3)/hm^(2)、W3:2020 m^(3)/hm^(2)、W4:1560 m^(3)/hm^(2),夏玉米:W1:1306 m^(3)/hm^(2)、W2:1088 m^(3)/hm^(2)、W3:814 m^(3)/hm^(2)、W4:650 m^(3)/hm^(2),2个施氮水平,冬小麦、夏玉米均为:F1:180 kg/hm^(2)、F2:100 kg/hm^(2),研究水氮耦合对冬小麦、夏玉米水氮利用效率及产量影响。【结果】W2F1处理冬小麦产量最大,继续增加灌水量冬小麦产量并未增加,而夏玉米产量随灌水量增加而增加;土壤氮素残留量均表现为F1处理>F2处理,且冬小麦氮素残留量随灌水量增加先减少后增加,W1处理夏玉米氮素残留量最大,冬小麦、夏玉米氮肥偏生产力均与产量变化趋势一致;冬小麦、夏玉米耗水量均随灌水量增加而增加,水分利用效率均随灌水量增加呈先增大后减小趋势。【结论】拟合优化表明,冬小麦的适宜灌水量为214 mm,适宜施氮量100 kg/hm^(2);夏玉米适宜灌水量为103 mm,适宜施氮量100 kg/hm^(2)。

追肥减施下加气对番茄生长及土壤酶活性的影响

[目的]为探究化肥减施条件下加气对作物生长特性和根层土壤特征的影响。[方法]通过开展连续2年野外田间试验,以宁夏银北灌区大田栽培番茄为研究对象,设置4组微纳米加气比例(0,5%,10%,15%)和3个追肥(尿素—重过磷酸钙—硫酸钾)水平(180—400—480,135—300—360,90—200—240 kg/hm^(2))。[结果]在相同追肥水平下,植株的干物质和营养元素(氮、磷、钾)积累量随加气比例增加而增加,提高加气比例有利于番茄开花坐果期根系磷素积累和果实膨大期钾素积累;在相同追肥水平下提高加气比例5%~15%对应番茄产量增加14.0%~44.2%;在相同加气比例下相对传统施肥模式适当降低追肥水平(-25%)对应番茄产量增加0.4%~9.1%;提高加气比例和追肥水平有利于在番茄开花坐果期和果实膨大期显著提高土壤相关酶(过氧化氢酶、碱性磷酸酶和脲酶)活性,相同追肥水平下提高加气比例5%~15%对应土壤相关酶活性提高27.5%~122.9%。[结论]在宁夏银北灌区地埋滴灌条件下,为促进植株生长、稳定番茄产量和提高土壤酶活性,适宜的“尿素—重过磷酸钙—硫酸钾”追施水平为180—400—480 kg/hm^(2)(相对传统追肥定额减施25%),适宜的微纳米加气比例为10%。

2种土壤地下滴灌滴头流量变化规律及对入渗空腔的响应

为研究入渗空腔对地下滴灌滴头流量和土水势的影响规律,通过土箱试验和数值模拟相结合的方法,对比分析了黏土和壤质砂土2种土壤灌水过程中土壤正压及滴头流量的变化规律,反演了滴头出口处空腔半径,并建立了黏土中空腔半径的计算模型.研究结果表明:相同条件下,壤质砂土中的滴头流量大于黏土中的,但变化幅度小于黏土中的;壤质砂土中土壤正压随时间变化呈上升趋势,黏土中土壤正压随时间变化呈下降趋势,受空腔影响,滴头流量与土壤正压随时间的变化趋势不存在必然关系.模拟中,壤质砂土入渗空腔半径可选择较小值或认为与滴头出口半径相同.黏土中空腔半径随滴头额定流量和容重增大而增大.相对于选用固定值,研究得到的空腔半径可以提高现有计算公式在求解滴头流量和土壤正压的精度,拟合的空腔半径经验模型可以应用于地下滴灌水力设计,同时为土壤水分入渗数值模拟的边界条件设置提供依据.

不同生育期曝气滴灌对温室番茄生长品质影响

为探究不同生育期循环曝气地下滴灌对温室番茄生长及品质的影响规律,设置不同生育期以及全生育期循环曝气处理,以全生育期不曝气处理作为对照组,研究不同生育期循环曝气处理对温室番茄株高、茎粗、叶绿素含量、根系活力及品质的影响.结果表明:开花坐果期循环曝气处理有利于温室番茄株高的增长,果实膨大期循环曝气处理有利于温室番茄茎粗的增长,多生育期连续循环曝气较单一生育期曝气优势不明显;相较于对照组处理,果实膨大期曝气处理温室番茄果实单果质量提高36.12%,果实横纵径分别提高11.52%,20.24%,可溶性固形物含量提高29.25%,有机酸含量降低20.41%,糖酸比提高47.53%,维生素C含量提高40.58%,可溶性糖含量提高12.65%,可溶性蛋白含量提升38.62%,果实膨大期曝气处理有利于温室番茄单果质量的增加和品质的优化.因此,综合果实品质和作物生长各指标,开花坐果期循环曝气处理更有利于温室番茄株高的生长,果实膨大期曝气处理更有利于温室番茄茎粗、单果质量及果实品质的提升.

不同播种灌溉方式对夏玉米出苗、干物质积累及转运和产量的影响

设置地面灌溉常规播种(CK)、地表滴灌常规播种(DI)、地下滴灌深播(SDI)处理,研究不同播种灌溉方式对夏玉米出苗、干物质积累及转运和产量的影响,以期筛选出适宜夏玉米大田生产的播种灌溉方式。结果表明,播种后灌溉40 mm情况下,SDI处理土壤水分可以上移至种床层,下渗到距地表80 cm处,5~10、10~20 cm土层的土壤含水量分别达到田间持水量的68.69%、75.35%;CK和DI处理土壤湿润体在60 cm以上土层。SDI处理显著延长夏玉米的出苗时间,导致其苗期单株叶面积和干质量较其他处理显著降低,但其出苗率并未显著降低。在生育期间灌溉的条件下,与CK相比,SDI处理降低拔节后期和灌浆初期0~20 cm土层的土壤含水量,但增加40~120 cm土层的土壤含水量;DI处理增加拔节后期中上层土壤和灌浆初期土壤含水量。与CK相比,SDI和DI处理不仅能够促进花前干物质的转运,而且还能提高开花期和灌浆期的叶面积指数、地上部干物质积累量以及产量和水分利用效率,SDI和DI处理成熟期地上部干物质积累量、产量、水分利用效率分别提高8.51%、11.22%、11.41%和6.18%、6.38%、9.94%。SDI处理较DI处理提高了夏玉米的穗粒数和产量,但两处理间水分利用效率差异不显著。综上,地下滴灌深播未显著影响夏玉米的出苗率,并且地下滴灌能够提高中下层土壤的含水量,对花前干物质转运量及花后叶面积指数和地上部干物质积累量的提高有利,最终获得最高的产量和水分利用效率。

地下滴灌灌水器水力性能试验研究

地下滴灌与地表滴灌的最大差异在于地下滴灌的灌水器出水口被土壤包围 ,其出流受到土壤的限制。在室内将灌水器埋入土槽中 ,模拟研究了灌水器类型、自由出流时的流量、工作压力、土壤初始含水率等因素 ,对地下滴灌条件下灌水器水力性能的影响。试验结果表明 :灌水器埋入土壤后 ,流量是其自由出流时流量的 1/2～ 1/4。方差分析表明 ,影响地下滴灌灌水器水力性能的主要因素是自由出流时的水力特性和土壤特性。针对测试土壤 ,建立了地下滴灌灌水器流量计算的修正关系式。

加气滴灌提高大棚甜瓜品质及灌溉水分利用效率

为揭示加气频率和滴灌带埋深等对甜瓜产量、品质及水分利用效率的影响,以甜瓜(陕甜一号)为研究对象,采用追加正交试验设计,研究不同加气频率、地下滴灌带埋深及灌水控制上限对大棚甜瓜果实形态、产量、品质及灌溉水分利用效率的影响。结果表明:对果实形态、品质及产量影响的大小顺序依次为加气频率、滴灌带埋深和灌水控制上限。对水分利用效率的影响大小顺序依次为灌水控制上限、加气频率和滴灌带埋深。根区加气能够显著改善果实产量及品质,滴灌带埋深为25 cm,每天加气1次品质及果实形态指标最好,产量最高。灌水量控制在田间持水量的80%时,果实可溶性固形物含量最高,但灌水量为70%田间持水量时,可溶性总糖、产量、水分利用效率最高。综合考虑,最优处理组合为滴灌带埋深25 cm,每天通气一次,灌水控制上限为70%田间持水量。

地下滴灌灌水器堵塞研究

地下滴灌(SDI)是一种高效的节水灌溉技术,但系统易于堵塞,堵塞问题成为影响地下滴灌成败的关键。通过对运行8年的地下滴灌系统堵塞的实地调查,迷宫式、微管式和孔口式等3类型的灌水器均有不同程度的堵塞,堵塞率分别达到16.67%、25%和63.89%。分析3类型灌水器的堵塞状况,引起地下滴灌堵塞的主要原因是进入系统的微粒在流道壁的附着和发育。为此,提出加强过滤、定时冲洗和改变滴头流道设计等解决地下滴灌堵塞的建议。

果树地下滴灌灌水技术田间试验研究

采用正交试验方法,探讨了不同埋深、孔径、孔距、防堵套长度的简易地下滴灌在定压供水条件下渗水量、管道水压分布和土壤水分入渗规律。结果表明,滴水管的出水量随时间呈幂函数下降,单孔出水量随孔径和孔距的增大而显著增大;地下滴灌的灌水均匀度随孔径的增大、孔距的减小而降低;地下滴灌的土壤入渗宽度随孔径的增大、孔距的减小、埋深的减小而增大,入渗深度则相反;对渭北旱塬地区,现行的果树简易地下滴灌的管道埋深、孔径、孔距应分别为40cm,0.9mm,60～80cm。

间接地下滴灌灌溉深度对枣树根系和水分的影响

为探讨间接地下滴灌及导水装置埋深（灌溉深度）对南疆极端干旱区矮化密植红枣根系生长分布特征及产量、水分利用率的影响,试验设间接地下滴灌（ISDI）3个导水装置埋深水平,分别为20、27、35 cm,以地表滴灌（DI）为对照,共4个处理,经过2~4 a的田间试验后,采用环状壕沟分层挖掘法对以枣树树干为中心,半径为1 m的90°扇形区域内0~100 cm土层进行根系取样。结果表明,相对于DI,ISDI下各根系分布较均匀,生长方向基本向下延伸;ISDI显著增加了根径小于5 mm根系根长密度,细根（根径小于2 mm）是DI的3倍,但减少了根径大于5 mm根系根长密度,相对增加了20~40 cm土层根系根长占总根长的比率;垂直方向上随着灌溉深度的增加表层根系根长密度相对减少,深层相对增加;水平方向上各处理根系根长密度基本呈现随着与树干水平距离的增加而减小的趋势,但在0~20 cm土层减小的幅度较大,在20~40 cm土层其减小的幅度较小;随着灌溉技术由DI到ISDI及灌溉深度的增加,细根分布基本呈现出由＂宽浅型＂向＂深根型＂发展的趋势。相对DI,ISDI具有较好的节水增产效果,提高产量及灌溉水生产率最大达20%。建议幼龄期南疆密植枣树的导水装置埋深为27~35 cm。研究为极端干旱区枣树适宜灌溉技术的选择及其技术要素的制定提供依据。

温室地下滴灌灌水控制下限对番茄生长发育、果实品质和产量的影响

用温室小区试验的方法,通过对番茄株高和茎粗、果实品质和产量以及水分生产效率进行比较,探讨了温室栽培茄果类地下滴灌灌水控制下限的适宜取值范围。结果表明:在壤质土壤的试验地上,当地下滴灌管埋深为30 cm、计划湿润层深为15 cm^45 cm(厚度30 cm)、湿润比取0.7、灌水控制上限取田间持水量时,将土壤水吸力30 kPa作为控制灌水的下限,有利于番茄植株生长发育,可以达到高产、优质、节水的目的。