Effects of Alternative Partial Root-zone Irrigation and Nitrogen Fertilizer on Plukenetia volubilis Seedlings

This study was aimed to investigate the effects of alternative partial rootzone irrigation and nitrogen fertilizer on the potted seedlings of Plukenetia volubilis.A total of 7 treatments were designed with three factors, i.e., irrigation amount, irrigation mode and nitrogen fertilizer. The growth, photosynthesis and water use efficiency were analyzed. The results showed that compared with those under full irrigation, the biomass and water consumption under alternative partial root-zone irrigation were reduced by 5% and 75%, respectively, and the water use efficiency was increased by 60%. Under severe drought conditions, the root cap ratio in the nitrogen fertilizer treatment group was increased by 30%; the leaf area index, photosynthetic rate and biomass under alternative partial root-zone irrigation were reduced by 38%, 9% and 18%, respectively. It indicates that under severe drought conditions, alternative partial root-zone irrigation is not suitable to be matched with application of nitrogen fertilizer. In short, under moderate drought conditions, alternative partial root-zone irrigation could reduce transpiration and improve water use efficiency, and it is an effective water-saving irrigation technology for the plantation of P.volubilis plants.

Effect of fertigation frequency on soil nitrogen distribution and tomato yield under alternate partial root-zone drip irrigation

Alternate partial root-zone drip fertigation (ADF) is a combination of alternating irrigation and drip fertigation,with the potential to save water and increase nitrogen (N) fertilizer efficiency.A 2-year greenhouse experiment was conducted to evaluate the effect of different fertigation frequencies on the distribution of soil moisture and nutrients and tomato yield under ADF.The treatments included three ADF frequencies with intervals of 3 days (F3),6 days (F6) and 12 days (F12),and conventional drip fertigation as a control (CK),which was fertilized once every 6 days.For the ADF treatments,two drip tapes were placed 10 cm away on each side of the tomato row,and alternate drip irrigation was realized using a manual valve on the distribution tapes.For the CK treatment,a drip tape was located close to the roots of the tomato plants.The total N application rate of all treatments was 180 kg ha^(-1).The total irrigation amounts applied to the CK treatment were450.6 and 446.1 mm in 2019 and 2020,respectively;and the irrigation amounts applied to the ADF treatments were 60%of those of the CK treatment.The F3 treatment resulted in water and N being distributed mainly in the 0–40-cm soil layer with less water and N being distributed in the 40–60-cm soil layer.The F6 treatment led to 21.0 and 29.0%higher 2-year average concentration of mineral N in the 0–20 and 20–40-cm soil layer,respectively and a 23.0%lower N concentration in the 40–60-cm soil layer than in the CK treatment.The 2-year average tomato yields of the F3,F6,F12,and CK treatments were 107.5,102.6,87.2,and 98.7 t ha^(-1),respectively.The tomato yield of F3 was significantly higher (23.3%) than that in the F12 treatment,whereas there was no significant difference between the F3 and F6 treatment.The F6 treatment resulted in yield similar to the CK treatment,indicating that ADF could maintain tomato yield with a 40%saving in water use.Based on the distribution of water and N,and tomato yield,a fertigation frequency of 6 days under ADF should be considered as a water-saving strategy for greenhouse tomato production.

Influences of alternate partial root-zone irrigation and urea rate on water-and nitrogen-use efficiencies in tomato

Traditional water and fertilizer inputs are often much higher than the actual demands of tomato,which causes a reduction in water-and fertilizer-use efficiencies.To investigate the advantage of alternate partial root-zone irrigation(AI)on water-and nitrogen(N)-use efficiencies of tomato modified by water and N management,taking conventional irrigation(CI)as the control,the effects of AI on root morphology and activity,fruit yield and water and N use efficiency were studied using pot experiments.There were four combinations of irrigation levels and growing stages of tomato for AI,i.e.AI_(1)(high water(W_(H))from blooming to harvest stage(BHS)),AI_(2)(W_(H)from blooming to fruit setting stage(BFS)and low water(W_(L))at the harvest stage(HS)),AI_(3)(W_(L)at BFS and W_(H)at HS)and AI_(4)(W_(L)at BHS)at three urea rates,i.e.low urea rate(NL),middle urea rate(N_(M))and high urea rate(N_(H))in the form of urea.Irrigation quotas for W_(H)and W_(L)in AI at BFS or HS were 80%and 60%of that in CI,respectively.Compared to CI,AI decreased water consumption by 16.0%-33.1%and increased water use efficiency of yield(WUE_(y))and dry mass(WUE_(d))by 6.7%-11.9%and 10.2%-15.9%,respectively.AI_(1)did not decline yield,total N uptake(TNU)and N use efficiency(NUE)significantly.Compared to NL,N_(M)enhanced tomato yield,TNU,WUE_(y)and WUE_(d)by 28.5%,35.3%,22.6%and 16.3%,respectively.Compared to CINL,AI_(1)N_(M)reduced water consumption by 12.5%,but increased tomato yield,TNU,WUE_(y)and WUE_(d)by 35.5%,58.4%,54.4%and 53.7%,respectively.Therefore,AI_(1)can improve water use efficiency and total N uptake of tomato simultaneously at medium urea rate.

Alternate partial root-zone irrigation with high irrigation frequency improves root growth and reduces unproductive water loss by apple trees in arid north-west China

Alternate partial root-zone irrigation(APRI)can improve water use efficiency in arid areas. However,the effectiveness and outcomes of different frequencies of APRI on water uptake capacity and physiological water use have not been reported. A two-year field experiment was conducted with two irrigation amounts(400 and500 mm) and three irrigation methods(conventional irrigation, APRI with high and low frequencies). Root length density, stomatal conductance, photosynthetic rate,transpiration rate, leaf water use efficiency, midday stem and leaf water potentials were measured. The results show that in comparison with conventional irrigation, APRI with high frequency significantly increased root length density and decreased water potentials and stomatal conductance.No differences in the above indicators between the two APRI frequencies were detected. A significantly positive relationship between stomatal conductance and root length density was found under APRI. Overall, alternate partial root-zone irrigation with high frequency has a great potential to promote root growth, expand water uptake capacity and reduce unproductive water loss in the arid apple production area.

Evaluation of tomato fruit quality response to water and nitrogen management under alternate partial root-zone irrigation

A pot experiment was conducted to investigate the effects of different water and nitrogen supply amounts on the comprehensive assessment of tomato fruit quality and root growth parameters under alternate partial root-zone irrigation.Three upper irrigation limitations(i.e.70%(W1),80%(W2)and 90%(W3)of field capacity,respectively)and three N-fertilizer levels(i.e.0.18(N1),0.30(N2)and 0.42(N3)g/kg soil,respectively)were arranged with a randomized complete block design,and alternate partial root-zone irrigation method was applied.Results showed that fruit yields under deficit irrigation(W1 and W2)were decreased by 6.9%and 2.0%respectively compared with W3 under N1 level.Yields of tomato under W1N1 and W1N2 combinations were also reduced by 10.3%and 7.2%,respectively compared with W1N3 combination.Root dry weight,root length,root surface area and root volume were all increased in W1N2 treatment.According to two-way ANOVA,the root parameters except root dry weight,were extremely sensitive to water,nitrogen and the cross effect of the two factors.TSS(total soluble solids),SS(soluble sugars)and OA(organic acid)in the fruits increased with the decrease in irrigation water,OA and NC reduced with decreasing amount of nitrogen.Moreover,within an appropriate range,as more irrigation water and nitrogen were applied,the higher VC(vitamin C)and lycopene contents were identified in the fruits.Eventually,the combinational evaluation method(i.e.entropy method and gray relational analysis)showed that W2N2 ranked highest in comprehensive fruit quality.Therefore,considering the tradeoff between fruit comprehensive quality and yields,upper irrigation limitation of 80%θf and N-fertilizer of 0.30 g/kg soil with alternate partial root-zone irrigation was the optimal cultivation strategy for the greenhouse tomato in autumn-winter season in northwest China.

Biochar and alternate partial root-zone irrigation greatly enhance the effectiveness of mulberry in remediating lead-contaminated soils

Aims Soil lead contamination has become increasingly serious and phytoremediation can provide an effective way to reclaim the contaminated soils.This study aims to examine the growth,lead resistance and lead accumulation of mulberry(Morus alba L.)seedlings at four levels of soil lead contamination with or without biochar addition under normal or alternative partial root-zone irrigation(APRI).Methods We conducted a three-factor greenhouse experiment with biochar(with vs.without biochar addition),irrigation method(APRI vs.normal irrigation)and four levels of soil lead(0,50,200 and 800 mg·kg^(-1)).The performance of the seedlings under different treatments was evaluated by measuring growth traits,osmotic substances,antioxidant enzymes and lead accumulation and translocation.Important Findings The results reveal that mulberry had a strong ability to acclimate to soil lead contamination,and that biochar and APRI synergistically increased the biomass and surface area of absorption root across all levels of soil lead.The seedlings were able to resist the severe soil lead contamination(800 mg·kg^(-1) Pb)by adjusting glutathione metabolism,and enhancing the osmotic and oxidative regulating capacity via increasing proline content and the peroxidase activity.Lead ions in the seedlings were primarily concentrated in roots and exhibited a dose–effect associated with the lead concentration in the soil.Pb,biochar and ARPI interactively affected Pb concentrations in leaves and roots,translocation factor and bioconcentration.Our results suggest that planting mulberry trees in combination with biochar addition and APRI can be used to effectively remediate lead-contaminated soils.

Yield Response to Deficit Irrigation and Partial Root-Zone Drying in Processing Tomato （Lycopersicon esculentum Mill,）

Due to the global expansion of irrigated areas and the limited availability of irrigation water, it is necessary to optimize water use in order to maximize crop yields under water deficit conditions. To evaluate the yield response of two processing tomato hybrids （Ercole and Genius） grown under different irrigation treatments, a field trial was conducted during the 2008 growing season in Southern Italy. Three irrigation treatments were used： the restitution of 70% of maximum evapotranspiration （ETc） both under ＂Deficit Irrigation＂ （70DI） and ＂Partial Root-zone Drying＂ （70PRD） strategies; full irrigated （FI： 100% ETc）. The two water deficit irrigation treatments （DI and PRD） showed stomatal conductance values lower than FI treatment and saved a substantial amount of water maintaining reasonable marketable yield. Moreover, PRD strategy showed slightly higher ＂Water Use Efficiency＂ （WUE） values than DI. Finally, ＂yield response factor＂ （Ky） showed always values less than unity, indicating the possibility to adopt, within certain limited condition, both DI and PRD in field-grown processing tomato cultivated in Southern Italy. In conclusion, in our experimental conditions, deficit irrigation practices seem to be acceptable relatively to processing tomato yield aspects and Ky could be promoted as a useful indicator for irrigation in water deficit conditions.

Effect of Partial Root-Zone Irrigating Deuterium Oxide on the Properties of Water Transportation and Distribution in Young Apple Trees

Partial root-zone irrigation （PRI） has been proved to be an optimal water-saving irrigation technology, however, few studies were done on water transportation and distribution under PRI. The present study was performed to investigate the water transportation and distribution among the wet and dry root-zones and the shoot using deuterium water （D2O） in 1/4 root-zone PRI experiment. It also aimed to determine and analyze the D2O relative abundance within different types of roots and shoots. The results indicated that water could be transported from roots in wet root-zone to roots in dry root-zone and shoots within 2 h after irrigation. Water transportation in roots of wet-zone was carried out by absorbing root, 1-2 mm root, 2-5 mm root, and〉5 mm root progressively, while through a reverse process in three dry root-zones. In shoots, water was transported to trunk, central trunk, annual branches, shoot and leaf progressively. Thus in the young apple trees subjected to PRI, water was distributed ifrst in the roots, including the roots in the wet and dry root-zones, to satisfy the water need of roots itself, and then transported to the shoot within hours of irrigation.

Alternate Furrow Irrigation: A Practical Way to Improve Grape Quality and Water Use Efficiency in Arid Northwest China

Field experiments were conducted for two years to investigate the benefits of alternate furrow irrigation on fruit yield, quality and water use efficiency of grape （Vitis vinifera L. cv. Rizamat） in the arid region of Northwest China. Two irrigation treatments were included, i.e., conventional furrow irrigation （CFI, two root-zones were simultaneously irrigated during the consecutive irrigation） and alternate partial root-zone furrow irrigation （AFI, two root-zones were alternatively irrigated during the consecutive irrigation）. Results indicate that AFI maintained similar photosynthetic rate （Pn） but with a reduced transpiration rate when compared to CFI. As a consequence, AFI improved water use efficiency based on evapotranspiration （WUEEr, fruit yield over water consumed） and irrigation （WUE~, fruit yield over water irrigated） by 30.0 and 34.5%, respectively in 2005, and by 12.7 and 17.7%, respectively in 2006. AFI also increased the edible percentage of berry by 2.91-4.79% significantly in both years. Vitamin C （Vc） content content of berry was increased by 25.6-37.5%, and tritrated acidity （TA） was reduced by 9.5-18.1% in AFI. This resulted in an increased total soluble solid content （TSS） to TA ratio （TSS/TA） by 11.5-16.7% when compared to CFI in both years. Our results indicate that alternate furrow irrigation is a practical way to improve grape fruit quality and water use efficiency for irrigated crops in arid areas.

Stem flow of seed-maize under alternate furrow irrigation and double-row ridge planting in an arid region of Northwest China

Maize is widely planted throughout the world and has the highest yield of all the cereal crops. The arid region of North- west China has become the largest base for seed-maize production, but water shortage is the bottleneck for its long-term sustainability. Investigating the transpiration of seed-maize plants will offer valuable information for suitable planting and irrigation strategies in this arid area. In this study, stem flow was measured using a heat balance method under alternate furrow irrigation and double-row ridge planting. Meteorological factors, soil water content （e）, soil temperature （Ts） and leaf area （LA） were also monitored during 2012 and 2013. The diurnal stem flow and seasonal dynamics of maize plants in the zones of south side female parent （SFP）, north side female parent （NFP） and male parent （MP） were investigated. The order of stem flow rate was： SFP〉MP〉NFP. The relationships between stem flow and influential factors during three growth stages at different time scales were analyzed. On an hourly scale, solar radiation （Rs） was the main driving factor of stem flow. The influence of air temperature （Ta） during the maturity stage was significantly higher than in other periods. On a daily scale, Rs was the main driving factor of stem flow during the heading stage. During the filling growth stage, the main driving factor of NFP and MP stem flow was RH and Ts, respectively. However, during the maturity stage, the environ- mental factors had no significant influence on seed-maize stem flow. For different seed-maize plants, the main influential factors were different in each of the three growing seasons. Therefore, we identified them to accurately model the FP and MP stem flow and applied precision irrigation under alternate partial root-zone furrow irrigation to analyze major factors affecting stem flow in different scales.

Economic Potential of Compost Amendment as an Alternative to Irrigation in Maine Potato Production Systems

Potato productivity in the northeastern US has been relatively constant for over 50 years, raising questions about what factors are limiting productivity. Research was initiated in 2004 to identify key constraints to potato productivity by evaluating Status Quo (SQ), Soil Conserving (SC), and Soil Improving (SI) cropping systems under both rainfed and irrigated management, and it was found that addition of compost or irrigation substantially increased yield. In this study, we employed partial budgeting to determine cost differences and their impact on net revenue for these cropping systems. Differences in systems were primarily associated with rotation length, tillage operations, compost and application expenses, and water management practices. When compost (as composted dairy manure) was annually applied at 19 Mg haf-1 and evaluated over the entire 3-year crop rotation cycle, the compost-amended rainfed SI system was more expensive to maintain than the irrigated SC system if compost cost exceeded $3.63 Mg-1. Average marketable yields were used to calculate gross and net revenue for each system. Because average potato yield for the irrigated SQ system (28.4 Mg·ha-1) equaled that in the rainfed SI system (28.3 Mg·ha-1), we were able to compare cost of irrigation versus compost for achieving comparable yield. The compost-amended SI system under rainfed management generated more net revenue from the potato crop than the irrigated SQ system when compost costs were less than $7.42 Mg-1. When compared to the commonly used rainfed SQ system, rainfed SI achieved higher net revenue as long as compost cost was less than $22.95 Mg-1. The rainfed SI system achieved higher net revenue than the irrigated SC system when compost cost was $9.43 Mg-1or less, but generated greater net revenue than the rainfed SC system regardless of compost costs, due to substantially higher yields associated with compost amendment. This investigation demonstrates that compost is a potentially viable substitute to irrigation for potato in the northeastern US;however, such potential is highly dependent on suitable compost sources and application costs.

灌水施氮和缩节胺用量对南疆棉花产量品质和水肥利用效率的影响

为研究灌水量、施氮量和缩节胺用量对棉花籽棉产量、纤维品质和水肥利用效率的交互影响,于2020年和2021年在南疆库尔勒地区开展大田试验,设置3个灌水量(W1:60%ETc,W2:80%ETc,W_(3):100%ETc,ETc为作物蒸发蒸腾量),4个施氮量(N0:0,N200:200 kg/hm^(2),N_(300):300 kg/hm^(2),N_(400):400 kg/hm^(2))和2个缩节胺用量(D_(1):120 g/hm^(2),D_(2):240 g/hm^(2))。结果表明:灌水量、施氮量和缩节胺用量对籽棉产量、水分利用效率、肥料偏生产力和部分纤维品质指标影响显著(P<0.05)。灌水量、施氮量和缩节胺用量三者交互作用对肥料偏生产力和纤维品质影响显著(P<0.05)。株高、叶面积指数和干物质量也受灌水量、施氮量和缩节胺用量三者交互作用影响。W_(3)N_(300)D_(2)处理籽棉产量最高(2020年为7578 kg/hm^(2),2021年为7173 kg/hm^(2)),W1N_(400)D_(1)处理水分利用效率和W_(3)N0D_(2)处理肥料偏生产力最高,W_(3)N_(400)D_(2)处理的纤维长度、纤维强度和马克隆值均获得较大值,纤维品质最佳。基于TOPSIS综合评价方法对棉花产量品质和水肥利用效率进行综合评价,100%ETc灌水量、300 kg/hm^(2)施氮量和240 g/hm^(2)缩节胺用量组合最优,可作为南疆棉花适宜的水氮和化控管理模式。研究结果可为南疆棉花水肥高效利用提供理论依据和科学指导。

水氮运筹对滴灌冬小麦产量和水氮利用效率的影响

为探究水氮运筹对滴灌冬小麦产量和水氮利用效率的效应,于2019—2021年开展了连续2年小麦田间试验,设置2个施氮水平210(N1)和240(N_(2))kg·hm^(-2),4个灌水处理W1(不灌水)、W2(每次30 mm)、W_(3)(每次45 mm)、W_(4)(每次60 mm),分析不同处理小麦产量及水氮利用率相关指标。结果表明,2019—2021年,施氮量和灌水量对冬小麦抽穗期、扬花期和灌浆期叶片净光合速率的影响为极显著(P<0.01)或显著(P<0.05),且三个生育时期均以N_(2)W_(4)处理最高,与N1W_(4)和N_(2)W_(3)处理间没有显著差异;三个生育时期的土壤铵态氮和硝态氮含量均以N_(2)W_(3)、N1W_(4)或N_(2)W_(4)处理最低。小麦越冬期、灌浆期和成熟期土壤铵态氮与产量和氮肥偏生产力(NPFP)均呈显著或极显著负相关;抽穗期、灌浆期和成熟期土壤硝态氮与产量和NPFP均呈显著或极显著负相关。2个年度,水氮运筹较对照显著提高了冬小麦的产量和水氮利用效率,产量增幅分别为38.9%~62.0%和40.9%~68.3%,水分利用效率(WUE)增幅分别为8.0%~15.7%和10.1%~16.4%,NPFP增幅分别为38.9%~62.0%和40.9%~65.5%;冬小麦产量和WUE均以N_(2)W_(4)处理最高,N_(2)W_(3)处理次之,两者间没有显著性差异;但N_(2)W_(3)处理的水分利用效率均显著高于N_(2)W_(4)处理。综上,在本试验条件下,施氮量240 kg·hm^(-2)、每次灌水45 mm(N_(2)W_(3))为该地区滴灌冬小麦最佳水氮运筹组合,可以实现保障产量和提高水氮利用效率的目标。

不同灌溉方式和灌水量对土壤水盐及燕麦生长特征的影响

[目的]探究不同灌溉方式和灌水量对土壤水盐变化规律及燕麦生长特征的影响,为提高盐碱地作物的生产效能和土壤水分管理提供科学参考。[方法]采用盆栽试验,设置3种灌溉方式:常规灌溉、固定单侧灌溉(fixed unilateral root zone irrigation,FURI)、交替灌溉(alternative partial root zone irrigation,APRI),3组灌水量:W_1(60%θ_f~70%θ_f,θ_f为田间持水率),W_2(70%θ_f~80%θ_f)和W_3(80%θ_f~90%θ_f),以常规灌溉作为对照,共9组交互处理。[结果](1)不同灌溉方式下,土壤各层含水率变化趋势基本一致,随灌水量增加洗盐效果越显著,常规灌溉的深层含水率总体高于其他两种灌溉方式。(2)燕麦株高、叶绿素相对含量(relative chlorophyll content of leaves,SPAD)、品质随灌水量的增加而上升,与常规灌溉相比,W_2灌溉水平下,分根交替灌溉处理的粗脂肪,粗蛋白,β-葡聚糖含量分别增加7.02%,3.76%,6.06%,但降低了燕麦叶片的SPAD值,影响其光合能力。(3)随着燕麦生育期的推进,土壤盐分均呈现不同程度的累积,分根交替灌溉的积盐率最低,同时对燕麦根系生长、水分利用效率及产量影响显著,其中根系总长、根系总表面积、根系总体积较相同灌水量(W_2)的常规灌溉分别增加6.75%,6.92%,12.5%,水分利用效率提高17.32%。[结论]采用分根交替灌溉方式下的中等灌水量(W_2)有利于提高燕麦的生产效能,对盐分累积的控制效果较好。

分根区交替灌溉在农业生产中的应用研究进展

在全球水资源日益紧缺的背景下,如何提高农业用水利用效率,对于农业可持续发展具有重要意义。分根区交替灌溉作为一种具有较好前景的高效节水灌溉技术,被认为是未来最具发展潜力的灌溉技术之一。目前,各国科技工作者围绕分根区交替灌溉对作物生长、生理的影响方面开展了大量研究,并对其节水机制进行了解析,亟待总结梳理。本文回顾了分根区交替灌溉技术的发展历程,综述了分根区交替灌溉对作物生长发育、产量及品质的影响,归纳了该技术影响作物水分利用效率的生理机制,并对分根区交替灌溉在未来的研究方向进行了展望,以期为作物分根区交替灌溉节水灌溉机理研究和节水灌溉技术的革新提供参考。

基于部分预算法下加气灌溉技术经济效益分析

加气灌溉是目前最为高效的节水灌溉技术之一,是在地下滴灌的基础上,利用空气泵或气泡发射器提高土壤含氧量的一种灌溉方法。为了明确加气灌溉技术在大田作物种植中的主要应用效果与经济效益,为加气灌溉技术在农业生产中的推广及应用提供理论依据,采用部分预算法对田间加气灌溉后的经济效益进行综合评价。研究结果表明:与常规滴灌技术相比,加气灌溉技术与常规种植技术相比,总收益分别为25400.05元/hm^(2)和20162.14元/hm^(2);从农业净收益来看,加气灌溉技术可以增加326.03元/hm^(2),部分投资收益率超过700%;加气灌溉技术可以显著减少农业灌溉用水量,提高作物产量,提升农业经济收益,具有良好的应用推广价值。

基于产量品质及水肥利用率的核桃水肥耦合方案优化

针对干旱区核桃水肥利用效率低及高效水肥制度不明晰的问题,以新疆阿克苏地区核桃树为研究对象,以核桃提质增效为目标,研究水肥耦合条件下对滴灌核桃的生理生长指标、果实品质、产量的影响。为了更精准地预测水肥制度,以灌水量(225 m^(3)·hm^(-2),W1;300 m^(3)·hm^(-2),W2;375 m^(3)·hm^(-2),W3)、施肥量(常规施肥量0.5倍(236.93 kg·hm^(-2)),F1;常规施肥量(473.85 kg·hm^(-2)),F2;常规施肥量2倍(947.7 kg·hm^(-2)),F3)为试验因素,通过建立关于核桃的果实品质、产量、水分利用效率和肥料偏生产率的二元二次回归模型,并采用二代非支配排序遗传算法(NSGA-Ⅱ)对该回归模型进行验证求解,从而模拟出最优水肥制度。结果表明:灌水量和施肥量两因子及其耦合效应对核桃的生长指标均有显著影响,核桃的果实品质、产量和水肥利用率随着灌水量和施肥量的增加呈现先增加后减小的趋势,在各处理情况下,W2F2处理为最优的灌溉施肥处理。通过NSGA-Ⅱ模拟出的最优水肥制度为灌水量和施肥量分别是336.93 m^(3)·hm^(-2)和715.21 kg·hm^(-2)。最终对应的蛋白质含量、产量、水分利用效率和肥料偏生产率分别是21.36%、2971.66 kg·hm^(-2)、8.76 kg·mm^(-1)·hm^(-2)和1.02。

基于偏微分算法的水肥一体机系统设计

为进一步提升我国水肥一体机的综合作业效能,实现灌溉施肥的最优化配比,以偏微分算法作为改进切入点,针对其作业控制系统展开设计研究。通过搭建正确的多阶偏微分数学模型,得到水肥一体机的整机设计布局,并进行模块化的软件程序编制与功能化的硬件配置选型。采用设计的整机系统在一定的作业条件下完成灌溉施肥一体式作业,结果表明:基于偏微分算法设计的水肥一体机,整机在水分与肥量之间的配比关系得到很好的优化,配比准确率可保证在90.00%以上,施肥均匀度与水分利用率分别相对提高了9.56%和5.69%,灌施作业效果良好,设计正确可行,是今后灌溉施肥集成领域的重要革新思路之一,具有较强的推广应用价值。

Role of alternate and fixed partial root-zone drying on water use efficiency and growth of maize(Zea mays L.)in gypsiferous soils

Alternate partial root-zone drying(APRD)is a water-saving method but can regulate crop physiological responses.A pot experiment has been conducted to study the efficiency of partial and fixed root-zone drying on the growth and production of maize(Zea mays L)in addition to the water use efficiency in soils with different gypsum content.The experimental treatments include three irrigation treatments,i.e.Conventional Irrigation(CI),Alternate Partial Root-zone Drying(APRD)and Fixed Partial Root-zone Drying(FPRD),and three soils with different gypsum content"(60.0[G1],153.7[G2],and 314.2[G3]g kg^(-1))".The vegetative growth,root dry mass and physiological indices(leaf relative water content,carotenoid concentration,proline)have been studied during three stages of maize plant growth(jointing,tasselling,and maturing).The Results showed that compared to CI,APRD and FPRD increased water use efficiency by 38.93 and 14.94%based on dry seed yield.In addition,compared to CI,APRD increased maize seed yield by 4.62-20.71%,while FPRD decreased yield by 19.24-5.28%for the gypsiferous soils G2 and G3,respectively.APRD has a slight effect on leaf water potential,leaf relative water content,carotenoid and proline activities from jointing to maturing stages at the three gypsiferous soils.Results suggest that APRD could make maize plants use water even more productively with better adaptation to water shortages in the gypsiferous soils.

Optimization of water and nitrogen management for surge-root irrigated apple trees in the Loess Plateau of China

The Loess Plateau is one of the main regions for growing apple trees in China, but a shortage of water resources and low utilization of nitrogen have restricted its agricultural development. A 2-year field experiment was conducted which included three levels of soil water content(SWC), 90–75%, 75–60%, and 60–45% of field capacity, and five levels of nitrogen application(N(app)), 0.7, 0.6, 0.5, 0.4 and 0.3 kg/plant. The treatments were arranged in a strip-plot design with complete randomized blocks with three replications. For both years, the water and N(app) had significant(P<0.05) effects on leaf area index(LAI), yield, water use efficiency(WUE) and nitrogen partial factor productivity(NPFP) while the interaction effect of water and N(app) on yield, WUE and NPFP was significant(P<0.05) in 2018, and not in 2017. For the same SWC level, WUE first increased, then decreased as N(app) increased, while NPFP tended to decrease, but the trend of LAI with different N(app) was closely related to SWC. At the same N(app), the LAI increased as SWC increased, while the WUE and NPFP first increased, then decreased, but the yield showed different trends as the SWC increased. The dualistic and quadric regression equations of water and N(app) indicate that the yield, WUE and NPFP cannot reach the maximum at the same time. Considering the coupling effects of water and N(app) on yield, WUE and NPFP in 2017 and 2018, the SWC level shall be controlled in 75–60% of field capacity and the N(app) is 0.45 kg/plant, which can be as the suitable strategy of water and N(app) management for the maximum comprehensive benefits of yield, WUE and NPFP for apple trees in the Loess Plateau and other regions with similar environments.