Transpiration of table grape (Vitis vinifera L.) trained on an overhead trellis system under netting

The quantification of transpiration and corresponding basal crop coefficients is crucial for appropriate irrigation scheduling of drip-irrigated crops. Besides basal crop coefficients already published, there is the announcing need for setting values for the new growing practices such as cropping under netting. In this paper, measurements of unstressed table grape transpiration and basal crop coefficients under netting have been taken. Vineyards of two seedless cultivars (Crimson and Autumn Royal) were trained on an overhead trellis system which permitted the ground cover to reach values up to 90 %. Two campaigns of mid-season measurements were performed using one of the heat pulse techniques available (that known as the T _max approach). Obtained values for average seasonal daily transpiration ranged between 3.9 and 4.4 mm day^?1, for both cultivars, depending on the period considered. Weekly averages of the basal crop coefficients, from mid-May to end-September, ranged from 0.47 to 0.87. A polynomial equation was fit to the measured basal crop coefficients as a function of fraction of thermal units. After further validation for other cultivars with different cumulative thermal requirements, this equation could be considered helpful for farmers as a practical estimate of the table grape basal crop coefficient under the netting.     

Water use and the development of seasonal crop coefficients for Superior Seedless grapevines trained to an open-gable trellis system

Water consumption of table grapevines (Vitis vinifera cv. Superior Seedless) trained to a large open-canopy gable system was measured during six growing seasons (1999, 2001–2005) using 12 drainage lysimeters. The lysimeters (1.3 m³ each) were installed as part of a one-hectare vineyard in a semi-arid region in southern Israel. Water consumption of the lysimeter-grown vines (ET_c) was used as the basis for the calculation of irrigation applications in the vineyard. Three irrigation treatments, 80% (high), 60% (medium) and 40% (low) of ET_c of the lysimeter-grown vines, were applied in the vineyard. Reference evapotranspiration (ET_o) was calculated from regional meteorological data according to the Penman–Monteith equation. Seasonal curves for the crop coefficient (K _c) were calculated as K _c = ET_c/ET_o. Maximum ET_c values in different seasons ranged from 7.26 to 8.59 mm day⁻¹ and seasonal ET_c (from DOY 91 through DOY 304) ranged from 1,087 to 1,348 mm over the six growing seasons. Leaf area index (LAI) was measured monthly using the SunScan Canopy Analysis System. Maximum LAI ranged from 4.2 to 6.2 m² m⁻² for the 2002–2005 seasons. A second-order polynomial curve relating K _c to LAI (R² = 0.907, P < 0.0001) is proposed as the basis for efficient irrigation management. The effects of the irrigation treatments on canopy growth and yield are presented. The high ET_c and K _c values that were observed are explained by the wide canopy layout that characterize the large open-gable trellis system.     

Evapotranspiration losses for pepper under plastic mulch and shallow water table conditions

Use of literature crop coefficient (K _c) values for quantifying evapotranspiration (ET_c) under non-standard conditions such as plastic mulch, shallow water table, and sub-tropical conditions can lead to inaccurate ET_c estimates. A 5-year experiment was conducted for fall crop growing seasons in south Florida to quantity bi-weekly ET_c and K _c for bell pepper grown under shallow water table and plastic mulch environments using large drainage lysimeters. The ET_c values varied from 205 to 320 mm with a seasonal average of 267 mm. Average K _c values for bell pepper for development, mid-season, and late stages were 1.05, 1.21, and 1.28, respectively. Higher than literature initial K _c values were due to rainfall and use of sub-irrigation system to maintain artificially high water table which results in high soil moisture in the bare soil area—such high moisture results in high evaporation. The K _c values from this study were statistically higher than literature values. Use of literature K _c values resulted in underestimating ET_c by 27–37%. The K _c values would provide improved estimates of sub-irrigated pepper ET_c in subtropical Florida and elsewhere with similar environment.     

设施栽培番茄需水规律分析及其气象因子响应模型

基于江苏省南通市2001年、2002年的现场试验资料,计算分析了大棚番茄旬蒸发蒸腾量及其变化规律,建立了设施栽培条件下番茄蒸发蒸腾量的气象因子响应模型。结果显示:覆盖大棚明显降低了番茄的需水强度,大棚番茄蒸发蒸腾量随生育阶段延续、植株生长和外界气温增加呈现逐渐增加的趋势,且前期增长缓慢后期增长速度快;设施栽培番茄蒸发蒸腾量与“气温因子”和“地温因子”有着较为密切的联系,与“相对湿度因子”呈现负相关关系,而与蒸发皿水面蒸发强度的关系则较弱;选取较容易测得的重要因素,建立蒸发蒸腾量的气象因子响应模型,模拟结果较为满意。     

Evapotranspiration and responses to irrigation of broccoli

In cold, semi-arid areas, the options for crop diversification are limited by climate and by the water supply available. Growing irrigated crops outside the main season is not easy, because of climatic and market constraints. We carried out an experiment in Albacete, Central Spain, to measure the water use (evapotranspiration, ET) of broccoli (Brassica oleracea L. var. italica Plenck) planted in late summer and harvested at the end of fall. A weighing lysimeter was used to measure the seasonal ET under sprinkler irrigation. Consumptive use reached 359 mm for a period of 109 days after transplanting. The crop coefficient (K_c) for broccoli was obtained and compared to the standard recommendations for normal planting dates. Dual crop coefficient computations of the lysimeter ET data indicated that evaporation represented 31% of seasonal ET. An analysis of the variation in daily K_c values at a time of full cover suggested that the use of a grass lysimeter as a reference ET (ET_o) was superior to using the ASCE Penman-Monteith (ASCE PM) equation at hourly time steps, which in turn caused less variability in K_c than when using the FAO-56 Penman-Monteith (FAO-56 PM) equation at daily time steps for the ET_o calculation. An additional experiment aimed at evaluating the yield response to applied irrigation water by the drip method (seven treatments, from 59 to 108% of ET_c) generated a production function that gave maximum yields of near 12 t ha⁻¹ at an irrigation level of 345 mm, and a water use efficiency of 3.37 kg m⁻³. It is concluded that growing broccoli in the fall season is a viable alternative for crop diversification, as the lower yields obtained here may be more than compensated for by the higher produce prices in autumn, at a time of the year where irrigation water demand for other crops is very low.     

Evapotranspiration and crop coefficient of spring maize with plastic mulch using eddy covariance in northwest China

Spring maize under plastic mulch is the staple food crop in northwest China. Studying its evapotranspiration (ET) and crop coefficient (K_c) is important for managing water-saving irrigation in the region. Eddy covariance (EC) was applied to measure spring maize ET in 2007 in northwest China, focusing on the characteristics of the maize ET and K_c processes under plastic mulch. An interesting result was that a higher K_c in this study relative to the value of FAO 56 was presented in the mid and late season, e.g. average K_c was 1.46, 1.39 and 1.22 during the heading, filling and maturity stage, respectively. This result was mainly due to that (1) the plastic mulch had an effect on anti-senescence of maize and great green leaf still existed before the harvest; (2) the FAO 56 PM model may underestimate the reference crop ET in the mid and late season of maize in the region; (3) the planting density was higher in the study, which was about 374,800 plants ha⁻¹. Though K_c during the mid and late season was high, a high water use efficiency of 25.2 kg ha⁻¹ mm⁻¹ was still obtained in the study. Our study confirmed that plastic mulch has beneficial effect on improving maize water use efficiency in this severe water shortage region of northwest China.     

网室栽培香蕉耗水特征及合理灌溉水量确定

主要研究网室和不同灌溉水量下香蕉的耗水特征,确定香蕉的作物系数。处理包括大田充分灌溉处理(100%),网室充分灌溉处理(100%)和亏水处理(55%),香蕉的耗水量(ET)用热消散茎液流法测定。试验结果显示,在3种处理间香蕉叶面积差异不显著(P>0.05),网室内香蕉的耗水量比大田降低了44%~55%;网室内2种灌溉水量条件下香蕉蒸散量差异不显著(P>0.05),说明55%处理灌溉水量已经能够满足香蕉的生长,这个结果也和网室内蒸散量降低值一致。建议当地进行网室内香蕉栽培时,灌溉水量选取大田的一半即可。     

不同地下水埋深时甜椒需水量及作物系数试验研究

采用排水式蒸渗仪试验,研究了不同地下水埋深时,甜椒需水量和地下水利用量的变化规律及与外界环境因子的关系。分析和模拟了甜椒作物系数,并与FAO-56推荐作物系数值进行了比较。结果表明,地下水埋深为0.6~0.9m时,地下水与降雨利用量占需水量的40%~50%,灌溉量较低。地下水埋深较浅时,需水量与地下水利用量与蒸发量、气温和地温具有显著的线性关系。地下水埋深较深时,需水量主要受降雨的影响,与环境因子的相关性较小;地下水利用量与蒸发量、气温、地温及饱和水气压差仍具有显著的线性关系。甜椒全生育期作物系数为1.35,与移栽后旬数、地温和需水系数分别表现出3次、2次和3次多项式的关系。生长中期和后期,作物系数分别为1.25和1.25~1.1,高于FAO-56推荐值。研究结果为蔬菜类作物节水灌溉制度的制定和高效灌溉管理提供参考。     

玉米生产机械化沟垄全覆膜高速穴播技术应用与推广

近年来,甘肃在推广玉米沟垄全覆膜高速穴播集成技术中,总结出了其技术路线、作业质量标准及操作规程。该技术可减少机具在大田里作业次数,节约油耗、省工省时,降低劳动强度和作业成本,给农民带来增产增收的效果,同时能提高机械化作业水平及生产效率。     

Evapotranspiration and seed yield of field grown soybean under deficit irrigation conditions

Evapotranspiration was measured for a reference crop, rye grass (Lolium prerenne) and soybean (Glycine max L. Merril) grown over two seasons in 2000 and 2001 at Tal Amara Research Station, Lebanon, using drainage and weighing lysimeters. Climatic data from the field weather station were recorded daily. Within the experimental plots, irrigation was withheld at full bloom, R2 stage (S1 treatment), at seed enlargement, R5 stage (S2 treatment) and at mature seeds, R7 stage (S3 treatment). Further, a control (C) was fully-irrigated throughout the growing period.Average crop evapotranspiration (ETc) as measured by the drainage lysimeters in 2000 totaled 800 mm for a total growing period of 140 days. However, when ETc was measured by the weighing lysimeter in 2001, it was 725 mm during a growing period of 138 days. Average crop coefficients (K_c) were computed for different growth stages for the two growing periods by dividing the measured crop evapotranspiration (ETc) by the corresponding measured reference evapotranspiration (ETo-rye grass). K_c values ranged from 0.62 at V10 stage (10th node on the main stem beginning with the unifoliolate node) to 1.0 at pod initiation, then to 0.81 at mature pods.Growth parameters, leaf area index (LAI) and dry matter accumulation, have been shown to be sensitive to water stress caused by the deficit irrigations. However, growth parameters were found to compensate for water stress at early stages, while at seed maturity the compensation ability was decreased.Plants of the lysimeters produced average aboveground biomass and seed yield of 8.1 and 3.5 t ha⁻¹, respectively. However, in the well-irrigated field treatment, aboveground biomass and seed yield averaged 7.3 and 3.2 t ha⁻¹, respectively. Deficit irrigation at R2 stage reduced aboveground biomass and seed yield by 16 and 4%, respectively, while deficit irrigation at R5 stage reduced these two parameters by 6 and 28%, respectively, with comparison to the control. The significant decrease in biomass at R2 stage due to water deficit may be attributed to a pronounced reduction in the number of vegetative nodes. However, limited irrigation at this stage did not reduce significantly (P < 0.01) neither seed number nor seed weight, while at R5 stage these two parameters were reduced by 20 and 10%, respectively, with comparison to the control. Results showed also that deficit irrigation at R7 stage (S3) was more profitable than irrigation deficit at any other crop phenology and did not cause significant reductions either in seed number or seed weight.     

盐渍土壤覆膜种植条件潜水蒸发的探讨与分析

盐渍土区潜水蒸发机理、特性及其计算方法的研究,对防治土壤盐碱化、地下水资源评价及农田水分管理具有重要意义.基于潜水蒸发的最新国内外研究成果,提出了当前在潜水蒸发研究方面的薄弱之处:即以往有关潜水蒸发的研究较多集中于其常规影响因素,且大多是对裸土条件下潜水蒸发特性及其计算进行研究,而对种植作物、土表覆膜和特殊土壤等条件下潜水蒸发问题的认识和研究较为不足.根据我国干旱地区土壤特性和种植模式,分别对有无作物种植、土表覆膜和盐渍土壤等3种条件下的潜水蒸发特性及计算方法进行了较为详细地阐述和评价,并就目前研究中存在的不足和未来亟待深入研究的问题进行了探讨,认为在今后的研究工作中,应把潜水蒸发对作物耗水的补给比例、不同地区适宜潜水埋深和生态地下水位、潜水蒸发昼夜变化特性,以及盐碱地潜水蒸发与土壤积盐的数值模拟等内容,作为研究重点.     

Distribution of grapevine roots and salt under drip and full-ground cover microjet irrigation systems

We describe the three dimensional variation in root length density (L_v) within a quarter of the planting area of Colombard grapevines on Ramsey rootstock grown under drip and full-cover microjet irrigation. Under drip irrigation roots were concentrated under the vine row, whereas under microjet irrigation roots were evenly spread across the planting area. The maximum L_v were 1.2 and 0.6 cm/cm³ and the estimated total root lengths per vine were 32 and 26 km for drip and microjet irrigated vines, respectively. Under drip irrigation, 56% of the variation in L_v could be accounted for as a function of depth and radial distance into the row, and under microjet, 45% of the variation in L_v could be accounted for as a function of depth. Twenty five per cent of the vine roots were in soil with an air filled porosity at field capacity of 6% or less. Based on the variation of root length per unit area (L_a) across a quarter of the planting area and between vines, we concluded that selection of a location at which the L_a would be representative of that in the entire irrigation unit is feasible in microjet irrigated vines but not in those irrigated with drip. The absence of a location representative of L_a confounds the scheduling of drip irrigation based solely on measurements of soil moisture.     

气候变化下河北省宁晋县参考作物蒸散量变化趋势及敏感性分析

【目的】深入分析宁晋县气候变化及其蒸散发的变化,为该区域的作物种植管理和灌溉计划制定提供参考。【方法】根据1981—2018年河北省宁晋县气象站的逐日气象资料,计算了极端气候指数,并利用FAO56Penman-Monteith公式计算了参考作物蒸散量(ET0)。分析了各气象要素、极端气候指数和ET0的变化趋势,并利用敏感性分析找出影响ET0变化的主要气象因子。【结果】1981—2018年河北省宁晋县降水量无明显变化趋势,平均温度呈显著上升趋势,日照时间、相对湿度和风速呈显著下降趋势;极端高温指标呈上升趋势,极端低温指标呈下降趋势,极端降水指标无显著变化。【结论】相对湿度是ET0年均值主要影响因子;夏季对ET0月均值影响最大的气象因素为净辐射,其他季节,相对湿度对其影响最大;风速和辐射的降低不仅抵消了温度升高和相对湿度降低对ET0的正影响,还使得ET0呈下降趋势,但下降趋势不显著。     

Prototype decision support system based on the VegSyst simulation model to calculate crop N and water requirements for tomato under plastic cover

The simulation model VegSyst was calibrated and validated for tomato grown under plastic cover. Calibration was conducted with an autumn–winter soil-grown crop, and validation with five crops with differences in season, cropping media, and site. VegSyst accurately simulated daily dry matter production (DMP), N uptake, and ET_c. Comparing simulated and measured values by linear regression, slope and intercept values were not statistically significantly different (P < 0.05) from 1 and 0, respectively. Slopes between simulated and measured values indicated average differences of 4, 2, and ?1 % for DMP, N uptake, and ET_c, respectively. Model performance was good with autumn–winter and spring cropping cycles, and in soil and substrate. A prototype decision support system (VegSyst-DSS) based on VegSyst was developed to calculate daily irrigation and N fertilizer requirements and nutrient solution [N] for fertigated tomato. N fertilizer requirements are based on crop N uptake and consider soil mineral N, and N mineralized from manure and soil OM and the N efficiency of each N source. Irrigation requirements are based on ET_c and consider application efficiency and salinity. VegSyst-DSS requires very few inputs which are all readily available to farmers and advisors. Scenario analysis compared a scenario representative of local farming practice, where N supplied from soil is not considered, with scenarios with different amounts of N supplied from soil mineral N at planting and mineralization of soil OM and of manure. Relative to the scenario representative of farmer practice, VegSyst recommendations resulted in reductions of 34–65 % in fertilizer N.     

基于大型蒸渗仪和遗传算法的受旱玉米蒸发蒸腾量估算

受旱胁迫下作物蒸发蒸腾量估算重要且复杂,依托新马桥农水综合试验站6台大型称重式蒸渗仪开展玉米受旱胁迫专项试验,对不同受旱胁迫下玉米蒸发蒸腾量特征进行分析,在双作物系数法估算无受旱胁迫下玉米蒸发蒸腾量的基础上,采用遗传算法优化率定基础作物系数Kcbini、Kcbmid、Kcbend和作物系数上限Kcmax,同时基于试验站实测太阳辐射数据采用遗传算法优化率定了Angstrom公式经验参数a、b,进而优化了参考作物蒸发蒸腾量(ET0)的计算结果,并以此基础运用双作物系数法估算受旱胁迫下玉米蒸发蒸腾量。结果表明:营养生长中前期轻微的水分亏缺可能会刺激玉米适应性机能,复水后各项生理功能恢复正常;水分亏缺加重时不仅会使玉米当期的蒸发蒸腾量减少,而且会产生累积效应,将这种胁迫影响传递到之后的生育阶段;相同受旱胁迫强度对玉米生殖生长阶段影响更为明显,且易造成永久胁迫;Kcbini、Kcbmid、Kcbend、Kcmax的率定结果分别为0.150、1.090、0.152和1.400,在此基础上运用双作物系数法估算无受旱胁迫下玉米全生育期蒸发蒸腾量的均方根误差RMSE和平均绝对误差MAE分别为1.39 mm和0.97 mm,比对应的FAO-56推荐值估算结果小6.74%和8.23%,受旱胁迫下玉米计算的2个处理全生育期RMSE、MAE和MRE均值分别为1.60 mm、1.18 mm和6.73%,整体估算效果虽然没有无受旱胁迫下的好,但仍优于FAO-56推荐值的估算结果。因此,基于双作物系数法和遗传算法的受旱胁迫下玉米蒸发蒸腾量估算合理可靠,该研究可为区域制定适宜灌溉制度和降低农业旱灾损失风险提供理论依据。     

Response of hot pepper (Capsicum annuum L.) to mulching practices under planted greenhouse condition

Mulch is considered a desirable management technology for conserving soil moisture, improving soil temperature and soil quality. This study aimed to investigate soil conditions and hot pepper (Capsicum annuum L.) performance in terms of leaf photosynthetic capacity, fruit yield and quality, and irrigation water use efficiency (IWUE) under such practices in greenhouse condition. A field experiment across 3 years was carried out with four types of mulch (without mulch [CK], wheat straw mulch [SM], plastic film mulch [FM], and combined mulch with plastic film and wheat straw [CM]). Mulch could improve soil physical properties regardless of mulch materials. FM and CM treatments improved soil moistures status and soil temperature in comparison to CK control, while SM increased soil water content and decreased soil temperature. Mulch increased leaf net photosynthesis rate (P_N), stomatal conductance to water vapor (gs), intercellular CO₂ concentration (Ci), and transpiration rate (E), but declined instant water use efficiency (WUEi). No significant effect of mulch application on chlorophyll fluorescence was existent for the entire growth season. Fruit yield and irrigation water use efficiency (IWUE) showed some increment under all the mulch conditions. Compared to CK, the yield was enhanced by 82.3%, 65.0%, and 111.5% in 2008; 38.1%, 17.4%, and 46.5% in 2009; and 14.3%, 6.5%, and 19.6% in 2010 under SM, FM, and CM conditions, respectively. Although FM produced better fruit quality than other treatments, CM is the recommended practice for hot pepper cultivation in greenhouse condition due to working well to facilitate soil condition (moisture and temperature), plant growth, and marketable yield.     

黑龙港流域不同栽培方式下棉花腾发量及产量试验研究

河北省黑龙港流域素有"华北干槽"之称,是华北平原历史上受旱、涝、碱害最重的地区,长期贫困缺粮。针对华北平原黑龙港流域棉花,研究了膜沟栽培、覆膜平播及不覆膜平播3种栽培方式对棉花腾发量、产量及水分利用效率的影响。通过分析在中科院南皮生态农业试验站开展的覆膜棉花耗水试验数据,得到膜沟栽培、覆膜平播及不覆膜平播3种栽培方式下的棉花腾发量、产量及水分利用效率。结果表明,膜沟栽培、覆膜平播栽培与不覆膜平播栽培棉花相比,不仅皮棉产量较高,且其水分利用效率也较高。     

干旱区秸秆覆盖对滴灌棉花生长及产量的影响

为探索秸秆覆盖对北疆滴灌棉花生长特征和产量的影响,2009—2012年期间,以小麦秸秆为材料,在非盐碱土和盐碱土2种土壤条件下,进行了无覆盖（LUM）、表层覆盖（LSM）、地表以下30 cm深处覆盖（LM30）的测坑对比试验.结果表明：秸秆覆盖对棉花生长及产量具有一定的促进效果,对盐碱土种植的棉花株高、叶面积指数和产量的促进作用显著,而对非盐碱土棉花株高、叶面积指数和产量的促进作用不明显.地表覆盖综合调控效应优于30 cm深层覆盖,尤其是在棉花花铃期,在盐分抑制方面地表覆盖要比30 cm覆盖效果好;30 cm覆盖在苗期和蕾期可以给棉花生长创造比较好的条件,而在花铃期以后这种覆盖效果不太明显;表层覆盖处理棉花产量最高,高出无覆盖处理3.2%-17.9%,高出30 cm深层覆盖3.1%-16.3%.     

Evapotranspiration relationship with pan evaporation and evapotranspiration ratio of corn under different nitrogen levels and moisture regimes

In a field experiment with four moisture regimes and eight nitrogen levels, the ratios between evapotranspiration and pan evaporation ($\text{Et}\text{Eo}$) were low in the initial stages of crop growth and attained maximum values at 70–80% (20 and 40% available soil moisture depletion (ASMD)), 65% (60% ASMD) and 55% (80% ASMD) of the crop growth stage. Amongst nitrogen levels, the evapotranspiration ratio (ETR) was highest (3573) under no nitrogen and lowest (1312) with 180 kg N/ha. The 20% ASMD regime utilised less water (ETR= 1499 to produce a kilogram of grain than did the other moisture regimes. The lowest evapotranspiration ratio (914) was recorded with 20% ASMD and 180 kg N/ha in combination. The highest ETR (3954) was found with 60% ASMD and no nitrogen. An additive effect of nitrogen and moisture was found, in indicating that they can be substituted one for the other, when one of them becomes a constraint.     

冷凉地区膜下滴灌大白菜耗水规律及节水潜力

为探索冷凉地区露地大白菜在膜下滴灌条件下的耗水规律与节水潜力,在张家口市灌溉试验站内使用大型称重式蒸渗仪,采用灌水下限指标控制灌水的方法,研究了在膜下滴灌条件下大白菜生育期内蒸发蒸腾与棵间蒸发规律,并通过与常规滴灌和膜孔畦灌的耗水量、产量和水分利用效率等对比,揭示了膜下滴灌在该地区节水增产潜力.结果表明:膜下滴灌大白菜全生育期蒸发蒸腾量214.76 mm,其中:幼苗期、莲座期和结球期蒸腾耗水量分别为14.76,73.56和126.44 mm,日均蒸腾强度为3.64 mm/d;全生育期棵间土壤蒸发量41.10 mm,占总耗水量的19.14%.膜下滴灌相比常规滴灌、膜孔畦灌减少大白菜耗水量14.25,94.17 mm,棵间蒸发与膜孔畦灌相近,相比常规滴灌减少16.18 mm(28.25%),但产量、灌溉水利用效率和水分利用效率可以分别达到80 439.75 kg/hm²,350.24 kg/(hm²·mm),374.56 kg/(hm²·mm),相比常规滴灌提升11 152.65 kg/hm²,18.89 kg/(hm²·mm),72.54 kg/(hm²·mm),相比膜孔畦灌提升14.7 kg/hm²,134.11 kg/(hm²·mm),114.23 kg/(hm²·mm).