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1.
This work examines the long-term effects of deficit-irrigation (DI) practices in almond crop (Prunus dulcis Mill.) in agronomical and physiological terms. The trial was conducted during four-year monitoring period (2014–2017), in an experimental orchard (SW Spain), subjected to three irrigation regimes; i) a full-irrigation treatment (FI), which received 100% of crop evapotranspiration (ETC); ii) a regulated-deficit irrigation (RDI50), which received 50% of ETC during the kernel-filling period; and iii) a low-frequency deficit irrigation (LFDI), that was subjected to continuous periods of irrigation-restriction defined in terms of threshold values of leaf-water potential (Ψleaf) during the kernel-filling period. During the water stress period, there were monitored Ψleaf, stomatal conductance (gs) and canopy temperature (TC). Significant improvements in terms of water-use efficiency were found, as no differences in terms of yield between FI and LFDI were found, leading to the conclusion that significant water savings (between 27 and 40%) can be achieved without compromising the yield. Moreover, threshold values of Ψleaf and thermal indicators were defined which will allow establishing future irrigation scheduling without compromising almond yield, especially when DI strategies are being applied.  相似文献   

2.
本文回顾了中国科学院栾城农业生态系统试验站(以下简称栾城试验站)建站初期20 世纪80 年代以来在农田节水方面开展的研究。20 世纪80 年代以作物优化灌溉制度为研究重点, 解决生产实际问题; 20 世纪90 年代围绕土壤-植物-大气系统水分传输和界面调控开展了系统研究, 为农田节水措施的形成提供理论基础和技术途径; 近10 年来进一步深化了农田节水生理生态研究, 并根据多年研究积累, 形成了综合节水技术模式, 进行推广应用。未来栾城试验站农田节水工作将更加突出多学科渗透交叉, 以提高农田水分利用效率和效益为目标, 加强基础研究和节水技术的示范应用。  相似文献   

3.
Abstract

Muskmelon (Cucumis melo L. cv. ‘Polidor’) were grown under field conditions to investigate the effects of different nitrogen (N) levels (0, 40, 80, and 120 kg ha? 1) on plant growth, water use efficiency, fruit yield and quality (weight, sizes, and water-soluble dry matter), leaf relative water content, and macro nutrition under three different irrigation regimes. Irrigation was applied based on cumulative class A pan evaporation (Ep). Plant treatments were as follows: (1) well-watered treatment (C) received 100% replenishment of Ep on a daily basis, (2) water-stressed treatment (WS) received 75% replenishment of Ep at three-day intervals, and (3) severely water-stressed (SWS): treatment received 50% replenishment of Ep at six- day intervals. Plants grown under C at 120 kg N ha? 1 produced significantly higher biomass (175.6 g plant? 1), fruit yield (36.05 t ha? 1), fruit weight (2.25 kg fruit? 1), and leaf relative water content (93.5%) under increasing N levels than did the two deficit irrigation treatments. The WS or SWS treatments caused reductions in all parameters measured except water-soluble dry matter (SDM) concentrations in fruits compared with those receiving unstressed (C) treatment. The WS irrigation regime with 80 kg ha? 1 N significantly improved the fruit yield and size, plant dry matter, leaf area, and IWUE compared with the SWS regime. Increased N significantly enhanced foliar N in the unstressed plants. Increasing N rate in the SWS treatment did not increase fruit yield with the same trend found in the WS and C treatments with increasing N levels. The yield reduction under severe water shortage was much more severe at high N rates. Water use (ET) at the C treatment at 120 kg ha? 1 N ranged between 160 and 165 cm, while SWS reduced ET to 90 cm at 0 and 40 kg ha? 1 N. Nitrogen supply modified water use at C and WS irrigation regimes. Muskmelon yield response to N rate was quadratic and differed with the level of irrigation. This moderate water deficit (SW) may be an alternative irrigation choice with a suitable N application rate for muskmelon growers in arid and semi-arid regions if the goal is to irrigate an agricultural area with limited water supply for more growers, but not if it is maximizing economic yield. Growers should accept a significant yield reduction in exchange for water conservation.  相似文献   

4.
Drought stress is an important factor limiting the yield potential of peanut. In order to determine the effect of different irrigation scenarios on peanut production, field experiments were conducted in 2011 and 2012 growing seasons using factorial design with three replicates. On the other hand, the crop simulation models can be useful to predict crop yields and to investigate the impact of drought stress on plant growth and development. In this study, the Cropping System Model–Crop Growth (CSM-CROPGRO)-Peanut model was employed for the simulation of seed yield, pod yield, biomass, soil water balance components and water productivity for peanut in Astaneh-Ashrafiyeh, Iran. Results showed that the model was able to reasonably simulate seed yield, pod yield and final biomass for different irrigation scenarios (RMSEn < 20%, R2 > 0.8 and d > 0.8). According to the results, irrigation depth and interval were important factors affecting yield and biomass. In general, model error increased as the amount of water applied decreased. The least amount of water applied (40 mm) resulted in yield reductions by 76%, 70% and 67% of the greatest amount of water applied (480 mm) for seed yield, pod yield and final biomass, respectively. For each irrigation interval, larger irrigation depth led to lower water productivity (WP) of irrigation (WPI), but higher WP based on evapotranspiration (WPET) and transpiration (WPT).The average amounts of WPI, WPET, WPT based on seed yield were 1.2, 0.63 and 1.01 kg m?3, respectively.  相似文献   

5.
In this investigation, a model was developed to predict dry matter, seed yield and other crop parameters of rapeseed under deficit irrigation and salinity by using soil water and salt budget and other simple plant physiological relationships. Two-year experimental data were used. In calibration and validation of the presented model, results indicated that the model was able to estimate evapotranspiration, soil water content, leaf area index, evaporation, crop transpiration, dry matter and seed yield of rapeseed properly. The advantage of this model is its simplicity and easy calibration in other areas and climate conditions and it can be used to estimate yield and other crop parameters with common measurable data in the field. Prediction of crop yield by this model can be used for better management of agronomic systems to reduce administrative costs and in different environmental conditions. Finally, under scarce data, arid and semi-arid environments, this model is proposed to be used by irrigation managers and agricultural advisors.  相似文献   

6.
ABSTRACT

Parts of the Kern County have high nitrate levels in groundwater. A State Water Resources Control Board commissioned report has indicated that crop land agriculture is the main source of nitrates in the groundwater. Annual rainfall is less than 20 cm, thus irrigation is necessary for optimum crop production. A project was undertaken to evaluate current nitrogen fertility and irrigation scheduling in potato production and their contribution, or lack thereof, to nitrate movement in the soil profile and potential nitrate contamination of groundwater. A line-source sprinkler plot area was established to create soil moisture regimes of 120% of target, target (optimum soil moisture for potato growth) and 80% of target. Pre-plant and post-harvest soil samples were collected to a depth of 2 meters. Plant, root and tuber samples were collected and analyzed for nitrogen content. Soil moisture and irrigation amounts were monitored. Plant dry matter and tuber yield increased with each N rate increase. The high N rate increased plant growth disproportionally to the increased tuber yield. Appropriate irrigation scheduling did not produce water movement beyond the effective potato rooting zone. Excessive irrigation moved soil nitrate deeper into the soil profile.  相似文献   

7.
为探究省力化栽培模式下库尔勒香梨园适宜的灌溉制度，依据4种灌溉定额(3 750,5 250,6 750,8 250 m3/hm2)条件下2年香梨的田间试验数据，通过冠层覆盖度、土壤含水量和蒸散强度(ETa)和产量指标，确定AquaCrop模型参数。设置不同灌水场景，综合考虑产量、水分利用效率和灌溉水利用效率，利用AquaCrop模型优化香梨灌溉制度。结果表明：Y2W3处理产量高出其余处理3.87%～16.86%,Y2W1处理水分利用效率高出其余处理2.88%～27.20%;AquaCrop模型模拟与试验地实测结果的决定系数(R2)、均方根误差(RMSE)、标准均方根误差(NRMSE)、拟合度指数(d)和Nash效率系数(NSE)评价指标表明，冠层覆盖度R2变化范围为0.89～0.93,土壤含水量d为0.92～0.98,ETa的RMSE为1.06～1.61 mm/d; AquaCrop模型预测15种不同场景，灌溉定额7 200 m3/h...  相似文献   

8.
Water shortage is a serious environmental and agricultural problem and saline underground water has been widely used to make up the fresh water shortage in northwestern China. An open-field experiment was conducted to establish a proper irrigation scheme with saline water for cherry tomato in the Minqin oasis, where very severe salinization occurs. The experiment had four treatments including fresh or saline irrigation over the crop season (control, C, T3), fresh/saline-water irrigation change on days after thinning 50 (DAT 50, T1) and saline/fresh irrigation change on DAT 50 (T2). Leaf area index (LAI), photosynthesis rate (Pn), transpiration rate (Tr), leaf dry matter (LDM), stem dry matter (StDM), yield, marketable fruit and total soluble solids (TSS) of tomato were measured. Saline irrigation, irrespective of the timing, significantly decreased maximum LAI, LDM and StDM, Pn, Tr and stomatal conductance but significantly stimulated water use efficiency. The reduction in maximum LAI, LDM and StDM was lower in T2 than in T1 and T3. Harvest index (HI) and TSS were higher in T2 and T3 than in T1 and C. Marketable fruit had no significant change in T2 but significantly declined in T1 and T3. Maximum saturated soil conductivity without yield reduction (the salt tolerance threshold) was 3.69?dS m?1. Total yield of tomato would decrease by 9.85% with one unit increase of soil salinityhigher than the threshold. Final yield significantly reduced by 24.6% and 23.1% in T1 and T3 treatments, respectively. Our results suggest that irrigation with saline water before DAT 50 and fresh water after DAT 50 should be advocated for cherry tomato plantation in water-scarce areas like the Minqin oasis.  相似文献   

9.
Winged bean [Psophocarpus tetragonolobus (L.) DC] plants, line UPS31, were grown in pots of sulfur (S)-deficient soil in a glasshouse without added S or with five levels of added S. The seed was inoculated with rhizobia (Bradyrhizobia sp. strain CB756) and plants were later given additional mineral nitrogen (N). Harvests of shoots were made at 39 and 78 days after sowing (DAS). Shoot dry matter yield, total S (ST), S reducible by hydriodic acid (SHI) – a measure of sulfate – and N were determined. At 78 DAS, the critical concentration (at 90% maximum yield) of ST in shoots was 0.9 mg S g?1 dry matter and in young leaves was 1.4 mg S g?1 dry matter. Plants with these concentrations or below would be considered S-deficient. The usefulness of critical concentrations of SHI or ratios of SHI/ST, and N/ST as indicators of S status is discussed.  相似文献   

10.
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,W3：100% ETc,ETc为作物蒸发蒸腾量）,4个施氮量（N0：0 kg/hm2,N200：200 kg/hm2,N300：300 kg/hm2,N400：400 kg/hm2）和2个缩节胺用量（D1：120 g/hm2,D2：240 g/hm2）。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。W3N300D2处理籽棉产量最高（2020年为7 578 kg/hm2,2021年为7 173 kg/hm2）,W1N400D1处理水分利用效率和W3N0D2处理肥料偏生产力最高,W3N400D1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/hm2施氮量和240 g/hm2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。  相似文献   

11.
The model ORYZA2000 simulates the growth and development of rice under conditions of potential production and water and nitrogen (N) limitations. Crop simulation models could provide an alternative, less time-consuming, and inexpensive means of determining the optimum crop N and irrigation requirements under varied irrigation and nitrogen conditions. Water productivity (WP) is a concept of partial productivity and denotes the amount or value of product over volume or value of water used. For the evaluated ORYZA2000 model in Iran, a study was carried out in a randomized complete block design between 2005 and 2007, with three replications at the Rice Research Institute of Iran, Rasht. Irrigation management (three regimes) was the main plot and N application (four levels) was the subplot. In this study, simulation modeling was used to quantify water productivity and water balance components of water and nitrogen interactions in rice. Evaluation simulated and measured total aboveground biomass and yield, by adjusted coefficient of correlation, T test of means, and absolute and normalized root mean square errors (RMSE). Results showed that with normalized root mean square errors (RMSEn) of 5–28%, ORYZA2000 satisfactorily simulated crop biomass and yield that strongly varied among irrigation and nitrogen fertilizer conditions. Yield was simulated with an RMSE of 237–443 kg ha?1 and a normalized RMSE of 5–11%. Results showed that the significant (28–56%) share of evaporation into evapotranspiration, using the actual yield (measured) and simulated water balance (ORYZA2000), the calculated average WPET was significantly lower than the average WPT: 37%. The average WPI, WPI+R, WPET, WPT, and WPETQ were 1.4, 1.07, 1.07, 1.57, and 0.82 kg m?3. Results also showed that irrigation with 8-day intervals and 60 kg N ha?1, nitrogen level was the optimum irrigation regime and nitrogen level.  相似文献   

12.
Field water stress is a common problem in crop production, especially in arid and semi-arid zones and it is widely hypothesized that silicon (Si) could reduce water stress in plants. We set up a greenhouse study to evaluate some silicon sources—potassium silicate (K2SiO3), calcium silicate (CaSiO3) and silica gel for growth and nutrient uptake by four grass species under adequate and deficit irrigation. The four species studied were Rhodes grass (Chloris gayana), Timothy grass (Phleum pratense), Sudan grass (Sorghum sudanense) and Tall fescue (Festuca arundinacea). For all species, the biomass yield response to applied silicon under deficit irrigation was significantly better than under adequate irrigation. The yield response of Rhodes grass across silicon sources was 205% under deficit irrigation compared with only 59% under adequate irrigation; for Sudan grass it was 49% compared with 26% and for Timothy, it was 48% compared with a mere 1%. The higher responses under deficit irrigation suggest that the plants relied more on silicon to endure drought stress. Biomass yield of individual plants also differed according to soil water levels with Timothy grass being the most sensitive to water stress as it exhibited the highest yield response (209%) to adequate irrigation. This was followed by tall fescue (122%) and Rhodes grass (97%). Sudan grass was the least affected by deficit irrigation, possibly on account of improved root mass and its natural drought tolerance. Strong associations were noted between the uptake of silicon and those of nitrogen (N) and phosphorus (P) irrespective of soil water condition, but the uptake of potassium (K) was more strongly correlated with that of Si under deficit than adequate irrigation. Improvements in plant growth following Si application could therefore be linked to enhanced uptake of major essential nutrients.  相似文献   

13.
Soil nitrogen (N) availability is dominated by soil water regime and the N fertilizer levels, which affect crop growth in soil water stress. To determine the optimum N applications under different degrees of soil drought, this study investigated the effects of N fertilizer levels on the crop water stress index (CWSI) of summer corn under soil water stress. A 2-year field experiment was conducted in waterproof plots in upland red soils in subtropical China. Three N fertilizer levels and seven soil water deficit levels were employed in 2007 and 2008. Nitrogen fertilization had no influence on the CWSI of the corn under slight to moderate soil drought, but the high-N treatment increased the CWSI significantly (P < 0.01) under soil drought when the mean CWSI exceeded ～0.20. The results suggested that for scheduling irrigation or predicting crop yields, the equations between CWSI and yield should be established on comparable N fertilization levels.  相似文献   

14.
A better understanding of the impact of fertilizer nitrogen (N) on biomass and N accumulation, and their partitioning into different plant components is needed to optimize crop yield and quality. A field experiment with spring wheat (Triticum aestivum), hulless (Avena nuda), and hulled (Avena sativa) oats was conducted for 3 years in Ottawa, ON, Canada, to determine the crop responses to N addition (0, 75, and 150 kg N ha–1). Biomass, N, and phosphorus (P) accumulation and partitioning into different plant components were examined during the growth season. Lodging score was determined for all crops when it occurred and again at harvest. During the growth season, both hulless and hulled oats and the wheat cultivar showed almost similar patterns of N and P accumulation with maximum contents at late grain filling or at harvest. Plant N concentration was up to 60 g kg–1 during the seedling stage, decreased gradually with advancing growth stages, and was lowest at harvest. Nitrogen treatments significantly increased plant N and P contents. At heading stage, N treatments enhanced dry matter (24%–45%), N (35%–135%), and P (27%–45%) contents in plant components (i.e., culm, leaf, and head), but also enhanced crop lodging, especially in oats. Both hulled and hulless oats had higher total plant N (5%–35%), N : P ratio, and dry‐matter content in leaf (6%–43%) and head (0%–129%) along with higher P (up to 27%) in culm than the wheat cultivar. The wheat cultivar accumulated greater dry matter and higher N content in kernels than both hulled and hulless oats at harvest. Both hulled and hulless oat cultivars exhibited similar lodging susceptibility to N addition (75 or 150 kg N ha–1), produced lower dry weight and lower kernel N, and hence lower grain yield than the wheat cultivar. The larger vegetative dry‐matter accumulation at heading coupled with higher P content in culms under high‐N‐supply conditions may be related to severe lodging in oat cultivars.  相似文献   

15.
北京地区旱稻作物需水与降水的耦合分析   总被引：8，自引：1，他引：8  
基于4a的田间试验资料，采用农田水分平衡法确定了旱稻出苗后各生育阶段的需水量；利用1971年-2000年北京地区逐日降水资料，计算了旱稻各生育阶段在不同降水保证率下的降水量，并选取25％、50％、75％和95％保证率作为典型的湿润年、平水年、干旱年和极枯水年，进行旱稻各生育阶段降水与作物需水的耦合度分析和补灌量估算。结果表明：旱稻出苗后总需水量平均为596.1 mm，需水强度平均为4.3 mm/d，需水强度峰值出现在孕穗-抽穗阶段。4种降水年型下旱稻出苗后降水和旱稻需水的耦合度分别为0.82、0.71、0.50和0.39，所需的补灌量分别为106.6、171.1、296.0和363.9 mm。  相似文献   

16.
Abstract

Reliable assessments of erosion potential, N fertilization need, and nitrogen (N) non‐point pollution potential for soybean [Glycine max (L.) Merr.] cropping systems require accurate estimates of soybean dry matter and N accumulations. The objective of this field study was to determine dry matter and N accumulation in soybean during the growing season and at harvest in samples large enough to reduce sample variation and increase the confidence in measured values. A split‐plot design was used with cultivar (Braxton, Coker 338, and Davis) as the main plot treatment and sampling date as the split‐plot treatment. Each split‐plot contained eight rows 4.6 m in length on 0.75 m spacing. The seed were sown in a Norfolk loamy sand (fine‐loamy, siliceous, thermic, Typic Paleudult) on May 18 at the rate of 33 seeds/m. Water was applied by use of an overhead irrigation gun. Plant samples were collected from 20 m2 of the six center rows on 89, 115, and 138 days after planting as well as at seed harvest. Fallen plant material (crop litter) was collected from each plot at each sampling date. Itact plant samples, crop litter, and soil samples were analyzed for total Kjeldahl N. The mean seed yield was 2.01 Mg/ha; the mean maximum dry matter accumulation for intact shoots plus crop litter was 10.2 Mg/ha, and the coefficients of variation were <10%. The actual harvest index (seed yield/total dry matter accumulation) ranged from 0.19 to 0.28, and the mean maximum N accumulation was 293 kg/ha. These accumulations are greater than those reported for indeterminate soybean grown on high‐N soils in the midwestern United States, and they clearly show that determinate soybean grown in the southeastern United States accumulate substantial amounts of dry matter and N.  相似文献   

17.
The inadequacy of most models to simulate crop growth and yield is due to complexity, difficulty to understand, and lack of input data. Therefore, several simple crop growth models are presented to reduce these failures. In this investigation, yield and aboveground dry matter (DMabove) of rapeseed were simulated by two logistic growth models that were based on days after planting (DAP) and growing degree days (GDD) under water salinity and deficit irrigation, in a 2-year experiment. Data of first and second year were used for calibration and validation of the model, respectively. The coefficients of logistic function were determined as a function of irrigation water salinity and sum of applied water and rainfall in spring of the first year. Results indicated that logistic function based on GDD-predicted DMabove during growing season more accurately than logistic function based on DAP. Furthermore, seed yield of rapeseed was estimated based on harvest index with a good accuracy. Therefore, logistic function based on GDD that is based on the cumulative heat units can be used for different weather conditions and planting dates to determine rapeseed DMabove and yield under water salinity and deficit irrigation.  相似文献   

18.
A field study was conducted over two years on maize at Islam Abad Research Station at 34°7′42′′N and 46°27′23′′E and elevation of 1348 m a.s.l in Kermanshah Province, western Iran in order to compare the effects of different irrigation methods and treatments on irrigation water use efficiency, crop yield, yield response factor, pan and seasonal crop coefficients, and other maize parameters. The experiment was a complete randomized block design with three replicates. During the study, irrigation water was applied at 40, 60, 80 and 100% of the maize seasonal water requirement for different surface drip tape (SDT) treatments, and 100% only for conventional furrow irrigation treatments with and without soil and water monitoring. The results showed that by using the above-mentioned different drip tape and surface treatments with soil and water monitoring, maize seasonal irrigation water use savings of 81, 71, 61, 52 and 36% were achieved compared with local conventional furrow irrigation without any soil, water and root monitoring, respectively. The yield response factor (K y), seasonal crop (K c) and pan coefficient (K p) for maize were 0.80, 0.76 and 0.97, respectively.  相似文献   

19.
基于随机样本的神经网络模型估算参考作物腾发量   总被引：13，自引：5，他引：13       下载免费PDF全文
参考作物腾发量(ET0)是计算作物需水量、制定灌溉制度和进行水资源管理的主要参数之一。计算参考作物腾发量(ET0)的方法众多，为规范ET0的求法，联合国粮农组织(FAO)推荐采用修改的Penman-Monteith方法。该文指出不需要收集长序列气象资料，而以随机样本建立学习速率和动量因子自适应的BP神经网络模型估算参考作物腾发量(ET0)的方法，并且与FAO推荐的Penman-Monteith法计算值对比分析，结果表明：利用随机样本建立的的BP神经网络模型可以很好的反映气象因子(最高温度、最低温度、最大湿度、最小湿度、净辐射和风速)与参考作物腾发量(ET0)的非线性函数映射关系，并且取得了良好的估算效果，给出了国家自然科学基金重点项目研究区内蓝旗试验站2004年的时间尺度为日、十日参考作物腾发量(ET0)的计算及对比分析过程。  相似文献   

20.
Wheat (Triticum aestivum L.) productivity is generally affected by water limitation and inadequate nitrogen supply especially under semi-arid environment. The current study was conducted to determine whether the crop yield and irrigation water use efficiency (IWUE) could be manipulated through alteration of nitrogen and irrigation application. To meet the desired objectives, a two-year field study was carried out in 2013–2014 and 2014–2015, in a split-split plot arrangement with three factors i) irrigation in main plots, ii) nitrogen in sub-plots, and iii) twenty genotypes in sub-sub plots on a sandy loam soil. The analysis of variance revealed that the wheat performance was affected by genotypes and alteration of irrigation and nitrogen application with respect to IWUE and final grain yield. IWUE under water stress conditions was observed 56% higher than normal irrigated. Much higher values of IWUE under water stress indicated that the existing optimum water requirements of the crop needs to be revaluated. The regression model indicated that addition of nitrogen and irrigation patterns along with morphological traits cannot explain variation in yield related traits more than 65% under semi-arid conditions. Therefore, for better crop yields in semi-arid environment, more physiological parameters should be considered in evaluation of yield.  相似文献   

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