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1.
为探究河套灌区向日葵不同播前灌水量及现蕾—开花期复水对地上生物量累积、分配以及产量构成要素的影响,试验以当地常规灌溉量(播前135 mm,复水90 mm)为对照,设置A1(播前108 mm,复水90 mm)、A2(播前81 mm、复水90 mm)、B1(播前108 mm、复水72 mm)和B2(播前81 mm、复水72 mm)4个处理进行对比研究。结果表明,适当减少播前灌水量,向日葵在开花期生物量累积补偿效应表现显著,且充分复水较限制复水的生物累积量提高16.45%~32.24%。相同播前灌水量下,收获期充分复水处理总生物量高于限制复水处理(P0.01),不同复水处理收获期籽粒百分比差异显著(P0.05),且A1处理籽粒占总生物量的百分比最高,达到43.02%。播前适当的减少灌水量(108 mm),充分复水能显著提高(P0.05)经济产量,而相同播前灌水量下,现蕾—开花期减少灌水量会显著降低经济产量(P0.05)。采用隶属函数法综合评价不同灌溉下的产量和产量构成要素、灌溉水分生产率等相关指标,得出A1处理最优。A1处理经济产量、灌溉水分生产率分别较CK显著提高8.47%和23.19%,其原因是平均单株实粒数和结实率的显著提高(P0.05)。研究表明,河套灌区向日葵适宜的灌溉制度为播前灌水108 mm,现蕾-开花期复水90 mm。 相似文献
2.
温室番茄节水调质灌水方案评价 总被引：3，自引：0，他引：3
为寻求日光温室番茄优质高效的灌溉制度,采用设置于温室番茄冠层齐平位置的水面蒸发测定装置,设计3种基于水面蒸发量的灌水间隔水平和4种灌水量水平组合处理,依据小区试验观测结果,分析确定了以番茄产量、水分利用率、单果重、可溶性固形物质量分数及果实硬度等5项指标为主的节水调质灌溉制度评价体系;在采用变异系数法确定出各指标权重的基础上,借鉴TOPSIS综合评价方法,建立了温室番茄节水、优质、高产相统一的综合评价模型,应用该模型确定基于水面蒸发量的温室番茄节水调质灌溉制度,即当累积水面蒸发量Epan达到10mm±2mm时进行灌溉,灌水量为0.9Epan,在产量不降低的情况下,提高了水分利用率,并在一定程度上提高了果实的营养品质和储运品质. 相似文献
3.
《Agricultural Water Management》1987,12(4):311-321
Field studies were conducted for four years on alluvial soils of North India to determine the water use, water use efficiency and yield performance of a semi-dwarf high-yielding wheat variety (Triticum aestivum L.) in response to irrigation schedule and nitrogen fertilization. Irrigation scheduling was based on different ratios between irrigation water and cumulative pan evaporation (IW/CPE). Irrigations of 6-cm depth were applied on the basis of IW/CPE ratio of 0.45, 0.60, 0.75 and 0.90. Pan evaporation data were recorded daily using standard USWB-Class A Open pan (as prescribed by India Meterological Department) located at Research Farm, Selakui, Dehradun where the experiment was conducted. The CPE values were computed for each year individually. The crop was fertilized with nitrogen at the rate of 0, 60 and 120 kg/ha.The yield and yield attributes were highest and irrigation efficiency was maximum when irrigation was applied at an IW/CPE ratio of 0.75 in a normal-rainfall year and at 0.90 in a low-rainfall year. Water use efficiency decreased with increase in irrigation frequency. Nitrogen fertilization increased the yield of wheat linearly and was maximum at 120 kg nitrogen per hectare. 相似文献
4.
A 4-year field experiment was conducted in a semi-arid area to evaluate the response of each furrow and alternate furrow irrigation
in wheat-cotton system using irrigation waters of different qualities in a calcareous soil. Irrigation was applied to each
and alternate furrow of bed-planted wheat followed by ridge-planted cotton for comparison with standard check-basin method
of irrigation to both the crops. These methods of irrigation were evaluated under three water qualities namely good quality
canal water (CW), poor quality tube well water (TW) and pre-sowing irrigation to each crop with CW and all subsequent irrigations
with TW (CWpsi + TW). The pooled results over 4 years revealed that wheat grain yield was not affected significantly with
quality of irrigation water, but significant yield reduction was observed in alternate bed irrigation under canal water and
tube well water irrigations. In cotton, poor quality tube well water significantly reduced the seed cotton yield in all the
three methods of planting. The pre-sowing irrigation with canal water and all subsequent irrigations with tube well water
improved the seed cotton yield when compared with tube well water alone. However, this yield increase was significant only
in alternate furrow irrigation, and the yield obtained was on a par with yield under alternate furrow in CW. When compared
to check-basin irrigation, each furrow and alternate furrow irrigation resulted in a saving of 30 and 49% of irrigation water
in bed-planted wheat, whereas the corresponding savings in ridge-planted cotton were 20 and 42%, respectively. Reduced use
of irrigation water under alternate furrow, without any significant reduction in yield, resulted in 28.1, 23.9 and 43.2% higher
water use efficiency in wheat under CW, TW and CWpsi + TW, respectively. The corresponding increase under cotton was 8.2,
2.1 and 19.5%. The implementation of alternate furrow irrigation improved the water use efficiency without any loss in yield,
thus reduced use of irrigation water especially under poor quality irrigation water with pre-sowing irrigation with canal
water reduced the deteriorating effects on yield and soil under these calcareous soils. 相似文献
5.
该研究拟利用直径为20cm的标准蒸发皿,制定简单易行的喷灌冬小麦灌溉计划。试验于2005－2006年和2006－2007年冬小麦生长季节,在中国科学院通州农田水循环和节水灌溉试验基地进行。以布置在冠层上20 cm直径蒸发皿水面蒸发量（E）为基础,研究了不同水面蒸发量倍数（分别为0.25、0.50、0.75、1.00和1.25倍,以及不灌水对照处理）灌溉水量条件下,喷灌水量对土壤水分、冬小麦生长、产量、耗水量和水分利用效率的影响,分析了利用水面蒸发量制定喷灌灌溉计划的可行性。试验结果显示,喷灌条件下土壤水分主要在0～60 cm土层内变化。当灌溉水量小于0.25E时,冬小麦叶面积指数和生物量较小,而大于1.00E也会抑制冬小麦生长。喷灌条件下冬小麦单个生育期内的耗水量在 312～508 mm内变化,耗水量随着灌水量的增加而增加。喷灌0.50E～0.75E时,冬小麦产量和水分利用效率最高或者接近于最高;灌水量较小（≤0.25E）和较大（≥1.00E）时均会降低产量。建议在北京地区冬小麦返青后,喷灌水量可采用0.50～0.75倍的20 cm蒸发皿水面蒸发量,灌水间隔可采用5～7 d。 相似文献
6.
Summary Irrigation at 35 and 70 mm of pan evaporation applied during the pre and/or post early podfilling stages increased pod yield of Spanish peanuts (100 day maturity) three fold compared to a dryland crop. There was no difference in pod yield in crops receiving 12 compared to 6 irrigations. Soil water sampling immediately after irrigations on selected treatments revealed that infiltration of irrigation water was probably restricted to less than ca. 20 cm, a response which resulted in poor soil water replenishment and low irrigation efficiency (Fig. 3). Even though roots extracted soil water below the compaction layer which was at 20 cm severe crop water deficits had developed by the end of irrigation cycles during later but not early stages of growth. The dryland crop, which received no rainfall during the season, presumably extracted significant amounts of soil water at depths to and below 1.2 m (Fig. 3). Despite producing ca. 2.9 t ha-1 of total dry matter yield, pod yield was extremely low (0.5 t ha-1) arising from low pod numbers and high percentage of empty pods.This research was funded by the Australian Centre for International Agricultural Research (ACIAR-Project 8419) in collaboration with the Agency for Agricultural Research and Development (AARD). 相似文献
7.
In Northern India, insufficient soil moisture and excessively high soil temperatures are reported to restrict growth of crops during the hot, dry months of April–June. A 3-year field experiment was conducted to evaluate the effects of three irrigation schedules based on ratios of 0.50, 0.75 and 1.00 times pan evaporation, and two levels of paddy straw mulch of 0 and 6 tons/ha on yield and quality of sugarcane for a sandy loam. The differential irrigations were restricted to 10–12 weeks before the monsoon season.Both irrigation and straw mulching had favourable effects on plant height and yield. Cane yield increased by an average of 13.8% for the 1.00 over the 0.50 times pan evaporation. Similarly, yield averaged 13.8% higher with mulch than without it. Interestingly, the pan evaporation ratio of 0.50 with mulch gave a higher yield than the ratio 1.00 without mulch. For the same yield, irrigation under mulching averaged 34 cm less than under no mulch. These beneficial effects were attributed to better soil moisture and temperature regimes with mulching. Irrigation and mulching had no effect on the quality of cane juice. These results indicate that straw mulching and early season irrigation to sugarcane based on 1.00 times pan evaporation is a promising practice for increasing sugarcane production in subtropical areas. 相似文献
8.
Response of timely and late seeded wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) to three levels of irrigation and four rates of nitrogen was investigated under pre-seeding irrigation. Water extraction pattern and water use of these crops varied markedly. Barley outyielded wheat by 27 and 9%, but used 9 and 21 mm less water, when one and two irrigations were given at critical stages, respectively. These results indicate the possibilities of considerable saving of water (100 mm) for barley without any decrease in grain yield and increased water-use efficiency (WUE) of wheat and barley by irrigating at critical stages as compared to irrigation at 75% depletion of available soil water (ASW). In general WUE decreased with increase in irrigation frequency and delay in seeding.Nitrogen fertilization with marginal additional water use (4–9%) increased yield linearly (45–98%) and thus increased WUE of wheat and barley. This additional water was extracted from below 60 cm depth at tensions ? 1.5 MPa and particularly in maximum growth and reproductive stages. These results suggest that barley should be preferred to wheat under medium to severe water stress and late seeding conditions. 相似文献
9.
【目的】确定大田黄瓜最适宜的灌溉频率和灌水量。【方法】试验于2018年在华北水利水电大学农业高效用水试验场进行,以20cm标准蒸发皿的累积蒸发量(E20)作为灌水依据,灌溉处理分为2个灌溉间隔(I1:3d;I2:6d)和3种水面蒸发系数(K1:0.5;K2:0.7;K3:0.9),共6个处理,对黄瓜耗水特性、产量构成和水分利用效率进行了分析。【结果】黄瓜整个生育期耗水量在380~570mm之间波动,黄瓜的产量在18.2~46.1t/hm2之间波动。从不同灌水频率组合来看,I2K3处理的产量最高,其中,K3处理的早期产量最高,而I1与I2处理的水分利用效率无明显差异。果实数与灌水量之间、耗水量与产量之间均呈正线性相关关系。【结论】建议对于田间黄瓜栽培,灌溉间隔设置为6d,蒸发皿系数选择0.9为宜。 相似文献
10.
《Agricultural Water Management》2001,47(1):25-35
This research explores the limited irrigation strategies based on root-to-shoot communication that exists in spring wheat, and examines the effects of root-sourced signals on water use and yield performance of three genotypes of spring wheat (Triticum aestivum) under three different irrigation regimes. Four treatments, CT (well-watered management), DIu (supplying water to the upper layer to maintain soil moisture in the entire pot at 50–60% of field water capacity (FWC)), and DId (supplying water to the lower layer to maintain soil moisture in the entire pot at 50–60% FWC), were employed. The treatment DIu was used to simulate frequent post-sowing irrigation with small amount of water in each time, and DId was used to simulate pre-sowing irrigation with the same amount of water. Plants were grown in cylinder pots outdoors. A non-hydraulic root signal was induced from seedling to tillering stage in the treatment DId. But after the jointing stage, the signal resulted in a reduction in root biomass and root length in the upper layer and an increase in root biomass and root length in the middle layer as compared with the treatment DIu. The water use efficiencies of the three genotypes were the highest in the treatment DId and the lowest in the treatment DIu for the genotypes A and C. This suggests that under the conditions of the same amount of water supply frequent post-sowing irrigation to the upper soil layer had lower water use efficiency and grain yield, whereas pre-sowing irrigation to the lower soil layer tended to have higher grain yield and higher water use efficiency. 相似文献
11.
Summary The effect of various irrigation regimes on soil aeration was tested in a two-year experiment with 15 year-old apple trees growing in soil containing 67% clay. Irrigation was applied by sprinklers at four intervals ranging from 3 to 18 days and by trickle irrigation every 7 days. Each treatment received a total of 800–850 mm water from May until September. Irrigation by sprinkling at 7 day intervals appeared to be optimal for fruit growth. Less frequent irrigations resulted in smaller fruits; sprinkling at 3–4 day intervals, as well as trickle irrigation reduced the fruit growth rate in July. Leaves from plots irrigated once every 3–4 days had a low chlorophyll content and accumulated relatively large amounts of ethanol, particularly when grafted on the Khashabi rootstock, which is highly susceptible to damage caused by inadequate soil aeration. With increasing intervals between irrigations, the resistance of the leaf surface to the diffusion of water vapour measured prior to irrigation increased, and water loss relative to that from an evaporation pan decreased. Sprinkling at intervals of 14 days resulted in maximal, and at 3–4 days in minimal, air contents of the soil when calculated as averages for the total period of irrigation. The decrease in soil air content with very frequent irrigations was particularly marked in the upper soil layer; this same layer also had a relatively low air content near the emitters in trickle irrigation. After each irrigation, relatively large amounts of ethylene accumulated in the soil atmosphere, indicating inadequate soil aeration, particularly with sprinkling intervals of 3–4 days and at a depth of 30 cm. However, the influence of the irrigation treatments on the oxygen and carbon dioxide contents of the soil atmosphere was small and not consistent. 相似文献
12.
Experiments were undertaken at CCS Haryana Agricultural University Farm, Sirsa (India) to estimate the optimum irrigation
schedule for cotton resulting in minimum percolation losses. The sprinkler line source technique was adopted for creating
various irrigation regimes at different crop growth stages. The SWASALT (Simulation of Water And SALT) model after calibration
and validation provided water balance components. The wa-ter management response indicators (WMRI's) such as transpiration
efficiency Et/(Irr + P), relative transpiration Et/Etp, evapotranspiration efficiency ET/(Irr + P), soil moisture storage change ΔW/Wint (deficit/excess) and percolation loss Perc/(Irr. + P) were evaluated using water balance components as estimated by the simulation
study. Under limited water supply conditions, the optimum irrigation depth was found to be 57 mm at crop growth stages with
pre-sowing and 1st irrigation of 120 mm and 80 mm respectively for sandy clay loam underlain by sandy loam soil (Type I). The corresponding
values of relative transpiration, transpiration efficiency and evapotranspiration efficiency were 0.65, 0.65 and 0.89 respectively.
The crop yield varied linearly with increasing irrigation depth which was evident from increase in relative transpiration
with increasing depth of water application. However, increased depth of irrigation resulted in less moisture utilisation from
soil storage (20% depletion at 40 mm depth and 4.4% moisture built up at 100 mm depth). The extended simulation study for
sandy soil underlain by loamy sand (Type II) indicated that two pre-sowing irrigations each 40 mm and subsequent irrigations
of 40 mm at an interval of 20 days depending upon rainfall were optimum. This irrigation scenario resulted in zero percolation
loss accompanied by 74% relative transpiration and 14 per cent soil moisture depletion.
Received: 20 November 1995 相似文献
13.
The sensitivity of growth and yield of dwarf wheat to water stress at three growth stages 总被引：6，自引：0，他引：6
Summary Response of dwarf wheat (Triticum aestivum L. em Thell) to three different levels of water stress at three growth stages — seeding to maximum tillering, maximum tillering to flowering and flowering to maturity, was studied under field conditions for two seasons. At each of these three stages, plants were subject to three ratios of irrigation water to cumulative pan evaporation (IW/CPE) –0.45, 0.60 and 0.75. During the remaining stages the plants were irrigated with an IW/CPE ratio of 0.9. Thus mild, moderate and severe stress treatments were compared with a no-stress control. At all stages moderate and severe water stress decreased plant height, leaf area, ear number, 1000-grain weight, grain yield and water-use efficiency. In stage 3 the effect of water stress on straw yield was not marked. Wheat was most sensitive to water stress during stage 1 when the reduction in grain yield was caused by a reduction in numbers of ears and grains per ear. In stage 2, grain yield reduction was due to fewer grains perear and a lower 1000-grain weight. On rewatering, mild stressed plants showed recovery of plant height, tiller number and in consequence, yield. Results indicate that under the conditions of this study the wheat crop should be irrigated at a IW/CPE ratio of 0.75 when water resources are limited. With an unlimited water supply the ratio may be increased to 1.2 in stage 2 to maximise the yield. 相似文献
14.
《Agricultural Water Management》2005,76(1):8-23
In the North China Plain (NCP), more than 70% of irrigation water resources are used for winter wheat (Triticum aestivum L.). A crucial target of groundwater conservation and sustainable crop production is to develop water-saving agriculture, particularly for winter wheat. The purpose of this study was to optimize irrigation scheduling for high wheat yield and water use efficiency (WUE). Field experiments were conducted for three growing seasons at the Wuqiao Experiment Station of China Agriculture University. Eleven, four and six irrigation treatments, consisting of frequency of irrigation (zero to four times) and timing (at raising, jointing, booting, flowering and milking stage), were employed for 1994/95, 1995/96 and 1996/97 seasons, respectively. Available water content (AWC), rain events, soil water use (SWU), evapotranspiration (ET) and grain yield were recorded, and water use efficiency (WUE) and irrigation water use efficiency (IWUE) were calculated.The results showed that after a 75-mm pre-sowing irrigation, soil water content and AWC in the root zone of a 2-m soil profile during sowing were 31.1% (or 90.7% of field capacity) and 16.1%, respectively. Rainfall events were variable and showed a limited impact on AWC. The AWC decreased significantly with the growth of wheat. At the jointing stage no water deficits occurred for all treatments, at the flowering stage water deficits were found only in the rain-fed treatment, and at harvest all treatments had moderate to severe soil water deficits. The SWU in the 2-m soil profile was negatively related to the irrigation water volume, i.e. applying 75 mm irrigation reduced SWU by 28.2 mm. Regression analyses showed that relationships between ET and grain yield or WUE could be described by quadratic functions. Grain yield and WUE reached their maximum values of 7423 kg/ha and 1.645 kg/m3 at the ET rate of 509 and 382 mm, respectively. IWUE was negatively correlated with irrigated water volume. From the above results, three irrigation schedules: (1) pre-sowing irrigation only, (2) pre-sowing irrigation + irrigation at jointing or booting stage, and (3) pre-sowing irrigation + irrigations at jointing and flowering stages were identified and recommended for practical winter wheat production in the NCP. 相似文献
15.
Summary Development of a ploughpan has been reported in Bangladesh for almost all ploughed soils which are puddled for transplanted rice cultivation. Field information on the water requirement of dryland crops such as wheat and the effects of loosening the dense layer on crop yield and water use efficiency are very limited. Field experiments were, therefore, conducted in the grey floodplain soil of Sonatala series (Aeric Haplaquept) to study the irrigation and tillage effects on the yield and water relations of wheat (Triticum aestivum L. cv. Sonalika). The split plot design experiment comprised four irrigation treatments in the mainplots viz. W0 = no irrigation, W1 = irrigation of 5 cm at 4 weeks after planting, W2-W1 + irrigation(s) of 5 cm each at irrigation water to cummulative pan evaporation (IW/CPE) ratio of 0.75 and W3- W1 + irrigation(s) of 5 cm eacht at IW/CPE ratio of 0.50. The sub-plot tillage depth treatments were: A-7.5 cm (traditional), B-15 cm, C-22.5 cm, D-22.5 cm practised in alternate wheat seasons. Measurements were made of grain and straw yield, soil water depletion and water expense efficiency.Irrigation had no effect on grain or straw yield. Tillage to 15 cm increased wheat yield by about 15% over traditional depth to ploughing. In general, deep tillage coupled with one irrigation at four weeks after planting produced the largest wheat yield.Soil water depletion (SWD) in the 0–90 cm profile was greatest in the treatment receiving two irrigations, one at 4 weeks and again at IW/CPE ratio of 0.50. The average SWD in this treatment was 113 in 1982–83 and 82 mm in 1983–84. Plots receiving traditional tillage (7.5 cm) had the greatest SWD. Total water expense were the greatest in treatments receiving three irrigations. The maximum water expense efficiency (WEE) of wheat was observed in the non-irrigated plots in 1982–83 and 1983–84, respectively. Deep tillage treatments, in general, had significantly greater WEE than those under traditional ploughing. Intensive irrigation and efficient soil and water management are important factors in enhancing crop productivity. The former not only permits judicious water use but also better utilization of other production factors thereby leading to increased crop yield which, in turn, helps stabilize the farming economy. The best way to meet increasing demand for water is to adopt efficient water management practices to increase water use efficiency.Irrigation should aim at restoring the soil water in the root zone to a level at which the crop can fully meet its evapo-transpiration (ET) requirement. The amount of water to be applied at each irrigation and how often a soil should be irrigated depend, however, on several factors such as the degree of soil water deficit before irrigation, soil types, crops, and climatic conditions (Chaudhury and Gupta 1980).Knowledge of movement of water through the soil is imperative to efficient water management and utilization. The presence of a dense pan impedes water movement into the sub-soil. As a result, the top soil becomes saturated by irrigation and sensitive dryland crops can fail as this plough layer impedes the penetration of roots into deeper soil layers and decreases water extraction. Crops growing in these soils often undergo severe water stress within 5–8 days after rainfall or irrigation (Lowry et al. 1970). Due to decrease rates of water flow, the lower soil layer may remain unsaturated and as a result, the recharge and soil water storage in the profile are considerably decreased (Sur et al. 1981).In Bangladesh, ploughpans develop to varying degree in almost all ploughed soils (Brammer 1980). They are particularly marked in soils which are puddled for transplanted rice cultivation where the pan is usually only 8–10 cm below the soil surface and 3–5 cm thick. Its presence is generally regarded as advantageous for cultivation of transplanted rice in that it prevents excessive deep percolation losses of water. But in the same soil this cultivation for a subsequent dryland crop would adversely affect yield. A slight modification of the plough layer could enable good yields of both rice and a dryland crop to be obtained in the same soil in different seasons (Brammer 1980). The sub soils have a good bearing capacity, both when wet and dry and the pan can easily be reformed, if desired, for cultivating transplanted rice after a dryland crop like wheat.Professor of Soil Science, Dhaka University, Dhaka, Bangladesh 相似文献
16.
M.Govind Reddy Y.Yogeswara Rao K.Subba Rao K. Ramaseshaiah 《Agricultural Water Management》1983,6(4):403-407
Irrigation scheduling was carried out for wheat and maize grown in a semi-arid region, using cumulative pan evaporation (CPE). Scheduling of 60 mm depth of irrigation when CPE was 60 mm () was found to be optimum for wheat, while 60 mm depth of irrigation when CPE was 50 mm () was found to be optimum for maize. Cumulative evaporation from 1 l ‘Cans’ (CCE), exposed above these crops, was recorded simultaneously. The ratios were found to increase with the advance of the season. The ratios were higher over maize than over wheat.The CCE during the different stages of crop growth varied from 60.6 to 69.0 mm in wheat and from 51.5 to 94.0 mm in maize. 相似文献
17.
通过CROPWAT模型分析泾惠渠灌区冬小麦和玉米蒸发蒸腾量及灌溉需水量的变化,同时运用SPSS软件,计算灌区作物需水量与气象因子的相关系数,分析结果表明:冬小麦整个生育期蒸发蒸腾量平均值为634.04 mm,蒸发蒸腾量最高峰出现在4月中旬—5月中旬,灌区各分区蒸发蒸腾量趋势基本一致;玉米蒸发蒸腾量平均值为525.22 mm,蒸发蒸腾量高峰期出现在7月中旬—8月下旬,其中三原最大为535.97 mm,富平最小为514.68 mm;灌区冬小麦在播种—越冬期灌溉需水量最低,返青—拔节期需水量增加;灌区玉米在拔节—抽雄期需水量增加,灌溉平均需水量为133.04 mm;7月—8月为籽粒形成乳熟期,需水量为359.15 mm,至9月下旬,玉米灌溉需水量下降;灌区作物需水量与气温呈正相关,与降水呈负相关,与风速和相对湿度相关性较小,气温、日照时数和相对湿度是影响作物需水量的主要因素. 相似文献
18.
Field studies were conducted during a 3-year period to determine wheat (Triticum aestivum L.) yield in response to irrigation scheduling and variable fertilization.Irrigation scheduling was done on the basis of cumulative pan evaporation. Irrigations were given at 25, 50 and 75% available water in the top 60 cm soil profile. The amount of irrigation water applied at each irrigation was equivalent to 75% of the cumulative open pan evaporation. The crop was fertilized at the rate of 0, 60, and 120 kg/ha nitrogen.The yield of wheat was significantly affected by irrigation water and nitrogen treatments. Maximum yield was obtained with irrigation at 50% available soil water and 120 kg/ha nitrogen addition (5092 kg/ha). Consumptive use of water was maximum when irrigation was applied at 75% available soil water. The irrigation at 50% available soil water, however, resulted in greatest yield per cm water use by the crop. 相似文献
19.
High evaporative demand and limited precipitation restrict the yield of winter wheat (Triticum aestivum L.) grown in the Loess Plateau of China under semiarid climatic conditions. Grain yield can be improved by effective water management practices. A 13-year field experiment was conducted at the CERN Changwu Agro-ecological Experimental Station of the Loess Plateau to determine optimal irrigation strategies under limited water supply and to develop relationships among grain yield (Y), seasonal evapotranspiration (SET) and water-use efficiency (WUE). The experiment consisted of five irrigation treatments and three blocks. Measurements included grain yield, soil water content at various depth intervals in the 0–3,000 mm layer, irrigation amount, and precipitation. Results showed that winter wheat grown in this area experienced serious water stress during critical growth stages for the no-irrigation treatment. The amount and timing of irrigation had an important effect on grain yield, but significant differences in yield were not observed between the three-irrigation and the four-irrigation treatments. Grain yield was linearly related (R2=0.66) to SET, but differences in WUE were not significant for any of the treatments. The relationship between WUE and Y was best represented by a second order polynomial (R2=0.65) consisting of a nearly linear portion between 1.5 and 5.0 Mg ha–1. Optimum water management of winter wheat in the Loess Plateau should consist of three 87.5 mm irrigations applied at stem elongation, booting, and anthesis.Communicated by J.E. Ayars 相似文献
20.
Influence of season to season variability in weather on irrigation scheduling of wheat: A simulation study 总被引：2，自引：0，他引：2
Summary There is an increasing demand from farmers for irrigation scheduling advice. Where rainfall and evapotranspiration vary little from year to year, advice on a fixed irrigation schedule based on mean climatic data can be given. However where significant year to year variability in weather occurs a more flexible approach using actual weather data to predict the current level of soil water and mean climatic data to forecast the future rate of depletion and hence irrigation date may be needed. A technique for deciding the most appropriate scheduling approach was tested by using a simple model of crop growth combined with a soil water balance model to simulate year to year variability in scheduling advice. This technique was applied to irrigated wheat using a set of climatic data from 1968 to 1978 for Griffith in the Murrumbidgee Irrigation Area of New South Wales, Australia. A typical sowing date in early June was used and simulated irrigations were scheduled at an allowable soil water depletion (ASWD) of 62 mm for maximum yield and 93 mm for 80% of maximum. The analysis predicted that weather variability between years would cause the number of irrigations to vary from 2 to 7 for ASWD=62 mm and 1 to 4 for ASWD=93 mm. The interval between irrigations varied from 12 to 30 days, for ASWD=62 mm and from 16 to 28 days, for ASWD=93 mm. The first irrigation occurred between 76 and 131 days from sowing for ASWD=62 mm and from 100 to 140 days from sowing for ASWD=93 mm. The date of the last irrigation was similarly variable. This high degree of variability in the times and frequency of irrigations indicated that in south-eastern Australia accurate irrigation scheduling advice can only be given by using a flexible model using both actual and mean climatic data. A fixed schedule based on mean climatic data would lead to an inefficient use of water caused by the mistiming of irrigations. 相似文献