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1.
Irrigation water is a limited resource, and therefore irrigation practices must be rationalized for high water-use efficiency. Little is known about the influence of stored water in deep soils on the water needs and the post-sowing irrigation requirements of crops. A 3-year field experiment was conducted to determine the effects of combinations of light and heavy pre-sowing irrigations with two post-sowing irrigation regimes on yield, root growth, water use and water-use efficiency of wheat on a deep alluvial sandy loam soil. Post-sowing treatments consisted of (i) five 75-mm irrigations at five growth stages, and (ii) irrigations based on pan evaporation, i.e. at IW/PAN-E ratio of 0.75 (75 mm of irrigation water were provided as soon as the open-pan evaporation minus rainfall since previous irrigation was 100 mm).The latter regime required 175 mm less water than that with irrigation at growth stages. Profile water utilization was inversely related to post-sowing irrigation water. Where pre-sowing irrigation was light, post-sowing irrigations based on pan evaporation yielded significantly less than those based on growth stages. With heavy pre-sowing irrigation, irrigation based on the pan evaporation yielded as much as five irrigations at growth stages. The former decreased the mean water application by 153 mm and increased the water-use efficiency by 26%. Irrigation based on pan evaporation stimulated greater utilization of stored water by increasing the rooting density in deeper layers.It is indicated that for higher water-use efficiency and yield, wheat should be sown after a heavy pre-sowing irrigation, and post-sowing irrigation should be based on 0.75 pan evaporation. 相似文献
2.
绿洲新垦沙地春玉米农田有限灌溉试验研究 总被引：1，自引：0，他引：1
在临泽绿洲耕作层保水能力较差的新垦沙地,开展了春玉米有限灌溉试验研究。结果表明,不同水分处理玉米0~20 cm土层土壤含水量在玉米成熟期以前,以播前水分最高,拔节期达到次高点,灌浆期降至最低点,约为播前水分的39%。20~40 cm和40~100 cm土层土壤水分含量变化趋势基本一致,但与0~20 cm土层有较大差异。在成熟期以前,土壤水分以播前最高,抽雄期达到次高点,灌浆期降至最低点,分别为播前土壤含水量的54%和73%左右;0~100 cm土层全生育期土壤含水量变化趋势与40 cm以下土层基本相似,灌浆期降至最低点,约为播前含水量的55%。玉米的行粒数、穗粒重和千粒重,以对照处理CK为最高。在整个生育期内,植株株高WT1与对照差异不显著,WT2、WT3均高于对照,且WT2、WT3在六叶期分别比对照增加28.4%、8.1%,在抽雄期分别比对照增加17.3%、14.3%,在灌浆初期分别比对照增加5.2%、7.0%。叶面积指数增长最快的阶段在拔节期至抽雄期,增长幅度在72.7%~178.3%之间,WT1在拔节期之前高于对照,之后均低于对照,六叶期比对照增加9.1%;WT2除了在吐丝期略低于对照外,其他时期均高于对照,六叶期比对照增加63.6%;WT3在整个生育期都高于对照,六叶期比对照增加18.2%。 相似文献
3.
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
4.
《Agricultural Water Management》2006,79(1):28-42
A field experiment was conducted in 2003 and 2004 growing seasons to evaluate the effects of regulated deficit irrigation on yield performance in spring wheat (Triticum aestivum) in an arid area. Three regulated deficit irrigation treatments designed to subject the crops to various degrees of soil water deficit at different stages of crop development and a no-soil-water-deficit control was established. Soil moisture was measured gravimetrically in the increment of 0–20 cm every five to seven days in the given growth periods, while that in 20 increments to 40, 40–60, 60–80, and 80–100 cm depth measured by neutron probe. Compared to the no-soil-water-deficit treatment, grain yield, biomass, harvest index, water use efficiency (WUE), and water supply use efficiency (WsUE) in spring wheat were all greatly improved by 16.6–25.0, 12.4–19.2, 23.5–27.3, 32.7–39.9, and 44.6–58.8% under regulated deficit irrigation, and better yield components such as thousand-grain weight, grain weight per spike, number of grain, length of spike, and fertile spikelet number were also obtained, but irrigation water was substantially decreased by 14.0–22.9%. The patterns of soil moisture were similar in the regulated deficit treatments, and the soil moisture contents were greatly decreased by regulated deficit irrigation during wheat growing seasons. Significant differences were found between the no-soil-water-deficit treatment and the regulated soil water deficit treatments in grain yield, yield components, biomass, harvest index, WUE, and WsUE, but no significant differences occurred within the regulated soil water deficit treatments. Yield performance proved that regulated deficit irrigation treatment subjected to medium soil water deficit both during the middle vegetative stage (jointing) and the late reproductive stages (filling and maturity or filling) while subjected to no-soil-water-deficit both during the late vegetative stage (booting) and the early reproductive stage (heading) (MNNM) had the highest yield increase of 25.0 and 14.0% of significant water-saving, therefore, the optimum controlled soil water deficit levels in this study should range 50–60% of field water capacity (FWC) at the middle vegetative growth period (jointing), and 65–70% of FWC at both of the late vegetative period (booting) and early reproductive period (heading) followed by 50–60% of FWC at the late reproductive periods (the end of filling or filling and maturity) in treatment MNNM, with the corresponding optimum total irrigation water of 338 mm. In addition, the relationships among grain yield, biomass, and harvest index, the relationship between grain yield and WUE, WsUE, and the relationship between harvest index and WUE, WsUE under regulated deficit irrigation were also estimated through linear or non-linear regression models, which indicate that the highest grain yield was associated with the maximum biomass, harvest index, and water supply use efficiency, but not with the highest water use efficiency, which was reached by appropriate controlling soil moisture content and water consumption. The relations also indicate that the harvest index was associated with the maximum biomass and water supply use efficiency, but not with the highest water use efficiency. 相似文献
5.
咸水灌溉对土壤水盐分布和小麦产量的影响 总被引：1，自引：0，他引：1
在石羊河流域中游开展田间灌溉试验,试验设置3种灌水量,灌溉定额分别为355,280,205 mm(W1,W2和W3);4种灌水矿化度0.7,3.0,5.0和7.0 g/L(S1,S2,S3和S4),共12个处理,每个处理3组重复.研究结果表明:淡水灌溉条件下,土壤积盐率不超过15%,当灌水矿化度在3.0 g/L以上时,土壤剖面盐分积累峰值在20~40 cm层,灌溉水带入的盐分有40%~80%积累在60 cm深度.当灌水矿化度为3.0 g/L时,盐分胁迫造成春小麦减产在10%以下;灌水矿化度为5.0 g/L和7.0 g/L时,春小麦减产严重,最高可达28%.相同灌水矿化度条件下,与充分灌溉(W1)相比,W2和W3分别减产10%和15%左右.拔节期-灌浆期是春小麦需水关键期,灌水要及时,3种灌水量均可以保证春小麦根区含水量维持在田间持水量的60%~80%.因此,3.0 g/L的微咸水灌溉不会造成春小麦大幅减产,合理调控灌水时间,灌水量为205~355mm可以保证春小麦土壤含水量维持在适宜的水平. 相似文献
6.
为了探究石羊河流域适宜春玉米生长的咸水非充分灌溉模式,应用SWAP模型模拟不同灌溉模式下的土壤水盐平衡、春玉米相对产量和相对水分利用效率,并预测了较长时期土壤水盐动态变化规律.研究结果表明:灌溉水矿化度为0.71 g/L和3.00 g/L的春玉米最优灌溉模式为生育期内灌4次水,灌溉定额均为408 mm,2种灌溉模式均能达到节约灌溉用水、提高作物产量和水分利用效率以及减少土体盐分累积量的目的.较长时期土壤水盐动态变化规律模拟结果表明:在冬灌条件下,春玉米最优灌溉模式下的土壤水分和盐分能够在模拟期内保持相对平稳的状态;在不同年份,相同土层土壤含水率随着土层深度的增加而增大,0.71 g/L的淡水灌溉土壤盐分主要累积在40~80 cm土层,3.00 g/L的微咸水灌溉土壤盐分主要累积在10~40 cm土层;5 a的模拟结果表明0.71 g/L和3.00 g/L的水持续灌溉5 a,不会引起土壤次生盐渍化. 相似文献
7.
喷灌灌水与施肥对春小麦水分动态及产量的影响 总被引：4，自引：0，他引：4
为了探索河西走廊春小麦适宜的喷灌灌溉施肥制度,以当地畦灌模式为对照对比分析了不同灌水方式、灌溉施肥水平下土壤水分动态分布及产量效应并对春小麦产量进行了回归分析.研究了喷灌条件下灌水前后土壤水分分布动态、不同生育期内土壤含水率变化特征及不同灌水量水平下土壤水分下渗状况,分析了不同灌水、施肥水平对产量及产量构成要素的影响.结果表明,喷灌灌水定额为75 mm时,有部分水分下渗至春小麦主要根系活动层以下,但较畦灌量小;喷灌灌水定额在45~60 mm时,灌水后大部分水分储存在0~40 cm土层;春小麦整个生育期内,中等灌溉水平40~80 cm土层土壤水分变化不明显;春小麦产量及其构成要素对灌溉量响应大于施肥量,灌溉量过大时,产量有下降趋势;喷灌条件下,中等灌溉、追肥水平下产量较畦灌高1105%,节水增产效果显著.另外,根据产量拟合方程并结合水分利用效率,喷灌中等灌水、施肥水平为该地区适宜发展的灌溉施肥制度. 相似文献
8.
春小麦免储水灌全膜覆盖穴播与保水剂配合节水技术研究 总被引：1，自引：0，他引：1
通过对甘肃河西地区春小麦免储水灌全膜覆盖穴播与保水剂配合节水技术的试验研究,测定了春小麦地土壤水分变化规律、小麦耗水规律及产量效应,分析配套施用保水剂对春小麦地土壤水分的影响。研究结果表明,在河西地区,小麦采用免储水灌全膜覆盖施用保水剂穴播技术能有效地减少农田在休闲期的土壤蒸发量,提高农田的水分利用效率,可减少首次灌水量30mm,全生育期耗水量减少80.0mm,节水16.60%,增产4.37%,水分利用效率提高21.70%。 相似文献
9.
10.
为探求循环曝气地下滴灌对温室番茄土壤水分及耗水特性的影响规律,采用正交试验,研究了不同滴灌带埋深、曝气水平及灌水量对温室番茄土壤含水率、耗水量、产量及水分利用效率的影响.整个生育期内番茄耗水量呈先增大后减小的趋势,曝气处理番茄耗水量显著高于不曝气处理.相比于不曝气处理,曝气滴灌处理番茄产量提高10%,水分利用效率提升0.4%.15 cm滴灌带埋深、溶氧值30 mg/L以及75%ET0灌水量处理的番茄产量和水分利用效率达到最大值,分别为64 951.3 kg/hm2和23.26 kg/(hm2·mm).结果表明,曝气处理对番茄产量、水分利用效率的影响具有统计学意义(P<0.05).曝气对于土壤含水率有一定影响,且曝气处理有助于番茄对水分的吸收.滴灌带埋深和灌水量交互作用对番茄产量的影响具有统计学意义(P<0.05),滴灌带埋深和曝气量交互作用对番茄产量的影响具有统计学意义(P<0.01),灌水量与滴灌带埋深、灌水量与曝气水平交互作用分别对番茄水分利用效率的影响具有统计学意义(P<0.01). 相似文献
11.
Summary The effect of soil moisture regimes on the grain and straw yield, consumptive water use (Cu) and its relation with evaporation from free water surface (Eo), water use efficiency and soil moisture extraction pattern of lentil was studied in a field experiment conducted at the Indian Agricultural Research Institute, New Delhi during the fall-spring season of the crop years 1979–1980 and 1980–1981. The grain and straw yield, consumptive water use rate, Cu/Eo ratio and water use efficiency increased with an increase in irrigation frequency. Consumptive water use rate increased as the crop season advanced and reached its peak value during flowering and grain filling stage. The Cu/Eo ratio attained its minimum values 35 and 105 days after sowing at branching and grain filling stages. Depletion of soil moisture was most from the top 0–30 cm soil layer followed by 30–60 cm soil layer and was least from 90–120 cm soil layer. The pattern of soil moisture depletion was also influenced by soil moisture regime. During the vegetative and flowering stage the percent contribution from the top 0–30 cm soil layer decreased and that from the lower soil layers (30–60, 60–90, and 90–120 cm) increased with an increase in the soil moisture tension, however, the actual amount of moisture depleted from all the soil layers was always higher under low soil moisture tension regime than under high soil moisture tension regime. During the grain development stage the soil moisture treatment had no significant effect on the relative contribution from different soil layers under low and high soil moisture tension as the crop was irrigated at the same time under both these treatments. However, with no irrigation, the percent contribution from top soil layer continued to decrease, and from lower soil layers continued to increase, as the crop advanced from flowering stage to grain development stage. 相似文献
12.
以棉花各生育期适宜土壤含水率上、下限差值为灌水控制指标,设置3水平灌水处理,开展膜下滴灌大田试验,分析研究适宜试验区棉花生长、水分利用效率高的灌溉制度及膜下滴灌棉田土壤水盐运移规律。结果表明:适宜土壤含水率上、下限差值形成的灌溉制度,决定了土壤水盐运移规律、盐分分布和积累特征。总体表现为:空间上土壤水分分布与滴灌带间距呈负相关系,盐分分布则相反,0~40 cm深度土壤水分在灌后重分布,盐分在滴灌水分的淋洗作用下定向运移,至湿润体边缘积聚。综合分析关键点与主根层的土壤水盐时间序列变化,T2处理(385 mm/18次)主根层0~40 cm深度水分处于棉花生长的适宜含水率范围,并形成淡化脱盐区,对盐分的调控最佳。T2处理棉田产量最高,为6 083 kg/hm~2,水分利用效率为1.05 kg/(mm·hm~2),为适宜的灌溉制度。 相似文献
13.
The increasing demand for irrigation water to secure food for growing populations with limited water supply suggests re-thinking
the use of non-conventional water resources. The latter includes saline drainage water, brackish groundwater and treated waste
water. The effects of using saline drainage water (electrical conductivity of 4.2–4.8 dS m−1) to irrigate field-grown tomato (Lycopersicon esculentum Mill cv Floradade) using drip and furrow irrigation systems were evaluated, together with the distribution of soil moisture
and salt. The saline water was either diluted to different salinity levels using fresh water (blended) or used cyclically
with fresh water. The results of two seasons of study (2001 and 2002) showed that increasing salinity resulted in decreased
leaf area index, plant dry weight, fruit total yield and individual fruit weight. In all cases, the growth parameters and
yield as well as the water use efficiency were greater for drip irrigated tomato plants than furrow-irrigated plants. However,
furrow irrigation produced higher individual fruit weight. The electrical conductivity of the soil solution (extracted 48 h
after irrigation) showed greater fluctuations when cyclic water management was used compared to those plots irrigated with
blended water. In both drip and furrow irrigation, measurements of soil moisture one day after irrigation, showed that soil
moisture was higher at the top 20 cm layer and at the location of the irrigation water source; soil moisture was at a minimum
in the root zone (20–40 cm layer), but showed a gradual increase at 40–60 and 60–90 cm and was stable at 90–120 cm depth.
Soil water content decreased gradually as the distance from the irrigation water source increased. In addition, a few days
after irrigation, the soil moisture content decreased, but the deficit was most pronounced in the surface layer. Soil salinity
at the irrigation source was lower at a depth of 15 cm (surface layer) than that at 30 and 60 cm, and was minimal in deeper
layers (i.e. 90 cm). Salinity increased as the distance from the irrigation source increased particularly in the surface layer.
The results indicated that the salinity followed the water front. We concluded that the careful and efficient management of
irrigation with saline water can leave the groundwater salinity levels unaffected and recommended the use of drip irrigation
as the fruit yield per unit of water used was on average one-third higher than when using furrow irrigation. 相似文献
14.
为探究西北半干旱地区适宜的膜下滴灌技术参数,以春玉米为试验对象,以甘肃省武威市民勤县为典型试验区,于2017年3—9月开展大田试验,分析了膜下滴灌灌水频率（P1∶5 d、P2∶7 d、P3∶9 d）及滴灌带间距（J1∶0.9 m、J2∶1.1 m、J3∶1.3 m）交互组合下对土壤水氮分布规律、春玉米生理特性指标、产量及水分利用效率等的影响。试验结果表明:当滴灌带间距相同时,灌水频率越高,湿润带宽度越小、各层土壤水氮含量波动幅度越小,同一土层深度处中低频处理平均土壤含水率较高;当灌水频率相同时,滴灌带间距较大的处理向土壤深层运移的水分较多。灌水频率相同时,滴灌带间距较小的处理产量及水分利用效率较高;滴灌带间距相同时,中高频处理产量及水分利用效率较高;P1J1处理产量最高,为16 485.25 kg/hm2,其次是P2J2处理,产量为16 292.21 kg/hm2,但P2J2处理水分利用效率最高,达到3.66 kg/m3。 相似文献
15.
The 2-year field experiments were carried out to research the effect of different irrigation methods, namely border irrigation,
sprinkler irrigation, and surface drip irrigation, on root development and profile water uptake in winter wheat. Results showed
that the main root distribution zone moved upward under sprinkler and surface drip irrigation when compared to the traditional
border irrigation. Profile root distribution pattern changed with irrigation methods. Soil profile water uptake was correlated
to the root system and soil water dynamics. Due to the appropriate soil water and higher root density in the surface soil
layer under sprinkler and surface drip irrigation, the main water uptake zone was concentrated in the upper layer. Because
of the water deficit in the surface layer under border irrigation, water uptake in 50–100 cm depth was stimulated, which caused
the main uptake zone downward. The amount and pattern of root water uptake varied with irrigation methods. This may provide
valuable information on the aspect of agricultural management. 相似文献
16.
土壤水分含量对加工番茄产量和品质影响的研究 总被引：19，自引：1，他引：19
试验从加工番茄开花期开始，设4个水分处理（分别以0～60cm土层灌前土壤田间持水量的40％～45％、55％～60％、70％～75％和85％～90％作为各处理的灌溉下限含水量临界值，灌溉上限为田间持水量的90％），分析不同水分状况下加工番茄的产量和果实品质。试验结果表明，加工番茄的产量、品质与土壤含水量密切相关，灌前过高或过低的土壤含水量会影响产量及茄红素、可溶性固形物、可溶性糖、可溶性酸等品质指标，灌前土壤相对田间持水量为70％～75％处理的加工番茄产量最高，品质较好，水分利用效率最高，既能实现高产高效，又可达到节水灌溉的目的。 相似文献
17.
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
18.
《Agricultural Water Management》1999,41(1):57-70
The salinity condition in the root zone hinders moisture extraction from soil by plants, because of osmotic potential development in soil water due to presence of salts, which ultimately, decreases transpiration of plants and thereby affects crop yield. Therefore, an effort was made in this study to quantify the impact of salinity on soil water availability to plants. The movement of salts under irrigation and evapotranspiration regimes in root zone of soil profile was studied throughout the growing season of wheat crop with adopting exponential pattern of root water uptake. A model was developed to analyze soil water balance to find out moisture deficit because of salinity. A non-linear relationship was formulated between moisture content and salt concentration for simultaneous prediction. The Crank–Nicolson method of Finite Differencing was used to solve the differential equations of soil water and solute transport. The effect of various salt concentrations on transpiration was analyzed to develop a relationship between relative evapotranspiration and relative yield. Relationships among salt concentration, matric potential, moisture deficit and actual transpiration were also established to provide better understanding about impact of salinization and to provide guidelines for obtaining better crop yields in saline soils. 相似文献
19.
为提高旱区作物蒸发蒸腾量估算精度,以石羊河流域春玉米为研究对象,分析灌水量对FAO-56估算作物蒸发蒸腾量精度的影响,并对估算误差进行讨论,提出使用部分根区含水量平均值用于土壤水分胁迫系数计算.结果表明:FAO-56对不同灌水处理下作物蒸发蒸腾量的估算精度存在较大差异,可较精确地估算低灌水处理下作物蒸发蒸腾量;随着灌水量增大,其估算精度有所降低,对高灌水处理下作物蒸发蒸腾量的估算误差达-14.13%;根区上部土层含水量与土壤水分胁迫状况关系紧密,以缓变层及以上土层含水量平均值代替整个根区含水量平均值用于土壤水分胁迫系数计算,可有效改善高灌水处理下旱区作物蒸发蒸腾量计算精度,亦可较为精确地估算低灌水处理下作物蒸发蒸腾量. 相似文献
20.
In a comparison of methods of irrigating tomatoes on the sand dunes of northern Sinai (El-Arish region), yields obtained by trickling were higher than those by sprinkling. The present study attempts to explain these results from a physical point of view. Before each irrigation and during a complete irrigation cycle measurements were made of soil moisture content, moisture tension in the root zone, and plant water potential. The amount of water applied was based on Class A pan evaporation. At 24 h after the end of an irrigation the soil moisture content was 4% by weight, regardless of the quantity of water applied. The soil moisture tension and the plant water potential were similar for both methods during the first 24 h after irrigation, but the values rose gradually and were higher at the end of the sprinkle irrigation cycle which lasted 3 days, than at the end of the daily trickle irrigation cycle. These differences in soil moisture tension affected the plant water potential and in turn plant development and yield. 相似文献