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1.
水分调亏对地下滴灌夏玉米田水热动态的影响 总被引：1，自引：0，他引：1
通过北京地区地下滴灌夏玉米田间试验,研究了前期不同程度水分亏缺对土壤水热和夏玉米冠层温度、株高、叶面积指数及产量的影响。结果表明:在20～60 cm土层,除重度亏水处理外,其他处理的土壤含水率均在高位平稳变化;在60～100 cm土层,丰水处理的土壤含水率最大;对不同深度的土层,轻度与中度亏水处理两者间的土壤含水率差异较小。受作物覆盖度和亏水程度的影响,拔节期各处理间土壤温度和冠层温度有明显差异;在较浅土层(距地表30 cm和50 cm处)中,拔节期之前丰水处理的土壤温度较低,拔节期之后各处理间差异逐渐减小;在较深土层(距地表80 cm处)中,水分亏缺程度越大,土壤温度越高。轻度亏水处理能获得较高的产量,中度亏水处理能提高水分利用效率。 相似文献
2.
Summary A field study was conducted on cotton (Gossypium hirsutum L. c.v. Acala SJ-2) to investigate the effects of soil salinity on the responses of stress indices derived from canopy temperature, leaf diffusion resistance and leaf water potential. The four salinity treatments used in this study were obtained by mixtures of aqueduct and well water to provide mean soil water electrical conductivities of 17, 27, 32 and 38 dS/m in the upper 0.6 m of soil profile. The study was conducted on a sandy loam saline-alkali soil in the lower San Joaquin Valley of California on 30 July 1981, when the soil profile was adequately irrigated to remove any interference of soil matric potential on the stress measurements. Measurements of canopy temperature, leaf water potential and leaf diffusion resistance were made hourly throughout the day.Crop water stress index (CWSI) estimates derived from canopy temperature measurements in the least saline treatment had values similar to those found for cotton grown under minimum salinity profiles. Throughout the course of the day the treatments affected CWSI values with the maximum differences occurring in mid-afternoon. Salinity induced differences were also evident in the leaf diffusion resistance and leaf water potential measurements. Vapor pressure deficit was found to indicate the evaporative demand at which cotton could maintain potential water use for the various soil salinity levels studied. At vapor pressure deficits greater than 5 kPa, cotton would appear stressed at in situ soil water electrical conductivities exceeding 15 dS/m. The CWSI was as sensitive to osmotic stress as other, more traditional plant measures, provided a broader spatial resolution and appeared to be a practical tool for assessing osmotic stress occurring within irrigated cotton fields. 相似文献
3.
Infrared canopy temperature of early-ripening peach trees under postharvest deficit irrigation 总被引：1，自引：0，他引：1
Canopy temperature measurements with infrared thermometry have been extensively studied as a means of assessing plant water status for field and row crops but not for fruit trees such as peaches. Like in many regions of the world, the lack of water is beginning to impact production of tree fruit such as peaches in the San Joaquin Valley of California. This is an area where irrigation is the only source of water for agricultural crops in the summer growing season. A two-year field study was conducted to assess plant water stress using infrared canopy temperature measurements and to examine its feasibility for managing postharvest deficit irrigation of peach trees. Twelve infrared temperature sensors were installed in a mature peach orchard which received four irrigation treatments: furrow and subsurface drip irrigation with or without postharvest water stress. During the two-year period, measured midday canopy to air temperature differences in the water-stressed postharvest deficit irrigation treatments were in the 5-7 °C range, which were consistently higher than the 1.4-2 °C range found in the non-water-stressed control treatments. A reasonable correlation (R2 = 0.67-0.70) was obtained between stem water potential and the canopy to air temperature difference, indicating the possibility of using the canopy temperature to trigger irrigation events. Crop water stress index (CWSI) was estimated and consistently higher CWSI values were found in the deficit irrigation than in the control treatments. Results of yield and fruit quality assessments were consistent with the literature when deficit irrigation was deployed. 相似文献
4.
Accurate irrigation scheduling is important to ensure maximum yield and optimal water use in irrigated cotton. This study
hypothesizes that cotton water stress in relatively humid areas can be detected from crop stress indices derived from canopy
reflectance or temperature. Field experiments were conducted in the 2003 and 2004 crop seasons with three irrigation treatments
and multiple cultivars to study cotton response to water stress. The experiment plots were monitored for soil water potential
(SWP), canopy reflectance and canopy temperature. Four crop stress indices namely normalized difference vegetative index (NDVI),
green NDVI (GNDVI), stress time (ST) index and crop water stress index (CWSI) were evaluated for their ability to indicate
water stress. These indices were analyzed with classic mixed regression models and spatial regression models for split-plot
design. Rainfall was plentiful in both seasons, providing conditions representative of irrigated agriculture in relatively
wet regions. Under such wet weather conditions, excessive irrigation decreased lint yield, indicating the necessity for accurate
irrigation scheduling. The four crop stress indices showed significant responses to irrigation treatments and strong correlation
to SWP at shallow (0.2 m) depth. Spatial regression models were able to accurately explain the effect of irrigation treatment,
while classic split-plot ANOVA models were confounded by collinearity in data across space and time. The results also verified
that extreme humidity can mask canopy temperature differences with respect to ambient temperature, adding errors to canopy
temperature-based stress indicators.
相似文献
| Sreekala G. BajwaEmail: |
5.
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
6.
咸水灌溉对土壤水热盐变化及棉花产量和品质的影响 总被引：5，自引：0，他引：5
为了充分利用咸水资源,采用田间对比试验,研究了1、3、5、7 g/L等4个矿化度咸水(分别用S1、S2、S3、S4表示)灌溉对棉田土壤水热盐变化特征及棉花长势、产量和纤维品质的影响。结果表明,棉花生育期内各处理0~40 cm土层土壤含水率及地下5 cm处土壤温度总体上都随着灌溉水矿化度的增加而增大,但差异不大;处理间土壤电导率差异明显,灌溉水矿化度愈高,土壤电导率愈大,棉花生育期结束后,降雨对各处理盐分的淋洗率介于29.40%~40.40%。土壤水分和盐分剖面分布受制于土壤质地、降雨和棉花蒸发蒸腾耗水;干旱时期,土壤干燥,盐分表聚,湿润时期与之相反。棉花成苗率、株高、单株最大叶面积和霜前花率均随着灌溉水矿化度的增加而降低,籽棉产量从大到小依次为S2、S1、S3和S4,其中,S4与S1处理间的差异达显著水平。咸水灌溉通过改变马克隆值对纤维品质产生了负面影响,尤其是S4处理。研究结果可为丰富棉花咸水灌溉技术体系提供理论支撑。 相似文献
7.
The effect of partial wetting of the root zone on yield and water use efficiency in a drip-and sprinkler-irrigated mature grapefruit grove 总被引：4，自引：0，他引：4
H. Bielorai 《Irrigation Science》1982,3(2):89-100
Summary The effect of partial wetting of the root zone on yield and water use efficiency in a drip- and sprinkler-irrigated mature grapefruit grove was tested in a long-term experiment from 1976 to 1979. Three different percentages of the surface soil areas ( 30%, 40% and 70%) were wetted by the use of single and double drip laterals and sprinklers, respectively. Irrigation frequencies were 3 and 7 days for the drip treatments and 14 and 21 days for the sprinkler-irrigated plots.Two amounts of water, 80% and 100% of the total seasonal water application as previously determined from the soil moisture depletion data (ca. 630 and 800 mm), were applied at the different irrigation intervals for the drip- and sprinkler-irrigated treatments during the irrigation season (April–November). Soil moisture and salinity patterns were determined by the neutron scattering method and by gravimetric sampling. The partition of water extraction from the wet and dry zones in the drip-irrigated treatments was determined. About 86% of the total amount of water depletion was from the wet zone and 14% from the dry zone. Percolation losses in the irrigated treatments receiving 80% of the total seasonal water application decreased as compared with the 100% irrigated plots. Salts accumulated during the irrigation season were leached out by the winter rainfall.The effect of the reduction of irrigation application amount, first introduced in 1976, on the grapefruit yield was cumulative. The average yield (for the three years 1977, 1978, 1979) in the 80%, drip-irrigated plots at 3-day intervals, was 89 t/ha, compared with 98 t/ha in the 100% irrigated plots. The average yields obtained in the sprinkler and trickle irrigation treatments receiving 100% of the water application was 84 t/ha and 100 t/ha, respectively. Yield reductions in the plots receiving reduced water application of 80% were 11% for the drip treatments and 13% for the sprinkler treatment; the extent of the yield reduction varied according to the time interval between irrigations. The fruit quality was up to the required standards in all treatments. Water use efficiency was greater in the drip-irrigated plots than in the sprinkled ones, and also greater in the plots given the reduced water applications (80% of the maximum seasonal amount of the irrigation water applied), as compared with plots receiving the full amount of irrigation.Contribution from the Agricultural Research Organization, The Volcani Center, P.O.B. 6, Bet Dagan 50–250, Israel. No. 175-E, 1981 series 相似文献
8.
冬小麦冠气温差及其相关影响因素关系研究 总被引：7，自引：0，他引：7
在冬小麦主要生育期(2002年的4月初到5月底),对3个不同水分处理测定了冠层温度、气温以及土壤含水率和叶面积指数,并进一步计算了冠气温差并分析了冠气温差与土壤含水率和叶面积指数间的关系。结果表明:不同的灌溉措施对冠气温差的影响是有差异的;中午14:00左右在H2高度处(冠层之上)的冠气温差能反映作物的水分特征,可以用此时刻的实验结果来检验遥感数据反演冠气温差的精度;在60～80cm土层的土壤体积含水率能较好地反映中午14:00冠层之上冬小麦冠气温差的变化情况,不同水分处理二者的相关系数(R2)分别为0.60361(节水灌溉),0.95668(充分灌溉),0.84597(不灌溉);不同水分处理下的冬小麦主要生育期的叶面积指数与冠气温差也有一定的相关性,冠层之上二者的相关系数分别为:0.76082(节水灌溉),0.40548(充分灌溉),0.99499(不灌溉),这为区域上遥感反演作物冠气温差来监测土壤含水率及作物估产提供了依据。 相似文献
9.
Relationships between available soil water and indicators of plant water status of sweet sorghum to be applied in irrigation scheduling 总被引：3，自引：0，他引：3
Optimal crop production depends greatly on available soil water, and it is therefore important to know when and how much
to irrigate in order to attain agronomic potential. In this work, plant indicators are used to assess water stress. These
are compared with available soil water to find the critical point for irrigation scheduling of sweet sorghum. The experimental
trial was carried out in Bečej, in the Vojvodina region, on a sweet sorghum crop, grown in moderate climatic conditions on
a well-drained, deep chernozemolic meadow soil. Plant indicators tested were predawn and midday leaf water potential and crop
and air temperature difference. All the methods were sensitive to water deficit in plants, but not all can be used for irrigation
scheduling. The predawn leaf water potential was the most reliable parameter among those tested due to its relative independence
from weather conditions and a valid indicator of plant water status. This was not the case with canopy-air temperature difference.
The predawn leaf water potential corelation with available soil water indicates that the threshold value for irrigation scheduling
of sweet sorghum is when the former has decreased to –0.45 MPa. This corresponds to a soil water depletion to about 10% of
available water in the active root zone. The canopy-air temperature difference was sufficiently sensitive to indicate the
onset of mild plant water stress, although it showed a certain threshold value when water shortage appeared, which occurred
when the air and canopy temperature were the same.
Received: 9 April 1996 相似文献
10.
Kamal H. Amer 《Agricultural Water Management》2010,97(10):1553-1206
Non-uniformity of water distribution under irrigation system creates both deficit and surplus irrigation areas. Water salinity can be hazard on crop production; however, there is little information on the interaction of irrigation and salinity conditions on corn (Zea Mays) growth and production. This study evaluated the effect of salinity and irrigation levels on growth and yield of corn grown in the arid area of Egypt. A field experiment was conducted using corn grown in northern Egypt at Quesina, Menofia in 2009 summer season to evaluate amount of water applied, salinity hazard and their interactions. Three salinity levels and five irrigation treatments were arranged in a randomized split-plot design with salinity treatments as main plots and irrigation rates within salinity treatments. Salinity treatments were to apply fresh water (0.89 dS m−1), saline water (4.73 dS m−1), or mixing fresh plus saline water (2.81 dS m−1). Irrigation treatments were a ratio of crop evapotranspiration (ET) as: 0.6ET, 0.8ET, 1.0ET, 1.2ET, and 1.4ET. In well-watered conditions (1.0ET), seasonal water usable by corn was 453, 423, and 380 mm for 0.89EC, 2.81EC and 4.73EC over the 122-day growing season, respectively. Soil salt accumulation was significantly increased by either irrigation salinity increase or amount decrease. But, soil infiltration was significantly decreased by either salinity level or its interaction with irrigation amount. Leaf temperature, transpiration rate, and stomata resistance were significantly affected by both irrigation and salinity levels with interaction. Leaf area index, harvest index, and yield were the greatest when fresh and adequate irrigation was applied. Grain yield was significantly affected in a linear relationship (r2 ≥ 0.95) by either irrigation or salinity conditions with no interaction. An optimal irrigation scheduling was statistically developed based on crop response for a given salinity level to extrapolate data from the small experiment (uniform condition) to big field (non-uniformity condition) under the experiment constraints. 相似文献
11.
《Agricultural Water Management》1996,30(1):77-90
This research was initiated to examine water use of differentially irrigated sorghum (Sorghum bicolor (L.) Moench) and to evaluate the plant water stress using canopy temperature measurements.Field experiments were conducted for 3 years characterised by different weather conditions at Montpellier, France. The crop was subjected to 14 differentially irrigated treatments which included, each year, a full irrigated and a dry treatment. Plant and soil measurements monitored during the crop cycle included soil water content, leaf water potential, and canopy temperature.Mid-day measurement of crop canopy temperature (Tc) /air temperature (Ta) difference reached a maximum of 7°C in the dry treatment and was maintained close to 0°C in full irrigated treatment. The relationships between (Tc-Ta) and vapour pressure deficit (VPD) commonly referred to as ‘baseline’ in the determination of crop water stress indicator (CWSI) were examined on function of wind speed and global solar radiation. Three approaches of estimating CWSI were compared. Summations of stress-degree-day (SDD) and temperature-stress-day (TSD) were well related to both relative evapotranspiration and yield (r2 > 0.70). 相似文献
12.
《Agricultural Water Management》2006,79(3):209-224
Iran's groundwater resources have been over-exploited, often at the expense of deteriorating water and land quality, and there is limited room for expanding its irrigation agriculture. Thus, the possible use of Caspian Sea water, whose salinity is well below that of open seas, for supplementary irrigation has some appeal. The impact of irrigation with diluted Caspian Sea water on the growth and yield of barley and on the characteristics of soil was investigated in field plots and in pot experiments during the 2001–2002 growing season. Three irrigation regimes of well water alone (I0); Caspian Sea water diluted with well water and used at stem elongation (I1); and the same diluted sea water used at ear formation (I2). A rainfed treatment (Ir) was also added to the field experiments. The results of both pot and field experiments show that a 1:1 mixture of Caspian Sea and well water can be used for irrigation without a significant reduction in the growth and yield of barley, provided that it is not applied earlier than the time of ear formation. This would amount to a significantly reduced demand on the limited ground water resources of the region for agricultural use. However, when this mixture was applied at the earlier time of stem elongation, significant yield reduction occurred. All other growth components of barley plants were also adversely affected by this early application of diluted sea water. Soil analysis after harvest showed that the electrical conductivity of the saturation extract had increased significantly in both diluted sea water treatments. This may suggest that the mixing of sea and ground waters at the rates used in these experiments may not be sustainable over a long period of time and soil salinization may occur unless soils are of light texture and sufficient good quality fresh water or winter rain is available to lower the salinity of soil between successive crops. No significant interaction between irrigation salinity and fertiliser treatments was observed. 相似文献
13.
Using radiation thermography and thermometry to evaluate crop water stress in soybean and cotton 总被引：2，自引：0，他引：2
S.A. O'Shaughnessy S.R. EvettP.D. Colaizzi T.A. Howell 《Agricultural Water Management》2011,98(10):1523-1535
The use of digital infrared thermography and thermometry to investigate early crop water stress offers a producer improved management tools to avoid yield declines or to deal with variability in crop water status. This study used canopy temperature data to investigate whether an empirical crop water stress index could be used to monitor spatial and temporal crop water stress. Different irrigation treatment amounts (100%, 67%, 33%, and 0% of full replenishment of soil water to field capacity to a depth of 1.5 m) were applied by a center pivot system to soybean (Glycine max L.) in 2004 and 2005, and to cotton (Gossypium hirsutum L.) in 2007 and 2008. Canopy temperature data from infrared thermography were used to benchmark the relationship between an empirical crop water stress index (CWSIe) and leaf water potential (ΨL) across a block of eight treatment plots (of two replications). There was a significant negative linear correlation between midday ΨL measurements and the CWSIe after soil water differences due to irrigation treatments were well established and during the absence of heavy rainfall. Average seasonal CWSIe values calculated for each plot from temperature measurements made by infrared thermometer thermocouples mounted on a center pivot lateral were inversely related to crop water use with r2 values >0.89 and 0.55 for soybean and cotton, respectively. There was also a significant inverse relationship between the CWSIe and soybean yields in 2004 (r2 = 0.88) and 2005 (r2 = 0.83), and cotton in 2007 (r2 = 0.78). The correlations were not significant in 2008 for cotton. Contour plots of the CWSIe may be used as maps to indicate the spatial variability of within-field crop water stress. These maps may be useful for irrigation scheduling or identifying areas within a field where water stress may impact crop water use and yield. 相似文献
14.
Debashis Chakraborty Shantha Nagarajan V.K. Gupta R.N. Garg A. Sarkar K.S. Sundara Sarma 《Agricultural Water Management》2008,95(12):1323-1334
Mulching is one of the important agronomic practices in conserving the soil moisture and modifying the soil physical environment. Wheat, the second most important cereal crop in India, is sensitive to soil moisture stress. Field experiments were conducted during winter seasons of 2004-2005 and 2005-2006 in a sandy loam soil to evaluate the soil and plant water status in wheat under synthetic (transparent and black polyethylene) and organic (rice husk) mulches with limited irrigation and compared with adequate irrigation with no mulch (conventional practices by the farmers). Though all the mulch treatments improved the soil moisture status, rice husk was found to be superior in maintaining optimum soil moisture condition for crop use. The residual soil moisture was also minimum, indicating effective utilization of moisture by the crop under RH. The plant water status, as evaluated by relative water content and leaf water potential were favourable under RH. Specific leaf weight, root length density and dry biomass were also greater in this treatment. Optimum soil and canopy thermal environment of wheat with limited fluctuations were observed under RH, even during dry periods. This produced comparable yield with less water use, enhancing the water use efficiency. Therefore, it may be concluded that under limited irrigation condition, RH mulching will be beneficial for wheat as it is able to maintain better soil and plant water status, leading to higher grain yield and enhanced water use efficiency. 相似文献
15.
咸水灌溉对棉花耗水特性和水分利用效率的影响 总被引：4，自引：0，他引：4
采用田间对比试验,连续3 a研究了1、3、5、7 g/L 4个矿化度咸水(记作S1、S2、S3、S4)灌溉对棉田土壤水盐、土壤蒸发、棉花阶段耗水量、籽棉产量和水分利用效率的影响。结果表明,棉花生育期内根系层土壤含水率和电导率有随灌溉水矿化度的增加而增大的趋势,土壤电导率增加尤为明显;年际间,各处理土壤含水率和电导率差异非常大,经过连续3 a灌溉,根系层土壤电导率均未逐年增加。S3和S4处理的平均土壤蒸发强度大于S1处理,S2与S1处理间的差异很小;7 g/L以下咸水灌溉对棉花耗水过程产生了一定影响,但对总耗水量影响并不明显。3 a的平均籽棉产量和水分利用效率由大到小顺序均为:S2、S1、S3、S4,S2比S1处理增产2.43%,水分利用效率增加1.15%,S3和S4比S1处理减产1.67%和8.88%,水分利用效率降低0.25%和7.31%,其中,S2和S3与S1处理间差异不显著,S4处理产量和水分利用效率降低显著。 相似文献
16.
利用18个不同水分处理的大田试验探讨了调亏灌溉对旱坡地浓香型烤烟农艺性状、经济特性及耗水规律的影响。结果显示,伸根期调亏处理后复水补偿效果显著,其轻旱处理(60%~70%FC)有利于获得较高产量和水分效率;旺长期亏水后复水补偿效果有限,此时的亏水对烤烟产量和质量负面影响显著,需维持正常水分处理(70%~80%FC);成熟期轻旱处理(60%~70%FC)有利于提高上等烟比例;伸根期、成熟期都为轻旱处理(60%~70%FC)的可以在不减产情况下获得较高的水分效率和上等烟比例。产量、上等烟比例和水分效率与耗水量的关系为具有极大值的二次函数,产量的极值偏后于水分效率和上等烟比例的极值。利用18个试验数据所建立的水分生产函数符合烤烟生长规律,能为该地区水利工程规模的确定及产量的预测提供依据。 相似文献
17.
M.V.K. Sivakumar N. Seetharama K.S. Gill R.C. Sachan 《Agricultural Water Management》1981,3(4):279-289
The response of sorghum (Sorghum bicolor L.) to moisture stress during the post-rainy season was studied at ICRISAT research center on a medium deep Alfisol using a line source sprinkler irrigation system. Changes in soil moisture content, stomatal conductance, leaf-water potential and leaf temperature of sorghum as a function of distance away from the line source sprinkler system were monitored throughout the season. Use of the line source technique facilitated the imposition of a range of moisture stress levels as indicated by increased water use by sorghum closer to the line source compared with the crop farther away from the line source. Canopy response measured in terms of stomatal conductance, leaf-water potential, and leaf temperature clearly reflected the gradient in moisture stress perpendicular to the line source. 相似文献
18.
Summary Since the development of commercial versions of infrared sensors, they have been increasingly used to determine canopy temperature and schedule irrigations. However, some shortcomings of the technique have been identified, among them the sensitivity of canopy temperature measurements to weather fluctuations. Based on field and computer simulated data, an analysis of the suitability of crop water stress indices (CWSI's) developed from canopy temperature under variable weather conditions was done. Important day to day fluctuations of CWSI values determined using an empirical baseline (empirical CWSI) appeared common for nonstressed crops, particularly under low vapor pressure deficit conditions. These fluctuations generate uncertainty in the use of this empirical index to determine needs for irrigation. The use of an improved index (theoretical CWSI) requiring measurements of net radiation, soil heat flux and wind speed, and estimates of aerodynamic and canopy resistances reduced but did not eliminate these fluctuations. Results using a simulation model showed that the empirical CWSI provided late indication of irrigation needs, after some water stress has developed, which may limit its application for crops sensitive to water stress. These simulations also indicated that the theoretical CWSI was able to track the development of water stress and provide reasonable indication of irrigation needs. However, this result may not be fully realized in field applications where the determination of CWSI may be affected by various sources of variability which are not accounted for by the model. 相似文献
19.
D.A. Bucks F.S. Nakayama O.F. French W.W. Legard W.L. Alexander 《Agricultural Water Management》1985,10(1):61-79
Natural rubber is a critical agricultural material, and guayule (Parthenium argentatum Gray) is the most promising domestic, agricultural source. A study on guayule was initiated to provide information on the water requirements and plant water stress behavior for this new perennial crop. Measured evapotranspiration averaged 3000, 2410, 2040, 1720, 1470 and 1520 mm, from May 1981 to December 1982, in decreasing order of water applications on the six irrigation treatments from the wettest to the driest. These evapotranspiration values indicated that the water use by guayule can be higher than many former estimates for an arid-type crop. Plant canopy temperatures also showed a progressive increase in plant water stress as irrigation water amounts decreased. The two-fold decrease in evapotranspiration from the wet to dry treatments corresponded to a four-fold increase in plant water stress indices based on remote infrared thermometer measurements. Both the concepts of stress degree days and crop water stress index, evaluated over the entire growing cycle, correlated well with the measured evapotranspiration. Even though the guayule plant can withstand long periods of drought, moisture stress will occur within a relatively short period of time after an irrigation for the guayule crop. 相似文献