共查询到19条相似文献，搜索用时 997 毫秒
1.
夏玉米茎流和茎直径变化规律及其关系分析 总被引：3，自引：0，他引：3
通过对夏玉米生育期的茎直径微变化和茎流变化过程的监测,分析了茎直径微变化、茎流随土壤含水率和气象因子的变化规律,并对茎流与茎直径微变化之间的关系进行了分析。结果表明,茎直径微变化的日变化过程呈现明显的昼夜变化规律,白天收缩,夜间复原;茎直径日最大收缩量随含水量的升高而降低,可将其作为诊断作物水分状况的一个指标。茎流同样呈现明显的昼夜变化规律,白天茎流逐渐增大,在13:30左右达到最大值,然后减小。茎直径微变化、茎流的变化均受到太阳辐射、饱和水汽压差、空气温度、风速的影响。茎直径微变化与主要气象因子均呈负相关,茎流与其均为正相关关系。茎直径微变化与茎流之间呈负相关关系,且相关性很好。 相似文献
2.
为探明滴灌条件下温室番茄植株茎流速率变化规律及其影响因素,本文采用Dynamax公司开发的包裹式茎流计观测日光温室番茄植株的茎流变化,研究茎流速率的变化规律及茎流速率监测结果的标准化处理技术,探索植株茎流与气象因子的相互关系,分析水分胁迫对番茄植株茎流速率的影响。研究表明,采用单位叶面积上的茎流速率表征茎流变化规律可在一定程度上降低因探头安装位置不同对监测结果的影响;在充分供水条件下,影响番茄植株茎流速率的主要因子是太阳辐射和饱和水气压差,番茄植株的日茎流速率与太阳辐射呈线性关系,与饱和差呈对数关系（R2＞0.90,P＜0.01）;土壤水分状况会明显影响番茄植株茎流状况,茎流速率随水分胁迫加剧而骤减。研究结果证明番茄植株茎流速率经标准化处理后可以真实的反映植株蒸腾规律。 相似文献
3.
气象因子对滴灌条件下核桃树茎流速率的影响 总被引：1，自引：0，他引：1
《节水灌溉》2015,(7)
通过田间试验,利用SF-G液流传感器研究滴灌核桃树茎流速率变化规律及其与气象因子间的关系。结果表明:茎流速率的日变化在16∶00左右达到峰值;全生育期中,茎流速率先变大后减小,最大茎流速率出现在核桃油脂转化期;晴天条件下茎流速率日变化呈单峰曲线,先增后减,多云天气条件下茎流速率的日变化呈多峰曲线;核桃树茎流速率与太阳辐射和大气温度具有较好的正相关关系,与大气相对湿度呈负相关;建立滴灌核桃树茎流速率与气象因子之间的回归方程。 相似文献
4.
干旱区香梨茎流特征及其与环境因子的关系 总被引：2，自引：0，他引：2
通过对新疆巴州灌溉试验站香梨地在滴灌条件下香梨树茎流速率和环境因子的监测,分析了香梨树茎流速率连日变化和日变化趋势以及茎流速率和环境因子的关系,分析结果显示:香梨树茎流速率表现出明显的昼夜变化规律,茎流在早8∶00时开始启动,而后迅速上升,在12∶00-17∶00达到最大值,然后逐渐降至最低值,最大值约在17∶00,值为3.45L/h。茎流速率连日变化表现出明显的多峰变化规律,从早8∶00时开始迅速上升且在12∶00左右达到最大值,之后保持较大茎流速率的时间较长,基本保持在5h左右,其昼夜差值约3.3L/h。香梨树茎流速率与各环境因子的相关性由高到低依次为:太阳辐射空气温度相对湿度风速,其相关系数分别为0.918、0.779、-0.587和0.186。其中茎流速率与太阳辐射、空气温度和风速呈正相关,而与相对湿度呈负相关,回归方程为Y=-0.776+0.003 X1+0.064 X2。 相似文献
5.
《中国农村水利水电》2017,(3)
通过在新疆南疆田间试验,利用SF-G液流传感器和CIRAS-3便携式光合作用仪研究滴灌核桃树茎流速率变化规律及其与光合参数间的关系。结果表明:茎流速率的日变化在晴天条件下呈双峰曲线,峰值在13∶30与17∶30左右达到,多云天气条件下茎流速率的日变化呈多峰曲线;核桃树茎流速率与太阳辐射和大气温度具有显著性正相关,与大气相对湿度呈显著性负相关;核桃树茎流速率变化与光和参数Gs、Tleaf、WUE呈极显著性正相关,与RH、Ci呈极显著性负相关,与Pn、Tr显著性相关。 相似文献
6.
为了深入了解茶花茎流特征这一重要生理指标,对滇山茶茎流及同期气象因子进行了1年的连续观测,利用相关分析法和错位对比法研究滇山茶茎流与气象因子的关系和茎流对气象因子的滞后情况.结果表明:茶花在夜间存在茎流现象,在11:00-17:30期间存在"午休"现象,夏季茶花茎流约6:15启动,8:00达到第1个峰值,春秋次之,冬季最晚.滇山茶茎流通量曲线在晴天呈现双峰型,茎流与温度和相对湿度相关性最好,雨天茎流通量曲线呈现多峰型,茎流与温湿度相关性较好,晴天和雨天茎流与气象因子存在时滞现象;得出结论:日出时间的季节性差异,可能导致夏季茎流启动最早,冬季最晚;滇山茶茎流形态曲线在晴天和雨天存在差异,这种差异可能是由于晴天和雨天的太阳辐射、相对湿度和空气温度的差异所导致;不同强度的太阳辐射对滇山茶的茎流具有不同的影响,晴天和雨天下空气温度、相对湿度与茎流表现出较好的相关性;茶花茎流与太阳辐射存在明显的时滞现象,结合其他气象因子对茎流的影响,建立了茎流的多元回归模型. 相似文献
7.
8.
根据避雨番茄筒栽试验结果,分析了不同旱渍胁迫组合及不同天气条件下的茎流速率日变化,采用通径分析和灰色关联分析的方法,计算了以太阳辐射、气温、相对湿度和土壤含水率4种环境影响指标为自变量对番茄茎流速率的相关系数、决定系数及灰色关联度.结果表明:不同天气下番茄茎流速率日变化规律差异显著,晴天下呈现峰值在正午的单峰型曲线,多云下呈现在10:00和14:00左右达到峰值的双峰型曲线,阴雨下茎流速率较小且波动不大;相同环境下不同旱渍组合的茎流速率日变化曲线可以反映水分的亏缺和渍害程度,轻度亏缺能够抵抗渍水的迫害,增大茎流速率,但是亏缺程度超过一定范围会显著降低茎流速率;通径分析与灰色关联分析的结果基本一致,影响茎流速率最大的是太阳辐射,决定系数达到0.91. 相似文献
9.
《中国农村水利水电》2020,(6)
为探究葡萄着色成熟期在不同施肥处理下茎流速率变化规律和与气象因子的关系,以"户太8号"葡萄为研究对象,对其着色成熟期进行了茎流速率和气象因子的同步监测。结果表明,葡萄茎流呈明显的昼夜变化,日变化曲线呈"几"字形,不同施肥处理下茎流速率为:中肥低肥高肥;阴天时茎流启动和峰值迟于晴天,不同天气下茎流速率与净辐射、饱和水汽压差和气温呈正相关,而与相对湿度呈负相关;施肥量不同会改变茎流速率对气象因子的响应,净辐射是不同处理下茎流速率的主要气象影响因子,决定系数均在0.791以上。 相似文献
10.
日光温室负压自动灌溉下番茄蒸腾规律研究 总被引：3，自引：0，他引：3
针对农业生产中蔬菜栽培灌溉费水费时的现状,采用一种自制负压自动灌溉系统,将供水压力设定在负值,利用土壤自动吸水的特性,达到自动灌溉和节水的效果.在此系统灌溉下采用茎热平衡技术测定番茄植株的茎流规律,分析了茎流变化规律与环境因子之间的关系,同时分析了番茄植株不同部位茎流差异以及剪叶对番茄植株茎流的影响.结果表明,在设定灌溉系统负压为60 hPa下,温室土壤含水量基本控制在阴天20.19%、晴天18.75%左右;茎流数据表明番茄植株蒸腾与太阳辐射值呈显著正相关,适当遮阴降温可以减少植株蒸腾.实验也进一步证明了叶片是植株蒸腾的主要器官,植株底层叶片蒸腾速率相对较微弱. 相似文献
11.
12.
13.
《Agricultural Water Management》1997,33(1):63-78
The oft-touted reason for the efficiency of drip irrigation is that roots can preferentially take up water from localised zones of water availability. Here we provide definitive evidence of this phenomenon. The heat-pulse technique was used to monitor rates of sap flow in the stem and in two large surface roots of a 14 year old apple tree (Malus domestica Borkh. cv. Braeburn). The aim was to determine the ability of an apple tree to modify its pattern of root water uptake in response to local changes in soil water content. We monitored the water status of the soil close to the instrumented roots by using time domain reflectometry (TDR) to measure the soil's volumetric water content, θ, and by using ceramic-tipped tensiometers to measure the soil's matric pressure head, h. A variation in soil water content surrounding the two roots was achieved by supplying a single localised irrigation to just one root, while the other root remained unwatered. Sap flow in the wetted root increased straight away by 50% following this drip irrigation which wetted the soil over a zone of approximately 0.6 m in diameter and 0.25 m in depth. Sap flow in the wetted root remained elevated for a period of about 10 days, that is until most of the irrigation water had been consumed. A comparative study of localised and uniform irrigation was then made. Following irrigation over the full root zone no further change in sap flow in the previously wetted root was observed when referenced to the corresponding sap flow measured in the stem of the apple tree. However sap flow in the previously dry root responded to subsequent irrigations by increasing its flow rate by almost 50%. These results show that apple roots have the capacity to transfer water from local wet areas at much higher rates than normally occurs when the entire root zone is supplied with water. They are also able to shift rapidly their pattern of uptake and begin to extract water preferentially from those regions where it is more freely available. Such an ability supports the use of drip irrigation for the efficient use of scarce water resources. We conclude that the soil-to-root pathway represents a major resistance to water uptake by apple, even at the relatively high soil water pressure heads developed during parts of this experiment, during which the tree was not even under any stress. 相似文献
14.
植物茎干液流量可表征其蒸腾耗水量,反映植被水分传输状况,可用于计算植被生态需水量。以玛纳斯河流域古尔班通古特沙漠南缘典型荒漠植被梭梭、柽柳为研究对象,通过数据监测,研究植被茎干液流及光合蒸腾特性,分析气象因子及土壤含水率对茎干液流的影响。结果表明：（1）梭梭、柽柳茎干液流速率呈明显的昼夜变化规律,白天液流速率远高于夜间。（2）梭梭的净光合速率日变化模式为双峰型;柽柳为单峰型。（3）梭梭蒸腾速率的日变化有明显上升和下降过程,柽柳趋势不明显,呈小幅震荡。（4）液流速率变化与相对空气湿度呈负相关,空气湿度高时液流速率低;气温、总辐射与液流速率的变化趋势基本一致,液流速率随着气温或总辐射的增强而增大。（5）随着土壤含水率降低,液流速率降低。 相似文献
15.
《灌溉排水学报》2019,(8)
【目的】精准模拟温室梨枣树液流量。【方法】基于粒子群算法(PSO)优化的极限学习机(ELM)模型,选取了西北旱区的温室梨枣树逐日气象资料和梨枣树生理指标作为输入参数,构建了16种不同参数组合的PSO-ELM模型对梨枣树各生育期的液流量进行模拟,并与实测液流值进行对比。【结果】PSO-ELM模型能通过较少的输入参数实现梨枣树液流量的高精度模拟:全生育期液流量模拟中M_2模型(输入参数为叶面积指数、平均气温、实际水汽压、平均相对湿度、净辐射和风速)、M_4模型(输入参数为叶面积指数、平均气温、实际水汽压、平均相对湿度、风速和土壤含水率)及M_(12)模型(输入参数为叶面积指数、实际水汽压和平均相对湿度)的MAE、MBE、R~2、MRE及RRMSE范围分别为1.467 6～1.598 6 mm/d、-0.000 9～0 mm/d、0.370 6～0.435 4、0.177 2～0.185 5及0.202 6～0.214 0,GPI排名分别1、2和5,其中M_(12)的输入参数较少且模拟精度较高,其MAE、MBE、R~2、MRE、RRMSE分别为1.598 6 mm/d、0、0.370 6、0.185 5、0.214 0;萌芽展叶期、开花坐果期、果实膨大期和果实成熟期液流量模拟结果分别以M_(Ⅰ-11)模型(输入参数为净辐射、叶面积指数和实际水汽压)、M_(Ⅱ-15)模型(输入参数为实际水汽压和平均气温)、M_(Ⅲ-11)模型(输入参数为平均相对湿度、叶面积指数和土壤含水率)和M_(Ⅳ-12)模型(输入参数为叶面积指数、净辐射和平均气温)模拟精度较高,GPI排名分别为8、2、4和5。【结论】PSO-ELM模型模拟温室梨枣树不同生育期液流量均具有较高的精度,可作为温室梨枣树液流量估算的新方法。 相似文献
16.
17.
《Agricultural Water Management》2001,51(2):99-123
The compensation heat-pulse method for measuring sap flow is tested here in olive trees (Olea europaea L.). We describe a rigorous three-way examination of the robustness of the technique for this species, and examine the potential of the technique for an automatic control of the irrigation system. Two tests were carried out using heat-pulse gear inserted into the stem of 12-year-old ‘Manzanilla’ olive trees. One test used forced-flow through a stem section, and the other involved measured water uptake by an excised tree. The measured sap flow in these two tests was in agreement with calculations from heat-pulse velocities when using a standard ‘wound correction’ to account for the presence of the probes and the disruption to the sap flow. Thus, this technique for monitoring transpiration can, we feel, be used with confidence in olives.The third experiment was carried out in the field, where we analysed sap flow data from two 29-year-old olive trees — one tree was under regular drip irrigation and the other was from dry-farming conditions. We use measurements of sap flow in the trunk to examine the hydraulic functioning of the tree, and to explore some diagnostics of water stress. Our heat-pulse measurements in the irrigated olive tree exhibited a profile of sap flow that was weighted towards the outer xylem of the tree trunk while the water-stressed trees in the field showed a profile of sap flow weighted towards the centre of the trunk. The loss of hydraulic functioning in the outermost section of the vascular system, as a result of water stress, we consider to be due both to stomatal control and to embolisms in the xylem vessels.The fourth experiment was also carried out in the field, in which sap flow measurements were made at three locations in the trunk as well as in two roots of another 29-year-old olive tree. The soil explored by each root, on opposite sides of the trunk, was differentially wetted by separate irrigation of each side. Our data showed that the surface roots were able to absorb water immediately after wetting, despite a reasonably prolonged period of moderate drought. Root activity quickly shifted to the regions where the soil had been wetted. A root in dry soil exhibited no flow at night, whereas sap flows of about 0.02 l h−1 were measured around midnight in the root drawing water from the wetter soil. Our observations suggest that the hydraulic behaviour of the trunk and surface roots might be used as a diagnostic of the onset, or severity, of water stress. Here there is not the imperative to replicate, for the prime goal is not transpiration estimation. Rather interpretation of the diurnal dynamics is used to infer the onset, or severity of water stress.The compensation heat-pulse seems a suitable technique for automatically controlling the irrigation system of olives, and probably other trees, based either on the estimation of the short-time dynamics of transpiration, or on changes in the hydraulic behaviour of the trees. 相似文献
18.
土壤质地对机采棉土壤水热状况及生长发育影响研究 总被引：2，自引：0，他引：2
为了进一步明确玛纳斯河流域土壤质地对机采棉水热状况及生长发育的影响,通过测坑试验,对3种不同土壤质地(壤土、砂土、黏土)下的土壤温度、土壤含水率、机采棉、株高、叶面积及产量进行了对比分析。结果表明,不同土壤质地条件下地温日变化及不同时间段温度增量表现为:砂土黏土壤土;不同土壤质地条件下0~60 cm和0~100 cm土层土壤质量含水率大小顺序为:黏土壤土砂土;不同土壤质地下机采棉的生长及产量均表现为壤土黏土砂土。研究认为壤土质地种植机采棉,提高了其生育前期的土壤温度,有效保持了土壤水分,有利于其生长发育。因此,为了提高水分利用效率及产量,建议玛纳斯河流域应增加壤土质地种植机采棉的比例。 相似文献
19.
Because of the increasing worldwide shortage of freshwater and costs of irrigation, a new plant-based irrigation scheduling
method is proposed. In this method, two real-time plant-based measurements (sap flow and stem diameter variations) are used
in combination with a mathematical water flow and storage model in order to predict the stem water potential. The amount of
required irrigation water is derived from a time integration of the sap flow profile, while the timing of the irrigation is
controlled based on a reference value for the predicted stem water potential. This reference value is derived from the relationship
between midday values of maximum photosynthesis rates and stem water potential. Since modelling is an important part of the
proposed methodology, a thorough mathematical analysis (identifiability analysis) of the model was performed. This analysis
showed that an initial (offline) model calibration was needed based on measurements of sap flow, stem diameter variation and
stem water potential. Regarding irrigation scheduling, however, only sap flow and stem diameter variation measurements are
needed for online simulation and daily model calibration. Model calibration is performed using a moving window of 4 days of
past data of stem diameter variations. The research tool STACI (Software Tool for Automatic Control of Irrigation) was used
to optimally combine the continuous measurements, the mathematical modelling and the real-time irrigation scheduling. The
new methodology was successfully tested in a pilot-scale setup with young potted apple trees (Malus domestica Borkh) and its performance was critically evaluated. 相似文献