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排序方式: 共有423条查询结果,搜索用时 31 毫秒
91.
92.
[目的]研究南疆棉花叶片水分利用效率的日动态变化。[方法]在新疆巴州水管处重点灌溉试验站利用LCpro+全自动便携式光合仪对试验田内棉花光合作用进行系统监测,同时将数据转化为棉叶水分利用效率(WUE)并进行动态特征分析。[结果]在日内,棉叶光合速率变化呈双峰型曲线,蒸腾速率的变化因棉叶温度差异呈双峰型或单峰型曲线;光合和蒸腾日内动态都具有不对称性,且二者动态反向;棉叶水分利用效率的日动态呈双峰型曲线,上午棉叶水分利用效率高于下午,且在不同叶位之间差异较大,自主茎第2叶向下依次减小;花铃期主茎不同叶位之间的水分利用效率变幅大于蕾期。[结论]该研究为提高棉花叶片水分利用效率提供了科学依据。 相似文献
93.
Noah Adamtey Olufunke Cofie K.G. Ofosu-Budu J. Ofosu-Anim K.B. Laryea Dionys Forster 《Agricultural Water Management》2010,97(7):995-1005
Population growth, urban expansion and economic development are increasing competition for water use between agriculture and other users. In addition, the high rate of soil degradation and declining soil moisture in the Sub-Saharan African Region have called for several crop production management and irrigation options to improve soil fertility, reduce water use by crops and produce ‘more crops per drop of water’. Notwithstanding this, considerable variations exist in the literature on water-use efficiency, WUEcwu (economic yield per water used) for maize (Zea mays L.) across climates and soil management practices. Different views have been expressed on the effect of different rates of nitrogen (N) application on transpiration efficiency, TE (biomass produced per unit of water transpired). The objectives of the study were to assess the effect of different rates of N-enriched municipal waste co-compost and its derivatives on TE, WUEcwu and yield of maize (Z. mays L.) in comparison to inorganic fertiliser. The greenhouse pot experiment was conducted in Accra, Ghana on a sandy loam soil (Ferric Lixisol) using a split plot design. The main plot treatments were soil (S), dewatered faecal sludge (DFS), municipal solid waste compost (C), co-compost from municipal solid waste and dewatered faecal sludge (Co), compost enriched with (NH4)2SO4 (EC), co-compost enriched with (NH4)2SO4 (ECO), (NH4)2SO4 and NPK15-15-15 + (NH4)2SO4. The sub-plot treatments were different rates of application of nitrogen fertiliser applied at the rate of 91, 150 and 210 kg N ha−1 respectively. Maize cv. Abelehii was grown in a poly bag filled with 15 kg soil. Eight plants per treatment were selected randomly and used for the collection of data on growth parameters forth-nightly. At physiological maturity two plants per treatment were also selected randomly from each treatment plot for yield data. The results showed that TE of maize (Z. mays) varied for the different treatments and these are 6.9 Pa in soil (S) alone to 8.6 Pa in ECO. Increase in N application rate increased TE at the vegetative phase for fast nutrient releasing fertilisers (DFS, ECO, EC, NPK + (NH4)2SO4, (NH4)2SO4) and at the reproductive phase for slow nutrient releasing fertilisers (C and CO). Water-use efficiency increased significantly as rate of N application increased. Treatment ECO improved crop WUEcwu and was 11% and 4 times higher than that for NPK + (NH4)2SO4 or soil alone; and 18-36% higher than those for DFS and CO. Treatment ECO used less amount of water to produce dry matter yield (DMY) and grain yield (GY) that was 5.2% and 12.6%, respectively, higher than NPK + (NH4)2SO4. Similarly, the DMY and GY for ECO was 8.9-18.5% and 23.4-34.7%, respectively, higher than DFS and CO. High nutrient (N and K) uptake, TE, and low leaf senescence accounts for 83% of the variations in DMY whereas WUEcwu accounts for 99% of the variations in GY. Thus, the study concluded that different sources of fertiliser increased TE and WUEcwu of maize differently as N application rate increases. 相似文献
94.
Whole-tree water balance and indicators for short-term drought stress in non-bearing ‘Barnea’ olives
Alon Ben-Gal Dilia Kool Gerardo E. van Halsema Ariel Yafe Ran Erel Isaac Zipori Simon Rüger Yafit Cohen Arnon Dag 《Agricultural Water Management》2010,98(1):124-133
Drainage-weighing lysimeters allowed monitoring of water balance components of non-bearing olive (Olea europaea cv Barnea) trees over a 3-month period including short-term events of controlled but severe water stress. The objective of the study was to evaluate a variety of soil and plant-based water status and drought stress monitoring methods on the basis of tree-scale evapotranspiration (ET). As the trees entered into and recovered from water stress, meteorological data, actual ET (ETa), soil water content and changes in leaf turgor pressure were continuously monitored. Additionally, midday measurements of stem water potential, stomatal conductance, canopy temperature, and quantum yield of PSII photochemistry were conducted. Diurnal (dawn to dusk) measurements of all the above were made hourly on days of maximum stress. Shoot elongation rate was measured for periods of stress and recovery. Quantum yield of PSII photochemistry, stomatal conductance, and stem water potential all successfully indicated reductions in whole-tree water consumption beginning at moderate stress levels. These measured parameters fully recovered to the levels of non-stressed trees soon after water application was renewed. Shoot elongation was reduced 25-30% for the 10-day period during and following drought and recovered thereafter to levels of non-stressed trees. Whole-tree ETa was reduced by as much as 20% even following full recovery of the leaf level parameters, suggesting reduced canopy size and growth due to the stress period. Non-destructive, continuous (turgor pressure) and remotely sensed (canopy temperature) methods showed promising potential for monitoring effects of water stress, in spite of technological and data interpretation challenges requiring further attention. 相似文献
95.
引种台湾桤木的蒸腾特性及其影响因子 总被引:7,自引:0,他引:7
采用L1—6400光合测定系统对引种2a生台湾桤木苗木的蒸腾作用及环境因子进行研究。结果表明:(1)在整个生长期,叶片蒸腾速率日变化均表现为宽大的单峰型曲线,以13∶00~15∶00时左右蒸腾速率最高,不同部位叶片在不同生长期峰值有所不同,属非蒸腾午休型植物;(2)蒸腾速率季节变化表现为单峰曲线,以7月为最高,整个生长期叶片平均蒸腾速率为3 116mmol·m-2·s-1~3 383mmol·m-2·s-1;(3)在光响应过程中,蒸腾速率的变化与光合有效辐射和气孔导度的变化密切相关;(4)光合有效辐射(Par)、气孔导度(Cond)、空气温度(Tair)和叶面水汽压亏缺(Vpdl)是影响蒸腾速率日变化的主要生理生态因子;以Par、Cond、Vpdl、Tair和相对湿度(RH)对蒸腾速率季节变化的直接作用为明显。 相似文献
96.
Grapevine cultivars are known to differ in their drought adaptation mechanisms, but there is little knowledge on how they behave when recovering after a drought event. The effects of increasing water deficit and recovery after rewatering were evaluated on four widely grown red grapevine cultivars native from different climates (Cabernet Sauvignon, Cs; Garnacha, syn. Grenache, Ga; Merlot, Me; and Tempranillo, Te) through the study of gas exchange (GE) measurements and transpiration decline curves (TDC). As a whole, Ga has proved to be the cultivar best adapted to water deficit, since it showed the highest water use efficiency (WUE) and the greatest water saving ability after leaf excision. Te, on the contrary showed the lowest values for those parameters under increasing stress, although when rewatered showed greater acclimation ability than Cs and Me, remarkably improving its behaviour. The two methodological approaches (GE and TDC) used at different water deficit levels and after rewatering, have complemented each other, allowing a better cultivar characterization than each method would had allowed itself. 相似文献
97.
98.
树木蒸腾耗水测算技术的比较研究 总被引:104,自引:13,他引:104
1989—1991年,分别在山东(I-69杨)与宁夏(合作杨)人工林中,用五种方法(整树容器法、热脉冲法、快速称重法、稳态气孔计法和微气象法)进行了蒸腾耗水的比较测定,结果表明:1.以整树容器法测定的单株日耗水量为100%,则水分饱和下快称法相应值为130%—140%;气孔计法值为291%;热脉冲法值为90.14%。2.以热脉冲法测定的日耗水量为100%,则快称法的测值为88%(六年生树)与112%(二年生树)。3.气孔计法测值高于快称法,在宁夏干旱地区为后者的130%—190%,在山东较湿润地区为240%—320%。4.微气象法中午蒸腾值十分接近整树容器法与热脉冲法,其误差小于2%。 相似文献
99.
100.
大气[CO2]和温度升高对农作物生理及生产的影响 总被引:3,自引:6,他引:3
全球大气[CO2]和气温升高是全球气候变化对农作物产量影响最为重要的两个因子。本文着重介绍了[CO2]和温度升高对农作物光合作用、呼吸作用、蒸腾作用、产量、品质等方面影响的研究进展。研究表明随着[CO2]升高,作物光合速率及蒸腾速率有上升趋势,呼吸作用和气孔导度下降,产量有所提高,品质将会降低,但研究仍有不确定性。随着[CO2]变化,不同光合途径(C3、C4)作物的响应不一致且存在短期和长期效应。普遍认为大气温度升高抑制作物光合作用,作物产量下降。现有的研究多采用模型或模拟试验的方法研究气候变化对作物产量的影响,但研究发现模型研究结果与模拟试验研究结果有差异,不同学者对产量的评估结果也不一致。最新研究认为温度对作物产量影响成非线性,当温度高于关键温度后产量会迅速下降。现阶段大部分模拟试验均在气室中研究,与野外实际情况差异较大,结论仍需进一步验证。目前尚缺乏对作物模型结果的实验验证。 相似文献