控制性隔沟交替灌溉玉米根系吸水模型的试验研究

以影响根系吸水强度的三大要素即作物蒸腾强度、土壤含水率和根系分布密度为影响因子,结合土壤水动力学理论得到的根系吸水率,建立了控制性隔沟交替灌溉条件下玉米的二维根系吸水模型,并进行验证得到较好的结果。模型对预报控制性交替灌溉具有重要的理论及实用价值。     

苹果树根系吸水模型研究

根据苹果园苹果树的根系密度资料和根区土壤水分动态资料,采用二种方法建立了苹果树的根系吸水模型,其一是根据根长密度资料建立的根系吸水模型,其二是根据土壤水分动态资料采用反推的方法建立的根系吸水模型;在此基础上采用2003年5月21日至5月30日、6月2日至6月20日和7月18日至8月1日3个阶段的实测资料对所建立的根系吸水模型进行了验证。结果表明:第二种方法建立的苹果树根系吸水模型的模拟精度略高于第一种方法。     

水盐胁迫条件下作物根系吸水模型研究进展及展望

提高盐渍化土壤农业生产力已成为边际土壤地力提升的重要组成部分及途径,研究盐分胁迫对根系吸水的影响及其根系吸水模型的建立是该方面的重要研究内容之一。首先介绍了作物根系吸水模型的研究进展,在此基础上,对目前国内外常用的水盐胁迫条件下作物根系吸水模型及其相关研究作了综述,指出由静态向动态方向发展、突出水分胁迫与盐分胁迫对根系吸水耦合、体现作物根系吸水特征空间差异是水盐胁迫条件下作物根系吸水模型研究的重点。     

水稻根系吸水模型的初步研究

以沈农9660号水稻品种为试材,随机选取一个蒸渗仪(面积为2.5m×2m)进行根系生长观测试验。采用水洗法,测定水稻根系重量根密度。运用非称重式钢筋混凝土蒸渗仪的蒸腾量观测结果,在总结国内外作物根系吸水模型研究的基础上,运用有限差分法对有根系吸水条件下的稻田土壤水分运动进行了模拟,导出了水稻根系吸水模型。     

粉煤灰改性膨胀土的试验

研究了南阳粉煤灰改性膨胀土的各项性能指标.通过对在膨胀土中加入不同比例的粉谋灰进行物理性质试验、力学性质试验、水理性质试验和特殊性质试验的改性试验研究,结果表明掺入了粉煤灰的膨胀土各项性能指标均有一定量的提升,试验获得原始的数据资料可为工程施工提供参考依据.     

根系吸水模型参数的混合遗传算法估算方

构建了遗传算法与Levenberg-Marquardt算法相结合的混合遗传算法,用于求解根系吸水模型参数。分别进行数值试验和棉花根系吸水试验对混合遗传算法求解精度进行验证。数值试验表明,采用混合遗传算法优化求解根系吸水模型参数的优化值具有较高的精度,含水率资料的时间步长和空间步长对根系吸水模型参数的优化精度有较大影响,在实际中时间步长可取值5～10d,空间步长取值5～10cm。对室内棉花根系吸水进行模拟分析,结果表明混合遗传算法求解的根系吸水模型可以很好地模拟根系吸水。该方法可用于求解根系吸水参数。     

根系吸水模型参数的混合遗传算法估算方法

构建了遗传算法与Levenberg-Marquardt算法相结合的混合遗传算法,用于求解根系吸水模型参数.分别进行数值试验和棉花根系吸水试验对混合遗传算法求解精度进行验证.数值试验表明,采用混合遗传算法优化求解根系吸水模型参数的优化值具有较高的精度,含水率资料的时间步长和空间步长对根系吸水模型参数的优化精度有较大影响,在实际中时间步长可取值5～10 d,空间步长取值5～10 cm.对室内棉花根系吸水进行模拟分析,结果表明混合遗传算法求解的根系吸水模型可以很好地模拟根系吸水.该方法可用于求解根系吸水参数.     

水轮机应用蜂窝密封的吸水和减振模拟试验

为减少混流式水轮机止漏环中流体产生的自激振动,根据止漏环各种密封结构,简化并提出密封模型,并根据模型搭建了试验台.采取直接测量转轴振动的方法,对比了简化后的密封模型与蜂窝密封在调整转子偏心程度的情况下振动幅值、波形图和频谱图的差别,以及增加转子质量不平衡块后两种密封振动幅值的变化.结果表明,蜂窝密封比普通的迷宫密封更能够抑制由于偏心和不平衡引起的振动.在最小密封间隙的上下游安置吸水装置,对比其振动情况,上游吸水可有效地降低转子振动.     

不同灌水深度条件下南疆枣树根系吸水模型研究

为探究不同灌水深度条件下,南疆枣树根系分布特征及吸水机理。以枣树为研究对象,试验导水装置设置3个深埋水平,分别为20 cm (T1)、35 cm (T2)和55 cm (T3),以地表滴灌（T0）为对照组;结合土壤水分运动基本方程建立枣树根系一维吸水模型,并利用实测数据对吸水模型进行验证。研究结果表明,各处理下枣树根系随土层的增加呈负指数趋势分布,相比于T0,T1、T2和T3处理下出水口范围内枣树有效根长分别增长18.2%、15.3%和10.9%,即深层灌水处理促进了枣树深层扎根;不同灌水深度处理下,各土层含水率大小为T2>T3>T1>T0,同一灌水深度处理下,各土层土壤含水率随土壤深度的增加呈现先变大后变小的趋势;通过建立的根系吸水模型模拟土壤含水率,计算值和测量值差异性在允许范围内,满足枣树根系吸水模型对土壤含水率预测的精度要求。综上可得,当灌水深度设置为35 cm左右时,利于枣树根系充分吸收水分和提高水分利用效率。     

中瑞保水剂及其对土壤与作物的效应

中瑞保水剂 ( PAMN-LC)对无离子水的吸水能力为 67.5ml/g,且随着产品配方和生产工艺的改进 ,其吸水性能有着不断提高的趋势。试验结果表明 ,中瑞保水剂 ( PAMN-LC)吸水总量的 78.4 2 %为有效水 ,无效水所占比例只有 2 1 .58% ;随着保水剂施用量的增加 ,土壤的持水能力也明显增加 ;施用中瑞保水剂PAMN-JCN对提高冬小麦出苗率有明显的效果 ,当土壤含水率介于 1 2 .1 %～ 1 6.8%之间时 ,用保水剂拌种可使冬小麦提早 1～ 3d出苗 ,出苗增加 2 5%～ 31 .7% ;沟施保水剂可使出苗率增加 3.3%～ 8.3% ;施用中瑞保水剂 PAMN-LC,其在苗期的主要作用是促进根系发育、增大根冠比 ,拔节以后则转为促进地上部发育。另外 ,施用中瑞保水剂有利于保持冬小麦叶片较长时间地处于展开状态 ,根系的颜色也比较深 ,多呈浅褐色。     

无土栽培基质水分特性参数研究

选用设施无土栽培常用8种基质,试验测定其孔隙度、渗透系数、水分特性曲线、扩散率等水分特性参数,分析得到:基质的水分扩散率与基质含水率之间的关系都符合经验公式D(θ=aebθ,呈指数函数变化,且决定系数较高;基质的导水性用扩散率来表示,得到珍珠岩和蛭石的供水速度快,但不利于保水,降低了灌水效率.综合分析8种基质得到,除珍珠岩、蛭石外,其他6种基质总孔隙度均在70％～ 90％之间,水气比均在2.0～4.0之间,均可作为育苗和栽培基质;采用矩阵法综合评价,得出以国产草炭与珍珠岩质量比2:1,国产草炭、蛭石、珍珠岩质量比3:1:1为基质时最优.     

昆明市松华坝水源地水源涵养能力时空变化研究

水源涵养能力是水源地脆弱性诊断的重要指标之一。在对比直线分割、直线斜割和滤波3种基流分割方法的基础上,选取松华坝水源地径流区内4个水文站实测流量资料,用滤波法分割基流,并计算基流量和基流指数。结果显示,左支流冷水河上、下游平均基流指数分别为0.589、0.485,右支流牧羊河上、下游平均基流指数分别为0.528、0.484。此外,1954-1992年冷水河下游地区基流量呈显著减小的趋势,其余区域基流量减小的趋势不显著。水源涵养能力空间上表现为,冷水河流域的水源涵养能力较牧羊河流域强,两流域上游的水源涵养能力均较下游强。     

Impact of global warming on cowpea bean cultivation in northeastern Brazil

This study evaluated the effects of climate change on cowpea bean crop grown in northeastern Brazil based on the reports of the Intergovernmental Panel on Climate Change (IPCC). The water balance model combined with Geographic Information System techniques was used to identify regional areas where the cowpea bean crop will suffer yield reduction due to climate changes. Model input variables were: rainfall, crop coefficients, potential evapotranspiration and duration of the crop cycle. A limit value of 0.5 was adopted for the water requirement satisfaction index (WRSI), being the ratio of actual to maximum evapotranspiration. The acceptable seeding date was defined as the date at which the water balance simulation presented a WRSI value greater than the limit value, with a frequency of at least 80%. An increase in air temperature will cause a significant reduction in the areas currently favorable to cowpea bean crop growth in northeastern Brazil, and it is recommended that bean varieties better suited to high-temperature conditions should be planted.     

非充分灌溉条件下水稻生长发育及生理机制研究

本文以水稻非充分灌溉试验的大量实测资料为基础,分析了水分胁迫对水稻主要形态指标、生理机制及产量的影响,对非充分灌溉条件下水稻所持有的生理机制进行了较细致的研究。研究结果对于指导有效、省水的稻田灌溉具有重要意义。     

Hydrological impact of biofuel production: A case study of the Khlong Phlo Watershed in Thailand

This study evaluates the potential impact of increased biofuel production on the hydrology of a small watershed, Khlong Phlo, in the eastern part of Thailand. The water footprint of biofuel energy was estimated for three crops in order to identify the most water-efficient crop. The Soil and Water Assessment Tool (SWAT) model was used to evaluate the impact of land use change (LUC) caused by the expansion of biofuel crops on the components of water balance and water quality in the studied watershed. Several LUC scenarios consisting of oil palm (biodiesel), cassava and sugarcane (bio-ethanol) expansion were evaluated. The water footprint results indicated that cassava is more water-efficient than the other two crops considered. Simulation results revealed that although oil palm expansion would have negligible alteration in evapotranspiration (0.5 to 1.6%) and water yield (−0.5 to −1.1%), there would be an increased nitrate loading (1.3 to 51.7%) to the surface water. On the contrary, expansion of cassava and sugarcane would decrease evapotranspiration (0.8 to 11.8%) and increase water yield (1.6 to 18.0%), which would lead to increased sediment (10.9 to 91.5%), nitrate (1.9 to 44.5%) and total phosphorus (15.0 to 165.0%) loading to surface water. Based on the results, it can be concluded that land use change for biodiesel production would affect water quality, while both the water balance components and water quality would be affected by the expansion of bio-ethanol crops. Overall, the study indicates that biofuel production would have a negative impact on the water quality of the studied watershed. Further research at large scale (e.g. basin level) and on the economic aspect is recommended, in order to contribute to developing suitable land use and energy policies.     

生物物料颗粒空隙率对其干燥质量的影响

为研究干燥过程中生物物料颗粒结构对质量的影响,在不同的进口风温条件下,利用振动流化床干燥机对由清蛋白,面粉及麦麸构成的具有不同初始体积空隙率的混合物颗粒进行了干燥试验。建立了其干燥动力学及质量降解动力学的用于预测热力干燥过程中颗粒结构对产品质量的影响。     

Hydro-physical characteristics of selected media used for containerized agriculture systems

Containerized plant production represents an extremely intensive agricultural practice with large amounts of moisture and fertilizer application. Hydro-physical characteristics such as water infiltration, texture and structure, particle size distribution affect the quality of the media used in containerized agricultural systems and the water availability to plants. Water retention characteristics depend on particle size distribution as well as the composition of the media used. Materials with coarser particles allow faster percolation of water and also retain relatively higher amounts moisture per unit weight due to higher porosity, while draining faster due to smaller surface area per unit weight. Faster drainage can result into airflow through coarser materials causing the media to dry. The objectives of this study were to characterize the selected hydro-physical properties of plant growth media that are commonly used by nurseries in South Florida. Characterization of the plant growing media can allow modeling of soil-water interactions and development of best management practices for more efficient use of water and agrochemicals by nurseries. Experimental analyses were performed to characterize the plant growth mixtures in terms of particle size distribution and hydraulic conductivity using three different methods (i.e., constant head permeability, falling head permeability test, and tension infiltrometer test). The saturated hydraulic conductivity of the mixtures measured by constant head method ranged from 0.029 to 0.042 cm/s (104-151 cm/h) and by falling head method ranged from 0.078 to 0.112 cm/s (281-403 cm/h). The saturated hydraulic conductivity of the mixtures measured by tension infiltrometer ranged from 0.02 to 0.34 cm/h. Understanding water retention and permeation characteristics of the plant growing media could assist development of best management practices (BMP) for containerized agricultural systems for efficient management of irrigation water and agrochemical use.     

化学调控技术在旱地水肥利用中的应用进展

围绕旱地农业生产中的水肥资源高效利用展开讨论,主要介绍了以3种典型化学调控制剂(土壤改良剂PAM、土壤保水剂SAP和蒸腾抑制剂FA)为代表的化学调控技术在旱地农业水肥资源利用方面的调控机制和应用方法,重点对化学调控技术在旱地农业生产中的增强水肥保蓄、提高坡地水土保持、改善作物水肥利用性能及提升作物品质和产量4个重要环节上的应用研究进行了综述,最后提出未来化学调控技术在旱地农业中应用的重点研究方向.     

复水前后冬小麦光合生理特征对保水剂用量的响应

为探明干旱胁迫复水前后作物水分消耗过程中冬小麦生理特征对保水剂用量的响应及作用机理,采用盆栽试验以不施保水剂为对照,测定了保水剂不同用量(无保水剂、27 mg/kg、54 mg/kg、81 mg/kg)条件下,复水前后的土壤含水率及光合参数的持续变化特征.结果表明:干旱胁迫时,保水剂降低了小麦叶片光合速率、蒸腾速率、气孔导度,提高了水分利用效率.复水后,对照的光合速率、蒸腾速率及气孔导度仍较高,保水剂处理依次为:54 mg/kg、81 mg/kg、27 mg/kg.而当土壤含水率降至田间持水量的55％左右时,各处理光合参数依次为:27 mg/kg、CK、54 mg/kg、81 mg/kg;水分利用效率依次为:81 mg/kg、27 mg/kg、CK、54 mg/kg.随保水剂用量的增加,小麦生物量增加,但81 mg/kg处理显著高于对照.同时,保水剂会影响叶片光合参数之间的相关性,其中,小麦气孔导度与光合速率、蒸腾速率的相关性以54 mg/kg处理最紧密,依次为81 mg/kg处理、对照,27 mg/kg处理最差.而气孔导度与土壤含水率、水分利用效率及光合速率与土壤含水率、蒸腾速率、水分利用效率的相关性强弱从大到小的处理依次为:81 mg/kg、54 mg/kg、CK、27 mg/kg.说明小麦叶片光合参数对保水剂的响应以54 mg/kg与81 mg/kg处理最显著.