【作者】 邱让建；

【导师】 康绍忠；

【作者基本信息】 中国农业大学 ， 农业水土工程， 2014， 博士

【摘要】 我国西北旱区水资源严重匮乏,但光热资源丰富,适合日光温室产业的发展。近年来,调整农业结构,发展日光温室已成为该地区节水与农民增益的重要措施。温室环境下土壤-植物系统水热动态与模拟研究对于认识温室环境下物质与能量交换和指导温室作物高效用水具有重要的理论意义和实际价值。本文以日光温室辣椒和西红柿为研究对象,于2008-2012年进行了不同小区对比试验,采用包裹式茎流计、自动气象站、净辐射仪、红外测温仪、热线式风速计等仪器定位观测及定量模拟的方法,对不同灌水技术条件下的水热传输动态、耗水规律及控制因子、耗水估算模型、根系分布特征和根系吸水等方面进行了系统的试验研究,取得以下成果：(1)温室沟灌及滴灌辣椒和沟灌西红柿全生育期白天感热通量占净辐射的比例为52.4-62.5%,潜热通量占净辐射的比例为32.4-40.7%,土壤热通量占净辐射的比例仅为3.6-7.9%。与滴灌辣椒相比,除初期外,沟灌辣椒白天净辐射、潜热通量和感热通量分别提高了5-44%、39-70%和26-33%,而土壤热通量降低了7-15%。沟灌辣椒和西红柿潜热通量占净辐射的比例与叶面积指数(LAI)呈线性增加关系,而感热通量占净辐射的比例与LAI呈线性降低关系,土壤热通量占净辐射的比例与LAI呈e指数降低关系。(2)温室沟灌和滴灌辣椒全生育期总耗水量(ETc)分别为519.3-559.8mm口361.6-412.7mm；温室沟灌西红柿全生育期总ETc为341.0-562.3mm。沟灌辣椒和西红柿日均ETc均随着太阳辐射、气温、水汽压差和叶面积指数的增加而线性增加,累积ETc与积温为二次抛物线关系。(3)与充分供水处理相比,2/3充分供水和1/2充分供水处理西红柿平均日均茎秆液流分别降低了22.1%和42.8%。当地推荐施氮量处理和2/3当地推荐施氮量处理的西红柿日均茎秆液流量接近,但均高于1/2当地推荐施氮量处理约30%。不同水分和氮素处理西红柿夜间液流量占总液流量的比例分别为12.6-14.8%和11.8-21.2%。(4)温室内71-88%的时间为混合对流,且主要在白天,其余时间为纯自由对流,纯强迫对流没有发生。纯自由对流条件下,热传输系数(h)用McAdams公式计算时,Penman-Monteith (P-M)模型显著低估了辣椒和西红柿的耗水量,且与h用Stanghellini公式计算时P-M模型估算值接近；混合对流条件下,h用Stanghellini公式计算时P-M模型能较好预测辣椒和西红柿的耗水量。因此,可不区分对流条件,采用h用Stanghellini公式计算时的P-M模型模拟日光温室辣椒和西红柿的瞬时耗水量。双作物系数法能较好的模拟温室覆膜条件下辣椒和西红柿的日均耗水量,模型估算误差较小,沟灌及滴灌辣椒和沟灌西红柿平均标准误差分别为0.54mmd-1、0.21mm d-1和0.55mm d-1,平均绝对误差分别为0.44mmd-1、0.17mm d-1和0.44mmd-1。(5)温室西红柿根系主要分布在深度0-50cm,水平径向为沟侧0-18cm,垄侧0-30cm范围内,所占比例为72.3%,其根系密度在垂向和径向均呈e指数衰减。采用Hydrus2D软件能较好的模拟西红柿根区土壤水分分布,模拟值与测定值回归方程的斜率为0.987,决定系数为0.89。根系分布较少的底层土壤含水量模拟值与实测值的误差稍大。更多还原

【Abstract】 Water resourse is shortage in northwest China, but the region has abundant light resource and is highly suited for developing solar greenhouse industry. Adjustment of agriculture structure and developing solar greenhouse industry have become more and more important for water saving and increasing farmers’ income in this region in recently years. The study on dynamics and simulation of water and heat transfer in soil-plant system in greenhouse is of great importance and can help to recognize water and heat transfer mechanism and provide basic information for improving crop water use.This paper mainly studied the dynamics of water and heat transfer under different irrigation method, evapotranspiration patten and control factors, evapotranspiration models, root distribution character and root water uptake using stem sap flow meters, automatic wheather station, net radiometer, infrared radiation pyrometer and air velocity meter in2008-2012. The main results were shown as follows:(1) The ratio of daytime sensible heat flux to net radiation of hot pepper under drip and furrow irrigation and tomato under furrow irrigation over the whole growth stage was52.4-62.5%. The ratio of daytime latent heat flux to net radiation was32.440.7%. And the ratio of daytime soil heat flux to net radiation was only3.5-7.9%. Compared to drip irrigation, except for initial stage, the daytime net radiation, latent heat flux and sensible heat flux was increased by5-44%,39-70%and26-33%, respectively. While the daytime soil heat flux was decreasd by7-15%. The ratio of daytime latent heat flux to net radiation increasd linearly, while the ratio of daytime sensible heat flux to net radiation decreased linearly, with the leaf area index. The relationship between the ratio of daytime soil heat flux to net radiation and leaf area index was minus exponent.(2) The total seasonal evapotranspiration (ETC) of hot pepper under furrow and drip irrigation was519.3-559.8mm and361.6-412.7mm, respectively. The total seasonal ETC of tomato under furrow irrigation was341.0-562.3mm. The dairy average ETC of hot pepper and tomato was increased as solar radiation, air temperature, vapour pressure deficit and leaf area index increased. The relationship between the accumulated ETC and accumulated temperature was quadratic parabola.(3) Compared to sufficient water supply treatement, the average daily stem sap flow decreased by22.1%and42.8%, respectively, for2/3sufficient water supply and1/2sufficient water supply. The average daily stem sap flow between typical nitrogen application rate treatement and2/3typical nitrogen application rate treatment was similar, and both were about30%higher than that of1/2typical nitrogen application rate treatment. The nighttime stem sap flow of tomato under different water and nitrogen treatments accounted for12.6-14.8%and11.8-21.2%, respectively, of daily total stem sap flow.(4) Heat transfer in the greenhouses was conducted through mixed convection during about71-88%of study periods, while the rest was pure free convection (no pure forced convection occurred). Under pure free convection, the Penman-Monteith (P-M) model substantially underestimated the evapotranspiration of hot pepper with heat transfer coefficient (h) calculated by the McAdams equation and the model with h calculated by the Stanghellini equation performed similar to the ones by McAdams equation. Under mixed convection, the P-M model can accurately estimate the evapotranspiration of hot pepper with h calculated by the Stanghellini equation. To sum up, the P-M model with h calculated by the Stanghellini equation can well estimate the evapotranspiration rates of hot peppers and tomatoes grown in the solar greenhouses over short-time interval in northwest China without distinguishing the convection types. Dual crop coefficient model can accurate estimate daily evapotranspiration of hot pepper and tomato grown in solar greenhouse under plastic mulch condition. The average root mean square error was0.54mmd-1,0.21mmd-1and0.54mm d-1, respectively, for hot pepper under furrow and drip irrigation and tomato under furrow irrigation. And the average mean absolute error was0.44mm d-1,0.17mm d-1and0.44mm d-1, respectively.(5) The root of tomato in greenhouse centralized in the depth between0-50cm, and radial space between0-18cm at furrow side and0-30cm at bed side. And the amount of the roots accounted for over72.3%of total roots. The horizontal and vertical distributions of root density of tomao were minus exponent. The soil water distribution of tomato can be better simulated by Hydrrus2D. The slope of simulated and measured soil water content was0.987and the determine coefficient was0.89. The difference between estimated and measured soil water content was higher in the bottom layer due to the less root.更多还原