【作者】 于婵；

【导师】 朝伦巴根； 朱仲元；

【作者基本信息】 内蒙古农业大学 ， 农业水土工程， 2011， 博士

【摘要】 内蒙古草原由于超载放牧和不合理垦植,绿草逐渐稀疏,沙漠开始蔓延,草原生态日益恶化,农牧业发展受到严重影响,为维持生态平衡,保护生态环境,缓解草原放牧的压力,发展牧草的人工种植已成为当前农牧业结构调整与建设的重要内容。牧草的需水量决定牧草的生长发育态势,当前有关植物需水的研究越来越多地涉及到植物生理生态学的有关内容。本文在浑善达克沙地选择典型区域建立灌溉试验场,以老芒麦、披碱草、蒙古冰草和紫花苜蓿作为典型牧草,进行人工牧草生理生态过程模拟、需水量计算、高效用水灌溉制度制定及有效根系层的土壤含水率阈值与无效需水量等内容的研究,主要成果如下:(1)通过人工牧草蒸腾速率和光合速率与环境因子的相关分析、偏相关分析、通径分析和决策系数分析,从不同角度说明了人工牧草蒸腾速率和光合速率与环境因子的关系。人工牧草的蒸腾作用和光合作用主要受光合有效辐射(PAR)的影响,其次是其它环境要素不同程度的直接影响和间接影响。(2)基于AGA求解的非直角双曲线模型、直角双曲线模型和直角双曲线修正模型,建立了人工牧草的光响应模型,三种模型对于人工牧草的光合速率和蒸腾速率的光响应模拟效果很好,差异性不大;分别建立了人工牧草蒸腾速率对于空气温度和湿度响应的指数模型。(3)在分析人工牧草气孔导度与环境因子关系的基础上,考虑到经典气孔导度模型(Jarvis类模型和BWB模型)的适用性和局限性,提出了模拟人工牧草气孔导度与环境变量关系的复合S曲线模型,并以AGA进行求解,研究表明复合S曲线模型可以很好的反映环境变量与人工牧草气孔导度之间的复杂的非线性函数关系。(4)以能量平衡为基础,将气孔导度模型与能量平衡模型相耦合,用湍流扩散理论建立了冠层尺度上的双涌源模型,并提出从不同角度识别模型参数的方法,进而实现了人工牧草冠层潜热通量和作物蒸腾量的模拟,取得了较好的模拟效果。(5)利用AGA优化找出残差平方和最小时牧草的基本作物系数,进而提出了适用于本地区牧草需水量计算的基本作物系数修正值,基于此,以双作物系数法逐日计算了2004、2005年不同灌溉处理下老芒麦、披碱草、蒙古冰草和紫花苜蓿全生育期的需水量,计算结果很好地反映了各生育期蒸腾蒸发的变化规律。(6)利用拟合相关图法、残差估计误差指示法和相关分析法,以定性、定量相结合的方法分析了人工牧草蒸腾量、株间土壤蒸发量和有效根系层土壤含水率的有效性。(7)确定了人工牧草的高效用水灌溉制度,提出典型优质人工牧草合理灌溉的指导方法。实施高效用水灌溉制度后人工牧草水分利用效率均有不同程度的提高,老芒麦、披碱草、蒙古冰草和紫花苜蓿的水分利用效率分别提高0.19、0.1、0.09和0.17 kg·m-3。(8)以作物有无水分胁迫作为分析土壤含水率阈值的出发点,从耗水角度提出灌溉制度的设计应该满足Dr小于RAW或DP等于零的条件,并认为有效根系层土壤含水率阈值是光合利用率较高的土壤含水率的下界值,其上界值不宜超过阈值过多。以作物是否发生无效蒸腾作为分析土壤含水率阈值的出发点,从作物产量与需水量、光合作用与根系层土壤含水率的关系角度出发,估算出人工牧草的含水率阈值,并根据试验结果认为:生育期内土壤含水率维持在田间持水率的55%-70%时无效蒸腾较少、产量较高。更多还原

【Abstract】 Because of the over-grazing and unreasonable reclamation, the ecological condition of the grassland in Inner Mongolia is worsening, for example, the grass gradually sparsing, desert spreading etc, and agricultural development has been seriously affected. In order to maintaining the ecological balance, protecting the environment and alleviating the pressure of grazing, forage grass is planted that becomes one of important content in agricultural structure adjusting and constructing. Water requirement of forage grass is one of decisive factors in the course of the growth and development. At present, more and more research on crop water requirement are related to the content of plant physiological ecology.In this paper, Elymus, Leymus, Agropyron and Medicago in the Otinday Sandy area are selected as a typical forage grass for irrigation experiment. The research contents include grass physiological and and ecological process simulation,crop water requirement, high efficient water irrigation plan, the soil moisture content threshold in effective root zone and invalid water requirement, etc. The main results are as follows:(1)By correlation analysis, partial correlation analysis, path analysis and decision-making coefficient between the transpiration rate and photosynthetic rate of the planted grass and environmental factors, the relations of the transpiration rate and photosynthetic rate of the planted grass with environmental factors are revealed. The transpiration and photosynthesis of the planted grass is mainly affected by photosynthetic active radiation(PAR), followed by the other environmental factors in different degree.(2)Based on AGA , the non-rectangular hyperbolic model, rectangular hyperbolic model and rectangular hyperbola correction model are established to modelling the light response of the planted grass. The results show that the simulated effects of three models for the photosynthesis rate and transpiration rate on the light response of Elymus, Leymus, Agropyron and Medicago are better. The exponential models are established to describe the transpiration rate of planted grass for air temperature and humidity response.(3)Based on analysing the relationships between stomatal conductance of the planted grass and environmental factors, and considering the applicability and limitations of classical stomatal conductance model (Jarvis class model and the BWB model), the composite S curve model solved by AGA is proposed to simulate the stomatal conductance changes with environmental variables. The studies show that the composite S curve model can reflect the complicated nonlinear relationships between the environmental variables and stomatal conductance of planted grass better.(4)Based on the energy balance principle and the turbulent diffusion theory, and the stomatal conductance model coupled with energy balance model, the two-source model in canopy-scale are established by two kinds identifying methods for model parameters. The simulated effects of the crop latent heat flux and transpiration are better.(5)The revised basal crop coefficients are proposed for local planted grass by AGA with globe convergence in terms of local metrological and hydrological condition. The water requirement of Elymus, Leymus, Agropyron and Medicago are caculated by the dual crop coefficient approach presented in FAO-56 during 2004 and 2005. The results show better for modelling variation of the evapotranspiration of the planted grass.(6)From qualitative and quantitative view , the correlation diagram method, fitting the residuals indicated the estimation error and correlation analysis are used for verifying the validity of the evapotranspiration, soil evaporation between plants and the effective soil moisture content in root zone.(7)The high efficiency water irrigation scheduling of the planted grass are determined. After the implementation of the high efficiency water irrigation plan, water use efficiency of the planted grass are improved in some degree, for example, the water use efficiency of Elymus, Leymus, Agropyron and Medicago are increased 0.19,0.1,0.09 and 0.17 kg·m-3.(8)Taking crop water stress as the starting point to analysis the soil moisture threshold, irrigation plan should be designed to meet Dr less than RAW or DP equal to zero. The soil moisture threshold in effective root zone is the down bound of photosynthetic efficiency. The upper bound should not exceed the threshold too much. From crop transpiration validity view to analysis the soil moisture threshold and from the crop yield and water demand, photosynthesis and soil moisture in root zone view to estimate the moisture content of planted grass threshold. According to the experiment results, the invalid transpiration is less and higher yield when the soil moisture content maintain in 55% -70% of the field water capacity during the growing season.更多还原