【作者】 王仰仁；

【导师】 康绍忠；

【作者基本信息】 西北农林科技大学 ， 农业水土工程， 2004， 博士

【摘要】 作物产量与水分、养分的定量关系是合理制定灌溉施肥方案的重要依据,对于提高水分、养分利用效率、改善农田生态环境,具有重要的指导意义。　作物产量与水分、养分的定量关系,国内外都进行了广泛的研究,积累了大量的宝贵资料,得出了许多有价值的成果。然而,这些作物水分(或养分)生产函数的模型参数都是以统计方法求得,属于经验性模型,缺乏生理学和生物学的解释,其普适性较差。具有四十余年历史的作物生长模拟模型,在很大程度上克服了这些缺点。　但是,目前的作物生长模拟模型多是农学家研究的结果,其模拟研究的重点多在作物种植期、种植密度和植株形态等方面,对于水分、土壤温度,以及水热耦合模拟方面的研究较少,或做了过多的简化。因此,这些模型难以满足灌溉用水管理决策的需要,也难于对水分胁迫对作物生长影响问题做出机理性的解释。本文研究的目标是对现有的作物生长模拟模型进行选择和概化,构建出一套系统的适用于灌溉施肥管理的作物生长模拟模型,并利用现代计算机的图形化技术,将作物生长过程及其相关的水肥、光热时空变化过程,以图形的形式展现出来,以便于认识和研究环境因子变化对作物生长过程的影响。　研究过程中,依据可获得的试验资料,采用了三种方法分析确定模型参数。一种是从文献中查取,直接引用;一种是利用文献提供的试验观测结果和本项目研究中的部分试验资料,加以分析计算确定;第三种是以2004 年度冬小麦实测产量为依据,以模拟产量与实测产量误差平方和最小为目标函数,通过模型运行调试分析。最后,从土壤水分随时间的变化过程、不同深度的地温随时间的变化过程、作物产量和茎、叶、籽粒干物重几个方面对本文构建的作物生长模拟模型进行了检验。检验结果表明,模型构建是合理的,选取和确定的模型参数的是可靠的,整体模型模拟结果具有足够的精度。　本论文的主要结论和创新点有如下几个方面:　1、利用土壤—植物—大气连续体物质传输理论,把光合产物生产过程、呼吸消耗过程和积累过程、作物蒸发蒸腾过程、根系吸水过程、降雨灌溉入渗过程,以及土壤水分、土壤温度、土壤养分的时空变化等过程有机结合,形成了一个系统的、完整的作物生长模拟模型。该模型重点考虑了水、肥、光、热(温度)对作物生长的影响,以及对光合产物在根、茎、叶和籽实间分配和转移的影响。简化、忽略了冬小麦分蘖和茎节生长、叶片分布形状等的植物形态模拟。因此该模型可方便地用于农业用水和施肥管理,而且具有足够的精度。　2、采用联合国粮农组织(FAO)灌溉排水报告(第56 号)作物蒸发蒸腾量计算中推荐的方法,以小时为时段分析计算了试区(山西榆次)2003 和2004 年度小麦生长期的理论太阳辐射,依据作物系数与叶面积指数的关系,分析计算了冬小麦潜在蒸更多还原

【Abstract】 The quantitative relationship among crop yield, water and nutrient is the base for rational irrigation and fertilization scheduling, which is important for the increase of water and nutrient use efficiency and the improvement of farmland environment. The relationship among crop yield, water and nutrient has been studied extensively both in China and abroad. From these studies, a large amount of valuable data and results were obtained. However, most of the models are empirical model based on statistics of experiment data with less consideration to the physiological and biological mechanism. Therefore, the applicability of these models is usually limited. Crop growth simulation model, which has a history of over 40 years, can overcome these disadvantages. However, most of the crop simulation models are developed by agronomist. Main emphasis of these models are crop growing period, plant density and plant configuration, while soil water and temperature are often neglected or over-simplified. As a result, these models can not meet the requirement of irrigation water management, and are difficult to explain the impact of water stress on crop growth. The objective of this thesis is to develop a crop simulation model suitable for irrigation and fertilization management based on available models, and to present the crop growth process and relevant processes of water, fertilizer, light and heat in graphics, so as to study the crop growth process and the impact of environmental factors to crop growth. In the study, three methods were used to determine parameters of the model. Some parameters were cited directly from literatures, some were estimated from the analysis of experiment results from literatures and experiment of this project. The rest parameters were optimized with the objective of minimum square errors between simulated and measured crop yield of experiment in 2004. Then, the crop growth simulation model developed in this thesis was validated with experiment results of soil water variations, the process of soil temperature at different depth, crop yield and dry weight of stem, leaf and grain. It shows that the model is appropriate, parameters are reliable and the simulation precision is acceptable. Main conclusions and innovations of this thesis include: 1. In this thesis a systematic crop growth simulation model was developed based on the theory of mass transfer in soil-plant-atmosphere continuum (SPAC). The model integrated the processes of photosynthesis, respiration and biomass cumulation, field evapotranspiration, root uptake, infiltration of precipitation and irrigation, as well as the spatial and temporal variations of soil water, temperature and nutrient. The model mainly concerned with the impact of water, fertilize, light and heat on crop growth, and the distribution and transfer of photosynthetic product in crop root, stem, leaf and seed, while the tillering of winter wheat, growth of stem node and leaf distribution were simplified or neglected. Therefore, the model can be used conveniently in irrigation and fertilization management with sufficient accuracy. 2. Using the method recommended in FAO Irrigation and Drainage Paper No. 56 to calculate crop evapotranspiration, hourly solar radiation in the growing period of winter wheat in 2003 and 2004 at the experiment site of Yuci was estimated. Daily variation of potential evapotranspiration of winter wheat were calculated and analyzed from the relationship between crop coefficient and leaf area index. Then, daily variation of photosynthetic product was calculated, and it was integrated with respect to canopy depth and time with trapezoidal integration method to obtain the daily potential photosynthetic product. 3. Coefficients of growth balance between root and canopy, stem and leaf, seed and stem were proposed. Based on these coefficients of growth balance, distribution coefficient and transfer coefficient of photosynthetic product were deduced. Crop growth simulation results of different water and fertilizer treatment showed that the　distribution and transfer coefficients of photosynthetic product is effective in modeling the distribution of photosynthetic product among root, stem, leaf and seed and the impact of the amount and time of irrigation and fertilization on crop economic coefficient. 4. Soil particle distribution was used to determine unsaturated soil hydraulic conductivity and diffusivity, soil water content and hydraulic conductivity at saturation. From the comparison of simulated and measured soil water, the method above is acceptable. 5. In the modeling, partial difference equations for soil moisture and soil temperature were used to describe the transfer of soil moisture and variation of temperature. Partial difference equations for ammoniacal nitrogen and nitrate nitrogen were used to describe the transfer and transformation of soil nitrogen. Therefore, it avoided some simplifications and hypothesizes in a lot of crop simulation models. 6. Coefficients for water and nutrient stress take the power function of relative daily evapotranspiration and relative plant nitrogen content, respectively. Two parameters were optimized with the objective of minimum square errors between simulated and measured cropyield of 30 experiment plots with 20 treatments in 2004, then they were validated with the experiment results of 22 treatments in 2003. The results show that the maximum and average relative errors in 2004 are 20% and 7.05%, and the relative errors in 2003 are 34% and 13.2%, respectively. These indicate that the model and parameters are reliable and the simulation precision is acceptable. 7. The simulation results, including crop growth process, the variation of soil water, nutrition, temperature and some parameters, can be displayed in graphics with Matlab software. The visualization of crop growth simulation is convenient for relevant studies. 8. Crop growth simulation model can simulate crop yield of different irrigation and fertilization with enough accuracy, and provide the base for beneficial evaluation of irrigation and fertilization. The simulation model of water and nitrogen can estimate vertical water and nitrogen flux at different soil depth, which is helpful in the evaluation of water and nitrogen use efficiency and the impact to environment. Therefore, the crop growth simulation model in this thesis considered agricultural benefit and the impact of agricultural activity on environment together, and can evaluate the agricultural benefit and environment impact as a whole. The mechanism model of photosynthetic product distribution and transfer needs further validation with field experiment data of root, stem, leaf and seed. The assumption that the biomass of root, stem and leaf changed suddenly from accumulation to decreasing needs further improvement.更多还原