基于土壤水分分布的滴灌棉花根系构型模拟方法研究
发布时间：2018-11-28 10:25
【摘要】：根系是作物从土壤中吸收水分和养分的器官,土壤水分是影响根系构型发展的主要因素。但是根系的生长介质——土壤的不可视性,这一特性给根系研究带来了很大困难,所以进行根系构型的量化和模拟研究成为了根系研究的必要。本文在综述国内外根系研究及可视化的基础上,以分形理论基础知识分析了桶栽棉花根系构型分形特征;以水量平衡原理,建立了棉花根系生长的动态规划模型;以迭代函数系统为基础,对桶栽棉花根系构型进行了可视化重现。得到如下结论:(1)棉花整根构型的计盒维数和侧根构型的计盒维数都随生育阶段的推进而增大,而且前者始终大于后者;但是进入花期以后,二者基本接近。这说明苗期棉花的主根生长占主导地位,而进入蕾期以后,棉花侧根生长占主导地位,甚至到后期主要是侧根在发展;而且,随着侧根的发展,根系的分布空间更加连续。(2)与根构型计盒维数的变化规律相似,棉花整根构型的根丰度和侧根构型的根丰度也都随生育阶段的推进而增大,而且前者始终大于后者。然而,侧根构型的根丰度增加幅度较大,直至进入花期以后,侧根构型的根丰度(4.1113)接近于整根构型的根丰度(4.189)。这反映了棉花侧根上二级和三级侧根的发展速率和空间扩展能力增加较快。另外,随着根系长度的增加,侧根构型的根丰度也增大,说明虽然根构型的分布模式将趋于稳定,但其对土壤湿润空间的占有将持续加强,根系分布密度增大。(3)在棉花主要生育阶段没有水分胁迫以及所有根系都吸水的条件下,以水量平衡原则为基础,利用动态规划理论,建立了根系生长过程中总根长变化模型,经桶栽棉花试验验证,模拟的根长生长过程与实测值基本一致。模型计算值与试验测定值的相对误差随模拟进程呈先增大后减小再增大的规律,总体误差为15.41%,证明了模型作为土壤湿润区设计手段的有效性。(4)各生育阶段棉花叶面积的变化率始终大于根长的变化率,表明在水量平衡条件下叶面积的生长占主导作用,冠层蒸腾拉力是棉花根系吸水的主要动力,根系的生长首先是满足冠层耗水。当冠层蒸腾量增大时,根系长度必须增大才能满足植株耗水,保持水量平衡;棉花生长后期,冠层蒸腾量降低,需要的吸水根系减少,使得根系衰减,一些无用根系则将衰老死去。(5)采用迭代函数系统对A、B处理的桶栽棉花根系构型可视化,模拟结果表明,整体根形符合根系生长的形态;对于棉花需水关键期,模拟根系构型的根长密度的二维分布等值线图与实测结果相似度不低于75%,对滴灌棉花土壤湿润区的设计很有帮助,证明了该方法的有效性。θ,φ控制了一级侧根与主根生长的夹角,总体表现为随土层深度增加而逐渐减小的特点;侧根分生位置主要沿土层深度变化,所以e=0,f≠0;各分形元仿射变换调用概率p与对应区域棉花根长密度呈正相关。
[Abstract]:Root system is the organ for crops to absorb water and nutrients from soil, and soil moisture is the main factor that affects the development of root system configuration. However, the invisibility of soil, the growth medium of root system, brings great difficulties to the study of root system, so it is necessary to study the quantitative and simulation of root system configuration. On the basis of summarizing the research and visualization of cotton roots at home and abroad, this paper analyzes the fractal characteristics of cotton root system configuration based on fractal theory, and establishes the dynamic programming model of cotton root growth based on the principle of water balance. Based on the iterative function system, a visual reconstruction of cotton root system was carried out. The main conclusions are as follows: (1) the box-counting dimension of cotton whole root configuration and the box-counting dimension of lateral root configuration increase with the development of growth stage, and the former is always larger than the latter, but after flowering, the two dimensions are similar. This indicated that the main root growth of cotton in seedling stage was dominant, but after entering bud stage, the lateral root growth of cotton was dominant, and even the lateral root was mainly developing in the later stage. Moreover, with the development of lateral roots, the distribution space of roots became more continuous. (2) the root abundance of cotton whole root configuration and the root abundance of lateral root configuration also increased with the development of growth stage. And the former is always greater than the latter. However, the root abundance of lateral root configuration increased greatly until the flowering stage, and the root abundance of lateral root configuration (4.1113) was close to that of the whole root configuration (4.189). The results showed that the development rate and spatial expansion ability of the secondary and tertiary lateral roots on the lateral roots of cotton increased rapidly. In addition, with the increase of root length, the root abundance of lateral root configuration also increased, which indicated that the distribution pattern of root configuration would be stable, but the occupation of soil moist space would continue to be strengthened. (3) under the condition of no water stress and all the roots absorbing water in the main growing stage of cotton, based on the principle of water balance, the dynamic programming theory was used. The change model of total root length in the process of root growth was established, and the experimental results showed that the simulated growth process of root length was basically consistent with the measured value. The relative error between the calculated value of the model and the measured value of the experiment increases first and then decreases and then increases with the simulation process. The total error is 15.41. It was proved that the model was effective as a design method for soil wetting area. (4) the change rate of cotton leaf area was always greater than that of root length in each growing stage, indicating that the growth of leaf area played a dominant role under the condition of water balance. Canopy transpiration is the main driving force for cotton roots to absorb water, and the root growth is to satisfy the canopy water consumption. When the canopy transpiration increased, the root length must be increased to satisfy the water consumption of plants and maintain water balance. In the later stage of cotton growth, the transpiration of canopy decreased, the needed water absorbing root decreased, and some useless roots were decayed. (5) using iterative function system to visualize the structure of cotton root system treated with Anb. The simulation results showed that the whole root shape was consistent with the growth of root system. For the critical period of cotton water demand, the similarity between the 2D contour map of root length density and the measured results is not lower than 75, which is helpful to the design of cotton soil wetting area under drip irrigation, and proves the effectiveness of this method. 蠁 controlled the angle between the primary lateral root and the main root, and showed that the growth angle of the primary lateral root and the main root gradually decreased with the increase of soil depth. The meristem position of lateral roots mainly varies with the depth of soil layer, so eOFO f 鈮，
本文编号：2362571
[Abstract]:Root system is the organ for crops to absorb water and nutrients from soil, and soil moisture is the main factor that affects the development of root system configuration. However, the invisibility of soil, the growth medium of root system, brings great difficulties to the study of root system, so it is necessary to study the quantitative and simulation of root system configuration. On the basis of summarizing the research and visualization of cotton roots at home and abroad, this paper analyzes the fractal characteristics of cotton root system configuration based on fractal theory, and establishes the dynamic programming model of cotton root growth based on the principle of water balance. Based on the iterative function system, a visual reconstruction of cotton root system was carried out. The main conclusions are as follows: (1) the box-counting dimension of cotton whole root configuration and the box-counting dimension of lateral root configuration increase with the development of growth stage, and the former is always larger than the latter, but after flowering, the two dimensions are similar. This indicated that the main root growth of cotton in seedling stage was dominant, but after entering bud stage, the lateral root growth of cotton was dominant, and even the lateral root was mainly developing in the later stage. Moreover, with the development of lateral roots, the distribution space of roots became more continuous. (2) the root abundance of cotton whole root configuration and the root abundance of lateral root configuration also increased with the development of growth stage. And the former is always greater than the latter. However, the root abundance of lateral root configuration increased greatly until the flowering stage, and the root abundance of lateral root configuration (4.1113) was close to that of the whole root configuration (4.189). The results showed that the development rate and spatial expansion ability of the secondary and tertiary lateral roots on the lateral roots of cotton increased rapidly. In addition, with the increase of root length, the root abundance of lateral root configuration also increased, which indicated that the distribution pattern of root configuration would be stable, but the occupation of soil moist space would continue to be strengthened. (3) under the condition of no water stress and all the roots absorbing water in the main growing stage of cotton, based on the principle of water balance, the dynamic programming theory was used. The change model of total root length in the process of root growth was established, and the experimental results showed that the simulated growth process of root length was basically consistent with the measured value. The relative error between the calculated value of the model and the measured value of the experiment increases first and then decreases and then increases with the simulation process. The total error is 15.41. It was proved that the model was effective as a design method for soil wetting area. (4) the change rate of cotton leaf area was always greater than that of root length in each growing stage, indicating that the growth of leaf area played a dominant role under the condition of water balance. Canopy transpiration is the main driving force for cotton roots to absorb water, and the root growth is to satisfy the canopy water consumption. When the canopy transpiration increased, the root length must be increased to satisfy the water consumption of plants and maintain water balance. In the later stage of cotton growth, the transpiration of canopy decreased, the needed water absorbing root decreased, and some useless roots were decayed. (5) using iterative function system to visualize the structure of cotton root system treated with Anb. The simulation results showed that the whole root shape was consistent with the growth of root system. For the critical period of cotton water demand, the similarity between the 2D contour map of root length density and the measured results is not lower than 75, which is helpful to the design of cotton soil wetting area under drip irrigation, and proves the effectiveness of this method. 蠁 controlled the angle between the primary lateral root and the main root, and showed that the growth angle of the primary lateral root and the main root gradually decreased with the increase of soil depth. The meristem position of lateral roots mainly varies with the depth of soil layer, so eOFO f 鈮，
本文编号：2362571
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