【摘要】：根系是作物從土壤中吸收水分和養(yǎng)分的器官,土壤水分是影響根系構(gòu)型發(fā)展的主要因素。但是根系的生長介質(zhì)——土壤的不可視性,這一特性給根系研究帶來了很大困難,所以進(jìn)行根系構(gòu)型的量化和模擬研究成為了根系研究的必要。本文在綜述國內(nèi)外根系研究及可視化的基礎(chǔ)上,以分形理論基礎(chǔ)知識(shí)分析了桶栽棉花根系構(gòu)型分形特征;以水量平衡原理,建立了棉花根系生長的動(dòng)態(tài)規(guī)劃模型;以迭代函數(shù)系統(tǒng)為基礎(chǔ),對(duì)桶栽棉花根系構(gòu)型進(jìn)行了可視化重現(xiàn)。得到如下結(jié)論:(1)棉花整根構(gòu)型的計(jì)盒維數(shù)和側(cè)根構(gòu)型的計(jì)盒維數(shù)都隨生育階段的推進(jìn)而增大,而且前者始終大于后者;但是進(jìn)入花期以后,二者基本接近。這說明苗期棉花的主根生長占主導(dǎo)地位,而進(jìn)入蕾期以后,棉花側(cè)根生長占主導(dǎo)地位,甚至到后期主要是側(cè)根在發(fā)展;而且,隨著側(cè)根的發(fā)展,根系的分布空間更加連續(xù)。(2)與根構(gòu)型計(jì)盒維數(shù)的變化規(guī)律相似,棉花整根構(gòu)型的根豐度和側(cè)根構(gòu)型的根豐度也都隨生育階段的推進(jìn)而增大,而且前者始終大于后者。然而,側(cè)根構(gòu)型的根豐度增加幅度較大,直至進(jìn)入花期以后,側(cè)根構(gòu)型的根豐度(4.1113)接近于整根構(gòu)型的根豐度(4.189)。這反映了棉花側(cè)根上二級(jí)和三級(jí)側(cè)根的發(fā)展速率和空間擴(kuò)展能力增加較快。另外,隨著根系長度的增加,側(cè)根構(gòu)型的根豐度也增大,說明雖然根構(gòu)型的分布模式將趨于穩(wěn)定,但其對(duì)土壤濕潤空間的占有將持續(xù)加強(qiáng),根系分布密度增大。(3)在棉花主要生育階段沒有水分脅迫以及所有根系都吸水的條件下,以水量平衡原則為基礎(chǔ),利用動(dòng)態(tài)規(guī)劃理論,建立了根系生長過程中總根長變化模型,經(jīng)桶栽棉花試驗(yàn)驗(yàn)證,模擬的根長生長過程與實(shí)測值基本一致。模型計(jì)算值與試驗(yàn)測定值的相對(duì)誤差隨模擬進(jìn)程呈先增大后減小再增大的規(guī)律,總體誤差為15.41%,證明了模型作為土壤濕潤區(qū)設(shè)計(jì)手段的有效性。(4)各生育階段棉花葉面積的變化率始終大于根長的變化率,表明在水量平衡條件下葉面積的生長占主導(dǎo)作用,冠層蒸騰拉力是棉花根系吸水的主要?jiǎng)恿?根系的生長首先是滿足冠層耗水。當(dāng)冠層蒸騰量增大時(shí),根系長度必須增大才能滿足植株耗水,保持水量平衡;棉花生長后期,冠層蒸騰量降低,需要的吸水根系減少,使得根系衰減,一些無用根系則將衰老死去。(5)采用迭代函數(shù)系統(tǒng)對(duì)A、B處理的桶栽棉花根系構(gòu)型可視化,模擬結(jié)果表明,整體根形符合根系生長的形態(tài);對(duì)于棉花需水關(guān)鍵期,模擬根系構(gòu)型的根長密度的二維分布等值線圖與實(shí)測結(jié)果相似度不低于75%,對(duì)滴灌棉花土壤濕潤區(qū)的設(shè)計(jì)很有幫助,證明了該方法的有效性。θ,φ控制了一級(jí)側(cè)根與主根生長的夾角,總體表現(xiàn)為隨土層深度增加而逐漸減小的特點(diǎn);側(cè)根分生位置主要沿土層深度變化,所以e=0,f≠0;各分形元仿射變換調(diào)用概率p與對(duì)應(yīng)區(qū)域棉花根長密度呈正相關(guān)。
[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，

本文編號(hào)：2362571