本文選題：拓?fù)浣Y(jié)構(gòu) + 根直徑��； 參考：《中國(guó)農(nóng)業(yè)大學(xué)》2016年博士論文

【摘要】：根系是植物吸收水分、養(yǎng)分資源和響應(yīng)土壤環(huán)境變化的重要器官。三維根系結(jié)構(gòu)模型能夠精確描述根系在土壤中的空間分布�；谕�?fù)浣Y(jié)構(gòu)定量化研究側(cè)根形態(tài)對(duì)探索根系功能-結(jié)構(gòu)具有重要意義,并可為參數(shù)化根系結(jié)構(gòu)模型提供重要依據(jù)。本論文基于整根取樣掃描測(cè)定的側(cè)根拓?fù)浣Y(jié)構(gòu)和幾何形態(tài)數(shù)據(jù),量化了各級(jí)側(cè)根形態(tài),并分析了各個(gè)根系性狀間的關(guān)系；結(jié)合田間原位測(cè)定的軸根三維數(shù)據(jù),構(gòu)建了不同根構(gòu)型的玉米根系三維結(jié)構(gòu)模型；基于模型評(píng)估了不同根鉆取樣策略的可靠性和適用性。主要結(jié)果如下：(1)側(cè)根的基部直徑具有較高的變異性。側(cè)根的基部直徑部分決定于支撐根直徑的大小。基部直徑?jīng)Q定了根的潛在生長(zhǎng)長(zhǎng)度,然而,大部分根的長(zhǎng)度遠(yuǎn)低于其潛在生長(zhǎng)長(zhǎng)度。這可能是由于伴隨根生長(zhǎng)根直徑變化模式的差異性造成的。對(duì)于大部分根,從根基到根尖,直徑大多呈現(xiàn)下降趨勢(shì),且直徑下降梯度的斜率依賴于根基部直徑。較長(zhǎng)的根多為在生長(zhǎng)過(guò)程中能維持(或增加)其直徑的根。側(cè)根的分枝密度也受到支撐根直徑大小的影響。然而,支撐根段在父級(jí)根所處的位置也影響到根段上側(cè)根的分支密度。較高的側(cè)根分支密度往往出現(xiàn)在父級(jí)根的中間位置。(2)1級(jí)側(cè)根的長(zhǎng)度和密度并不總是相關(guān)于其在軸根上的生長(zhǎng)位置,而是相關(guān)于軸根直徑的大小。有側(cè)根分枝的1級(jí)側(cè)根占1級(jí)側(cè)根總數(shù)不到50%,但其對(duì)根系總長(zhǎng)的貢獻(xiàn)高達(dá)85-91%。1級(jí)側(cè)根上分枝總數(shù)和總長(zhǎng)的變異性不僅依賴于1級(jí)側(cè)根的長(zhǎng)度,還依賴于側(cè)根單元(LRU)的級(jí)別。LRU級(jí)別越高,各級(jí)側(cè)根長(zhǎng)度、直徑和分枝個(gè)數(shù)越大。1級(jí)側(cè)根基部直徑與2級(jí)側(cè)根最大直徑的正相關(guān)關(guān)系以及1級(jí)側(cè)根基部直徑和長(zhǎng)度的正相關(guān)關(guān)系的斜率隨著LRU級(jí)別的增加而升高。(3)基于實(shí)測(cè)數(shù)據(jù)構(gòu)建了個(gè)體和群體玉米根系三維結(jié)構(gòu)模型,對(duì)常用的根鉆取樣策略進(jìn)行了虛擬取樣評(píng)估。結(jié)果表明,采用單點(diǎn)取樣策略所估測(cè)的根長(zhǎng)密度(RLD)都存在顯著偏差；采用兩點(diǎn)取樣策略估算RLD同樣存在顯著偏差,只有在賦予兩個(gè)取樣點(diǎn)特定權(quán)重時(shí),才能得到偏差較小的RLD估算值。本研究提出基于面積權(quán)重估算RLD的行間多點(diǎn)取樣策略。結(jié)果表明,采用行間3點(diǎn)取樣策略時(shí),使用較大直徑根鉆(10和7.5 cm)能獲得偏差較小的RLD估算結(jié)果。忽略行間最遠(yuǎn)的取樣點(diǎn),僅使用2點(diǎn)取樣時(shí),也能得到偏差較小的RLD估算結(jié)果。本研究基于根段尺度量化了側(cè)根直徑和分支,系統(tǒng)檢測(cè)了根系形態(tài)特征和幾何結(jié)構(gòu),揭示的各個(gè)根系性狀間的相關(guān)關(guān)系為庫(kù)-源模型中根系的生長(zhǎng)和分枝的模擬提供了重要依據(jù)�；谕�?fù)浣Y(jié)構(gòu)量化的各級(jí)側(cè)根形態(tài)特征及其相關(guān)關(guān)系充分體現(xiàn)了側(cè)根分枝在形態(tài)學(xué)上的連續(xù)性�；诟的Ｐ偷奶摂M評(píng)估在優(yōu)化根鉆取樣策略方面具有重要價(jià)值,為大田中后期玉米根系RLD分布的估測(cè)提供了最優(yōu)取樣策略。
[Abstract]:Root system is an important organ for plants to absorb water, nutrient resources and respond to changes in soil environment. Three-dimensional root structure model can accurately describe the spatial distribution of root system in soil. Quantitative study of lateral root morphology based on topological structure is of great significance in exploring root function-structure and can provide important basis for parameterized root structure model. In this paper, based on the topological structure and geometry data of lateral roots measured by whole root sampling scanning, we quantify the lateral root morphology of all levels and analyze the relationships among root characters, and combine with the axial root 3D data measured in situ in the field. The 3D structure model of maize root system with different root configurations was constructed, and the reliability and applicability of different sampling strategies of root drill were evaluated based on the model. The main results are as follows: 1) the base diameter of lateral roots has high variability. The basal diameter of lateral roots depends partly on the diameter of the supporting roots. The diameter of base determines the potential growth length of root, however, the length of most roots is much lower than its potential growth length. This may be due to the variation of root diameter with root growth. For most roots, the diameters tend to decrease from root to tip, and the slope of diameters gradient depends on the diameter of root. The longer roots are the ones that can maintain (or increase) their diameters during growth. The branch density of lateral roots was also affected by the diameter of supporting roots. However, the position of the supporting root segment in the parent root also affects the branch density of the lateral root on the root segment. The higher lateral root branching density often appears in the middle position of the parent root. The length and density of the lateral root are not always related to the growth position of the lateral root, but to the diameter of the axial root. The number of lateral roots with lateral roots branching is less than 50, but its contribution to the total root length is as high as 85-91.1 lateral roots. The variability of the total number of branches and the total length of lateral roots depends not only on the length of the first lateral root, but also on the total length of lateral roots. The higher the level. LRU is also dependent on the lateral root unit (LRU), the higher the lateral root length at each level, The larger the diameter and the number of branches, the higher the slope of the positive correlation between the basal diameter of the lateral root of order .1 and the maximum diameter of the lateral root of the second order, and the positive correlation between the diameter of the base of the lateral root of the first order and the length of the lateral root of the first order, and the increase of the slope with the increase of the LRU level. Three dimensional structure model of individual and population maize root system was constructed. The common sampling strategy of root drill is evaluated by virtual sampling. The results show that there are significant deviations in the estimation of root length densities by single point sampling strategy, and significant deviations exist in estimating RLD by two-point sampling strategy, only when two sampling points are given specific weights, In order to get the small deviation of the RLD estimate. In this study, a multi-point sampling strategy based on area weight estimation (RLD) is proposed. The results show that the RLD estimation results with small deviation can be obtained by using the large diameter root drill (10 and 7.5 cm) using the three-point sampling strategy between rows. RLD estimation results with small deviation can be obtained when only two sampling points are used to ignore the farthest sampling points between rows. In this study, the diameter and branch of lateral root were quantified based on root segment scale, and the morphological characteristics and geometric structure of root system were systematically examined. The correlation between root traits revealed provides an important basis for the simulation of root system growth and branching in the sink-source model. Morphological characteristics of lateral roots based on topological quantization and their correlation fully reflect the morphological continuity of lateral root branches. Virtual evaluation based on root model plays an important role in optimizing the sampling strategy of root drilling and provides the optimal sampling strategy for estimating the RLD distribution of maize roots in the middle and late stage of the field.
【學(xué)位授予單位】：中國(guó)農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：S513

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本文編號(hào)：1990090