基于μCT的番茄穴盘苗根系结构及分布特征

Root structure and distribution characteristics of tomato seedlings based on μCT

为了获得清晰的番茄穴盘苗根系原位三维图形和表达根系的分布特征,利用X射线μCT对番茄苗钵进行扫描和根系重构,当扫描电压、电流和分辨率分别为55 kV,72μA,45μm时,重构的根系体积与实测的体积相对误差为4.77%.垂直方向上,根系密度变化显著,苗钵在根系分布密度较低的中间区域易发生断裂,可以用各区域根系分布密度的最小和最大值的比值作为评价根系分布均匀程度的指标;水平方向上,侧根主要分布在苗钵外围,起到包裹育苗基质和防止苗钵散坨的作用,可以用苗钵外围的根系分布密度作为评价根系包裹基质紧密程度的指标.当育苗基质用草炭、蛭石和珍珠岩按3∶1∶1体积比混合制成,基质的压实度取1.2倍穴孔体积时,根系分布均匀程度为0.564,外围根系分布密度为0.021 1.

To obtain the clear three-dimensional figures and the distribution characteristics of tomato roots, X-ray μCT was used to scan tomato plug seedlings and realize root reconstruction. For the scanning parameters with voltage of 55 kV, current of 72 μA and resolution of 45 μm, the relative error of root volumes between 3D reconstruction and actual measurement is 4.77%. At the vertical direction, the root distribution density changes significantly. The seedling plugs are more prone to fracture in the middle of root density lower areas. The ratio of the minimum and the maximum root distribution densities can be considered as evaluation indicator of root distribution uniformity. At the horizontal direction, the seedling plugs are surrounded by the lateral roots, and the soil substrate is shaped without dispersing. The peripheral root distribution density can be used as another evaluation indicator of root-soil tightness. When the seedling substrate is mixed with peat, vermiculite and perlite in volume ratio of 3 ∶ 1 ∶ 1, and the compaction degree of seedling substrate is 1.2 times the pore volume of tray, the root distribution uniformity and the peripheral root distribution density are 0.564 and 0.021 1,respectively.