Quantitative study of root morphological characteristics of plants is helpful for understanding the relationships between their morphology and function. However, few studies and little detailed and accurate information of root characteristics were reported in fine-rooted plants like rice (Oryza sativa L.). The aims of this study were to quantitatively classify fine lateral roots (FLRs), thick lateral roots (TLRs), and nodal roots (NRs) and analyze their dynamics of mean diameter (MD), lengths and surface area percentage with growth stages in rice plant. Pot experiments were carried out during three years with three rice cultivars, three nitrogen (N) rates and three water regimes. In cultivar experiment, among the three cultivars, root length of ‘Yangdao 6’ was longest, while the MD of its FLR was the smallest, and the mean diameters for TLR and NR were the largest, the surface area percentage (SAP) of TLRs (SAPT) was the highest, indicating that Yangdao 6 has better nitrogen and water uptake ability. High N rate increased the length of different types of roots and increased the MD of lateral roots, decreased the SAP of FLRs (SAPF) and TLRs, but increased the SAP of NRs (SAPN). Moderate decrease of water supply increased root length and diameter, water stress increased the SAPF and SAPT, but decreased SAPN. The quantitative results indicate that rice plant tends to increase lateral roots to get more surface area for nitrogen and water uptake when available assimilates are limiting under nitrogen and water stress environments.

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顾东祥 汤 亮 曹卫星 朱 艳 * 南京农业大学 / 江苏省信息农业高技术研究重点实验室, 江苏南京 210095 摘 要: 利用图像分析方法定量研究水稻根系形态特征指标的变化规律。通过实施不同水氮处理和不同品种的水稻 桶栽试验, 选用 WinRhizo (WR)软件的不同模式(LM 和 T200)分析根系图像, 分别提取根直径范围 0~0.30 mm 和 0.25~1.80 mm 的根系形态数据, 并与基于 Image-Pro Plus 6.0 软件(IP)的根直径和不定根长的测量结果进行比较分析; 确定了 3 种水稻品种不同类型根直径的范围; 对不同生育时期水稻根长、根体积、根表面积、根系干重和不定根数 量等水稻根系形态特征指标变化差异, 以及分枝特征进行了分析。结果表明：(1)基于 WR 软件 LM 和 T200 模式下 的根直径测量结果与基于 IP 软件的测量结果之间 NRMSE 分别为 5.44%和 10.95%。(2)界定细分枝根直径范围为 0.03~0.10 mm, 扬稻 6 号(V3)粗分枝根和不定根分别为 0.10~0.30 mm 和 0.30~1.65 mm, 而日本晴(V1)和武香粳 14(V2) 分别为 0.10~0.25 mm 和 0.25~1.40 mm, 不定根长与 IP 测量结果进行比较, 其 NRMSE 为 10.78%~12.01%。(3)各指标

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