摘要
应用分形理论中的周长面积法和曲线长度法分析了水稻纹枯病、玉米大斑病、玉米小斑病和桃细菌性穿孔病4种病害病斑形状的分形维数。结果表明 ,病斑形状具有明显的分形特征 ,其复杂性可以用分形维数的大小来表示 ,形状愈复杂 ,分形维数愈大 ,反之则愈小。周长面积法所得的分形维数分别是水稻纹枯病 1 3385 ,玉米大斑病1 3799,玉米小斑病 1 16 33,桃细菌性穿孔病 1 0 4 70。曲线长度法所得的分形维数依次为水稻纹枯病 1 30 84 ,玉米大斑病 1 2 919,玉米小斑病 1 0 2 2 3,桃细菌性穿孔病 1 0 5 6 1。同一种病害中不同病斑之间分形维数变化范围表明了单个病斑之间形状差异。两种方法均可用于单个病斑或一类病斑分形维数的测算 。
Fractal characteristics of patch patterns of sheath blight on rice, Northern blight on corn, Southern blight on corn and Xanthomonas shot hole on peach were described by fractal geometry, and fractal dimensions determined by perimeter-area and walk-divider. The results indicate that patch patterns of these plant diseases, like many naturally irregular structures, are approximately fractal; thus fractal dimension values can be used to quantify their complex extent. Fractal dimensions of rice sheath blight, Northern blight of corn, Southern blight of corn and peach Xanthomonas shot hole are 1.338 5, 1.379 9, 1.163 3, and 1.047 0, respectively with perimeter-area. And those of them are 1.308 4, 1.291 9, 1.022 3, and 1.056 1, respectively with walk-divider. The result also shows that patch pattern changes at the same disease are reflected in the variation of fractal dimension. Alathough both perimeter-area and walk-divider are reliable, it is suggested that the former is better to analyze the disease patch patterns.
出处
《植物保护》
CAS
CSCD
北大核心
2002年第6期9-13,共5页
Plant Protection
