<正>用松材线虫接种1年生抗病和感病黑松苗，比较线虫侵染后引起寄主细胞和组织的变化。结果表明：接种后相同时间的茎段上抗病黑松细胞的病变及破坏程度要比感病松苗轻。感病黑松苗皮层树脂道及其周围薄壁细胞较早出现可见的病理变化，木质部最外层病变也明显。抗病黑松首先在皮层薄壁细胞出现可见的病理变化，然后发生变性和死亡的是树脂道及其周围薄壁细胞，而木质部最外层完好。可见，松材线虫诱导寄主组织病理学变化与松苗抗性相关。

In the instrument of lignum automatic measurement, the length of lignum was measured by CCD. The design of the time sequence driving circuit of CCD was a critical problem of its application. According to the complex programmable logic device, the method of designing the time sequence driving circuit was introduced. The CPLD was used as hardware design platform and VHDL was employed to describe the driving sequencer. The designed generator had successfully fulfilled system simulation with Quartus Ⅱ software and was fitted into MAX7000S. It was also observed by Oscilloscape. The simulation and the results of measurement demonstrated that this method is feasible. The time sequence was used to drive the CCD. This driving circuit of CCD was not only used by lignum automatic measurement but also by others CCD.