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根据松树针叶变色程度及流脂状况,野外分别选取不同感病阶段的黑松、马尾松为对象,以研究松材线虫自然侵染黑松和马尾松后,两种松树的光合作用及其相关生理生化变化过程。结果表明,黑松、马尾松在感病初期,针叶净光合速率(Pn)大于健康阶段数值,随后逐渐下降,感病重期为负值,即松材线虫的侵入破坏了黑松、马尾松的光合作用。由叶绿素荧光参数分析可看出,光合作用的下降是由于光合系统Ⅱ反应中心实际进行光化学反应的效率(ФPSⅡ)下降引起的,而ФPSⅡ的下降是由于PSⅡ反应中心捕获光能效率Fv’/Fm’下降和开放的PSⅡ中心数目qP下降共同导致。两种松树在感病进程中,针叶叶绿素含量和类胡萝卜素含量整体呈下降趋势,但在感病初期含量上升,这也是引起光合作用速率下降的因素之一。此外,针叶含水量变化也一直呈下降趋势,是引起松树萎蔫,叶绿素含量下降,光合作用速率下降的主要原因之一。实验表明,随着松材线虫侵染的加重,植株体内与抗性相关的抗氧化酶系统活性也会发生变化。黑松和马尾松过氧化氢酶(CAT)活性随着感病进程逐渐下降,过氧化物酶(POD)活性和超氧化物歧化酶(SOD)活性略有上升,但不显著,说明松材线虫的侵入破坏了黑松、马尾松的抗氧化酶系统,导致松树自我保护作用减弱,同时由于两种松树热耗散能力(NPQ)的下降,产生的多余电子进一步破坏了抗氧化酶系统,导致光合速率下降。研究表明,松材线虫的侵染,对寄主光合作用产生了破坏,同时寄主也作出相应防御反应,但随着松材线虫的大量繁殖,寄主自身保护作用逐渐丧失。
According to the degree of discoloration of pine needles and the status of flowering fat, black pine and masson pine were selected in the field to study the photosynthesis of pine and masson pine Related physiological and biochemical changes process. The results showed that the net photosynthetic rate (Pn) of needles was higher than that of healthy stage in early stage of susceptible disease, then decreased gradually, and the negative relapse period was negative, that is, the invasion of pine wood nematode destroyed the black pine and the cauda equina Pine photosynthesis. From the analysis of the chlorophyll fluorescence parameters, the decline of photosynthesis was caused by the decrease of the actual photochemical reaction (ФPSⅡ) of the photosystem Ⅱ reaction center, and the decrease of ФPSⅡ was due to the capture of the light energy efficiency Fv ’/ Fm The decline in the number of open PS Ⅱ center and qP together lead to. During the process of susceptible, the chlorophyll content and carotenoid content of coniferous trees decreased, but the content of chlorophyll and carotenoids increased at the early stage of susceptibleness, which was also one of the factors that caused the decline of photosynthesis rate. In addition, the change of coniferous water content has also been a downward trend, which is caused by the wilting pine, chlorophyll content decreased, the photosynthesis rate is one of the main reasons. Experiments show that with the aggravation of the pine wood nematode, the antioxidant enzyme activity of the plant body system will change. Catalase (CAT) activity of Pinus thunbergii and Pinus massoniana decreased slightly with the progress of susceptible disease. Peroxidase (POD) activity and superoxide dismutase (SOD) activity increased slightly, but not significantly The nematode invaded the antioxidant enzyme system of Pinus thunbergii and Pinus massoniana, resulting in weakened self-protection of pine trees. At the same time, due to the decline of heat-dissipating capacity (NPQ) of the two pine species, the excess electron produced further destroyed the antioxidant enzyme system, Resulting in decreased photosynthetic rate. The results showed that the infection of pine wood nematode damaged the photosynthesis of the host, and the host also made the corresponding defensive response. However, with the large population of pine wood nematode, the host self-protection gradually lost.