受小蠹虫不同阶段为害的云南松光合生理反应分析

Analysis on Photosynthetic Physiological Responses of Pinus yunnanensis Franchet to Bark Beetles Attacking in Different Stages

分析了15年生云南松在横坑切梢小蠹、云南纵坑切梢小蠹在蛀梢和蛀干为害期的针叶光合生理反应。Dun-can多重比较结果表明:云南松在小蠹虫蛀梢和蛀干期显著影响了针叶同化CO2的能力,针叶净光合速率分别下降了31%和65%,气孔导度、蒸腾速率等光合指标也出现极显著下降(P<0.01)。相关性分析表明:针叶净光合速率与各生理生态因子的相关关系以及主要生理生态因子之间的相关关系在小蠹虫不同的蛀害期而不同。小蠹虫蛀梢和蛀干为害显著降低了针叶叶绿素含量(P<0.05),但受蛀梢为害的云南松针叶叶绿素a/b值显著高于健康或受蛀干为害的云南松。针叶最大荧光(Fm)、最大光量子效率(Fv/Fm)以及Fv/Fo均因小蠹虫蛀梢和蛀干为害而显著下降,尤以在被蛀干时的针叶Fm、Fv/Fm、Fv/Fo下降幅度更大。综合分析表明:受小蠹虫"胁迫"(蛀梢、蛀干)后针叶叶绿素合成受到显著影响,引起了寄主云南松光合机构的破坏,导致寄主云南松树势下降,这必为喜欢攻击亚健康或衰弱林木的次期性昆虫创造合适的寄主。

Tomicus minor （Hartig） and Tomicus yunnanensis （Kirkendall ＆ Faccoli ）are two severely boring bark beetles of coniferous forest of Pinus yunnanensis （Franchet） in Yunnan Province. The geographical distribution and the boring period of the both were mutually overlapping, shoot and trunk could be attacked by them also in their damage progress. Hence, the character of combined damage to host P. yunnanensis was presented. In this paper, the needle photosynthetic physiology of P. yunnanensis attacked by the two bark beetles at different stages （shoot boring stage and trunk boring stage） were analyzed in a 15-year-old Pinus plantation in Yunnan Province. The results showed that both shoot and trunk bored by the bark beetles caused a significant decrease in photosynthesis of P. yunnanensis needles. The results from Duncan multiple comparison showed that the main photosynthetic indexes, such as net photosynthetic rate, transpiration rate, and stomatal conductance decreased very significantly （P 〈0.01）. The net boring. photosynthetic rate The simple correlati decreased by 31% and 65% separately when in the periods of shoot boring and trunk on and partial correlation of physio-ecological factors with net photosynthetic rate or the correlations among main physio-ecological factors of trees were different due to attacking by the two bark beetles at different stages respectively. Total chlorophyll content of needles also decreased significantly in P. yunnanensis after bark beetles attack, both for shoot boring and for trunk boring （P 〈0.05）, but the value of chlorophyll a/b of needles for shoot boring was significantly higher than that were healthy or tnmk boring; The analysis of chlorophyll fluorescence parameters of needles showed that the bark beetles＇ shoot boring or trunk boring also caused Fm, Fv/Fm Fv/Fo of PSII decreased significantly and photo inhibition. The results indicated that there was significant effects on chlorophyll biosynthesis under the herbivore stress by bark beetles. To a great extent, it was a damage to photosynthetic apparatus of host plants P. yunnanensis and resulted in photosynthetic ability decreased. Furthermore, weakened the host tree vigour and paved the way for the following secondary shoot borer insects on P. yunnanensis.