| We carried out a systematic research on the photosynthetic characteristics of Yunnan Pine (Pinus yunnanensis Franch.), and the change of photosynthetic physiology of P. yunnanensis needles after being attacked by bark beetles and pine sawyer.The results showed that:(1) The net photosynthetic rate (Pn) of P. yunnanensis increased with the increase of light intensity and CO2 concentation, and the respond curves both fitted with the non-rectangular hyperbola. The maximum net photosynthetic rate (Pmax) of P. yunnanensis conifer needles reached 14.768μmol.m-2.s-1 under the saturated CO2 concentation, which was higher by 56.9% than that (9.412μmol.m-2.s-1) under saturated light intensity, and higher by 132.5% compared with Armand Pine (Pinus armandii Franch. ) under saturated light intensity. P. yunnanensis belonged to the conifer needles species with high light production potential, because it had the photosynthetic characteristics of high light and CO2 use efficiency, so it has higher light saturation point(LSP), Pmax,RuBP carboxylation efficiency(CE), photorespiration rate(Rp) and CO2 saturation point(CSP), but lower dark respiration rate (Rd), light compensation point(LCP) and CO2 compensation point(CCP).(2) Light response characteristics of P. yunnanensis differed in seasons(in May, Augest and November). Because of the different of the maturity of needles, the photosynthetic indexes responded differently to the light intensity individually. Except the apparent quantum yield(AQY), each major light respond parameter differed significantly in different seasons, especially for the maximum photosynthesis capacity. Pmax was 4.244μmol.m-2.s-1, 9.412μmol.m-2.s-1 and 8.160μmol.m-2.s-1 in May, Augest and Novembe respectively, and which in Augest was much higher than than in May and November. The utilization ability of low light intensity was the highest in May and the LCP was the lowest. While, the utilization ability of high light was the highest in Augest and the LSP was highest. So Augest was the main photosynthesis growth and timber volume accumulation period of P. yunnanensis.(3) In the dry season, the results of diurnal changes of photosynthesis showed: the diurnal changes of photosynthesis of P. yunnanensis showed a single-peak curve both in December and March next year. The Pn peak value appeared at about 10:00 a.m. in December, but the value appeared at 14:00 p.m. in March next year, which delayed a little and 36% higher compared with that in December. And the value of Pn diurnal accumulation apparently was higher in March next year than that in December. The change tendency of transpiration rate (Tr) and stomatal conductance (Cond) was similar to Pn, while the trend of intercellular CO2 concentration (Ci) was opposite to Pn. Diurnal changes of water utilization efficiency (WUE) both showed a double-peak curve in December and March next year. Photosynthetically active radiation(PAR) and relative humidity(RH) were the strongest environmental factors affected the photosynthesis of P. yunnanensis , and Tr was the physiological parameters controled by environmental factors most significantly. The simulation method, we put forward to solve the conifer needles transpiration of P. yunnanensis by Ball-Berry model and non-rectangular hyperbola photosynthetic model, which was based the observation datas of the P. yunnanensis diurnal changes of phtosynthesis and combined with the regression model of Tr and Cond, had a certain guiding significance.(4) Tomicus minor (Hartig) and Tomicus yunnanensis Kirkendall & Faccoli were 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. After P. yunnanensis was attacted by Bark beetles ( shoot boring or trunk boring), the ability of its CO2 assimilation was affected significantly. Net photosynthetic rate (Pn) decreased by 31% and 65% respectively when in the periods of shoot boring and trunk boring. the photosynthetic indexes as stomatal conductance (Cond) and transpiration rate (Tr) etc. also decreased very significantly(p<0.01), and the chlorophyll content of conifer needles decreased significantly(p<0.05). The ratio of chlorophyll a and chlorophyll b (Chla/b) of conifer needles after shoot boring was significant higher than those who was healthy or after trunk boring. The correlation analysis showed: the correlation of Pn and each physio-ecological factors, especially between Pn and main physio-ecological factors was different at different stages caused by the borer damage of Bark beetles. The maximum fluorescence (Fm), the maximum light quantum efficiency (Fv/Fm) and Fv/Fo all decreased significantly becaused of the shoot boring and trunk boring of Bark beetles. The results indicated that there were 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 borer insects on P. yunnanens.The analysis of diurnal variation of photosynthesis of P. yunnanensis in March showed that: after shoot bored (50%), the Cond and Tr decreased significantly, Ci increased and the photosynthesis daily progress had a very significant difference compared with healthy pines. Diurnal Variation curve of Pn of needles being attacked was one single peak curve, having hardly midday depression of Pn. and the Pn peak value of the bored pine appeared 2 hours ahead (compared with 14:00) and decreased by 32% compared with the healthy, and the main period of photosynthesis of P. yunnanensis shoot bored appeared in the morning.(5) During the period of M. alternatus complementary nutrition(from the 1st day to 13th day), their choice of different branch age had significant differences, showed that the amount of they ate current-year branch was significantly higher than the perennial branch and their feeding amount in their different growth phases showed significant differences. After the first day, the Pn of needles increased by 20% compared with the control, but with the prolonging of fed and aggravation of feeding degree, the Pn of needles showed obviously downtrend, but the WUE of needles was higher than the control during the period of complementary nutrition and reach the highest value in the 6th day.
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