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本文研究了不同光照条件下生长的油松播种苗和2年生苗木的光合、呼吸和生长特性;并测定了在光照条件突然改变后,油松播种苗的净光合作用速率和叶绿素含量的变化.采用遮荫法获得其光照强度分别占温室内全光的17.7%、50.0%、100.0%的Ⅰ、Ⅱ、Ⅲ三种处理.按叶表面积计算其净光合速率,处理Ⅰ只占处理Ⅱ的60%;如按叶干重计算播种苗的净光合速率,处理Ⅱ只占处理Ⅰ的59%.各处理的光呼吸速率在0.30～0.39mg/dm2.h之间,占净光合速率的10%左右;暗呼吸速率为0.10～0.30mg/dm2.h,占净光合速率的5%～8%.处理Ⅱ、Ⅲ2年生苗木的总叶绿素含量各为1.16mg/gFW、0.95mg/gFW,分别占处理Ⅰ的82%和67%.处理Ⅱ、Ⅲ的苗高分别为处理Ⅰ的72%和62%.处理Ⅰ的干重只有处理Ⅱ的60%.光照条件改Ⅰ→Ⅱ3天内,播种苗的净光合作用就下降了30%,总叶绿素含量下降25%.在实验的18天内,变后,从没有发现光合速率的恢复.a/b值也略有升高(0.11);Ⅰ→Ⅱ和Ⅱ→Ⅲ光合和总叶绿素含量无明显变化、Ⅱ→Ⅱ3天内,叶绿素含量升高25%左右,a/b值下降0.3,但净光合速率无明显变化.
In this paper, the photosynthetic, respiration and growth characteristics of seedlings and two-year-old seedlings of Pinus tabulaeformis and Pinus tabulaeformis seedlings grown under different light conditions were studied. The net photosynthesis rate and chlorophyll content of seedlings were measured after the light conditions changed suddenly. The shading method was used to obtain the three treatments of Ⅰ, Ⅱ and Ⅲ with the light intensity of 17.7%, 50.0% and 100.0% of the total light in the greenhouse, respectively, and the net photosynthetic rate %, The net photosynthetic rate of sowing seedlings was calculated according to the leaf dry weight, and the treatment II only accounted for 59% of the treatment I. The photorespiration rate of the treatments was 0.30-0.39mg / dm2.h, accounting for 10% of the net photosynthetic rate , The dark respiration rate was 0.10 ~ 0.30mg / dm2.h, accounting for 5% ~ 8% of the net photosynthetic rate.The total chlorophyll content of the seedlings treated with Ⅱ and Ⅲ years were 1.16mg / gFW and 0.95mg / gFW, The seedling height of treatment Ⅱ and Ⅲ were 72% and 62% of that of treatment Ⅰ respectively, and the dry weight of treatment Ⅰ was only 60% of that of treatment Ⅱ. Light conditions changed Ⅰ → Ⅱ Within 3 days, Net photosynthesis decreased by 30%, the total chlorophyll content decreased by 25% in the experiment within 18 days, after the change, never found photosynthesis The rate of a / b was also slightly increased (0.11). There was no significant change in photosynthesis and total chlorophyll content of Ⅰ → Ⅱ and Ⅱ → Ⅲ. The content of chlorophyll increased about 25% in Ⅱ → Ⅱ days, the value of a / b Decreased 0.3, but no significant changes in net photosynthetic rate.