冬、春田间枇杷叶片光合机构的运转

冬季枇杷光合作用的最适温度低于春季,光合作用的最适叶温高于环境温度;冬季枇杷的叶绿素含量、净光合速率(Pn)、Rubisco活性、RuBP再生速率、表观量子效率(AQY)、PSⅡ最大光化学效率(Fv/Fm)、光下的光化学效率(Fv'/Fm')、光化学猝灭系数(qP)及电子传递速率较低,PSⅡ反应中心失活或破坏,细胞间隙CO2浓度与环境CO2浓度比值(Ci/Ca)、光呼吸速率与净光合速率比值(Rp/Pn)、光呼吸速率与暗呼吸速率的比值(Rp/Rd)及非光化学猝灭系数(qN)较高。这些结果说明,枇杷光合作用的最适温度与环境温度的变化相适应,低温环境是限制枇杷光合作用的重要因子;光合碳代谢和光化学反应受到低温的限制是冬季光合作用较低的重要原因;在碳代谢中光呼吸所占的比例增加和非辐射能量耗散对光合机构运转有保护作用。

The Operation of Photosynthetic Apparatus of Loquat Leaves in Winter and Spring

The temperature optimum for photosynthesis of loquat(Eriobotrya japonica Lindl.) leaf was lower in winter than in spring. The leaf temperature optimum for photosynthesis of loquat leaves was higher than environmental temperature. In the winter, the chlorophyll content, net photosynthetic rate (Pn), Rubisco activity, rate of RuBP regeneration, apparent quantum yield (AQY), photochemical efficiency of PSⅡ(Fv/Fm), photochemical efficiency under light(Fv'/Fm'), photochemical quenching coefficient(qP), and electron transport rate (ETR) were lower, but the ratio of photorespiratory rate (Rp) to dark respiration(Rd), the ratio of photorespiratory rate (Rp) to net photosynthetic rate (Pn), and non-photochemical quenching coefficient(qN) were higher, PSⅡ reaction centers is reversible inactivation or damage. These results indicated that the temperature optimum for photosynthesis of loquat leaves was adaptable to the changing natural environment temperature. Low temperature of winter limited photosynthetic carbohydrate metabolism and photochemical reaction caused low photosynthesis, increased proportion between photorespiratory and photosynthesis in the carbohydrate metabolism,and non-radiative energy dissipation, played important protective role in the photosynthetic apparatus operation in loquat leaves.