橡胶树籽苗芽接苗不同物候期的光合特性

Study of Photosynthesis Characteristics of Grafted Mini-Seedling of Hevea brasiliensis at Different phenophases

在适宜温度(28.5+0.5)℃,相对湿度(75+5)%和正常大气CO2浓度条件下,采用活体测定方法,在不同物候期,对橡胶树籽苗芽接苗砧木和接穗第1蓬叶的光合特性进行了研究。结果表明,橡胶树籽苗芽接苗砧木和接穗第1蓬叶的光合特性变化规律基本相似,从变色期、淡绿期、稳定期,到衰老期,其叶片的表观量子效率(α)、最大净光合速率(Pmax)、光饱和点(PSLI)和叶绿素含量(CHL)等均随着物候期变化而不断变化,变化趋势为先迅速升高,达到最高值后缓慢下降;光补偿点(LCP)的变化趋势则相反。不同物候期的光补偿点和光饱和点有较大的差异,光补偿点为12￣78μmol/(m2·s),光饱点为256￣1109μmol/(m2·s)。与砧木相比,接穗有较高的光饱和点和较低的光补偿点。

Dynamic light responses to net photosynthetic rate of grafted mini-seedlings of Hevea brasiliensis at different phenophases within the first whorl of leaves of stock and cion were measured under a temperature of （28 ±0.5） ℃, a relative humidity of （75±5） % and normal ambient concentration of CO2. Results showed that the change of photosynthesis of the first whorl of leaves was similar generally between the stock and the cion, changing from leaf discolor, grey green, stable to senescent stages, and that the max net photosynthetic rate （Pmax）, photosynthetic saturated light intensity （PSLI） and chlorophyll content of the leaves changed continuously with the phenophases, which rose rapidly and then dropped slowly after the peak, whereas the change of their light compensation point （LCP） was just the opposite. The PSLI and LCP were highly different at different leaf phenophases with the PSLI ranging from 256 to 1 156 μmol/（m^2·s） and the LCP from 12 to 78 μmol/（m^2·s）. The cion had higher PSLI in the first whorl of leaves but lower LCP as conlpared to the stock.