不同钾水平下杂交稻~(14)C-光合产物运转动力学

用~(14)CO_2饲喂杂交籼稻威优35功能叶,研究光合产物在体内的运转。结果表明,源叶光合产物的输出及库(幼叶或谷粒)同化物输入的百分率(v)和时间(t)之间的关系均极显著地符合回归方程v=Vt+k)/K_m+(t+k))。在分蘖期,主茎顶部完全展开叶可输出66％～79％的~(14)C-光合产物;低钾处理使源叶输出潜能和速率下降,过量钾处理加快光合产物输出速率;未展开的幼叶可输入28％～59％的~(14)C-光合产物,低钾不仅降低输入潜力,且使输入延迟。在灌浆期,剑叶可输出83％～97％的光合产物,其中77％～88％运往谷粒;低钾处理延迟光合产物输出时间,降低输出速率;过量钾处理降低输出潜力,但提高输出速率;低钾处理还降低同化物输入谷粒的比例和速率,过量钾处理降低同化物输入谷粒的比例,但提高输入速率。所以,从总体上看,低钾和过量钾处理都不利于新固定的同化物在体内的运输。

TRANSLOCATION KINETICS OF ~(14)C-PHOTOSYNTHATE IN HYBRID RICE GROWN AT DIFFERENT POTASSIUM LEVELS

The kinetics of translocation of 14C-assimilate in hybrid rice plant was studied with 14CO2 fed to functional leaf at the tillering and filling stages.The results indicated that the relationship between percentage(V) of photosynthate exporting out of the source leaf or that of assimilate into sink,expanding young leaf or filling panicle,respectively,and time(t) after introducing 14CO2 into the leaf was extremely coincided with the regression equation;v=V(t + k)/Km+(t+k).At the tillering stage,fully extended top leaf could export 66%~79% of its photosynthate assimilated at different potassium levels,and both export potential and rate of 14C-photosynthate in the fed leaf decreased under the low potassium (1ppm K supplied),but the rate obviously increased in the superflous potassium(80ppm K supplied) in spite of slightly low exporting capacity.Main sink,the expanding young leaf on the top of stem could obtain 28%-59% of 14C-assimilate at various potassium levels.Both the importation potential and rate were lowered with low potassium application while hastened by super-supplied potassium at the same development stage.At the filling stage,source,flag leaf,was able to export 83%~97% of its photosynthate and low potassium(5ppm) application not only delayed the time of 14C-photosynthate exportation but also diminished the export rate,whereas the rate was accelerated by superflous potassium.Low potassium resulted in desrease in both the capacity and the rate of assimilate importing into grain,nevertheless,high potassium caused decrease of percentage assimilate importing into grain and the increase of importing rate.Therefore,it was strategically considered that neither deficient nor superflous potassium application was beneficial for assimilate transportation.