薏苡生育期中叶片光合性能的研究

A study on leaf photosynthetic performance of Job's tears during growing period

以田间栽培的薏苡[Coix lacryma-jobi(L.)var.frumentacea Makino]为材料,对薏苡生长发育过程中叶片的光合速率等光合性能进行了研究。结果表明:薏苡全生育期中叶片的光合色素含量在苗期较低,营养生长旺盛期含量提高,分蘖末期到穗花期初期达到最高值后又逐渐降低。生育期中叶片净光合速率(Pn)、蒸腾速率(E)和水分利用效率(WUE)都呈单峰曲线变化,其中Pn和E的高峰较明显,WUE在全生育期中起伏变化较小。晴天条件下,Pn、E和气孔导度(gs)从早晨开始随光合有效辐射(PAR)和气温同步升高,Pn和gs在11:30左右达到高峰值后即呈下降趋势,E则在下午出现另一峰值。由叶片可溶性糖与游离氨基酸含量的比值计算的C/N比在成熟期最高,穗花期其次,苗期和分蘖期较低,这可能是有利于穗发育和开花的碳氮代谢特性。

With field materials, photosyn The results showed -grown Job＇s tears [Coix lacryma-jobi （L.） var. frumentacea Makino thetic performance, such as net photosynthetic rate （Pn）, was studi that, during the life span of Job＇s tears, the contents of photosynth as ed. eric pigments in leaves were lower during seeding period, and increased during the prosperous vege tative growth period, reached the maximum value between late tillering to early spike-anthesis, and gradually decreased again thereafter. Leaf Pn, transpiration rate （E） and water use effi- ciency （WUE） were all single peak curves during the life span of Job＇s tears, with obvious peaks of Pn and E, and smaller fluctuation of WUE. On a sunny day, Pn, E and stomatal con ductivity （gs） increased from morning simultaneously with the increase of photosynthetically active radiation （PAR） and air temperature. Pn and E reached their peaks at about 11..30 and decreased thereafter, but E showed another peak at afternoon. The C/N ratio calculated from the content ratio of soluble sugar to free amino acid was the highest during maturity period,then the spike-anthesis period, and the ratios during seedling and tillering periods were lower. This is probably a characteristic beneficial to spike development and anthesis.