中文摘要：

分别于9月、11月和12月将菹草（Potrmogeton cripus）繁殖体石芽种植于盆中（沙：土=1：3），并将盆放置于露天水池70cm水深处．定期统计菹草石芽的萌发率和幼苗的株高、叶片数和叶宽，并利用水下饱和脉冲荧光仪（DIVING—PAM）测定幼苗的Fv／Fm和快速光响应曲线．结果表明，9～12月石芽均能萌发，第17d时萌发率为100％；9月、11月和12月的正午温度和光照差异显著，随着萌发月份的增大，幼苗的株高、叶宽和叶片数呈显著的降低趋势，差异达极显著水平（P〈0．01）；9月组和11月组幼苗叶片的Fv／Fm、rETRmax和饱和光强显著大于12月组幼苗；相关性分析表明，对于秋冬季的菹草萌发幼苗，水下光强和水温均对株高、叶片数和叶宽发育具有影响，特别是水温显著影响叶片的光合能力，因而相对于水下光强来说，在浅水水体中水温是幼苗生长发育的主要影响因素．

英文摘要：

In September, November and December, winter buds of Potrnwgeton cripus were cultivated in some pots （ sand： soil = 1 ： 3 ）, and pots were placed at 70 cm depth of the water in the open - air pool. Some statistics on a regular basis were made for germination ratio, plant height, and number of leaves and leaf width of seedlings, and Fv/Fm and rapid light response curves of the seedlings were determinated by use of underwater saturation pulse fluorescence instrument （ DIVING - PAM）. The results show that winter buds could germinate from September to December and germination ratio of all groups were 100% on the 17^th day. Temperature and light in September, November and December were significantly different at noon, and with the germination month increasing, plant height, leaf width and leaves number of the seedlings remarkably decreased （P 〈0.01 ）. Fv/Fm, rETRmax and saturation light intensity of leaves of September group seedlings and November group seedlings were significantly greater than those of December group seedlings. Correlation analysis shows that for germinated seedlings during autumn and winter, both of underwater light intensity and temperature have a wide impact on the development of plant height, number of leaves and leaf width. In particular, the water temperature evidently affected photosynthetic capacity of the leaves. As a result, compared with the underwater light intensity, water temperature was the main factor for these seedling＇ s growth and development in the shallow water.