松嫩平原两个趋异类型羊草无性系种群特征的比较研究

COMPARITIVE STUDY ON CHARACTERS OF TWO DIVERGENCE TYPES OF THE CLONE POPULATION LEYMUS CHINENSIS IN THE SONGNEN PLAIN OF CHINA

松嫩平原上羊草(Leymus chinensis(Tzvel.)Tzvel.)有两个趋异类型:灰绿型和黄绿型。两个类型羊草的分蘖节一般均存活2～4年,最多可存活5年;根茎一般存活2～3年,最多可存活4年。两个类型无性系种群的分蘖株均为增长型的年龄结构类型。种群根茎的累积长度,灰绿型为18035cm/m^2,黄绿型为21218cm/m^2,其中,均以1、2龄占绝对比重。两个类型均以1龄分蘖株生产力最大,至3龄分蘖株明显减小;各龄根茎的生物量随着年龄的增加呈直线下降;1龄根茎的营养繁殖力甚强,至8月中旬所形成的芽数均已远远多于地上全部分蘖株数;2龄根茎尚存在较小的营养繁殖潜力,3、4龄根茎均已丧失了营养繁殖力。两个类型羊草无性系种群都是通过根茎芽补充更新。

Leymus chinensis (Trin.) Tzvel. is a rhizome grass species with high vegetative prop-agativity. A single species dominancy community of L. chinensis is often developed by vegetative propagation in suitable habitat. The species has two divergence types, a grey-green and a yellow-green , in the Songnen Plain of China. The age structures of the tillers and rhizomes of the two types of clonal populations in the single species dominancy communities of L. chinensis in natural grassland were comparatively analysed. The standards of age differentiation were that the tillers developed from rhizome buds were age one, while the ages of others were identified with the generation numbers of vegetative propagations of the tiller nodes. Rhizomes of age one were developed in the current growing season, and the ages of others were defined as the number of their surviving years. The ages of each tiller or rhizome were respectively distinguished by morphological characteristics including positions of the tiller nodes and the marks of surviving tillers of vegetative daughters. The results showed that the tiller node lived 2 to 4 years in general, the oldest could live up to 5 years, and the rhizome lived 2 to 3 years in general, occasionally up to 4 years. The age spectrum of tillers from age one to age four in the grey-green population was 65.5%, 26.6%, 6.6% and 1.3% respectively, and likewise that in the yellow-green population was 63.2%, 27.8%, 6.9% and 2.1% respectively . For the clonal populations of the two types, the tillers showed expanding age structures, and the tillers of age one had largest productivities, while those of the age three had evidently decreased. The accumulative length of the rhizomes of the yellow-green population was 21 218 cm/m ,and that of the grey-green populations was 18 035 cm/m2 . The biomass of rhizomes demonstrated a linear decrease in relation to age increase. The vegetative propagativity of age one rhizomes was the largest, the number of buds being far more than the total above-ground tillers at the mid-ten days of August. The age two rhizomes had less potentiality of vegetative propagation and those of age three and age four had lost all the vegetative propagativity. The clonal populations of the two types of L. chinensls were always recruited through the rhizome budding.