Study On Germination And Growth Of Lespedeza Davurica

The experiment was conducted to study on germination of seeds responsing to hydration-dehydration cycles, growth rule and population density dependence of Lespedeza davurica, which theoretically studied the adaptability of seed germination in arid environment and the law of L. davurica population density dependence, it riched the theory of plant ecology and also provided basic date and science foundation of application of L. davurica. The results showed: 1 Undergoing the hydration-dehydration cycles; the water-absorbing rate of seed is quicker than untreated seeds, which improved efficiency of water utilized. The germination. rate and the indexes of germination of four treated seeds of hydration-dehydration cycles were similar to the other four treated seeds delayed with 120days. It relates that seed can retain "memory" that had accumulated during hydration and hydration-dehydration cycles which can improve the germination rate of seed. The germination indexes of seeds on HD-1 and HD-2 were higher than the untreated seeds, which suggested that seeds reduce the time lag between the beginning of seed water absorbing and germination; it was ecological adaptability of L. davurica in arid environment. 2 The growth rule of L. davurica were investigated. The results showed that the seedling stage was long in sow year, L. davurica turned green in the middle of May the second year; It had two or three branches in first year and five or six branches the second year; In the middle of July, it began to flower, flower season was short, and also blossom was concentrated; The root was abundant, it growed fast in side direction and longitudinal direction, which finely utilized the water of soil in different layers and adapted to arid environment. The results also showed that, the seed was small and inside calyx, the weight of thousand seeds was 2.726g and 2.385g without calyx, and most of the seed were hard seeds; The aboveground biomass of a plant is 15.7g, the ratio of stem/leaf was 1.1:1, the reproductive organ yield was 8.1g in ripe season; In the second year, The aboveground biomass of one plant is 35.7g, the ratio of stem/leaf was 1.9:1, the reproductive organ yield was 13.0g, the water content of plant was low; The protein content of leaf and reproductive organ was high. Considering plant regeneration and biomass, we can use flower as forage, also can harvest seed for using. 3 The plants have higher height, higher grow rate and longer shoot length in low density, while the plants in high density have shorter plant, smaller grow rate and smaller shoot length. It was suggested that the geometry morphology plasticity highly responsed to intraspecies competition in different density. After growing two years, the biomass of L. davurica was restricted in high density in later growth season, and the yield in low density exceeded that in high density. The individual biomass was significantly negative correlated with the density. The absolute value of slope (β) of the linear regression increased with growth season. The underground biomass was higher in high density than that in low density. The root is the main competitive position of perennial plants. The seed yield was different in different density, the highest is 125.82g/m2, and the lowest is 48.18g/m2, thus plant have higher sexual reproduction allocation in appropriate density population.