Study On Relationship Between Planting Density And Alfalfa Seed Yield

Through different planting density treatments of different row space and plant space, we study on the change of row space and plant space and the relationships between two-year-alfalfa growth, fructification, colony development traits, light pass thought ratio, the change of soil water content, the change of LAI and seed yield component. Planting density lever designed: row space of 60cm, 80cm, 100cm and plant space of 2cm, 10cm, 20cm, 30cm, its add up to 12 treatments. Results showed that planting density has littler influence on height and growth speed at vegetable stage, but planting density has significance influence on height and growth speed at budding stage and flower stage. At flower stage, LAI increased when planting density was increased, while it fall down at pod stage. Leaves area at pod stage was less than it at initiation flower stage and full-blown stage. No significant difference was fled on leaf area between all treatments. At the early stage, No significance difference was fled on average soil water content between all treatments, but at harvesting stage, the average soil water content of high-planting-density treatments was higher than low-planting-density treatments. Effect of planting density on the amount of nods was more than it on the length of nodes. Significance difference was fled on the first grade valid branch and the second grade valid branch between higher-plant-space treatments and lower-plant-space treatments. With the increasing of plant space, the amount of the second grade valid branch was increasing. The correlation coefficients were very high between the amount of fertile branch and seed yield (r=0.859). The amount of fertile branch per square meter increased when enlarged planting density. Results show that the influence of plant space upon alfalfa seed yield was far larger than row space, when plant space less than 20 cm, the lessen the plant space, the lower seed yield we got.