Aims- Planting density, as one of the most important factors affecting crop yield and quality, will result in plant competition for light, water and nutrients. The objective of this study is to explore the effect of planting density on growth and yield of Medicago sativa population.
Methods The population density experiments of M. sativa was conducted in a greenhouse with six planting densities, i.e. 25, 100, 400, 800, 1 500 and 2 000 plants·m -2. At each plot, we measured plant height, basal diameter, branch number, biomass, and number of survivors.
Important findings The results showed that the average planting density was 25, 100, 373, 745, 1 255 and 1 938 plants·m -2 in the 15 days after sowing. With the growth of M. sativa, except for the low density treatments (25 and 100 plants·m -2), the number of plant individuals under other density treatments decreased, and self-thinning occurred at some degrees. At the second harvest (187 days after sowing), the number of surviving plants decreased to 297, 571, 759 and 839 plants·m -2, respectively. The plant height, basal diameter and branch number of individual plants decreased exponentially with the increase of existing density. The relationships between individual biomass and existing density followed the competitive density effect law, that is, individual biomass decreased with the increase of density. The results also showed that the aboveground biomass of M. sativa per unit area has no significant differences among different densities, but the underground biomass tended to increase first and then decrease with the increase of planting density.