Effects of seeding rate on botanical characteristics of Medicago sativa under different salt concentration

Salinized land is one of the important land resources for planting alfalfa (Medicago sativa). This field study was conducted to determine the effects of seeding rate on the planting, biomass and stem-leaf ratio of alfalfa under different soil salt concentrations. The results showed that the seed germination rate, survival rate, and wintering rate of alfalfa did not significantly change when the salt concentration increased from 0.3% to 0.5%; however, the seed germination rate, survival rate and wintering rate of alfalfa significantly decreased when the soil salt content was over 0.7%. With the increase of soil salt content, plant density, plant height, and aboveground biomass of alfalfa significantly decreased, while the stem-leaf ratio of alfalfa increased. With the increase of seeding rate of alfalfa, plant density, and aboveground biomass of alfalfa also increased, while the stem-leaf ratio and plant density of alfalfa did not significantly change. The change in aboveground biomass showed a downwardly opening “Turtle Back” under the interaction between seeding rate and soil salt content. All the above results suggest that the salinized land could be used for planting alfalfa when soil salinity was less than 0.5%, and that a seeding rate which was more than the common seeding rate (26.25 kg·ha-1) used by local farmers was required to improve the aboveground biomass of alfalfa.