Effect of soil extract from an apple orchard on ryegrass and alfalfa seed germination and seedling growth in eastern Gansu

Inclusion of grass into fruit-tree orchards, is a new strategy of soil management. Successful grassland establishment is essential for the construction of this model. However, the specificity of soils in apple orchards may affect grass seed germination and seedling growth; thereby, affecting grassland establishment. The effect of soil extract on ryegrass (Lolium perenne) and alfalfa (Medicago sativa) seed germination and seedling growth was studied in an apple orchard. Soil extract increased the number of germinated ryegrass seeds, but decreased the number of germinated alfalfa seeds. There was no effect of soil extract on seed germination rate of either species. Compared with no leaves remaining on the soil, extract from the soil with leaves accelerated the germination of the two grassseeds and tended to increase the germination rate. The soil extract from the apple orchard inhibited root growth and reduced seedling fresh weight of ryegrass and alfalfa seedlings. The root growth of alfalfa and ryegrass was inhibited by the falling leaves remaining on the soil. Therefore, in apple orchards, the effect of the soil on grassland development may be attributed mainly to the inhibition of seedling growth of grass species, rather than to the inhibition of seed germination. Falling leaves from apple trees may enhance such inhibition. Compared with the herbaceous species, the leguminous species was more susceptible to the inhibition observed.