6Dario S,Roberto J Z,Ronald L P,et al. Organic orchard floor manage- ment systems for apple: effect on rootstock performance in the midwestern United States[J]. Hort Science, 2009,44 (2) : 263-267.
7Sanchez E E, Giayetto A, Cichon L, et al. Cover crops influence soil properties and tree performance in an organic apple (Malus domestica Borkh)orchard in northern Patagonia [J]. Plant Soil, 2007,292 : 193-203.
8Oliveira M T, Merwin I A. Soil physical conditions in a New York orchard after eight years under different groundcover management systems [J]. Plant Soil,2001,234:233-237.
9Lakatos T, Buban T, Helmeczi B. Effects on the number of soil microor- ganisms and tree nutrition of groundcover management systems[J]. Acta Horticulture, 2001,56 (4) : 201-208.