[1] Northwest A&F Univ, Coll Nat Resources & Environm, Yangling 712100, Shaanxi, Peoples R China
[2] Nanjing Forestry Univ, Coll Informat Sci & Technol, Nanjing 210037, Peoples R China
[3] Minist Agr, Key Lab Plant Nutr & Agrienvironm Northwest China, Yangling 712100, Shaanxi, Peoples R China