陕北南泥湾湿地农田养分及AM真菌多样性

摘要

Wetland is invaluable natural resource,especially in Northern Shaanxi known as serious water loss and soil erosion areas of the loess plateau.Soil samples from seven agrotypes were selected and collected in Nanniwan wetland in Northern Shaanxi,China,aiming to research farmland nutrient concentration and biodiversity of Arbuscular mycorrhiza fungi,and thereby presenting suggestions for local agriculture development.The soil samples were collected from a depth of 30 cm into 3 sections,i.e.0 ～ 10,10 ～ 20 cm and 20 ～ 30 cm in the different farmlands in 2015.The spore density and biodiversity of AM fungi were measured.The result showed that at the 0 ～ 30 cm soil layer,the concentration of organic matter ranged from 7.54 g· kg-1 to 17.23 g· kg-1,organic matter in vegetable site was significantly higher than that in other layers.The concentration of available nitrogen ranged from 12.01 mg· kg-1 to 27.10 mg· kg-1.The concentration of available phosphorus ranged from 3.08 mg· kg-1 to 9.67 mg· kg-1,and the lowest value was detected in soil sample of Picea asperata.The concentration of available potassium ranged from 98.61 mg· kg-1 to 152.51 mg· kg-1.10 AM fungi taxa in three genera were isolated and identified,of which 60％ belonged to the genus Glomus,30％ to Acaulospora,and 10％ to Scutellospora.The most abundance of AM fungi was found in the forest,second most in the field of Picea asperata,and the lowest in paddy field.The spore density showed significant differences among sites,with an order of forest soil (2.24·g-1),Picea asperata soil (2.18·g-1),millet soil (1.46·g-1),maize soil (1.31·g-1),vegetable soil (0.76· g-1),paddy soil (0.73· g-1),and soybean soil (0.68· g-1).%研究选取南泥湾湿地6种不同作物类别的农田为样地,并设荒野次生林地为对照,分0～ 10、10～ 20cm和20～ 30 cm土层深度采集土壤样品,测定土壤养分含量,分析丛枝菌根(Arbuscular mycorrhiza,AM)真菌多样性及其孢子密度.结果表明:0～30 cm土层范围,土壤有机质含量为7.54～ 17.23 g·kg-1,蔬菜地有机质含量显著高于其它地类;土壤速效氮含量为12.01～ 27.10 mg·kg-1;土壤速效磷的含量为3.08～9.67 mg·kg-1,云杉和林地土壤速效磷的含量显著低于其它地类;土壤速效钾含量为98.61～152.51 ng·kg-1;南泥湾农田养分含量偏低,尤其缺乏土壤速效氮和土壤速效磷.试验共分离出3属10种AM真菌,其中球囊霉属(Glomus)6种,占60％;无梗囊霉属(Acaulospora)3种,占30％;盾巨孢囊霉属(Scutellospora)1种,占10％.林地AM真菌物种丰度最大,其次是云杉,水稻地AM真菌物种丰度最小.地球囊霉(G.Geosporum)是优势种类,美丽盾巨孢囊霉(Scu.Calospora)属于偶见种,摩西球囊霉(G.mosseae)只出现在耕作土壤.不同地类孢子密度差异显著,以0～30 cm土层平均值比较:林地土孢子密度(2.24个·g-1)＞云杉幼苗地土孢子密度(2.18个·g-1)＞谷子地土孢子密度(1.46个·g-1)＞玉米地土孢子密度(1.31个·g-1)＞蔬菜土孢子密度(0.76个·g-1)＞水稻土孢子密度(0.73个·g-1)＞黄豆土孢子密度(0.67个·g-1).