蒙古沙冬青根系DSE定殖与土壤因子典范对应分析

CCA analysis of colonization of DSE in the rhizosphere of Ammopiptanthus mongolicus in relation to soil factors

为进一步明确不同荒漠地区蒙古沙冬青(Ammopiptanthus mongolicus)根系深色有隔内生真菌(DSE)生态分布与土壤环境之间的关系,分别于2015年7月从乌海、磴口、阿拉善左旗、民勤和沙坡头5个样地采集蒙古沙冬青根围0~10、10~20、20~30、30~40和40~50cm共5个土层土壤样品,运用典范对应分析(CCA)方法系统研究了DSE生态分布及其与土壤因子的相关性.结果表明,蒙古沙冬青根系DSE分布与环境密切相关,其分布在不同样地间差异显著,定殖率表现为阿拉善左旗>乌海>沙坡头>民勤>磴口.5个样地DSE平均定殖率为52.02%,说明蒙古沙冬青与DSE能形成良好根-菌共生关系.不同样地土壤性质差异显著,对DSE分布具有重要影响.主要表现为同一样地不同土层,DSE分布与土壤理化指标均表现出浅土层大于深土层的趋势.CCA结果表明,DSE菌丝、微菌核、定殖率和定殖强度在CCA排序轴上得到较好分化.CCA二维排序图表明,乌海样地影响DSE菌丝定殖的主要土壤因子为酸性磷酸酶(ACP)、碱性磷酸酶(ALP)和速效P;磴口样地主要为碱解N和有机C;阿拉善左旗样地主要为ALP和pH;民勤样地主要为pH、ALP和土壤脲酶(Urease);沙坡头样地主要为ACP、Urease和碱解N.研究表明,不同地区DSE分布受不同土壤因子影响,这可为荒漠地区土壤状况评估以及改善提供依据.

Ammopiptanthus mongolicus is the only evergreen broadleaf shrub grown in the northwest China that has the characteristics of cold and drought resistance,salt resistance and wind resistance.It plays an important role in windbreak and soil and water conservation.To elucidate the spatial distribution of dark septate endophytes（DSE）and the relationship of DSE with soil factors associated with the desert plant A.mongolicus based on canonical correspondence analysis（CCA）,the author sampled from five different sites in northwest China in July 2015,which are Wuhai,Dengkou,Alxa,Minqin and Shapotou,respectively.Root samples were collected from four robust A.mongolicus,and soil samples were taken from the rhizosphere of A.mongolicus in five sites and divided into five depth intervals,0-10 cm,10-20 cm,20-30 cm,30-40 cm and 40-50 cm,respectively.The results showed that the roots of A.mongolicus could be infected highly by DSE and formed a typical type of septate hyphae and microsclerotia.The distribution of DSE was significantly affected by ecological conditions.There were significant differences in distribution of DSE among the five sites.The colonization rates of DSE among the five sites exhibited a pattern as Alxa WuhaiShapotou MinqinDengkou.The average colonization rate of five sites was52.02%,which showed that A.mongolicus and DSE could form a symbiotic relationship.There were also significant differences in soil factors among different sites.In the same site,DSE distribution and soil indicators had the maximum values in the profile of a surface layer and showed the trend of decreasing with the depth of the profile.The results of CCA showed that DSE hyphae,microsclerotia,colonization rate and colonization intensity in the axis of CCA got better differentiation.The species-environment biplots were drawn based on the result of CCA.The relationships between the colonization of DSE and the seven soil factors were clearly revealed on these biplots.Accoding to the biplots,the main soil factors of five sites were different.The acid phosphatase（ACP）,alkaline phosphatase（ALP）and available phosphate were found to be main soil factors affecting the hypha colonization of DSE in Wuhai.The main soil factors of Dengkou were available nitrogen and organic carbon.The hypha colonization of DSE in Alxa were mainly affected by ALP and pH.The main soil factors affecting the hypha colonization of DSE were pH,ALP and Urease,in Minqin.And the main soil factors affecting the hypha colonization of DSE in Shapotou were ACP,Urease and available nitrogen.The research results showed that the distribution of DSE in different regions was affected by different soil factors,which could provide the basis for the evaluation and improvement of soil conditions in the desert area.