Soil enzymes and microbial endophytes as indicators of climate variation along an altitudinal gradient with respect to wheat rhizosphere under mountain ecosystem

Microorganisms are always a crucial part of any ecosystem as they carry out various activities to maintain the sustainability of that ecosystem. Microbial activity in soils depends on the chemical structure of soils and the climatic conditions. In mountain ecosystem, change in climate is observed along with the change in altitude. Such change in climate, in turn, are likely to cause change in the community structure of microorganisms. In the present study, enzyme activities in soils and root colonization with respect to wheat rhizosphere are studied at three different altitudes (referred as S1, S2, S3 with increasing altitude) for two consecutive years. Activity of six soil enzymes including acid and alkaline phosphatase, β-glucosidase, aryl sulfatase, urease and dehydrogenase are estimated. All the soil enzymes, except dehydrogenase, were found to be governed by the soil quality defined by its nutrient content in the respective soil. Dehydrogenase enzyme activity was found to increase with the altitude indicating high rate of biological oxidation of soil organic matter at high altitude (S3) by native microbiota. Fungal counts in soil at higher altitude (S3) in both bulk soil as well as rhizosphere were minimum. Wheat plant roots at each altitude were observed to be colonized with specific type of microbial structures; S1 with higher population of small vesicular and bacterial endophytes, S2 possessing large vesicles and dark septate endophytes, and S3 showing lobed vesicles and dark septate endophytic structures. Total root colonization, recorded in both the study years, was maximum in the roots of S3 site followed by S2 and S1. Such patterned variations, arising due to altitudinal difference, may be considered as indicators for climate manipulations at small scale. The study will have implications in understanding the role of soil enzymes and the microbial communities, endophytes in particular, in wheat productivity grown in high altitudes under mountain ecosystem.