Dissertation Research: Rhizosheath Formation and Hydraulic Lift in Indian Ricegrass: Rhizosphere Composition and Nitrogen Fixation

本研究将评估根鞘形成和非根鞘形成植物的固氮作用。这是第一次。从大气或土壤来源获得的形成植物根鞘的氮(N)的数量将用15N同位素稀释法进行量化。还将测量根鞘根在水力提升中的作用。根鞘土壤可以作为深层土壤水分供应的汇(水力提升)，或者根鞘根可以作为水分流失的屏障，这可以直接影响根鞘内的微生物活动，并可以显著改变氮素固定。研究将确定从深层根到根鞘土壤的水分储备是否发生水力抬升，以及水力抬升是否刺激根鞘中的微生物数量和固氮。

This study will assess N-fixation in rhizosheath forming and non-rhizosheath forming plants. For the first time. The quantity of nitrogen (N) rhizosheath forming plants obtain from either atmospheric or soil sources will be quantified 15N isotope dilution methods. The function of rhizosheath roots in hydraulic lift will also be measured. Rhizosheath soil may act as sinks for deep soil moisture supplies (hydraulic lift) or rhizosheath roots may act as barriers to moisture loss, which can have a direct effect on microbial activity within rhizosheaths and can significantly alter N-fixation. Research will determine whether hydraulic lift of moisture reserves from deep roots to rhizosheath soil occurs and whether hydraulic lift stimulates microbial numbers and N- fixation in rhizosheaths.