Belowground carbon sequestration potential of apple trees

目的本项目将扩大我们对陆地碳固存能力与苹果砧木基因型特异性性状（包括抗性、根际沉积和相关根际微生物群落）之间关系的理解。这些知识将使种植者能够选择具有更大生态系统服务能力的砧木，就其碳储存能力而言，这将有利于土壤肥力并促进大气二氧化碳的捕获。反过来，决策者可以将这些信息纳入环境奖励支付方案。本项目将通过分析三个关键成分来评估广泛使用的苹果砧木品种的固碳能力：物理根测量：将使用生化方法来评估根的顽固性，以量化各种化合物（如总C、可溶性酚类物质、缩合单宁、酸不溶性组分（木质素））。将使用根管、完整的根芯（Dornbush等，2002年）和在微型环境中培养根，对根的厚度、分解率和根深分布进行额外的测量。根分泌物生化分析：根沉积物的收集可以通过收集盆栽砧木的渗透（径流）水来完成（Leisso等，2017），或者通过将无土生长的砧木的根浸入含有银（Ag+）的蒸馏水中来完成，Gransee和Wittenmayer（2000）进行了描述和评估。初级（糖，有机酸）和次级（酚类）代谢物将通过高效液相色谱（HPLC）或气相色谱-质谱（GC-MS）进行分析。根际群落分析：高通量测序方法的最新进展极大地增强了微生物群落分析。将通过扩增通用16S rRNA基因（细菌）和ITS序列（真菌）来研究根际群落的细菌和真菌组成。该项目将重点关注与C循环相关的官能团，如甲烷氧化菌（甲烷生产者）、甲烷生成菌（甲烷消耗者）和AMF。

ObjectivesThis project will expand our understanding of the associations between terrestrial C sequestration capacity and genotype-specific apple rootstock traits, including recalcitrance, rhizodeposition and the associated rhizosphere microbial communities. This knowledge will then enable growers to select rootstocks with greater ecosystem service capacity, in terms of their C storage abilities, which will benefit soil fertility and promote the capture of atmospheric CO2. In turn, policy makers may incorporate this information into environmental reward payment schemes.ApproachesThis project will assess a selection of widely-used apple rootstock cultivars for their C-sequestering abilities by analysing three key components:Physical root measurements: Root recalcitrance will be assessed using biochemical methods to quantify various compounds (e.g. total C, soluble phenolics, condensed tannins, acid-insoluble fractions (lignin)). Additional measurements will be made for root thickness, decomposition rate, and root depth distribution using rhizotrons, intact cores (Dornbush, et al., 2002) and incubation of roots in microcosms.Root exudate biochemical analysis: Rhizodeposit collection may be done either by collection of percolated (run-off) water from pot-grown rootstocks (Leisso, et al., 2017), or by dipping roots of axenically-grown rootstocks in distilled water containing silver (Ag+) as described and evaluated by Gransee & Wittenmayer (2000). Primary (sugars, organic acids) and secondary (phenolics) metabolites will be analysed by high performance liquid chromatography (HPLC) or gas chromatography-mass spectrometry (GC-MS).Rhizosphere community analysis: Recent advances in high-throughput sequencing methods have greatly enhanced microbial community analysis. The bacterial and fungal composition of the rhizosphere community will be investigated via amplification of the universal 16S rRNA gene (bacteria) and ITS sequences (fungi). In particular, the project will focus on functional groups related to C cycling, such as methanotrophs (methane producers), methanogens (methane consumers), and AMF.