Interaction between root hairs and soil phosphorus on rhizosphere priming of soil organic matter
Interaction between root hairs and soil phosphorus on rhizosphere priming of soil organic matter
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DOI：
10.1016/j.soilbio.2019.05.013
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发表时间：
2019-08-01
影响因子：
9.7
通讯作者：
Carubba, Aaron
中科院分区：
文献类型：
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作者：
Boilard, Gabriel;Bradley, Robert L.;Carubba, Aaron
我们推测，根毛缺失突变大麦对土壤有机质的根际引发效应依赖于大量的共生丛枝菌根真菌(AMF)网络。因此，我们预测，施磷肥会降低AMF的丰度，进而降低突变大麦的RPE。我们在微观世界里种植了对磷敏感的土壤，在那里我们种植了没有根毛的突变大麦，以及野生型大麦和狭叶车前草，每种大麦都有根毛。一组微观世界施磷肥，另一组不施磷。这些植物是在一个带有C-13耗尽的二氧化碳的标签室中种植的。分别于3、4、5周测定土壤呼吸和顶空CO2的增量C-13，并用同位素质量平衡法计算RPE。测量了根毛长度，并分析了土壤中16：1的omega 5中性脂肪脂肪酸(即AMF生物标志物)。低磷条件下突变大麦土壤的AMF丰度高于高磷条件下的AMF丰度，而RPE较低。在其他两种株型中，P对AMF和RPE均无影响。由于我们的结果与我们的预测相矛盾，我们提出了一种基于高磷下植物氮素需求的替代解释。
We hypothesized that the rhizosphere priming effect (RPE) of soil organic matter by mutant barley lacking root hairs is dependant on a large network of symbiotic arbuscular mycorrhizal fungi (AMF). We thus predicted that fertilizing with phosphate-P would reduce AMF abundance and, in turn, reduce RPE of mutant barley. We packed microcosms with a P-responsive soil in which we grew mutant barley lacking root hairs as well as wild type barley and narrowleaf plantain, each possessing root hairs. One set of microcosms was fertilized with phosphate-P while another set was not fertilized. The plants were grown in a labelling chamber with C-13-depleted CO2. Soil respiration and delta C-13 of headspace CO2 were measured after 3, 4 and 5 weeks and RPE was calculated using an isotope mass balance approach. Root hair length was measured and soils were analyzed for the 16:1 omega 5 neutral lipid fatty acid (i.e. AMF biomarker). AMF abundance was greater, whereas RPE was lower, in mutant barley soil under low-P than under high-P conditions. In the other two plant-types, P had no effect on AMF or on RPE. As our results contradict our prediction, we propose an alternative explanation based on plant N demand under high-P.