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首页> 外文学位 >A greener grass: Improving biofuel feedstock production of switchgrass (Panicum virgatum L.) by inoculation with endophytic rhizobacteria.
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A greener grass: Improving biofuel feedstock production of switchgrass (Panicum virgatum L.) by inoculation with endophytic rhizobacteria.

机译：更绿色的草：通过接种内生根瘤菌来改善柳枝（（Panicum virgatum L.）的生物燃料原料生产。

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摘要

Switchgrass (SG, Panicum virgatum L.), a temperate perennial grass, was chosen by the US Department of Energy's Herbaceous Energy Crops Program as the 'model' bioenergy crop for further research in North America. Current research on SG for bioenergy feedstock production focuses on improving breeding selection, agronomy and crop physiology, energy potential, and its contribution to mitigating greenhouse gas emissions. However, there is a lack of knowledge regarding plant-microbe interactions with SG, how these associations play a role in its growth and productivity, and their function and potential role in agro-ecosystems. Moreover, as SG has been reported to produce high biomass yields with minimal to no synthetic nitrogen (N) fertilizer, this suggested to us that SG could be obtaining at least some of the N to meet its requirements from plant growth promoting rhizobacteria (PGPR) capable of biological N2-fixation (BNF). The objectives of this research were to determine if: (1) SG associates with PGPR, (2) PGPR we isolated from SG can be used as inoculants capable of promoting SG growth under a controlled environment, and (3) inoculation with PGPR can increase the growth and productivity of SG for biofuel production under a low-N input system. Switchgrass rhizomes were collected in Québec, Canada from a discontinued biomass trial of 11 varieties that had not received N fertilizer or any other management input since 2000. Isolates were chosen on N-free solidified media and screened for their ability to promote plant growth using plant assays conducted in growth chambers. Switchgrass seedlings were inoculated, or not, with batches of mixed isolates and fertilized with N-free Hoagland's solution. Molecular analyses of 16S rRNA gene sequences identified the mixed bacterial inoculum as Paenibacillus polymyxa, a N2-fixing bacterium, and several other PGPR (Pseudomonas, Serratia, and Rahnella spp.) capable of producing auxin and/or solubilizing phosphate. Field trials of inoculated SG seeds were conducted in 2010 on three sites comprising different soil types. The factors tested were the bacterial treatment, either uninoculated control or seed inoculated, and a fertilizer treatment, either 0 or 100 kg N ha−1.;Establishment year results showed that inoculation with a mixed PGPR produced higher tiller density and larger tillers than uninoculated plants, which was the probable cause of the 40% yield increase. This 40% yield increase persisted under N fertilization, at least at the 100 kg N ha−1 rate. Inoculated SG plants also had better N cycling than uninoculated plants, as they contained more N within tillers during anthesis but not after senescence, suggesting a greater amount of N was translocated to below-ground roots and rhizomes of inoculated than uninoculated plants. Greater N storage in roots and rhizomes could mean better early-season regrowth and provide an advantage over weeds. PGPR inoculation also affected the N balance of the harvested biomass by contributing additional non-fertilizer N (ANFN) to SG plants. Interestingly, this bacterial effect was not inhibited in the presence of N fertilizer. The combination of PGPR and nitrogen fertilizer provided a substantial N contribution to SG plants, although the exact amount will require additional research. This investigation showed that SG does associate with PGPR and that PGPR can be effectively utilized as inoculants to enhance SG yields in low-N input systems. This research will help in the development of an environmentally beneficial switchgrass-microbe system, reduces N requirements and has the potential to become a best N management practice.
机译：多年生温带的多年生禾本科植物柳枝（（SG， Panicum virgatum L。）被美国能源部的草本能源作物计划选为“典范”生物能源作物，需要在北美进行进一步研究。用于生物能源原料生产的SG的当前研究集中在改善选育，农艺和作物生理，能源潜力及其对减少温室气体排放的贡献上。但是，缺乏有关植物微生物与SG相互作用，这些协会如何在其生长和生产力中发挥作用以及它们在农业生态系统中的功能和潜在作用的知识。此外，由于据报导SG可以产生高的生物量产量，而合成氮肥几乎没有甚至没有，因此，这提示我们SG可以从植物促生根瘤菌（PGPR）中获取至少一部分N，以满足其需求。具有生物N 2 固定（BNF）的能力。这项研究的目的是确定：（1）SG与PGPR相关，（2）我们从SG中分离出的PGPR可以用作能够在受控环境下促进SG生长的接种剂，并且（3）PGPR接种可以增加低氮输入系统下用于生物燃料生产的SG的增长和生产率。柳枝rh的根茎是在加拿大魁北克的一项已停止生产的生物量试验中收集的，该试验自2000年以来一直没有施用氮肥或任何其他管理投入。在无氮固化培养基上选择了分离株，并筛选了它们利用植物促进植物生长的能力。在生长室中进行测定。是否将柳枝gra幼苗接种成批次的混合分离株，并用无氮的霍格兰氏溶液施肥。对16S rRNA基因序列的分子分析确定了混合细菌接种物为多粘芽孢杆菌， N 2 固定细菌和其他几种PGPR（假单胞菌，沙雷氏菌， / italic>和 Rahnella spp。），能够产生生长素和/或增溶磷酸盐。 2010年在包含不同土壤类型的三个地点进行了接种的SG种子的田间试验。测试的因素是细菌处理（未接种对照或种子接种）以及肥料处理（0或100 kg N ha -1 ）。建立年份的结果表明，混合PGPR的接种产生更高的分un密度和比未接种植物更大的分ers，这可能是产量增加40％的原因。在氮肥条件下，至少以100 kg N ha -1 的速率持续增加了40％的产量。接种的SG植物也比未接种的植物具有更好的氮素循环，因为它们在花期中而不是在衰老后在分ers中含有更多的N，这表明与未接种的植物相比，大量N转移到了接种的地下根和根茎上。根茎和根茎中较高的氮存储量可能意味着更好的早期再生长，并比杂草更具优势。 PGPR接种还通过为SG植物贡献了额外的非肥料氮（ANFN），也影响了收获生物量的氮平衡。有趣的是，在氮肥的存在下，这种细菌作用并没有被抑制。 PGPR和氮肥的结合为SG植物提供了大量的N贡献，尽管确切的数量将需要进一步的研究。这项研究表明，SG确实与PGPR相关，并且PGPR可以有效地用作孕育剂，以提高低氮输入系统中的SG产量。这项研究将有助于开发对环境有益的柳枝-微生物系统，减少氮的需求，并有可能成为最佳的氮管理实践。

著录项

  • 作者

    Ker, Keomany.;

  • 作者单位

    McGill University (Canada).;

  • 授予单位 McGill University (Canada).;
  • 学科 Agriculture Agronomy.;Biology Microbiology.;Alternative Energy.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 179 p.
  • 总页数 179
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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