不同园龄可可园土壤有机碳矿化及微生物群落组成研究

Cacao (Theobroma cacao L.) is an important tropical drinks crop in the world, which is used in the agro-food industry, owns great development potential. It has earned the reputation of 'mother of chocolate'. The planting areas of cocoa in China are mainly distributed in Hainan and Yunnan provinces. Plantations of cocoa in China or abroad are relatively extensive. Many areas almost don’t use fertilization. For the majority of farmers, fertility of soils and microbial activity under cocoa plantations are maintained through the recycling of nutrients through litterfall and decomposition.However, litter inputs in the soil organic matter needs to be mineralized to be absorbed by crops. In addition, cocoa is a perennial plant, the continuous cropping disturbed soil mineral nutrients and soil microflora balance, susceptible to disease, consequently, leading to heavily economic losses. In the previous research, we have already found the soil microbial community composition has significant difference in cocoa plantations of different ages. Here, we study the soil organic carbon mineralization. Analyze the correlation of soil nutrient and organic carbon mineralization. Microbial diversity is estimated by 454 pyrosequencing. Study soil microbial community composition and diversity effect on soil organic carbon mineralization in cocoa plantations of different ages. To provide theoretical basis for the establishment of maintenance and management measures.

可可是世界重要的热带饮料作物，广泛应用于食品工业，具有“巧克力之母”的誉称，有巨大的发展潜力，在我国海南、云南等热带地区有规模化种植。国内外可可园管理均比较粗放，许多地区几乎不对可可施肥，依赖凋落物分解保持养分循环和土壤微生物活性。然而，凋落物输入土壤中的有机质需要被矿化才可被作物吸收利用。另外，可可为多年生作物，随着种植年限的增加，土壤矿质养分失衡，微生物区系失调，造成土壤退化，植株易受病虫危害，产量和品质下降。针对上述问题，在前期已测定不同园龄土壤微生物群落组成具有巨大差异的基础上，本项目拟研究不同园龄土壤有机碳矿化的规律，分析土壤质量与土壤有机碳矿化的相关性，通过分析土壤微生物群落组成和多样性，揭示土壤微生物对土壤有机碳矿化的作用机制，以其为我国可可种植园养分管理和经营措施的制定提供理论依据。

可可是世界重要的热带经济作物，具有“巧克力之母”的誉称，发展潜力巨大，在我国海南、云南等热带地区有规模化种植。国内外可可园管理均比较粗放，许多地区几乎不对可可施肥，依赖凋落物分解保持养分循环和土壤微生物活性。然而，凋落物输入土壤中的有机质需要被矿化才可被作物吸收利用。本项目采用室内培养方法研究可可园土壤有机碳矿化特征，结果表明，不同园龄的土壤培养140d后C-CO2累积矿化量为18.24~43.79mg/kg，随着园龄增加，土壤有机碳累积矿化量显著提高，累积矿化量占土壤总有机碳的0.20%~0.49%。可可园土壤有机碳矿化与土壤有机碳、碱解氮、微生物量碳、可溶性有机碳含量显著正相关，与pH值显著负相关，与酸性磷酸酶和多酚氧化酶显著正相关，与纤维素酶显著负相关。采用16S和MiSeq测序技术开展可可园土壤微生物多样性和群落结构分析，并开展了土壤微生物—土壤养分—土壤有机碳矿化互作关系研究，明确了土壤微生物对土壤有机碳矿化的影响机制，即通过土壤细菌Crenarchaeota和Nitrospira菌门发挥作用促进土壤有机碳含量增加；老龄园中相对较高的有机碳积累量增加了可用于土壤微生物代谢的基质含量，从而影响了土壤有机碳矿化。本项目研究成果为深入开展可可园土壤碳循环的微生物机制研究提供理论依据，对指导优化可可园养分管理技术、提高养分利用效率、保障可可产业健康可持续发展具有重要意义。