园龄对可可苗期生长及其根际土壤环境的影响

摘要

可可是世界最重要的多年生经济作物之一,为了揭示不同园龄可可园土壤演变规律,为其可持续生产提供依据.以休耕地为对照(CK),研究低龄(4 a)、 中龄(12 a)和老龄(32 a)3种不同园龄土壤培育可可苗期生长及其与根际土壤有机碳(SOC)含量、 土壤酶活性和微生物区系等关系.结果表明,32 a园龄土壤培育可可苗生物量显著高于4 a、12 a和CK,分别增加了89.15%、29.24%和28.03%;32 a和12 a园龄处理根际SOC含量显著高于4 a园龄,老龄园有利于SOC的积累;随着园龄增加,脲酶活性增加,且与SOC含量极显著正相关,12 a和32 a园龄土壤脲酶活性分别比CK显著增加了44.36%和43.11%;12 a园龄处理根际土壤中可培养细菌数量减少,真菌数量则显著增加,12 a土壤可培养真菌数量分别是4 a、32 a和CK的3.04、1.46和3.23倍,园龄可能导致土壤微生物区系变化.综上所述,随着土壤园龄增加,可可苗生物量、 根际SOC含量和脲酶活性均增加,根际土壤微生物区系发生变化,根际土壤真菌数量与SOC含量、 脲酶活性极显著正相关,可可根际SOC含量是光合作用、 植株生长、 土壤酶活性和土壤微生物共同作用的结果.%Cocoa is one of the most important perennial cash crops worldwide. Our aim was to analyze the development laws of soil quality, provide the basis for promoting sustainable production. Comparing seedling biomass, soil organic carbon (SOC) content, enzyme activities, rhizosphere microorganism population quantifies and their relationships of 4 years, 12 years and 32 years soil of cocoa plantations. Short fallow was used as treeless references (CK). The main results obtained were as follows: The seedling biomass were significantly increased by 89.15%, 29.24% and 28.03% in soil of 32 years compared with that of 4 years, 12 years and CK, respectively. The SOC content was significantly increased in soil of 32 years and 12 years compared with that of 4 years, and aging was conductive to the accumulation of SOC. As the planting age increased, soil urease activities increased, which was extremely significantly positive correlation with the SOC content. Soil urease activities of 12 and 32 years obviously increased by 44.36% and 43.11%, respectively compared with that of CK. The culturable bacteria in rhizosphere soil decreased, and the culturable fungi significant increased. The culturable fungi number in 12 years soil were 3.04, 1.46 and 3.23 times higher compared with that in 4 years, 32 years and CK, respectively. Planting age may lead to changes of soil microflora. In conclusion, with the increase of planting age, the seedling biomass, rhizosphere SOC content and soil urease activities were increased, and the soil microflora changed. The culturable fungi in rhizosphere soil was significantly positively related to SOC content and urease activities. The SOC content in rhizosphere soil was the result of photosynthesis, seedlings growth, enzyme activities and microorganism.