香蕉-甘蔗轮作模式防控香蕉枯萎病的持续效果与土壤微生态机理(Ⅱ)

Continual effect and mechanism of banana-sugarcane plantation on control of Fusarium wilt (Ⅱ)

  • 摘要: 香蕉枯萎病是由尖孢镰刀菌古巴专化型Fusarium oxysporum f.sp.cubense侵染引起维管束坏死的一种毁灭性真菌病害,是世界范围内分布最广、毁灭性最强的植物病害之一。我们在古籍《广东新语》找到有关香蕉-甘蔗轮作的记载,经大田试验证明,连作蕉地轮作甘蔗2年后,后茬香蕉枯萎病发病率大幅下降至1.79%。在本研究中,我们试图探明连作蕉地轮作甘蔗,后茬香蕉的持续抑病效果及其机理。连作蕉地轮作甘蔗2年后,测定回种不同年限香蕉枯萎病发病率和土壤可培养微生物数量,并通过高通量测序技术分析土壤细菌微生物群落结构和组成的变化。结果表明:连作蕉地轮作甘蔗2年后,甘蔗地后茬香蕉枯萎病发病率仅为1.79%,后续3年发病率逐年递增,分别为21.93%、25.80%和28.81%,但均低于多年连作蕉地的平均发病率(49.15%)。土壤放线菌和尖孢镰刀菌总数随香蕉种植年限增加而显著增加。高通量测序结果表明,酸杆菌门(32.86%)、变形菌门(28.85%)和绿弯菌门(12.33%)3个菌门为香蕉-甘蔗轮作系统香蕉根围土细菌的优势菌门。酸杆菌目(Acidobacteriales)细菌相对丰度随回种香蕉逐年增加,并与香蕉枯萎病发病率呈显著正相关的关系;而假单胞菌目(Pseudomonadales)、浮霉菌目(Planctomycetales)、球杆菌目(Sphaerobacterales)、乳酸杆菌目(Lactobacillales)和土壤红杆菌目(Solirubrobacterales)细菌随香蕉回种年限的增加呈下降趋势,并与香蕉枯萎病发病率呈显著负相关的关系。连作蕉地轮作甘蔗2年后,4年内仍能保持较好的抑病效果。本模式具有轮作时间短、抑病效果好、持续时间长、经济效益高等特点。

     

    Abstract: Banana wilt caused by Fusarium oxysporum f. sp. cubense is one of the most widespread and destructive plant diseases in the world. To date, the efficient prevention and control of F. oxysporum in banana have not been found. Recently, banana-sugarcane rotation plantation (recorded in the Chinese ancient book Guangdong New Sight) has been noted to have the potential to control the disease. Furthermore, preliminary filed studies showed that the incidence of banana wilt disease reduced from 49.15% to 1.79% after two years of planting sugarcane in continuous cropped banana fields. In this study, the control effect and mechanism of banana-sugarcane rotation was investigated. Banana wilt disease incidence under various years (one, two and three years) of banana replanting after two years of sugarcane rotation were investigated. The number of soil culturable micro-organisms was measured and soil microbial community structure analyzed by high-throughput DNA sequencing technique. The results showed that banana wilt disease incidence was only 1.79% in first replanted banana field after two years of sugarcane rotation. Then it was respectively 21.93%, 25.80% and 28.81% in the second, third and fourth years of banana replantation; less than that under continuous cropping of banana fields (49.15%). The number of F. oxysporum and Actinomycetes significantly increased with increasing banana replantation years. Sequence analysis showed that Acidobacteria (32.86%), Proteobacteria (28.85%) and Chloroflexi (12.33%) constituted the dominant phyla in the banana-sugarcane rotation system. The relative abundance of bacteria of Acidobacteriales apparently increased with increasing banana replantation years and had a significant positive correlation with the incidence of banana wilt. Meanwhile, the bacteria number of Pseudomonadales, Planctomycetales, Sphaerobacterales, Lactobacillales and Solirubrobacterales apparently decreased and were significantly negatively correlated with the incidence of banana fusarium wilt. In conclusion, the control effect was still good in terms of replanting banana in less than four years after two years of sugarcane rotation. The best cultivation system was shorter rotation time, longer duration disease inhibition and higher economic efficiency, compared with other banana rotation patterns. The results showed that the inhibition of Acidobacteriales and the promotion of Pseudomonadales, Planctomycetales and Solirubrobacterales were the most important mechanisms to reduce the incidence of banana fusarium wilt under banana-sugarcane rotation systems.

     

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