Control Of Fusarium Oxysporum F.sp.Cubense In Banana By Rice-banana Rotation Combine With Application Of Organic Materials

Continuous cropping is one of the most important factors causing banana Fusarium wilt disease and seriously restricts the sustainable development of the banana industry. In this work, the method of banana-rice rotation incorporated with the application of organic materials (coconut husk, rice straw and eucalyptus slag) was used in pot experiment to assess its control efficiency on the disease. The soil used in pot experiment is from the banana garden which has a high disease incidence. The physical-chemical and biological properties of the soil, banana growth tendencies and disease incidences were analyzed. Besides, the antagonistic effects of organic materials with different C/N ratio, root exudates, rice residues and roots on FOC were also studied. The results showed that:(1) Rice cropping and the application of organic materials in rice cropping could decrease the soil Eh. The Eh value of the flooding soil incorporated with rice straw decreased to below-200mV in30days, and was lower than the incorporations of other organic materials.(2) The application of organic materials during the period of rice growth could increase the soil pH, and rice cropping incorporated with rice straw had the highest soil pH. Besides, the contents of soil organic matters and available nutrient were also increased in rice cropping soil incorporated with organic materials after one season of rice.(3) Rice rotation could significantly reduce the number of Fusarium oxysporum and prevent the disease. After rice rotation, the number of FOC and the disease incidence decreased by71.5%and81.7%, respectively, compared with control, and decreased by47.8%and71.2%, respectively, compared with those in flooding soil without rice cropping. Rice cropping incorporated with the application of rice residues had the best growth tendency and the lowest disease incidence of banana compared with other treatments.(4) The number of soil cultural fungi, bacteria and actinomyces changed during different periods in banana-rice rotation. During the period of rice growth, the number of fungi and actinomyces decreased, but they gradually during the period of banana growth. In the terms of bacteria, its population number fluctuated with the rotation periods although no obvious difference was observed. However, results of Denaturing gradient gel electrophoresis showed significant increase of bacteria Simpson index and Shannon diversity index, indicating that the soil diversity of bacteria was greatly improved via this kind of cultivation method (banana-rice rotation incorporated with rice straw application). Oppositely, the diversity of fungi was apparently reduced.(5) The water extract and alcoholic extract of dry rice straw inhibited FOC growth to some extent, whereas the water extract and the alcoholic extract of fresh rice root promoted it.In conclusion:This cultivation method, combining rice rotation with rice straw application, could not only dramatically reduce the soil Eh to below-200mV in30days, but also,increase the soil pH, organic matter content and available nutrient. The population of FOC and the abundance and diversity of fungi were both reduced via this cultivation method, but the diversity of bacteria was increased. Moreover, the water extract and alcoholic extract of dry rice straw had an inhibitory effect on the growth of Fusarium oxysporum. In a word, this method could improve the soil micro-ecological environment, and prevent the banana fusarium wilt disease incidence as well.