连作年限对香蕉园土壤线虫群落结构及多样性的影响

为研究连作对蕉园土壤生态系统的影响,以海南香蕉种植区为例,采集不同连作年限(l a、3 a、5 a、7a、10 a和15 a)蕉园土壤,采用线虫形态学鉴定方法,分析了不同连作年限蕉园土壤线虫群落结构及多样性的变化规律。结果表明:整个生育期不同连作年限地块共发现土壤线虫属45个。苗期随连作年限增加线虫总数、食细菌线虫数量和食真菌线虫数量逐渐降低(15 a除外);营养生长期随连作年限增加线虫总数、食细菌线虫数量和食真菌线虫数量先增加后降低;抽蕾期随连作年限增加线虫总数和食细菌线虫数量先增加后降低,食真菌线虫数量逐渐降低。整个生长季,随着连作年限增加植物寄生线虫数量先增加后降低。苗期、营养生长期和成熟期,随着连作年限增加捕食/杂食线虫数量逐渐降低。苗期和抽蕾期的线虫总数显著高于营养生长期和成熟期。苗期的食真菌线虫数量和营养生长期的植物寄生线虫数量显著低于其他各生长时期。苗期和营养生长期的捕食/杂食线虫数量显著低于抽蕾期和成熟期。苗期随连作年限增加,优势度指数(λ)先增加后降低,香农多样性指数(H)和植物寄生线虫成熟度指数(PPI)逐渐增加,瓦斯乐斯卡指数(WI)和通路指数(NCR)逐渐降低;营养生长期随连作年限增加,λ先增加后降低,NCR和PPI逐渐增加,H、自由生活线虫成熟度指数(MI)和WI逐渐降低;抽蕾期随连作年限增加,λ先增加后降低,NCR和PPI逐渐增加,H和WI逐渐降低;成熟期随连作年限增加,H和MI逐渐降低,PPI逐渐增加。从整个生育期来看,随生长时间推移,H逐渐增加,λ逐渐降低,苗期和营养生长期的MI低于抽蕾期和成熟期,苗期和成熟期的WI低于营养生长期和抽蕾期。本研究显示,土壤线虫群落结构可有效反映连作蕉园土壤的健康状况,土壤线虫可作为土壤中重要的指示生物。

Effect of continuous cropping of banana on soil nematodecommunity structure and diversity

To study the effect of long-term banana continuous cropping on soil ecosystem,nematode classification methods were adopted to study the changes of soil nematode community structure and diversity under different continuous cropping years(l a,3 a,5 a,7 a,10 a and 15 a).The results indicated that 45 nematode genera were identified during the whole banana growing season.The abundance of total nematodes and bacterivores decreased with the increase of continuous cropping years at seedling stage,and exhib-ited low to high to low trend with the increase of continuous cropping years at jointing and booting stages.The abundance of fungi-vores decreased with the increase of continuous planting years at seedling and booting stages,and exhibited low to high to low trend with the increase of continuous planting years at jointing stage.The abundance of plant parasites exhibited low to high to low trend with the increase of continuous planting years at four growing stages.The abundance of omnivores-predators was decreased with the increase of continuous cropping years at seedling,jointing and ripening stages.The abundance of total nematodes was higher at seed-ling and booting stages than that at the jointing and ripening stages.The abundance of fungivores at seedling stage and plant parasites at jointing stage was lower than that at the other stages.The abundance of omnivores-predators was lower at seedling and jointing stages than that at booting and ripening stages.The values of dominance(λ) exhibited low to high to low trend at seedling,jointing and booting stages with the increase of continuous cropping years.The values of plant parasite index(PPI) increased with the in-crease of continuous cropping years at four growing stages while Wasilewska(WI) exhibited a reverse pattern at seedling,jointing and booting stages.The values of diversity(H) increased with the increase of continuous cropping years at the seedling stage,while a reverse pattern was exhibited at other stages.The values of nematode channel ratio(NCR) increased with the increase of continuous cropping years at jointing and booting stages,while the values of maturity index(MI) exhibited a reverse pattern at jointing and rip-ening stages.The values of H increased with the increase of growing stages while λ exhibited a reverse pattern.The values of MI were higher at booting and ripening stages than that at seedling and jointing stages.The values of WI were higher at jointing and booting stages than that at seedling and ripening stages.It indicated that soil nematode community structure could be a useful bio-logical indicator to evaluate the status of soil health under banana continuous monocropping system in China.