连作对烤烟根际土壤微生物数量和酶活性的动态影响

Dynamic influence of continuous cropping of flue-cured tobacco on the amount of microbe and enzyme activities in the rhizosphere soil

分别用正茬植烟土壤和连作3,8 a的植烟土壤进行池栽试验,研究植烟后各处理5个生育时期的根际土壤中微生物数量及酶活性的动态变化.结果表明,连作年限对烤烟根际土壤中细菌和真菌的数量有明显影响.在整个烤烟生育期内,不同连作年限根际土壤中细菌数量大致呈"升-降-升-降"的趋势;真菌数量的变化是先升后降,在65 d左右达到最高;放线菌数量除连作8 a呈下降趋势外,其余2个处理均先降后升.随着烤烟连作年限的增加,根际土壤中细菌比例显著减少,真菌比例显著增加,放线菌比例变化没有规律.烤烟生育期内植烟土壤脲酶、磷酸酶、蔗糖酶及过氧化氢酶活性的变化规律大致呈"M"型变化态势;随连作年限的增加,烤烟根际土壤酶活性总的变化趋势是先增高后降低,即连作3 a>正茬>连作8 a,且各处理之间有显著性差异.

Growing tobacco with 0 year, 3 years, 8 years planted soil using a pool-culture experiment as conducted to study the dynamic changes of enzyme activity and the amount of rhizospheric microflora of soil in five different growth stages after transplanting of tobacco plants which were cultivated in di- fferent consecutive years. The results showed that the years of consecutive cropping had a significant impact on the amount of bacteria and fungi in the rhizospheric microflora of soil. In the entire growth period of tobacco, the amount of bacteria showed ＂up-down-up-down＂ trend; fungi first increased and then decreased, and reached a peak on 65 d after transplanting; excluding the 8 years treatment, which showed a declining trend, the other two treatments decline first and then rise. With the increase of the years of consecutive cropping, the proportion of rhizosphere bacteria was significantly reduced, a significant increase in the proportion of fungi, and actinomyces＇ ratio did not change the law. During flue-cured tobacco growth period, urease, phosphatase, invertase and catalase activity mainly showed a ＂M＂ type of trend, with the increase of the years of consecutive cropping, the general trend of enzyme activity in rhizospheric soil of tobacco plant was at the beginning increase and then decrease, that is, 3 years 〉 0 year 〉 8 years, there were significant differences among the treatments.