巨大芽孢杆菌与噁霉灵联用对甜瓜连作障碍的缓解效果

Effects of combination of hymexazol and Bacillus megaterium on Fusarium wilt of continuous cropping melon(Cucumis sativus L.)

为缓解连作甜瓜引起的连作障碍,在对河北省沧州市青县甜瓜连作区土壤障碍程度进行分析的基础上,通过室内盆栽和田间试验,研究了巨大芽孢杆菌Bacillus megaterium b1菌株与噁霉灵联用对连作甜瓜枯萎病的缓解效果及对甜瓜植株生长的影响,并初步分析了该地区土壤中微生物数量及群落结构变化。结果表明:采用11年连作甜瓜土壤培育南瓜和甜瓜,其幼苗根冠比及全株干重均显著低于1年土壤组;11年连作土壤中真菌数量最多,细菌和放线菌数量最少,镰刀菌属(Fusarium)相对丰度最高,是1年土壤的4.27倍,而1年土壤中芽孢杆菌属(Bacillus)相对丰度是11年土壤的2.65倍。噁霉灵和巨大芽孢杆菌b1菌株间不存在拮抗作用,二者对甜瓜枯萎菌Fusarium oxysporum T2菌株的EC_(50)值分别为10.82 mg/L和2.02×10^(5) CFU/mL。室内分别采用巨大芽孢杆菌、噁霉灵单剂及二者联用处理连作11年土壤后培育甜瓜幼苗,结果表明:联用处理在开花结果期对甜瓜枯萎病的防效为42.85%,且甜瓜幼苗根冠比和全株干重均显著高于各单剂和空白对照处理。田间试验结果表明:巨大芽孢杆菌、噁霉灵单剂以及二者联用处理连作甜瓜土壤,对甜瓜枯萎病的防效分别为16.62%、100%和100%;各处理组甜瓜幼苗株高分别比空白对照提高11.19%、10.63%和16.03%;甜瓜增产率分别为20.35%、11.23%和26.15%;单株根系平均干重分别比空白对照提高40.63%、34.69%和64.38%,差异显著(P<0.05)。各处理组土壤中真菌数量降低,细菌和放线菌数量增加;镰刀菌属相对丰度分别比空白对照降低35.96%、59.55%和71.91%;芽孢杆菌属相对丰度分别比空白对照提高47.25%、3.52%和76.70%。研究表明:甜瓜连作存在明显的连作障碍,而巨大芽孢杆菌与噁霉灵联用能有效改善连作区土壤微生物群落结构,缓解连作障碍,减轻连作土壤甜瓜枯萎病的发生,促进甜瓜幼苗生长及提高甜瓜产量。

In order to alleviate the harm caused by Fusarium wilt to continuous cropping melon,the soil obstacle degree from melon continuous cropping area in Qing County of Hebei Province was analyzed.Moreover,the effects of the combination of hymexazol and Bacillus megaterium on the growth and the alleviation effect of melon wilt were studied through indoor pots and field trials,and the preliminary analysis of the soil microbial community composition was performed.The results showed that the rootshoot ratio and whole plant dry weights of pumpkin and melon seedlings cultivated in continuous cropping soil for 11 years were significantly lower than those for one year.In addition,the number of bacteria and actinomycetes were the lowest,but the number of fungi was the highest in the soil with continuous cropping melon for 11 years.Meanwhile,the relative abundance of Fusarium was the most obvious,showing a significant difference from that in the soil for one year,the relative abundance of Bacillus in one year soil was 2.65 times that of 11 years soil.There was no antagonism between hymexazol and B.megaterium b1.The EC_(50) of hymexazol and B.megaterium b1 to F.oxysporum T2 were 10.82 mg/L and 2.02×105 CFU/mL,respectively.When 11 years of continuous cropping soil was used to cultivate melon seedlings and treated with hymexazol and B.megaterium b1 strain with EC_(50) concentration,the controlling effects on melon Fusarium wilt were 42.85%in the melon flowering period,which was better than the treatments of hymexazol,B.megaterium b1 strain and blank control.The root-shoot ratio and the whole plant dry weight of melon seedlings treated with combination were promoted and significantly different from the single treatments and the control.The results of field experiments showed that the control efficiency of B.megaterium,hymexazol and combined agent to melon wilt on continuous cropping soil were 16.62%,100%,and 100%,respectively.The melon plant height of each treatment was 11.19%,10.63%,and 16.03%higher than that of the control,respectively.The yield increase rates were 20.35%,11.23%,and 26.15%respectively.The average root dry weight per plant was 40.63%,34.69%,and 64.38%higher than the control with significant differences(P<0.05),respectively.The number of fungi decreased whereas the number of bacteria and actinomycetes increased.The relative abundance of Fusarium was 35.96%,59.55%,and 71.91%lower than the control,respectively.The relative abundance of Bacillus increased by 47.25%,3.52%,and 76.70%compared with the control,respectively.The results indicated that the combination of hymexazol and B.megaterium could promote the growth of melon and relieve melon wilt in continuous cropping soil,effectively improve the soil microbial community composition,and alleviate continuous cropping obstacles.