链格孢菌DT-XRKA菌株的除草活性及对作物的安全性

Herbicidal Activity and Crop Safety of Alternaria alternata DT-XRKA

从青海省大通县达隆村农田采集自然感病的植物叶片并分离出真菌菌株,以密花香薷为靶标草,通过离体叶片和温室盆栽试验以及作物安全性评价,筛选获得1株具有较好除草活性的生防菌DT-XRKA。结果表明,离体叶片接种DT-XRKA 7 d后,密花香薷叶片上出现产3~4倍于菌饼大小的灰褐色病斑,病斑面积达到了整个叶片的50%以上,在接种处可见大量灰褐色的菌丝,中心黑色,边缘褐色,且叶片开始逐渐失绿变黄,病级达到5级。不同浓度(1.47×10^(1)~1.47×10^(4)个/mL)的DT-XRKA孢子悬浮液对密花香薷的发病率达到67.84%~96.42%,病情指数为51.11~97.97,鲜质量防效达到52.44%~82.67%。作物安全性评价结果表明,DT-XRKA菌株孢子悬浮液对油菜、白菜、番茄、黄瓜和辣椒安全。经形态学特征和rDNA-ITS序列分析将DT-XRKA鉴定为链格孢Alternaria alternata。

Fungal strains were isolated from the leaves of naturally diseased plants collected from the farmland of Dalong village,Datong county,Qinghai province.Among these strains,the antagonistic strain DT-XRKA exhibited effective herbicidal activities against Elsholtzia densa through detached leaves,greenhouse pot experiments,and crop safety evaluation.The results showed that grayish-black patches covering more than 50%of leaf area appeared on the detached leaves after 7 days inoculation,resulting in 3-4 times more than fungus plugs.Massive grayish-black hyphae with concentric blackish and brown margins were observed at the inoculation sites.As the disease progressed,chlorosis and the yellowish area increased,reaching a disease grade of 5.The spore suspension of strain DT-XRKA,with different concentrations ranging from 1.47×10^(1)to 1.47×10^(4)spores/mL,exhibied an incidence rate of 67.84%to 96.42%,a disease index ranging from 51.11 to 97.97,and a fresh mass control effect between 52.44%and 82.67%.Crop safety evaluation of strain DT-XRKA showed that its spore suspension was safe to rape,cabbage,tomato,cucumber and pepper.DT-XRKA was identified as Alternaria alternata by morphology and rDNA-ITS sequence analysis.