| Wheat-maize rotation system is typical planting patterns in Shandong province.In recent years,wheat crown rot and corn stalk rot are more and more seriously.Straw returned is a common measure,particularly,in wheat-maize rotation system,it will enhance soil fertility and increase crop yield,but also have hidden dangers.Whether infected straw returned to the field will aggravates some soil-borne disease,it has attractd cultivator and pathologist.In order to explore whether returned straw with infected to the field may aggravate the occurrence of wheat crown rot and corn stalk rot.This study collected infected samples from the representative regions of Shandong and isolated the pathogens.Morphological and molecular biological identification of the isolated strains were carried out,pathogenicity,perfect state and temperature adaptability were compared among different pathogens.It is expected to guide the straw returned from the perspective of etiology.The main results are as follows:1.More than 200 samples were collected from eight cities of Shandong province,including Ji'nan,Tai'an,Dezhou,Weifang,Yantai,Liaocheng,Heze and Linyi,and obtained 224 strains.EF-1? sequences were analyzed to identify the species of 190 representative strains.The results showed that these strains were identified as Fusarium pseudograminearum,F.graminearum,F.verticillioides and F.proliferatum respectively.Wherein F.pseudograminearum accounts for 74.7% and is the dominant pathogen of wheat crown rot in Shandong province.2.More than 100 samples were collected from Tai'an,Dezhou,Liaocheng citys of Shandong and obtained 203 strains.EF-1? sequences were analyzed to identify the species of 189 representative strains.The results showed that these strains were identified as F.verticillioides,F.proliferatum,F.graminearum and F.oxysporum respectively.Wherein F.verticillioides accounts for 55% and is the dominant pathogen of corn stalk rot in Shandong province.3.A comprehensive analysis were carried out to pathogens which were isolated from wheat crown rot and corn stalk rot.The results showed that these pathogens belong to genus Fusarium,including F.pseudograminearum,F.graminearum,F.verticillioides,F.proliferatum and F.oxysporum.F.pseudograminearum was obtained from wheat crown rot but not corn stalk rot.F.graminearum,F.verticillioides,F.proliferatum were obtained from two disease,and their proportions were different.4.The results of pathogenicity of five Fusarium spp.showed that F.pseudograminearum had the strongest pathogenicity to wheat seedlings and spike of wheat,disease index was 100 and 84.3.Most of pathogens had significant difference to wheat seedling,but not to spike of wheat and maize seedling in the pathogenicity.F.pseudograminearum failed to infect maize plants successfully.Same Fusarium spp.from different host had not significant difference in the pathogenicity.5.The results of artificial inducement of teleomorph about five Fusarium spp.showed that F.pseudograminearum could not produce perithecium.F.graminearum produced more perithecium than F.verticillioides,F.proliferatum and F.oxysporum.6.Pathogens had different adaptability to temperature.F.pseudograminearum and F.graminearum could not survive at 35°C.F.verticillioides,F.proliferatum and F.oxysporum have a wide temperature range and can grow in the range of 5°C~35°C.In conclusion,the dominant pathogens of wheat crown rot and corn stalk rot are different,and F.pseudograminearum can not infect maize plant.So returned infected straw to the field would not significantly aggravated the occurrence of disease of next crop,especially returned wheat straw infected by F.pseudograminearum would not directly lead to the occurrence of corn stalk rot.However,F.graminearum not only caused wheat crown rot and corn stalk rot,but also is the dominant pathogen of Fusarium head blight(FHB).In this respect,the occurrence of FHB may be related to returned infected straw to the field. |
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