| Maize is one of major grain crops in the world.In China,it is also an important food,feed crop,and industrial raw material.It plays an important role in China's national economy and agricultural production.Maize diseases,including southern leaf blight,curvularia leaf spot,southern rust,stalk rot,ear rot,and smut,are the main problems affecting maize production and food security.Breeding and planting resistance cultivar is the most effective and environment-friend way to reduce the losses.In this study,resistance of 400 maize cultivars(Lines),including 299 cultivars(lines)from outside of Shandong province and 101cultivars(lines)from Huang-Huai-Hai region,to those six diseases were identified using artificial inoculation in the field in Tai'an,Shandong Province.The main results are as follows:(1)Re-identification of the inoculums based on morphology and DNA sequences.The inoculums were obtained from Faculty of Hebei Agriculture Science,Institute of Crop Sciences,Chinese Academy of Agriculture Sciences,and our Lab.To exclude the possibility of contamination,all the inoculums were re-identified based on the spores morphology and phylogenetic relationship based on DNA sequences.Results showed that the inoculums used in this study belong to Bipolaris maydis(causing southern leaf blight),Curvularia lunata(causing curvularia leaf spot),and Fusarium graminearum(causing stalk rot and ear rot,respectively).(2)Field identification of Maize cultivars(lines)resistance to southern leaf blight.Different origins Bipolaris maydis were cultured on autoclaved Sorghum bicolor seeds.The spores were washed and diluted to a concentration of 1.0×10~5/mL,and sprayed on 13-leaves stage of maize plants.The survey was conducted at physiological maturity stage of maize plants.Results showed that,among the 400 maize cultivars(lines),there are 105(26.25%)maize cultivars(lines)were high resistance(HR),280(70.0%)showed resistance(R),12(3.0%)showed medium resistance(MR),and 3(0.75%)showed susceptible(S),respectively,No cultivars(lines)were high susceptible(HS)to southern leaf blight.(3)Field identification of Maize cultivars(lines)resistance to curvularia leaf spot.Different origins Curvularia lunata were cultured on autoclaved Sorghum bicolor seeds.The inoculums were prepared same as Bipolaris maydis and diluted to a concentration of1.0×10~7/mL.Spores were sprayed on 11-leaves stage of maize plants.The survey was conducted at physiological maturity stage of maize plants.Results showed that,among the400 maize cultivars(lines),only 1(0.25%)maize cultivars(lines)showed high resistance(HR)to curvularia leaf spot.In total,74(18.5%)showed resistance(R),163(40.75%)showed medium resistance(MR),152(38.0%)showed susceptible(S),10(2.5%)showed high susceptible(HS),respectively,to curvularia leaf spot.(4)Field identification of Maize cultivars(lines)resistance to southern rust.The pathogen of southern rust could not culture on artificial medium.Maize leaves infected by southern rust were collected from field in Guangxi province.The spores were bushed and diluted with the ratio of 2 g spores per 1000 m L water.The diluted spores were sprayed at 45days post maize planting.The survey was conducted 15 days before harvesting.Results showed that,among the 400 maize cultivars(lines),there are 3(0.75%)maize cultivars(lines)showed high resistance(HR),24(6.0%)showed resistance(R),36(9.0%)showed medium resistance(MR),31(7.75%)showed susceptible(S),most of the maize cultivars(lines)(76.5%)showed high susceptible(HS),respectively,to southern rust.(5)Field identification of Maize cultivars(lines)resistance to stalk rot.Different origins Fusarium graminearum were cultured on autoclaved maize.The maize seeds occupied by the Fusarium graminearum were inoculated near the hurt root of maize.The survey was conducted at physiological maturity stage of maize.Unfortunately,the susceptible cultivar showed medium resistance(MR),indicating the results were not reliable.The identification results were invalid.(6)Field identification of Maize cultivars(lines)resistance to ear rot.Different origins Fusarium graminearum were cultured on spore-inducing medium.The collected spores were diluted at a concentration of 5.0×10~6/mL,and injected to maize ear.The survey was conducted before harvesting.Results showed that,among the 400 maize cultivars(lines),there were 94(23.5%)showed resistance(R),298(74.5%)showed medium resistance(MR),8(2.0%)showed susceptible(S),respectively,and did not showed high resistance(HR)and high susceptible(HS)maize cultivars(lines)to ear rot.(7)Field identification of Maize cultivars(lines)resistance to smut.Different origins maize ear infected by smut were collected.The teliospores were collected and diluted in water to a concentration of 4.0×10~6/mL.The diluted teliospores were injected to maize stem at5-leaf stage of maize.The survey was conducted at early stage of maize ear formation.Results showed that,among the 400 maize cultivars(lines),there were 129(32.25%)showed high resistance(HR),215(53.75%)showed resistance(R),52(13.0%)showed medium resistance(MR),2(0.5%)showed susceptible(S)and high susceptible(HS),respectively,to smut. |
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