Study On Biological Characteristics Of Fusarium Moniliforme Related To Corn Ear Rot And Disease Resistance Of Corn

The corn ear rot on 51 malze breeds which were made to national test in Sichuan was investigated in 2005.It showed that the rate of corn ear rot was 35.1%, corn ear rot by Fusarium moniliforme was one of the most important, which was counted for 49.1% in all rot ears investigated.In 2006, the corn ear rot on 12 maize breeds which have different genetic background was investigated again. The results showed that the rate of corn ear rot was 35.1%, what was caused by F.moniliforme was counted for 77.1% in total,and this was also the primary corn ear rot.The investigation of two years showed that corn ear rot by F.moniliforme was the dominant corn ear rot,and F.moniliforme was the major pathogen to corn ear rot.When the corn was harvested,the pathogen of the corn ear rot were isolated from diseased kernel in Duoying farm in Yaan, Sichuan.The pathogen was identified to be F.moniliforme.It was conserved in refrigerator to make further study.Study on biological characteristics of F.moniliforme showed that hyphae could grow well in the meadium of Czapek and PDA, at the condition of 25～30℃, pH9, carbom source and KNO₃.The optimum conditions for the sporulation were PSA medium, 25～30℃, pH6, carbom source and KNO₃. The optimum conditions for spore germination were 25～30℃,pH6 and darkness.The light could inhibit the spore germination obviously.Study on the effects of several fungicides on the hyphal growth and conidia production and germination rate of conidia showed that the four species fungicides which were carbendazim,chlororthalonil,triadimefon and topsin-M possesed different function.The inhibition ratios of hyphal growth were the highst under the each concentration of topsin-M.And it could inhibit conidia productin and germination rate of conidia obviously.So the efficiency of topsin-M in the lab was the best among the four fungicides, the effects of carbendazim and chiororthalonil were good,too.So they could be also used to control corn ear rot in practice.Study on disease resistance assessment of corn ear rot by F.moniliforme showed that the method of injection spore suspension into corn ear was the best inoculation method.This method is to be close to the natural condition, and the disease occures very sufficiently.The best inoculation time is milk stage.In this period, the disease occures very sufficiently and the data are statisticed very easily.The best inoculation concentration of spore suspension was 1×10⁶ spores/mL,and the inoculation volume was 3mL/ear. The 15 breeds were tested for the resistance. It showed that the 15 breeds were disease resistance materials. Qi318 and 3411 were the high resistance materials. The disease severity and index were 0.17,3.3 and 0.43,8.6 respectively. This result showed that Qi318 and 3411 could be as resistance resource to use. The methods and technique used in this experiment could be used in the breeding for disease resistance.Study on the activity of PAL,POD and SOD in the corn after inoculated pathogen showed that there were big differences between resistance and susceptible materials. The changs were more stabilization in resistance materials than in susceptible materials. There is a wave crest of activities in resistance materials, but no activity wave crest in the susceptible.