| Maize, one of the most widely distributed grain crops in the world, is not only an important food crop, but also the important industrial raw materials and animal feeds. However, due to the influence of various unfavorable factors in recent years, for instance, the change of global climate and cultivation systems, the variation of pathogens physiological races, and numerously allocating the seeds from different places, the harmful extent of southern leaf blight (SLB) and also some other important maize diseases have been increasing year by year, which caused severe damage to maize production. Although there were a large number of researches on this disease both at home and abroad, the research methods subjected to certain restrictions as a result of the differences from geographic conditions and environmental factors. Therefore, the systematic study of maize cultivars resistance to SLB in Anhui province can lay the foundation not only for forming the integrated pest management techniques that is suitable for Anhui province, but also for providing the necessary basis for resistance breeding of maize and the rational distribution of disease-resistant cultivars.The biological characteristics of the SLB pathogen isolated from diseases leaves were studied, and the best preservation method for the pathogen was explored. On the basis of the above, the impact factors on resistance identification were ascertained, and the resistant cultivars were also screened out according to the resistance identification trails in Anhui province. The major results are summarized as follows:1. The best way to preserve the strains was confirmed by means of measuring the mycelia growth rate, sporulation and strain virulence under different preservation methods. The results presented that when SLB was preserved for short time (one month) or long time (seven months) with the humidity of about10%, temperature of5℃, the mycelia growth and sporulation in barley solid culture medium was higher than that of maize culture medium and wheat culture medium, and the strain virulence was also maintained much better.2. The differences of the mycelia growth, sporulation, pathogenicity and spore germination among the strains XX, SX, MC, SZ, JX and CF were studied. The results showed that the mycelia growth and sporulation among the six strains had no significant difference, but the pathogenicity was different. The pathogenicity of XX was higher than the other5strains.In addition the germination of the6strains was the same, from both spore ends. Also the germination rate was not significantly different, with the germination rate range93%-100%after three hours’culture.3. The impact factors of resistance identification to SLB were confirmed, among which the most important were the field temperature and humidity before and after inoculation, inoculation method and maize growth period. The results indicated that when the field temperature was about25℃, inoculating with the spore suspension spray, the SLB occurred and extended easily (horizontal expansion and vertical expansion) in tasseling stage of maize.4. on the basis of the above,68cultivars resistances to SLB were identified in Da yangdian and seed station of Hefei. The results manifested that there were8cultivars which were above moderately resistant, accounting for11.76%of the total68cultivars, and the cultivars are Y2011Q002, Y2011Q003, Y2011Q004, Y2011Q020, Y2011Q061, Y2011Q065, Y2011Q069and Y2011Q070. There were4highly susceptible cultivars which accounted for5.88%of the cultivars, and the severity ranges were from7.1to7.4.In addition, the significant difference analysis to the severity of68cultivars between these two places was conducted. The results presented that the resistances to SLB were extremely significant (p<0.0001) among cultivars While the resistance differences of different places were not significantly different. |
PDF Full Text Request