Identification And Selection Of The Rough Dwarf Disease Resistance In Maize

Maize rough dwarf disease (MRDV)caused by maize rough dwarf virus (MRDV) is the most widespread and serious virus disease of Maize in the world. In recent years, MRDV in major maize-growing area in China increased significantly year by year and caused great losses of maize production. As lack of resistant hybrids, the main approach to control MRDV is used by agricultural measures and chemical treatments, which are not only costly, but also pollution and low effective. Adjustion of maize sowing dates usually can prevent the occurrence of MRDV, but special climatic conditions can still cause outbreak of MRDV. Developing and cultivating resistant hybrids is the most effective way to control MRDV. The study dealed with investigation of the relationship between Laodelphax striatellus fluctuation and the occurrence of MRDV by comparative tests of maize sowing date, identification and Evaluation the resistance of maize germplasm to MRDV. The results are as follows:(1) Sowing dates palyed a significant role on MRDV in Jining. The incidence rate of maize were the highest being100%in sowing dates from May1to June5, significantly decreased since June10, and no rough dwarf disease occurred after sowing on June20. Dynamic of MRDV in different sowing dates was closely related to Laodelphax striatellus fluctuation. Sowing dates from beginning May to the first ten days in June significantly improved the chances of virus transmission when it was in the spreading peak of Laodelphax striatellus, and maize were in sensitive stages, planting after the June15, the probability of virus transmission reduced significantly as maize avoided the spreading peak of Laodelphax striatellus.(2) Identification of the disease resistance of maize hybrids to MRDV were carried out in Jining, where the disease has been seriously occurring in recent years. Among the test maize hybrids, no immune or resistant varieties to MRDV had been found, but the disease severity of different hybrids was variable. MRDV incidence rate of most hybrids were100%, and the disease index was distributed from14.8to99. Qingnong105, Zhongyu703and Denhai3622were highly resistant; Nongda108and Jinhai5were moderate resistant; Zhengdan958, Jundan20, Ludan981were highly sensitive, which can not be used to resolve the MRDV. In addition, the resistance of260conventional maize inbreeds and82recently selected materials were identified for2years. The results showed that the resistance of different maize germplasm to MRDV were great different,35of which were highly resistant,9were resistant,23were moderate resistant,275were sensitive or highly sensitive. The resistance of P germplasm population were outstanding, Lancaster population were moderate, Reid were poor, Lvdahonggu population population and Thangshipingtou population were normal. It was showed that maize germplasm played important role on resistance of MRDV.