Responses of tobacco associated with PVYN and tobacco aphid to elevated CO2 concentration Genetic Diversity Analysis on Tobacco Germplasm Resistance to PVY Sequence analysis of P1 gene of PVY tobacco isolate from Qianxi,Guizhou Molecular Markers Assisted Selection for Three QTLs Resistant to PVY in Pepper(Capsicum annuum L.) RESEARCH OF TUBE STORAGE TECHNIQUE AND ITS EFFECTS OF TABACCO CONTAINED VIRUSES