Bull. Spec. CORESTA Congress, Guangzhou 1988, p. 129, P-2.

Reaction of resistance to cucumber mosaic virus at different growth stages of tobacco

XIE C.S.; LI Y.; WANG Z.F.; ZHANG G.M.; CHEN R.T.
Shandong Agricultural University, Tobacco Research Laboratory, Taian, Shandong, China.
Three varieties, Speight G-28, NC 89, and China Tobacco-15 were inoculated at different stages of the growth phase with cucumber mosaic virus (CMV) from 1984 to 1986. The results indicated that the ability of these varieties to tolerate CMV infection varied considerably from seeding to squaring phase. From the first inoculation at the 4 true leaf phase up until the fiftieth day, the tobacco plants showed no tolerance to CMV. There are two highly susceptible days of the growth phase; the tenth and fortieth. The tenth day proved to be the most susceptible with the shortest incubation period, highest disease index (87.5), greatest reduced total output (40.33%), and longest postponement of the squaring period (approx. 45 days). The mechanism of susceptibility to CMV is inversely proportional and proportional to the amount of sugar and protein respectively. It is evident that the 6-7 true leaf phase of the seeding period is significant with respect to control of CMV.