Abstract
A simple and efficient glasshouse inoculation technique for the mass screening of sorghum [Sorghum bicolor (L.) Moench] lines against an isolate of maize stripe virus - sorghum infection was tested. Seedlings exposed at the 1- and 2-leaf growth stages using two viruliferous planthoppers (Peregrinus maidis) per plant resulted in 62 and 58% sorghum stripe virus (SStV) transmission respectively, after an incubation period of 8 and 10 days, whereas 47% transmission with an 18 -day incubation period was observed when seedlings were inoculated at the 10-leaf stage. Six per cent viral transmission was observed when an individual viruliferous vector was used for a group of 10 seedlings, compared to 98% transmission with 20 viruliferous insects. Among the five methods tested to expose groups of seedlings and adult plants to viruliferous vectors, exposure of groups of seedlings (2-leaf stage) to viruliferous vectors, at the rate of two viruliferous insects per seedling confined to a 48-h-inoculation feeding period in cylindrical cages, resulted in 95% sorghum stripe virus (SStV) transmission. Based on the group seedling inoculation technique, a flow chart was developed for mass screening of sorghum genotypes for assessing reactions of SStV. Out of 194 sorghum germplasms, hybrids, and varieties screened by the group seedlings inoculation technique, none of the genotypes was found resistant to SStV infection.
