CULTIVAR DIFFERENCES IN TOMATO SPOTTED WILT VIRUS TOLERANCE IN PEANUT

Tomato spotted wilt virus (TSWV), which is transmitted by various thri p species, can greatly reduce peanut (Arachis hypogea L.) production e specially following early infections. This study was conducted to exam ine the effect of TSWV on the tolerance of two peanut cultivars, 'Sout hern Runner' and 'Florunner', which show different levels of TSWV infe ction under field conditions. In a greenhouse environment, various qua ntitative growth parameters (main, cotyledonary, and primary stem leng th; number of pegs and pods; and fresh canopy and root weight) were me asured for controls and systemically infected plants mechanically inoc ulated with TSWV at two growth stages. Except for main stem length, no significant cultivar x infection level or cultivar x infection level x growth stage interactions were obtained for any character. Depending on cultivar and growth stage, TSWV infection reduced all parameters b y at least 60%, with the greater reductions occurring at the early gro wth stage. This degree of reduction is similar to that reported in the field. However, under these conditions, field-tolerance differences a mong cultivars was not expressed. Therefore, cultivar tolerance levels are influenced by the environment to which the plants are exposed dur ing development and growth.