Cultivar differences in tomato spotted wilt virus tolerance in peanut

Tomato spotted wilt virus (TSWV), which is transmitted by various thrip species, can greatly reduce peanut (Arachis hypogea L.) production especially following early infections. This study was conducted to examine the effect of TSWV on the tolerance of two peanut cultivars, 'Southern Runner' and 'Florunner', which show different levels of TSWV infection under field conditions. In a greenhouse environment, various quantitative growth parameters (main, cotyledonary, and primary stem length; number of pegs and pods; and fresh canopy and root weight) were measured for controls and systemically infected plants mechanically inoculated 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 by at least 60%, with the greater reductions occurring at the early growth stage. This degree of reduction is similar to that reported in the field. However, under these conditions, field-tolerance differences among cultivars was not expressed. Therefore, cultivar tolerance levels are influenced by the environment to which the plants are exposed during development and growth.