Optimal allocation of resources in evaluating current sunflower inbred lines for resistance to Sclerotinia

Sclerotinia sclerotiorum (Lib.) de Bary is a major limiting factor for sunf lower (Helianthus annuus) production. This study was conducted to (1) evalu ate a large number of current sunflower lines for their reaction to Sclerot inia, and (2) determine the optimum allocation of resources for their selec tion. A set of 85 inbred lines was screened under artificial leaf infection in three environments. The test revealed ample variation for all resistanc e traits in the current germplasm. A line selected from NDBLOS, an oilseed sunflower germplasm pool, and its derivatives were most resistant to Sclero tinia. Lines derived from interspecific crosses with the wild species Helia nthus tuberosus and Helianthus argophyllus also showed satisfactory Sclerot inia resistance. The evaluation of five plants per plot in two replications and four environments appears to be a reasonable allocation of resources i n order to optimize the selection response.