Selection of a multiple disease resistant runner-type peanut

Four F2:4 populations of peanut (Arachis hypogaea L.) resulting from the complex cross Tamrun 96 X Tx901639-3 X Sun Oleic 95R were grown in three disease nurseries over a 2 year period. Three separate selection techniques were applied to determine which technique would provide the most effective method for selecting a multiple disease resistant, runner-type peanut. Technique I involved selection at a tomato spotted wilt virus nursery during the first cycle of selection and transferring the selections to a Sclerotinia minor (Jagger) nursery for a second cycle of selection in year two. Technique II was the reciprocal of Technique I. Technique III involved selection of the populations at a multiple disease nursery for two consecutive years. Selections were based on disease ratings, growth habits, pod and seed characteristics, and oleic/linoleic acid ratios. Disease ratings were scored as percentage infection on a scale of 0 (0% plot infected) to 10 (100% plot infected). Disease severity was also rated on a scale of 1 (symptoms noted, but no yield effects) to 10 (plant death, no yield). There were two final selections for each population using each selection technique that were yield tested over a 2 year period to determine which technique was superior. The yield tests were conducted using completely randomized block design at all three disease nurseries with an additional disease-free site included. Data for disease ratings, yield, grade, and value per hectare were combined within locations across years. All three selection techniques provided lines with more disease resistance than the parents; however, there was no difference detected between the effectiveness of the three techniques in terms of disease resistance, yield, grade, or value per hectare.