|Holbrook, Carl - Corley|
Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/8/1996
Publication Date: N/A
Interpretive Summary: The root-knot nematode is a microscopic worm that feeds on the roots of peanut plants. This nematode can greatly reduce yield and quality and costs peanut farmers over 30 million dollars annually. All peanut varieties are susceptible to this pest. To begin the process of developing resistant varieties we are searching the germplasm collection (7,000 types of peanuts) for sources of genes for resistance. In a previous paper we reported the results of screening the first 1,500 peanut genotypes for sources of resistance. That work resulted in the identification of seven genotypes with moderate levels of resistance. The present study presents the results of screening an additional 1,000 peanut genotypes. This work resulted in the identification of eight additional sources of resistance. In addition, two of these new sources of resistance exhibited significantly higher yield than those previously identified when grown in a field that was heavily infested with the nematode. These genotypes should be valuabl in a breeding program to develop high yielding varieties with resistance to this nematode.
Technical Abstract: The root-knot nematode [Meloidogyne arenaria (Neal) Chitwood race 1] causes significant economic losses throughout the peanut (Arachis hypogaea L.) production area of the southern United States. Chemicals for control of this pest are becoming increasingly limited, and there are no peanut cultivars with resistance. Seven moderately-resistant plant introductions have been identified, however, less than 25% of the germplasm collection has been examined for resistance based on nematode reproduction. The objectives of this work were to examine an additional 1,000 plant introductions for resistance to the peanut root-knot nematode and to compare the most resistant P.I.'s to previously reported sources of resistance. Preliminary greenhouse screening trials were conducted to rate severity of galling and amount of egg mass production. Seventeen accession were selected based on a mean egg mass rating of less than or equal to three. These selections were reevaluated in additional greenhouse and field studies to quantify levels of resistance and to compare these sources of resistance to those previously reported. Eight accession were observed which had a significantly higher level of resistance (lower egg mass rating) than Florunner, however, none of these accession had a significantly higher level of resistance than those previously reported. Results of this study identified additional sources of resistance which may provide different genes for resistance. In addition, two of these new sources of resistance (PI 298848 and 311265) exhibited significantly higher yield than those previously identified when grown in soil heavily infested with M. arenaria.