Temperature Sensitivity of Sclerotium Stem Rot Resistance in Groundnut

Some 350 groundnut accessions originating from different geographic regions were evaluated in a greenhouse (ambient temperature 16-31°C) for resistance to Sclerotium rolfsii [Corticium rolfsii]. Eleven genotypes showed less than 20% stem rot incidence, and these were retested during May 1993 in the same greenhouse with ambient temperature of 23-36°C. All 11 genotypes developed 100% disease incidence within 30 days of inoculation. In a third test in January 1994, when temperature ranged from 15-32°C, 9 genotypes showed less than 20% mortality. Three resistant genotypes and 3 susceptible genotypes were compared under 4 temperature regimes: 15°C night, 30°C day; 20°C night, 30°C day; 25°C night, 30°C day; and 30°C day and 30°C night. The 3 resistant genotypes were only resistant at 15°C night, 30°C day and susceptible at higher temperatures