Identification of groundnut genotypes and wild species resistant to stem rot using an efficient field screening technique

Stem rot of groundnut caused by Sclerotium rolfsii Sacc. is one of the major constraint to groundnut production in many countries. The fungus is ubiquitous, soil inhabitant and non-target. Screening of groundnut genotypes for resistance to stem rot under field conditions is complicated by the non-uniform spatial distribution of the pathogen. While development and maintenance of artificial sick plot with optimum inoculums load under field conditions are also difficult because of sensitivity of the pathogen to temperature, humidity, soil type, cropping system and host preference. In the present study, a screening technique under field conditions with high disease pressure has been reported. Twenty-five wild Arachis accessions and 178 F3 progenies along with two parents were screened under pot and field conditions, respectively for resistance to stem rot. Two wild Arachis accessions and three F3 lines were found resistant to stem rot with mortality less than 20% and 10%, respectively.