Field Screening for Late Leaf Spot Resistance in the BC\(_1\)F\(_4\) Population in Groundnut (Arachis hypogaea L.)

Globally, late leaf spot (LLS), a foliar fungal disease is one of the most important biotic constraint in groundnut production. LLS is a major cause of yield loss accounting for over 70% in groundnut production. This study aimed to evaluate 115 BC1F4 groundnut lines for resistance to LLS long with parents was done at ICRISAT in Rainy 2024 (Kharif). The field screening was taken in Single plant progeny rows with 2m x 1 row and disease scoring was done at 75 Days After Planting (DAP), 90 DAP and 105 DAP in that progeny rows under natural disease conditions based on visual observation. Two lines BC1F4-1 and BC1F4-2 with score 4 at 105 Days after planting (DAP) was identified as resistant and four lines BC1F4-3, BC1F4-4, BC1F4-63 and BC1F4-65 with score 5 and 6 at 105 DAP exhibited moderate resistance were identified. In the present study out of 115 BC1F4 lines evaluated two lines showed resistance, and four lines showed moderate resistance. These lines will be advanced to the next generation and tested in multi-location trials to further assess their resistance and potential for use in breeding programs.