Comparison of two screening procedures and classification of soybean genotypes into insect‐resistant groups

Abstract

The two procedures for grouping genotypes: The All‐India Co‐ordinated Research Project on Soybean (AICRPS) method and a novel ‘maximin‐minimax’ approach, were compared for their effectiveness. Sixteen soybean (Glycine max (L.) Merrill) genotypes are grouped into different categories of resistance by using data from field experiments conducted during the rainy seasons of 1993 and 1994. According to the AICRPS method, which takes into account only the extent of injury or insect population (not the yield), Punjab‐1 and TG×814–54D are rated as resistant to stemfly (Melanagromyza sojae (Zehnt.), Diptera: Agromyzidae) damage. This method places marginally less resistant genotypes into other categories, even if they are not significantly different from the resistant ones. However, this procedure helps in the identification of sources resistant to particular insect species. On the other hand, the ‘maximin‐minimax’ approach involves a vital yield component and the entire insect‐pest complex, to classify the genotypes into resistant groups. It is possible to identify genotypes with resistance/tolerance to a location‐specific pest complex and good yield potential. Using this approach, cultivars JS 335 and NRC‐2 and a germplasm line L‐129 have been found to be tolerant to insect damage.

Keywords:

• soybean
• insects
• resistance
• screening procedures