INORGANIC NUTRIENT ANALYSIS OF LEAF TISSUE FROM SOYBEAN LINES SCREENED FOR MEXICAN BEAN BEETLE RESISTANCE1

Abstract

Leaf tissue of 49 F5 soybean [Glycine max (L). Merr.] lines derived from a cross between an experimental line, MBB 80-115, and the cultivar ‘Ware’ were fed to Mexican bean beetle (MBB), Epilachna varivestis Mulsant, larvae in laboratory studies. The parents, Ware and MBB 80-115, and PI 171451 which was the original source of MBB resistance were included as checks in all studies. Laboratory tests suggested the presence of non-preference (antixenosis) and/or antibiosis in the resistant soybean genotypes and were efficient in identifying most resistant lines and mechanisms of resistance. The larvae reared on leaves of lines 119-2 and 119-11 took longer to pupate and reach the adult stage and had fewer numbers of emerging adults. Leaf tissue of selected lines was analyzed for the elements phosphorus, calcium, potassium, magnesium, and silicon to determine if any of these elements are associated with the feeding response and might serve as a quick index of selection for plant resistance. Calcium, phosphorus, and potassium content was each negatively correlated with pupal weight (r = −0.23**, −0.26**, −0.20*, respectively). No significant correlations were observed between silicon and magnesium content and pupal weight. The progeny line 119-2 which demonstrated a high level of antibiosis had a higher calcium, phosphorus, and magnesium content than either parent or the resistant PI 171451 and also had a potassium content that was similar to that of the resistant PI. PI 171451 had the lowest silicon content of all lines tested.