Effect of soybean leaf position on the antibiosis expression to Anticarsia gemmatalis and the relation with nutrients and trichomes

This study aimed to evaluate the effect of soybean leaf position on the antibiosis expression to Anticarsia gemmatalis and the relation with nutrients and trichomes. Leaves of resistant and susceptible genotypes were excised from the upper or lower part of 30 day-old plants and put into Petri dishes, where one neonate larva was transferred and its development was followed. Quantification of the nutrients N, P and K and trichome density were performed. Leaves from the upper part of both genotypes provided the best results for most biological aspects. The resistant genotype had the lowest larval and larval-adult survival for both leaf positions. The most suitable development on the upper part and susceptible genotype leaves may be due the greater amount of nutrients. The trichome density seems not to influence the resistance expression. The use of the upper part leaves is more adequate to assay the antibiosis against A. gemmatalis.