Anatomical Phenomena in Seedlings of Sorghum Varieties Resistant to the Sorghum Shoot Fly (<i>Atherigona varia soccata</i>)¹

Abstract

Five varieties of sorghum resistant to the sorghum shoot fly were compared to a susceptible variety as to some anatomical characters which were expected to contribute towards the mechanical resistance of seedlings to penetration by the shoot fly larvae. All resistant varieties (but not the susceptible one) were characterizcd by a distinct lignification and thickness of the walls of cells enclosing the vascular bundle sheaths within the central whorl of young leaves. The resistant varieties, as compared to the susceptible one, possessed a much greater density of silica bodies (dumbbell‐shaped, intercostal and silicified prickle hairs) in the abaxial epidermis at the base of the first, second, and third leaf sheaths. The density increased from the first to the third leaf sheath. No differences were found between varieties in the mean density of vascular bundles within the leaf sheath, the mean number of fibers per bundle, or the amount of leaf sheath surface cuticular wax per unit area.