SEED COAT PUNCTURE RESISTANCE IN CEREAL AND OILSEED CULTIVARS—A POSSIBLE SOURCE OF SUSCEPTIBILITY TO INSECT DAMAGE IN STORED GRAINS

Abstract

Seed coat puncture resistance of 42 cultivars of common and durum wheat, oats, barley and rapeseed were measured by puncture tests believed to approximate seed penetration by weevils infesting stored grain. All seven species of crops, several cultivars, and germ and endosperm parts of the seed within the same cultivar varied significantly [Formula: see text] in puncture resistance of seeds when their moisture contents were m equilibrium at 0% and 70% RH. Dry durum wheat (cv. Wakooma) showed the highest puncture resistance, moist rapeseed (cv. Torch) the lowest. The mean puncture resistance of the endosperm coat of moist crop cultivars ranged from 2,074 to 2,456 g for common wheat; 3,316 to 4,131 g for durum wheat; 1,145 to 1,404 g for oats; 1,321 to 1,861 g for barley; and 184 to 222 g for rapeseed. These differences m seed coat strength suggest that it may be one of the sources governing susceptibility to insect damage of stored grain. Thus, the drier the seed, the greater would be the difficulty for an insect to penetrate the seed coat.