Pearl millet grain size and hardness in relation to resistance in Sitophilus oryzea (L.) (Coleoptera: Curcilionidae)

Abstract

Fifty-seven varieties of pearl millet (Pennisetum glaucum (L.) R. Br.) were evaluated for resistance to the rice weevil Sitophilus oryzea (L.) by using artificial infestation. Kernels of each cultivar were separated into three grain sizes; small, medium and large, to remove the effect of grain size from that of variety. Grain hardness was measured using the sodium nitrate specific gravity floaters test. In general, larger and softer grains supported more weevils. However, there seems to be a good spread of variability for weevil progeny production within the large grain fraction, suggesting the possibility of selecting for resistance among large grains. Most of the soft grain types had floury endosperm, but no relationship was found between grain size and endosperm type. This suggests that floury and/or vitreous endosperm is not influenced by size, and that it may be possible to develop varieties with a combination of large grain, vitreous endosperm, and weevil resistance. Irrespective of grain size, SDMV 90016, Nandi Code 24, TSPM 91018, and SDMV 89001 were resistant compared to the farmer's local variety.



Key Words: Grain size and hardness, Pennisetum glaucum, rice weevil


(African Crop Science Journal: 2000 8(1): 77-84)