1. Botanical indices of ploidy levels in some African accessions of Oryza punctata


Obafemi Awolowo University, Ile-Ife, Nigeria

Agrobotanical characteristics, foliar epidermal and nodal anatomical features were studied in 29 accessions of O. punctata Kotschy ex Steud., obtained from local and other African habitats.

The diploid plants of O. punctata are early-maturing annuals with a small biomass, while the tetraploids are vigorous perennials with a larger biomass. In anatomical and morphological traits, the diploid and tetraploid plants were found to differ in seven indices: 1) leaf breadth-the diploid has narrower leaves (0.95-1.36 cm in width) than the tetraploid (1.9-2.3 cm). 2) culm diameter-the culms of diploids are generally thin (0.28-0.35 cm in diameter) as compared with those of tetraploids which are thicker (0.37-0.57 cm). 3) Spikelet size and shape-the diploids have longer spikelets (6-20-7.04 mm) with a length/ width ratio greater than 3, than the tetraploids. 4) Awns-the diploids have longer awns (52-86 mm) than the tetraploids (20-31 mm). 5) In the diploids, the basal cells of microhairs are about twice the length of apical cells; these are only slightly longer than the apical cells in the tetraploids. 6) Prickle hairs-in the intercostal zone of diploids, the hairs are sparse, but they are abundant in tetraploids. 7) Short cells-in the intercostal zone, the diploids have abundant short cells which are mostly paired; in the tetraploids, the short cells are sparse and solitary.