Agro-Morphological Characterization of Rice Varieties in an Irrigated Lowland in the Guinean Savannah Zone of Côte d'Ivoire

Aim: To measure the agro-morphological characteristics of rice varieties and to evaluate grain yields.

Study Design: Split-plot design with three replicates.

Place and Duration of the Study: In the M'bé II valley (8°06 N, 6°00 W, 180 m), not far from the village of Tabako, on the Bouaké – Katiola axe; about 24 km from Bouaké.

Methodology: The area of 1,815 m2 was cleared and subdivided into subplots 3 m apart, in which 15 m2 sub-plots were spaced 1 m apart in a split-plot design. 10 hybrid and 10 local varieties were selected for the study.

NPK (15-15-15) was applied as a bottom dressing at 200 g per 15 m2 before transplanting. The varieties were transplanted at a spacing of 20 cm × 20 cm, after 21 days in the nursery. The trial was irrigated via the drainage canal using a run-of-river system. Urea was applied at rates of 14 g per 15 m2 at tillering and 19 g per 15 m2 at heading stages. Glyphosate, a broad-spectrum herbicide to kill all types of weeds or plant, and propanil, a post-emergence herbicide to kill weeds only. The insecticide DECIS (Lambda-cyhalothrine) was used to kill insect pests.

Results: The eight mean’s value of local rice varieties was higher than that of improved varieties, whatever the plant growth stage. Conversely, the average number of tillers was always higher for the improved varieties. With a vigour index of 4.12, the improved varieties had a lower mean flowering time of 83 days than the one of local varieties which was 100 days. However, there was no effect of variety (P > 0.05) on the vigour index of hybrid varieties. However, for the semi-flowering cycle, a highly significant difference (P = 0.0001) was observed among hybrid varieties. The local variety Dememba showed a higher chlorophyll content of 52 µg mg-1. Varieties AR043H, AR034H and AR051H had the highest grain yields, around 8 t ha-1, while local varieties Demamba and Kouiklonlé had the lowest. In contrast, the varieties Koitè and GT11 yielded about 5 t ha-1. The variety Danané had one of the lowest yields of 1.5 t ha-1.

Conclusion: Identification of parental germplasm is important to quantitatively and qualitatively improve lowland rice production on the basis of agro-morphological traits.