Agro-Morphological Diversity of some Improved and Local Rice (Oryza sativa) Varieties in Irrigated Lowland in Guinea Savannah of Côte D'ivoire

Problem: In Côte d'Ivoire, rice is a staple food crop for the populations. However, only half of local increasing demand is covered by domestic rice production because of poor seed quality and quantity. Objective: The general objective of this study is to determine the most discriminating phenotypic traits of 20 irrigated rice accessions, including 10 improved varieties produced by AfricaRice and 10 local varieties of Côte d'Ivoire, and identify those with the best production potential. Methodology and Results: Nine qualitative and 20 quantitative traits were scored in field conditions on each of the 20 rice varieties. A multiple correspondence analysis performed with the 9 qualitative descriptors separated the 20 rice varieties into 3 groups that globally distinguished improved varieties from local ones. Descriptive statistics of quantitative traits showed significant phenotypic differences between all the varieties. A principal component analysis revealed 6 rice variety groups determined by 79.82% of the observed variability. A hierarchical ascending classification separated the rice varieties into 6 agro-morphological diversity groups which were then all confirmed by a discriminant factorial analysis (DFA). The DFA also showed that plant height, number of tillers per plant, number of panicles per plant, leaf width, shape of the seeds, seed yield and weight of 1000 grains are the descriptors which most determine the agro-morphological diversity of the 20 varieties. Conclusions and Application of Results: The 10 improved rice varieties are characterized by medium stem height, high tillering, long and round grains, and higher grain yield than local varieties. These improved varieties thus have a certain interest in the sense that high yield is a capital characteristic for rice growers, but also because the high tillering plays a very important role in the control of weeds.