Genetic Diversity and Evaluation of Assembled Rice (Oryza sativa L.) Germplasm for Breeding Purposes in Northern Ghana

Abstract

Background of the Study: Rice (Oryza sativa L) is an important staple food crop that feed over half of the global population and it has become the cereal that provides a major source of calories for the urban and rural poor in Africa. Rice has is the second most important food staple after maize in Ghana and its consumption keeps increasing as a result of population growth, urbanization and change in consumer habits. Rice yield across Ghana is far below achievable yield. The need for increasing rice yield depends not only on cultural/traditional practices but also on their inbuilt genetic potential to withstand stresses. Adequate diverse rice germplasm is a pre-requisite for breeding varieties to meet local biotic, abiotic and grain quality challenges. Knowledge of germplasm diversity and genetic relationships among breeding materials is valuable information for crop improvement. Aim: To identify the diversity among assembled rice germplasms for evaluation and possibly exploit its genetic variability for earliness for cultivation in the Guinea and Sudan Savanna ecologies. Study Design: The experiment was conducted at CSIR-SARI research station, Nyanpkala. Using a Randomized Complete Block Design with two replications, and a plot size of 4 m x 3 m was used. Field data taken included 10 qualitative and 11 quantitative traits. The data were statistically analyzed for various descriptive statistics. Results: Correlation analysis, Principal Component Analysis (PCA) and Cluster analysis were used to assess genetic variability. Most of the morphological traits showed remarkable differences in their distribution. Five significant principal components were identified accounting for 78.11% of the total variation. Cluster analysis based on the morphological data grouped the germplasm into two distinct clusters suggesting diversity among the assembled rice germplasms. Conclusions: The rice germplasm used in the present study displayed variability for most of the studied traits with the exception of ligule. Twenty one out of the 100 germplasm were distant from the rest, and were selected to constitute a core collection for further improvement. Recommendations: Diversity revealed in this study is narrow. It is, therefore, recommended that rice breeding programs in Ghana should include new genetically unrelated genotypes in order to broaden the genetic base of Ghanaian rice germplasm.