Characterization, Stability and Genetic Diversity of Some Introduced Safflower (Carthamus tinctorius L.) Genotypes in the Semi-Arid Lands of Kenya

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Date
2008
Authors
Mabel J.M
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Mabel J.M
Abstract
Safflower is a drought tolerant oil crop and this gives it an advantage over the other crops in the drier parts of Kenya. It is widely cultivated as a source of high quality vegetable oil. Safflower germplasm has in the past been characterized on the basis of morphological, agronomic, biotic and abiotic stresses and biochemical characters. All these approaches lacked molecular characterization. The objective of this study was to characterize and assess genetic diversity using morphological traits and RAPD markers in 36 introduced safflower accessions and to evaluate yield stability in 4 semi arid environments (Lanet, Naivasha, Kinamba and Katumani). The experimental design was a partially balanced lattice design (6 x 6) with 3 replications. Each accession was grown in 4 row plots of 6 m length. The row-torow and plant-to-plant spacing was 45 cm and 30 cm, respectively. Recommended agronomic practices were followed through various stages of crop growth. The combined two-way analysis of variance for all the traits recorded was computed using SAS 6.12. Pooled analysis of variance indicated significant (PS 0.01) differences among genotypes suggesting the presence of variability among genotypes and environments. The first three PCs accounted for most of the variability (79%) in morphological traits. Accessions were grouped into 4 clusters based on morphological traits . Those from the same area tended to group together but occasionally a misclassification occurred. Biplots revealed that genotypes likely to be stable in most cases clustered around the origin. The significant G X E effects emphasize the necessity of multiple environmental testing through time and space so as to characterize genotypic differences and stabilities. The accessions PI 401474, PI 560177 and PI 560203 manifested relatively low G X E interaction hence are likely to be stable. The high correlation and direct effects of capitula planr', effective capitula planr' and seeds capitula-' on seed yield suggest selection for these components will improve seed yield in safflower. The number of seeds capitulum-' and yield planr', 100 seed weight and secondary branches showed significant negative correlation between them, hence indirect selection through increased number of one would be ineffective. Seed yield in safflower can be improved indirectly by selecting genotypes retaining a large number of effective capitula planr '. Path analysis of yield components revealed that the number of primary branches planr', secondary branches planr' and number of capitula planr', had the highest correlation to yield hence the negative direct effect to yield. Molecular characterization was carried out using RAPD markers to determine the genetic basis of observed morphological variations.
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