Characterization Of Yellow-, Red-, And Purple- Kernel Maize (Zea Mays L.) Accessions In Ghana.

Abstract

Twenty yellow-, red- and purple-kernel maize accessions were collected from three regions in Ghana for the study. The objectives were to characterize the yellow-, red- and purple-kernel maize accessions in Ghana using phenotypic traits in order to determine their identity, using molecular traits for confirmation of their identity and to determine the presence of the opaque -2 gene and -carotene content of the grains as a way of assessing nutritional quality. A replicated field experiment was conducted to evaluate and characterize the accessions based on 16 quantitative and eleven qualitative traits. The same accessions were characterized based on 16 SSR markers. Variability in -carotene content was determined by HPLC while presence of opaque 2-gene was determined by a light box. The results revealed that accessions GH4055 and GH4863 are extra early maturing and therefore can be very useful for urban farmers producing fresh maize and for cultivation in the coastal savanna ecological zone. However, they produce smaller cobs (Cob weight = 58.24g) as compared to other accessions. Significant variability in morphological traits was observed among the accessions with cob weight, number of kernels per row, plant height and 1000 seed weight having coefficient of variation of 42.7544, 20.5828, 11.4634, 13.0634 and 26.76 respectively. Few traits contributed to the variations observed as revealed by the principal components analysis and these include days to 50% anthesis, days to 50 % leaf senescence, plant height and cob weight. A dendrogram generated from morphological traits clustered the accessions based on kernel colour, physical structure of the plant and geographical location. Two duplicates were identified among the accessions and widest genetic distance was observed between NYR1 and GH4055. Strong correlation exist between most of the morphological traits measured (r = 0.9103) but negative correlation was observed between most important yield parameters and number of row per cob. Accession NYR1 showed promise in terms of yield (1000 seed weight = 281 g) as well as high carotenoid (4.7895 μg/g) and -carotene content (0.8507 μg/g) and therefore can be very useful in future breeding programmes. Population genetic analysis shows that the accession bear close resemblance to each other with high Nei's genetic identity coefficient 0.9587 and 0.9020 between accessions from Northern and Eastern region and Northern and Greater Accra region respectively with short genetic distances and this is confirmed by the high outcrossing rate (0.6642) and gene flow (0.7387) among the populations and the high heterozygosity (0.4023). A dendrogram generated by SSR markers revealed that the accessions are separate entries with no duplications. Significant variations were found in the -carotene and carotenoid contents of the accession. Accession DYF had the highest carotenoid and -carotene concentrations of 12.0327 and 2.0313 respectively. No significant correlation was observed between kernel colour and -carotene content. Generally the amount of -carotene increased with increasing carotenoid content but this is not always the case as few exceptions may be found as revealed by the experiment. None of the accessions contained the opaque-2 gene and therefore did not fit the description of Quality Protein Maize. It is recommended that accession DYF had the highest carotenoid and -carotene concentrations. The accession also performed well in various yield parameters and therefore can be useful in the fresh maize market as well as food for infants and accessions GH4055 and GH4863 are extra early maturing and can be useful for cultivation in the coastal savanna ecological zone and for minor season cropping in the forest and forest savanna transitional zones. Information presented may be useful to the breeder, the farmer and the consumer.