GENOTYPIC VARIABILITY ESTIMATES OF AGRONOMIC TRAITS FOR SELECTION IN A SWEETPOTATO (IPOMOEA BATATAS) POLYCROSS POPULATION IN PAPUA NEW GUINEA
Abstract
Successful crop breeding program incorporating agronomic and consumer preferred traits can be achieved by recognizing the existence and degree of variability among sweetpotato (Ipomoea batatas, (L.) Lam.) genotypes. Understanding genetic variability, genotypic and phenotypic correlation and inheritance among agronomic traits is fundamental to improvement of any crop. The study was carried out with the objective to estimate the genotypic variability and other yield related traits of highlands sweetpotato in Papua New Guinea in a polycross population. A total of 8 genotypes of sweetpotato derived from the polycross were considered in two cycles of replicated field experiments. Analysis of Variance was computed to contrast the variability within the selected genotypes based on high yielding β-carotene rich orange-fleshed sweetpotato. The results revealed significant differences among the genotypes. Genotypic coefficient of variation (GCV %) was lower than phenotypic coefficient of variation (PCV %) for all traits studied. Relatively high genetic variance, along with high heritability and expected genetic advances were observed in NMTN and ABYield. Harvest index (HI), scab and gall mite damage scores had heritability of 67%, 66% and 37% respectively. Marketable tuber yield (MTYield) and total tuber yield (TTYield) had lower genetic variance, low heritability and low genetic advance. There is need to investigate correlated inheritance among these traits. Selecting directly for yield improvement in polycross population may not be very efficient as indicated by the results. Therefore, it can be conclude that the variability within sweetpotato genotypes collected from polycross population in Aiyura Research Station for tuber yield is low and the extent of its yield improvement is narrow.
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Journal of Plant Breeding and Genetics
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