|Al maskri, A|
Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/7/2003
Publication Date: 1/1/2004
Citation: JARADAT, A.A., SHAHID, M.A., AL MASKRI, A.Y. GENETIC DIVERSITY IN THE BATINI BARLEY LANDRACE FROM OMAN. I. SPIKE AND SEED QUANTITATIVE AND QUALITATIVE TRAITS. CROP SCIENCE. 2004. V. 44. P. 304-315. Interpretive Summary: Subsistence farmers in the Batinah region of Oman grow a local landrace of barley in mixtures with alfalfa as a forage crop in a unique irrigated farming system. However, this landrace and the whole farming system are threatened by increasing salinity and replacement by high yielding cultivars. The objectives of this study were to characterize a germplasm collection for spike and seed qualitative and quantitative traits, quantify phenotypic diversity, and explore significant variation for future exploitation in selection and breeding. More than 3,000 spikes of the landrace were studied to search for qualitative and quantitative variation which can be used to select for better and more yielding genotypes than the average. The results indicate that the variation was large, readily available for selection, and most of it is available within subpopulations of the landrace. Farmers should be encouraged to select, or participate in selecting appropriate genotypes from their fields as a means of improving productivity and conserving the best selections on the farm. The readily available variation is of value to farmers, agronomists, and barley breeders.
Technical Abstract: The "Batini" landrace of barley is endemic to the coastal "Batinah" region of Oman. Subsistence farmers grow it in mixtures with alfalfa as a forage crop in a unique irrigated farming system. However, it is threatened by increasing salinity and replacement by high yielding cultivars. The objectives of this study were to characterize a germplasm collection for spike and seed qualitative and quantitative traits, quantify phenotypic diversity, and explore significant variation for future exploitation in selection and breeding. Variation for 26 morphological traits was assessed among 3,191 single spikes of seven subpopulations derived from a large germplasm collection. Phenotypic diversity indices (H') differed significantly among traits and among subpopulations. Weighted H' average for subpopulations was 0.501; whereas, it ranged from 0.154, for spike glaucousness to 0.853 for number of spikelets per spike. Differences in phenotypic frequencies for 20 traits were powerful enough to discriminate between subpopulations. Total genetic variation (HT) for quantitative and qualitative traits (0.717 and 0.533, respectively) differed significantly. Variance component due to subpopulations was significant for 19 traits, and the within subpopulation variance component decreased in the order: qualitative (82.12%)>quantitative (78.34)>spike-related (68.50)>grain-related (67.25) traits. On average, total genetic variation and genetic differentiation estimates for qualitative traits were 25% lower than the respective values for quantitative traits. Strong, non-random trait associations among phenotypic markers showed a hierarchical pattern, indicating an adaptive response to environmental conditions and human selection. Multivariate analyses procedures qualitatively identified differences and patterns of genetic diversity among subpopulations and reconfirmed results of univariate analyses procedures. The long history of in situ conservation of this landrace in a multitude of subsistence farming systems, undoubtedly, contributed to the high variability available in this landrace.