Genetic Diversity in the Batini Barley Landrace from Oman: I. Spike and Seed Quantitative and Qualitative Traits

The Batini landrace of barley (Hordeum vulgare L.) is endemic to the coastal Batinah region of Oman. Although it is important to subsistence farmers, it is threatened by increasing salinity and replacement by high yielding cultivars. Seven bulk seed samples (subpopulations) of the Batini landrace were collected from farmers' fields, which provided a germplasm collection of 3191 accessions. The objectives of this study were to characterize these accessions for spike and seed qualitative and quantitative traits, quantify phenotypic diversity, and explore significant variation in seed and spike morphological traits for future selection and breeding. Variation for 26 morphological traits was assessed among the progeny of 3191 single spikes. Phenotypic diversity indices (H') differed significantly among traits and subpopulations. Weighted H' average for subpopulations was 0.501; 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 sufficient to discriminate between subpopulations. Total genetic variation (HT) for quantitative (0.717) and qualitative (0.533) traits differed significantly. Variance component due to subpopulations was significant for seven quantitative and 12 qualitative 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. Total genetic variation and genetic differentiation estimates for qualitative traits were 25% lower than for quantitative traits. Strong, nonrandom trait associations among four seed phenotypic markers showed a hierarchical pattern, indicating an adaptive response to environmental conditions and human selection. The long history of in situ conservation of this landrace in a multitude of subsistence farming systems, undoubtedly, contributed to the high variability.