Evaluation of bermudagrass germplasm newly introduced from Africa for shade tolerance and simple sequence repeat (SSR) allelic diversity

Abstract

Bermudagrass is widely grown in the southern United States for its superior turfgrass quality and wear tolerance. However, inferior shade tolerance is a major limitation, especially in home lawns, parks or other landscapes where shady areas are prevalent. The identification of new sources of shade tolerance is key in development of cultivars with improved performance for this trait. In this study, 24 accessions collected from Southern Africa were evaluated for their ability to persist under continuous shade. Entries were established in a randomized complete block design with three replications under 63% shade, and evaluated for turfgrass quality traits, percent green cover, regrowth and the normalized difference vegetation index. Accessions WIN10F and STIL03 consistently ranked in the top group across all evaluated traits, while Q47620 performed similarly well, except in turfgrass density, where it ranked in the second group. A secondary goal of the study was to assess levels of genetic diversity and ploidy levels in these newly introduced materials as this information will be key to their successful use in cultivar development. Simple sequence repeat markers were used to evaluate allelic diversity, and principal coordinate analysis revealed new allelic variation in the collection absent in U.S. commercial cultivars. Flow cytometry analysis identified 23 accessions as tetraploids (2n = 4x = 36) and one accession as triploid. Aside from the unique genetic diversity found among these newly collected materials, accessions with superior shade tolerance identified in this study represent novel germplasm that can be used in future bermudagrass breeding efforts.

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