Golf Course Management

SEP 2018

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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74 GOLF COURSE MANAGEMENT 09.18 Seed propagation Other bermudagrass breeding programs develop and select highly self-incompatible superior genotypes and use these selections to produce two-parent or multi-parent hybrid seed for commercial sale. Most of the seed is hybrid because a parent will not typically produce seed from its own pollen; rather, seed is produced when crossed with pollen from other parents in the population. ese hybrid cultivars usually consist of a population of hy - brids because the number of cross combina- tions increases as the number of parents and/ or as the genetic diversity of each parent in - creases, and because most bermudagrass par- ents are heterozygous and not pure inbreds, as in corn and other crops (3). Commercial seed must be harvested from the fields with the parental combination each year. e identity of the original hybrid is lost if seed is harvested from subsequent genera - tions of the hybrid. e two- or multi-parent hybrids are still tetraploid common bermu - dagrass, but with desirable improved traits. Private companies usually do not reveal the identity of the parents and/or parental com - binations. Numerous seed-propagated bermu- dagrass turf cultivars are now available, in- cluding Princess 77, Riviera and Yukon. Triploid interspecific hybrid bermudagrass Most high-quality commercial interspe- cific hybrids in bermudagrass are a cross be- tween two distinct Cynodon species: C. trans- vaalensis (2n = 2x = 18 chromosomes) and C. dactylon (2n = 4x = 36 chromosomes). e hybrids from these crosses have 2n = 3x = 27 chromosomes and are triploid interspecific hy - brids that produce no pollen and no seed (2). Just as the mule born of a donkey × horse cross is sterile and cannot produce progeny, these bermudagrass triploid interspecific hybrids are pollen-sterile and seed-sterile. e sterility in interspecific hybrid bermudagrasses is also similar to the sterility in seedless watermelons, grapes and bananas. Examples of triploid interspecific hybrid bermudagrasses that have improved athletic and landscape turf around the world are Tif - green, Tifdwarf, Tifway, TifSport, TifEagle, TifGrand and Tif Tuf from the University of Georgia, and Latitude 36 from Oklahoma State University. Selected from thousands of man-made crosses of superior parents (2), these hybrids incorporate the fineness of C. transvaalensis with the toughness of C. dacty - lon. ey are propagated vegetatively by stems, stolons and shallow rhizomes (Figure 4) (1). Major differences exist between hybrid and triploid interspecific hybrid bermudagrass cultivars. When people refer to the high qual - ity of hybrid bermudagrasses in turf, most are referring to the triploid interspecific hybrids. Common hybrid bermudagrass cultivars have one or more desirable characteristics, such as better color, cold tolerance, close mowing tolerance, etc. However, common hybrid ber - mudagrass cultivars have the potential for pro- ducing pollen and seed, which, over time, can produce turf with a mosaic pattern (Figure 5). In addition, the common hybrids have deep rhizomes that can be invasive and are difficult Figure 4. Pollen- and seed-sterile interspecific hybrid bermudagrasses are much easier to maintain than hybrids of common bermudagrasses, no matter whether they are in an athletic field, golf course or home lawn or landscaped area. Photos by Wayne Hanna Figure 5. Common bermudagrasses are self-incompatible and can produce seed and pollen, which means they can produce natural hybrids within an area such as a lawn or fairway. The result may be an unattractive turfgrass mosaic.

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