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Turfgrasses
Published in L.B. (Bert) McCarty, Golf Turf Management, 2018
Perennial ryegrass (Lolium perenne L.) is a short-lived perennial with a medium leaf texture and good shoot density originating from open to fringed forest regions of southern Europe and western Asia to northern Africa (Figure 1.39). It has a nonspreading, bunch-type growth habit, good wear resistance, finer leaf texture, good soil compaction tolerance, good drought tolerance, good herbicide tolerance, fast establishment rate, and bright-green color (Table 1.9). Perennial ryegrass tolerates lower mowing heights than Kentucky bluegrass or tall fescue. However, it does not tolerate low or high temperature extremes, has slow recovery from divots, and has limited shade tolerance. It has become very susceptible to gray leaf spot disease, which is expensive and troublesome to control. Perennial ryegrass also is susceptible to Pythium blight and has marginal cold tolerance. Perennial ryegrass is primarily used as a component in seed mixtures with other cool-season turfgrasses, such as Kentucky bluegrass, to broaden the resistance to various diseases and other pests. It is often used for overseeding purposes in bermudagrass and zoysiagrass for winter color (Figure 1.40). Tetraploid varieties are being developed for better drought tolerance, disease resistance, and winter performance. Refer to your state turfgrass specialist, seed company representative, and www.ntep.org for comparison of cultivars.
Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Polyploid (Gr. polys, many + ploid, fold) is the tissue or cells with more than two complete sets of chromosomes, that results from chromosome replication without nuclear division or from union of gametes with different number of chromosome sets, hence triploid (3x), tetraploid (4x), pentaploid (5x), hexaploid (6x), heptaploid (7x), octoploid (8x)).
The importance and prevalence of allopolyploidy in Aotearoa New Zealand
Published in Journal of the Royal Society of New Zealand, 2020
Anna H. Behling, Lara D. Shepherd, Murray P. Cox
Ferns are another prominent feature of the damp understory of forested areas throughout New Zealand; the number of distinct species is unusually high for a temperate country (approximately 200, with 44% endemicity) (Schönberger et al. 2018). Among vascular plants globally, ferns demonstrate the highest frequency of polyploid species, with polyploidy implicated in up to 31% of speciation events (Wood et al. 2009). Consequently, ferns have long been used as a model system for studying polyploidy and its genetic repercussions (DeMaggio et al. 1971). The genus Asplenium (spleenworts) contains more than 700 species worldwide. Its Austral group, a polyploid complex centred in New Zealand (Brownsey 1977; Shepherd, Holland, et al. 2008), is unique when compared with European and North American groups of the same genus due to its absence of diploid organisms (Dawson et al. 2000; Perrie and Brownsey 2005). Seven tetraploid and eight octoploid Asplenium species are found in New Zealand, with allopolyploidy implicated in the origin of seven of the octoploid species (Shepherd, Perrie, et al. 2008), mirroring the high frequency of allopolyploidy found in Asplenium worldwide (Lovis 1978; Reichstein 1981; Wagner et al. 1993; Schneider et al. 2017). Interestingly, one of the tetraploids is thought to be the parent of five of the octoploids, suggesting that this single species has played a central role in the evolution of this fern complex (Shepherd, Perrie, et al. 2008). Despite extensive sympatry and having the same parental species, the allopolyploids A. cimmeriorum and A. gracillimum have each evolved independently at least twice, with the four lineages reproductively isolated (Perrie et al. 2010), thus emphasising the importance of allopolyploidy in the generation of biological diversity. It is possible that the octoploids A. shuttleworthianum and A. northlandicum have extinct parental species; nuclear sequences of the LFY gene obtained from the allopolyploids could not be identified among the tetraploid taxa analysed by Shepherd, Perrie, et al. (2008). However, it is also possible that these sequences were inherited from unsampled Pacific species.