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Morpholotical and genetic variation within perennial ryegrass (lylium perenne l.)

by Liu, Jianyang

Abstract (Summary)
Research has extensively showed that pastures with complex composition can increase production in some situations. However, there is a general lack of information on the role of within species (intra-specific) diversity and its contribution to the ecological functionality of a community. This research used perennial ryegrass as a model plant to (i) quantify within- and between-cultivar variation of L. perenne cultivar blend BG34 on the basis of several morphological characteristics and forage yield; (ii) investigate the responses of relative yield and production components of individual genotype, and how this was affected by the treatments of genotype and defoliation; and (iv) evaluate the suitability of SSR (simple sequence repeats) and ISSR (inter simple sequence repeats) markers to differentiate the cultivars of L. perenne that comprise BG34 and investigate the genetic structure of pastures sown with BG34 ryegrass from dairy fields in Ohio. With 100 potted plants of the four cultivars investigated, within-cultivar variation accounted for 73-97 % of the total variation for the morphological traits (i.e. height, tiller number, erectness, leaf width and yield), and 13.4 to 89.9% of the variation could be attributed to genetic variation. A genotype treatment by defoliation treatment experiment was established with cloned plants of eight genotypes, which had different production and tillering potentials, it was found that plot production was linearly related to genotype diversity, and mixtures had significantly greater yield than monoculture on average. Frequent (3-wk) defoliation reduced grass yield by 12.7%, while the 60 mm height clipping reduced grass yield by 14.3%. In general, large genotypes were favored in mixtures and small genotypes were at disadvantage. With both SSR and ISSR markers, individuals of BG34 were correctly allocated to lines and cultivars with 80.9-86.7% accuracy. There were distinct differences between cultivars, suggesting the suitability of the marker systems in identification of L. perenne cultivars. Divergent changes in the proportions of the respective cultivar of BG34 were found on the three 5-year old fields in Ohio.
Bibliographical Information:

Advisor:

School:The Ohio State University

School Location:USA - Ohio

Source Type:Master's Thesis

Keywords:perennial ryegrass variation genotype diversity ssrs marker

ISBN:

Date of Publication:01/01/2005

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