Three cycles of recurrent restricted phenotypic selection (RRPS) were carried out on two cultivars each of timothy (Phleum pratense L.) and orchardgrass (Dactylis glomerata L.). The selections were conducted at the E. A. Lods Agronomy Research Center of Macdonald Campus of McGill University from 1984 to 1988. Individual plant selections were based on dry matter yields of 25 plants. Within each of 16 grids, the five highest yielding genotypes were selected (i.e. 80 genotypes overall) and allowed to interpollinate. Equal weights of seeds from each of the 80 selected plants were mixed in each cycle. Evaluation trials were carried out in both sward and spaced stand from 1989 to 1993 to assess the effectiveness of selection in improving dry matter yield. Several other morphological and physiological characteristics of cycles were recorded to find possible associated changes. / Three cycles of RRPS were not effective in increasing forage dry matter yields. The lack of response may be due to a narrow genetic base in the source populations and/or the population size under selection may have been too small, resulting in inbreeding depression. Another explanation for the ineffective selection may be non-random pollination among selected plants. The selection for forage yield produced some minor changes in other characteristics. There was a tendency towards increased plant height and circumference in orchardgrass; however, for timothy, height and circumference were reduced by selection. Cycle 3 of Avon orchardgrass was one day later in maturity and there was also a tendency for later maturity for timothy.

The genome constitution and phylogeny of hexaploid timothy (Phleum pratense L., 2n = 42) have been studied with C-banding and genome-specific DNA techniques. The cultivated species and two diploid wild relatives P. alpinum (2n = 14) and P. bertolonii (2n = 14) were karyotyped. In P. pratense, two sets of seven chromosomes could not be distinguished from each other either in gross morphology or in C-banding patterns and the third set was found to be differentiated from them. Two genomes, A and B, were established in this species presumably with the genome formula of AAAABB. The banded karyotype in P. alpinum was close to the A genome and that of P. bertolonii was analogous to the B genome, which suggests these wild species were the genome donors of P. pratense. To reinforce this, a molecular assay was performed with genome-specific probes. Eight clones specific to the genome of P. alpinum and thirteen specific to the genome of P. bertolonii were respectively isolated from the genomic DNA libraries of P. alpinum and P. bertolonii. Three P. alpinum-specific sequences and three P. bertolonii-specific sequences were used as probes to hybridize the DNA of P. pratense on slot blot and Southern blot. All the three P. bertolonii-specific probes and two of the three P. alpinum specific probes exhibited cross-hybridization to P. pratense DNA. This has confirmed the allopolyploid origin of hexaploid P. pratense. In addition, phenotypic variations of seed storage proteins were investigated within the cultivated P. pratense with SDS-PAGE analysis. A total of 44 protein monomers were detected in mature seed extracts from 19 cultivars of timothy. The protein banding patterns were differentiated among all the examined cultivars except for two pairs. Such differentiation makes it possible to identify the timothy cultivars.

One major problem plaguing reed canarygrass (Phalaris arundinacea L.), a high yielding perennial grass, is its poor seed retention. Folded leaf progeny plants from a cross involving a seed-retaining clone were observed in a space-planted nursery. The objectives of this study were to determine whether the folded leaf trait was associated with higher seed retention and other agronomic traits. The inheritance of this trait was also investigated through crosses performed and evaluated in the field and greenhouse. Under solid stand conditions, highly significant differences (p < 0.01) existed between folded and flat leaf polycross progeny entries for heading date and seed retention percentage. Under space-planted conditions folded leaf plants were significantly different (p < 0.05) from flat leaf plants for height, head length, panicle number and growth habit. Widely divergent segregation ratios led to the rejection of the proposed model of inheritance -- disomic inheritance with duplicate gene action.

No description available.

There is little information comparing the impacts of bison and cattle grazing in the northern mixed-grass prairies; understanding which grazer to use for management is important. I collected data in sites grazed by bison or cattle using point counts to survey the songbird community, and habitat structure measurements. I used generalized- and non-linear mixed models to determine the relationships between grazers and habitat or songbird communities. Bison and cattle grazing caused changes in habitat structure, including decreased vegetation height and litter depth. Sprague’s pipits declined more steeply with bison grazing than with cattle grazing. 0.4 AUM/ha was an important threshold, because chestnut-collared longspurs increased in abundance at this stocking rate, and grasshopper sparrows decreased in abundance at this stocking rate. Either grazer is appropriate for managing for grassland birds. There is also an opportunity to encourage surrounding landowners to manage their lands for the benefit of wildlife.

No description available.

Zugl.: Bonn, Univ., Diss., 2004

Zugl.: Düsseldorf, Univ., Diss., 2005

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references. Also available via the Internet.

Zugl.: Poznañ, Uniw. Imienia Adama Mickiewicza, Diss., 2007