[No abstract submitted] / Land and Food Systems, Faculty of / Graduate

[No abstract submitted] / Land and Food Systems, Faculty of / Graduate

Two alfalfa varieties differing in root characteristics were studied under the climatic conditions existing at Agassiz, in the Lower Fraser Valley of British Columbia. The soil type of the experimental area was Monroe fine, sandy loam underlain with gravel. A preliminary study of plant densities in old established plots of alfalfa was conducted in the spring of 1951. The main study commenced in the early summer of 1951 and the first harvest data were obtained in 1952. Ladak alfalfa, a tap-rooted variety, and Rhizoma alfalfa, a branched-rooted variety, were grown in separate associations with Hercules orchardgrass and with Parkland bromegrass. Two planting methods, seeding and spaced-planting of seedlings, were compared as methods for obtaining the optimum rate of planting for alfalfa. Comparisons based on yield of dry matter were made between the two alfalfa varieties In relation to their response to the following factors: (a) Density of alfalfa in the association -- (1) Seeded at three rates (2) Spaced-planted at three densities. (b) Cutting managements -- (1) Clipping as continuous pasture (2) Cutting at the hay stage, followed by clipping the aftermath to simulate pasturing (3) Taking two cuts at the hay stage and a third cut at the silage or early hay stage. (c) The grass associate -- (1) Orchardgrass (2) Bromegrass. The findings presented are of the first harvest year of a continuing study. The two alfalfa varieties displayed a similar response to treatments. The tap-rooted variety Ladak produced more dry matter than did the branched-rooted variety Rhizoma. Superiority was not established for one grass over the other as the grass associate. Nearly identical results were obtained between methods of planting. The indications were that spaced-planting with its higher cost was only suitable for basic forage studies. The highest rate of planting gave the greatest yield of dry matter. However, the results are inconclusive as the effect of plant spread has not been determined. The spreading habit of Rhizoma was established for the particular area of the study. Its effect on managements has not been established. The hay cutting management produced the greatest yield of dry matter. The continued study will stress the effect of cutting managements, including interval between cuts, date of last fall cut, and date of first spring cut, on the root reserves and the production of nutrients per acre. / Land and Food Systems, Faculty of / Graduate

Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1939. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wyoming, 2007. / Title from PDF title page (viewed on Mar. 5, 2009). Includes bibliographical references (p. 57-65).

This investigation examined the efficiency of various screening procedures which could be used in breeding for increased production of root-proliferating (RP) genotypes of alfalfa (Medicago sativa L. s. l.). Also investigated were relationships between RP and winter growth characteristics in populations derived from crosses between dormant, RP clones and nondormant, non-RP clones. In addition, this investigation also considered the inheritance of the RP habit. Plants from an 11-month F₁ progeny test containing 3508 offspring were qualitatively analyzed for RP expression using three pairs of screening procedures. Procedures compared included: (1) direct-seeding vs. transplanting; (2) use of characterized parental clones (known RP-expressing genotypes selected from field nursery) vs. uncharacterized parental clones (genotypes derived from RP seed lots with no prior knowledge of their ability to express the RP habit) in RP x nondormant crosses; and (3) low vs. high harvest frequencies. A low frequency (3.3%) of F₁ plants exhibited adventitious shoot formation. No differences were observed in the frequency of RP-expressing genotypes between the direct-seeded and transplanted treatments or between the low and high harvest frequency treatments. Characterized RP parents produced a hybrid population with a significantly higher frequency of RP-expressing genotypes than did the F₁ population derived from uncharacterized RP parents. Average winter forage production of the F₁ hybrids were similar in magnitude to the midparent value. Plant height was significantly and positively correlated with forage yield and could be used as an accurate indicator of winter forage yield in analyses of RP segregants. Estimates of components of genetic variance for RP expressivity indicated a predominance of additive effects and narrow sense heritability of 8.4%. Family selection and progeny testing are suggested for maximum breeding progress.

Biparental inheritance of plastids has been demonstrated in approximately one-third of angiosperm species examined, although the species studied may not be representative of angiosperms in general. Biparental inheritance of mitochondria in angiosperms has been observed in only one case. Since essential cellular functions, as well as several important agronomic traits, are encoded by plant extranuclear genomes, biparental inheritance of organelles has important implications for plant genetics and breeding. Evidence of biparental inheritance of plastids in alfalfa (Medicago sativa L.) suggests the possibility that mitochondria may likewise be inherited biparentally. The objectives of this dissertation were to determine: (1) the inheritance of mitochondria in alfalfa (uniparental or biparental), and (2) the inheritance of cytoplasmic male sterility and the extent of male fertility restoration in single and population crosses of alfalfa. Several large RNA molecules observed in alfalfa mitochondrial preparations were inherited biparentally. These molecules were unaffected by RNase A added to preparations of intact mitochondria indicating that the RNA's were contained within an RNase impermeable compartment. Linear sucrose gradient purification failed to separate the RNA's from mitochondria and examination of sucrose gradient fractions using transmission electron microscopy (performed by J. K. Brown, Dept. of Plant Pathology, Univ. of Arizona) revealed that mitochondrial preparations were free of contamination by virus-like particles and other organelles. These results indicated that the large RNA's were contained within the mitochondrion. The inheritance of large mitochondrial RNA's in alfalfa provided evidence that mitochondria are inherited biparentally in this species. Association of cytoplasmic male sterility with a particular organelle has not been determined in alfalfa, although the mitochondrion has been implicated in several other species. Analysis of progeny from single and population crosses provided evidence of biparental inheritance of cytoplasmic male sterility. Biparental cytoplasmic inheritance as well as nuclear inheritance may influence male fertility restoration.

No description available.

Regrowth and yield of 23 Middle Eastern (ME) cultivars and the elite cultivar Lew were evaluated for twelve regrowth harvests in pure stands and 50:50 mixtures with Lew in 1988 at Tucson, Arizona. Stem elongation rate and crown shoot development were measured on selected ME cultivars and Lew in the spring of 1988. No significant differences in yield were observed between mixtures and monocultures. Few significant differences were observed over all yields among ME cultivars and Lew. Cultivars from Saudi Arabia and Egypt produced more forage than Lew in spring harvests. These cultivars developed crown shoots precociously and had high stem elongation rates during the first week of regrowth. Most ME cultivars had higher leaf area and leaf:stem ratio than did Lew. These findings suggest that ME cultivars may be useful in improving forage yield during the winter and spring and forage quality in elite nondormant cultivars.