LD2668 .T4 1940 M33 / Master of Science

Graduation date: 1991

Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on Jan. 26, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Agricultural and Resource Economics, Department of Rural Economy, University of Alberta. Includes bibliographical references.

Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 149-168). Also available on the World Wide Web.

Diss. Univ. Freiburg i.Br., 2007.

Thesis (M.Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on August 28, 2009). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of master of science in Agricultural and Resource Economics, Rural Economy Department. Includes bibliographical references.

No description available.

Master of Science / Department of Agronomy / Kraig Roozeboom / Winter survival of canola (Brassica napus L.) is a challenge for producers using high-residue, no-tillage, or reduced tillage systems. In addition, as hybrid cultivars have become more available in recent years, this has brought about questions regarding best management practices to aid in mitigating winter survival challenges associated with high residue production systems. Overcoming production challenges will allow producers to diversify their no-till cropping systems with an oil seed crop having strong domestic demand. This research was undertaken to identify practices that could improve performance of canola in high-residue cropping systems. Two sets of experiments were conducted at twelve sites across Kansas from 2014 to 2016 to evaluate practices that could improve stand establishment, winter survival, and yield of winter canola. The objective of the first study conducted at 10 site years was to determine the effect of residue management, seeding density, and row spacing on stand establishment, winter survival, and yield. An innovative residue management system being developed by AGCO Corp. was compared to cooperating canola producers’ no-till residue management and planting methods in wheat residue. This on-farm experiment was conducted at ten environments across Kansas. AGCO treatments were 20 or 30-in row spacing and three seeding rates for a total of six treatments. Producer treatments included their preferred row spacing, seeding rate, and residue management practices. Winter survival increased by 11% to 29% as seeding rate decreased in 20-in rows at four of the five harvested environments. At Stafford and Kingman, the lowest yielding AGCO treatment produced 3.7 to 4.2-bushel acre⁻¹ more than the respective cooperator treatments. Reduced seeding rates in the AGCO system produced yields similar to or superior than the cooperator practice in all environments. Producers have been turning to planting canola in wide rows to facilitate residue management with strip tillage or planter residue management attachments. The objective of the second study conducted at three site-years was to determine the effect of seeding rate on winter survival and yield of hybrid and open-pollinated winter canola cultivars in 30-in rows. Treatments were four genotypes and five seeding rates for a total of twenty treatments. Winter survival increased with the lowest seeding rate at one of the three environments. At two of the three environments neither genotype nor seeding rate affected yield. These results indicate that seeding rates can be reduced from those typically used by canola producers in high residue, no-till or reduced tillage systems if residue can be adequately removed from the seed row. Both hybrid and open-pollinated winter canola cultivars responded similarly to seeding rate in 30-in rows in these experiments, indicating that similar seeding rates could be used for each type of cultivar. Management practices such as, narrow row spacing, reducing seeding rates, and adequately managing residue at planting may result in small improvements to establishment, winter survival and yield.

A higher level of efficiency in the production of doubled-haploids must be achieved if this procedure is to be beneficial in plant improvement. Of equal importance is the development of protocols, which are not genotypic specific and result in progeny that represent a random sample of gametes from the parental lines. To address these issues seven diverse winter wheat genotypes and a spring wheat, previously shown to be responsive in haploid plant production from anther culture, represented the experimental material. Two methods of generating haploid plants were employed. These were anther culture and the intergeneric hybridization of wheat with maize. Three induction media (MN6, P2 and Liang's) in liquid and semi-solid forms were employed with anther culture a direct culture. A modified floret culture along with different concentrations (20 and 100 ppm) and mode of application of 2,4-D were examined for the wheat x maize approach, Measurements included callus and embryo production and haploid plantlet regeneration. Two winter genotypes 'Gene' and 'Yamhill' did not respond to the anther culture methodology. For responsive genotypes MN6 was superior to P2 and Liang's medium for the traits measured. In contrast 'Chris' the spring wheat was more responsive for plantlet regeneration on P2 medium. No differences in haploid plantlet regeneration for the traits were observed between liquid and semi-solid medium forms. For the wheat x maize approach, direct culture was superior to the modified floret culture for embryo and haploid plantlet production. No differences were found in either 2,4-D concentration or whether 2,4-D was applied through tiller injection or placed as droplets on the florets. The wheat x maize approach was superior to anther culture for both embryo and green haploid plant production based on the number of florets used. Albino plants were produced in all responsive genotypes with anther culture. In contrast, no albino plants were regenerated with the wheat x maize approach. All genotypes were responsive for both embryo production and haploid plant regeneration in the intercrossing approach. In addition no regeneration distortion was observed for specific population employing this protocol. The wheat x maize approach was superior to anther culture for embryo production. This was also true for green haploid production based on the number of florets used. A higher proportion of albino plants was also observed when anther culture was employed. A further attribute of the wheat x maize approach was that all genotypes tested were responsive to embryo and haploid production. It was also revealed that no segregation distortion was present in three doubled haploid populations developed from wheat x maize crosses. / Graduation date: 1999

Drought is a major limiting abiotic stress influencing wheat production in many parts of the world. The erratic nature of water deficits makes breeding and selection for drought resistance deficient. In environments with late season drought stress, yield losses are usually associated with kernel abortion or reduction in kernel growth. Remobilization of soluble carbohydrates from the stem has been associated with drought resistance. The objectives of this investigation were i) to asses the role of soluble carbohydrates in the determination of drought resistance, ii) their association with productivity, and iii) to evaluate a rapid technique to identify genotypes with higher capacity of soluble carbohydrate remobilization. Nine winter wheat cultivars differing in their response to drought stress were grown under irrigated and nonirrigated conditions during the grain filling period at the Sherman Branch Experiment Station, Moro. The cultivars were also grown at the Hyslop Crop Science Laboratory, where plots were chemically desiccated with Sodium Chlorate or left untreated. All control and treated plots were evaluated for soluble carbohydrates in two vegetative fractions, stem plus sheath and leaf blades. These values were correlated with the relative reductions in kernel weight and yield observed on the treated plots. Differences among cultivars were observed for the concentration of soluble carbohydrates in the stem and leaf fractions. Time elapsed from anthesis was a major determinant of the variation in carbohydrates concentration observed during grain filling. Stem soluble carbohydrates accumulated to a much greater extent than leaf soluble carbohydrates. The concentration of stem carbohydrates was not related with the reductions caused by chemical desiccation or drought stress. However, potential contributions from stem reserves (ratio between potential spike weight and stem reserves) were marginally associated with drought resistance. Stem soluble carbohydrates were positively associated with productivity, suggesting that stems are not competitive sinks, but temporary storage organs of excess of assimilates. Under chemical desiccation most of the soluble carbohydrates were lost in respiration, and the reductions in kernel weight and yield observed were not correlated with those observed under drought. It was concluded that the technique did not reasonably simulated drought in terms of yield reductions nor carbohydrate remobilization. / Graduation date: 1998