Breadmaking quality is an important criterion in breeding and development of hard wheat (Triticum aestivum L.) cultivars. Improvements in N management are needed to produce superior quality grain and satisfy market demands for protein content. Field experiments with three hard red and two hard white spring wheat cultivars were conducted in 1998 and 1999 at Corvallis and Pendleton, Oregon. Nitrogen rates were varied from 0 to 250 kg N ha�����, applied all at planting, or split between planting and stem elongation. Resulting grain was evaluated for protein content, protein quality, dough handling, and bread-making quality. Grain protein content of the five cultivars increased with increasing levels of applied nitrogen. There was a concurrent improvement in bread-making quality, as indicated by increasing protein quality, loaf volume, loaf crumb score. Use of split nitrogen applications contributed to increased grain protein content at both the intermediate and high N rates. At the higher N rates, a split application had no apparent influence on protein quality. However, at intermediate N rates, a split application contributed to improvements in protein quality and loaf volume. Nitrogen use efficiency and wheat end-use quality can be improved by using split applications of nitrogen during the crop cycle. / Graduation date: 2001

The effect of planting density and nitrogen (N) fertilization on growth, yield, and N partitioning in young and mature 'Bluecrop' blueberry plants was studied over a two year period. Depleted 15N-ammonium sulfate was applied at different rates and on different dates in a mature planting, and at different rates in a young, newly established planting during the first year of study (2002). Non-labeled fertilizer was applied the second year (2003). Three rates of N fertilizer (0, 100, and 200 kgha1 of N) in combination with two in-row spacing treatments (0.45 m and 1.2 m) were studied in the mature planting. In addition, three different dates of application of labeled fertilizer at the same rate was also tested. In a young planting, four N fertilizer rates (0, 50, 100 and 150 kgha^-1 of N) were applied in the establishment year. In all studies, the N fertilizer was divided into three equal portions and applied from April through June. Plants were destructively harvested from the field and divided into parts on 6 to 11 dates from Feb. 2002 to Jan. 2004, depending on experiment. Plant parts were analyzed for dry weight (DW), N, and '5N concentration (%) and nitrogen derived from the fertilizer (NDFF) calculated. Shoots on mature plants were divided into small (S), medium (M), large (L) and extra large (XL) categories, based on length, and the effect of N and plant spacing on the number, DW, and flushes of growth characterized. The number of shoots per plant ranged from 249 to 298 with plants spaced at 1.2 m having more shoots than those at 0.45 m. Fifty percent of the shoots in the plant were S, whereas only 8% were XL. Nitrogen rate did not affect shoot number, but higher rates of N did increase shoot biomass and the proportion of XL and S shoots. One to four flushes of growth per shoot were recorded, with the number of flushes dependent upon shoot size; 60 to 80% of S shoots had only one flush of growth compared to 8 to 12% of XL shoots. Eighty percent of total shoot biomass was in the first flush of growth and 20% in the second or later flushes with no effect of in-row spacing or N rate. Yield per plant was 30 to 80% greater at 1.2 m than at 0.45 m. However, yield per hectare was 30 to 140% higher in plants at 0.45 m than those at 1.2 m. The roots and crown were the heaviest organs, whereas roots and leaves contained the most nitrogen. Percent biomass partitioning was affected by sampling date for all plant parts, and by in-row spacing only for the crown and three-year-old wood. In the mature planting, total plant DW was affected by sampling date, in-row spacing, and N fertilization rate. Plants at the 1.2 m in-row spacing had 32% more DW over time than those at 0.45 m, but less DW per hectare. Nitrogen fertilization increased plant DW in the second year of study, affecting mainly the younger plant parts. Plants fertilized with 200 kgha^-1 of N had the greatest total N. Nitrogen concentration (%N) varied greatly with plant part and was affected by sampling date and N fertilization rate. Younger tissues had the highest %N in spring (3.5%) and flower buds in winter (2.4%). Total plant NDFF increased from Apr. 2002 to May 2003. The lowest NDFF per plant and per hectare was found in Apr. 2002, when almost 60% of the NDFF was in the new shoots. Nitrogen fertilization rate and in-row plant spacing had an impact on total NDFF accumulated per plant and per hectare. More total NDFF was found in plants fertilized with 200 kgha^-1 of N than with 100 kgha^-1 of N, independent of spacing. Fertilizer recovery was 17% for plants at 1.2 m and 23% for plants at 0.45 m, independent of N fertilization rate. Partitioning of 15N (mg per plant part) and percent of total 15N per part changed with sampling date. Nitrogen fertilization rate and spacing did affect the total amount of fertilizer-15N present in each part, but percent partitioning of 15N was only affected by plant part. Plants at 1.2 m had a higher percentage of 15N partitioned to the crown and three-year and older wood, but reduced partitioning to large roots than plants at 0.45 m. Application date had a large effect on the total amount of NIDFF recovered in the plant at the end of the first season. Application of N fertilizer in either April or May resulted in five times more NDFF in the plant than fertilizer application in July. Percent partitioning of NDFF was also affected by application date. Late fertilization resulted in labeled N allocated mainly to small roots, leaves and shoots, whereas spring-applied fertilizer was allocated mainly to leaves and fruits. In the new planting, established using two-year-old plants, N fertilization rate affected plant dry weight, total N content, percent NDFF, and fertilizer recovery. By October, plants fertilized with 50 kgha1 of N had the largest dry weight and N accumulation. Ammonium toxicity was observed in plants fertilized with 100 and 150 kgha1 of N. Percent NDFF was 60% and 67% for the 50 and 100 kgha^-1 of N, respectively. Fertilizer recovery reached a maximum of 10 to 17% in October, depending on N fertilization rate. / Graduation date: 2006

Thesis (M. Sc.)--University of Hong Kong, 1972. / Typewritten.

Potato requires high levels of nitrogen fertilizer. Up to now in Quebec, no nitrogen fertilizer recommendation has been based on nitrogen availability in the soil, even those soil nitrogen testing is available. The objectives of this study were: (1) to determine the relation between soil nitrate-N content, nitrogen fertilization and potato yield; and (2) to determine the time and the sampling depth of soil most appropriate to predict potato yields and response to nitrogen fertilizer under Quebec conditions. Soil samples were taken at two depths at planting and at hilling time in 28 sites fertilized at four levels of nitrogen. Laboratory measures of nitrate-N were carried out on those samples. A combination of nitrate-N and nitrogen fertilisation gave the best explanation of the variation potato yields. A maximum of 46% of yield variation was attributed to the combination of those two factors in general. Best coefficients of determination were obtained when the sampling of nitrate-N was done at planting time compared to time. Regression models predicted nitrogen fertilizer needs of 89 to 200 kg ha$ sp{-1}.$ The same conclusions were found in the case of the variety Superior alone. The variation of yield explained was up to 62%. Regression models predicted nitrogen fertilizer needs of 77 to 224 kg ha$ sp{-1}$ for Superior. It was concluded that the analysis of soil nitrate-N can improve the prediction of nitrogen fertilizer needs for an optimum potato production.

An experiment was conducted to investigate the effects of N formulation, application rate, and application time on corn yield and quality under Eastern Canadian conditions, to evaluate the hypothesis that application of N will increase corn grain yield and protein concentration without decreasing the total energy content. Three N formulations, each with the rates of 90, or 180 kg ha$ sp{-1}$ were applied at different times. The results indicated that the grain yield increased with increasing N fertilizer rate and with increasing numbers of N application times. N application significantly increased grain protein concentration, on both a per kernel and a dry matter basis, and protein yield. Such as, N application increased the averaged protein concentration, on a dry matter basis, of corn grain by about 8.40% as compared to the control. The protein concentration was not affected by the number of N application times before the plants were 90 cm high. Neither lipid nor non-structural carbohydrate concentration, on both a per kernel and a dry matter basis, were significantly affected by N application in most of the location-years. In addition Near infrared reflectance (NIR) was used to determine the lipid concentration in the aerial corn tissue at different growth stages. The correlation coefficients between the standard analytical method and the NIR method of lipid concentration were all above 0.95, and were significant at 0.01 level.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 89-96). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 74-82). Also available on the World Wide Web.

Thesis (M. Phil.)--University of Hong Kong, 1995. / Includes bibliographical references (leaves 117-127).

Thesis (Ph. D.)--Washington State University, December 2008. / Title from PDF title page (viewed on Apr. 29, 2010). "School of Economic Sciences." Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.