No description available.

Call number: LD2668 .T4 1948 J6 / Master of Science

Call number: LD2668 .T4 1949 B51 / Master of Science

Call number: LD2668 .T4 1958 K46 / Master of Science

This thesis examines the response to P fertiliser by wheat crops growing in the vertosol soils of the low rainfall areas of the northern grain zone of eastern Australia. Farmers in this region depend on water accumulated from rainfall over a fallow period and stored in the subsoil to increase wheat grain yield beyond that normally achievable from in-crop rainfall and to decrease the production risks due to rainfall variability. The large variability in stored water, seasonal rainfall and subsoil properties result in extremely varied yield and yield responses to P fertiliser between seasons and between sites. Finally, as a practical guide to predicting wheat response to P fertilizer: 1/. current sampling strategies of determining P only in the surface 10 cm appear to be adequate for soils with bicarbonate P concentrations greater than 15 mg/kg. 2/. For soils with lower concentrations in the surface, sampling of 80 cm is recommended. Crops with a mean concentration of bicarbonate P greater than 7 mg/kg between 10 - 80 cm are unlikely to respond to P fertiliser. 3/. No increase in profitable grain yield response was found for fertiliser applications greater than 10 kg P/ha. / Doctor of Philosophy (PhD)

Graduation date: 2000

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

Nitrogen is essential to obtain high yields of winter wheat in south coastal British Columbia, which includes Vancouver Island and the lower Fraser Valley. An accurate recommendation for N application is required to keep input costs down for most economical returns and to limit environmental problems related to leaching of excess N. The questions are how much, when and which form of N should be applied to winter wheat. The general objective of this study is to improve our understanding of winter wheat growth and N uptake. This study monitors the soil N supply and characterizes the plant development, dry matter accumulation, and N uptake of winter wheat in South Coastal B.C.. Also, it compares the effectiveness of conventional and intensive crop N management and urea and ammonium nitrate sources of fertilizer N under intensive crop management. A series of field experiments was conducted in 1986-87 and 1987-88 with winter wheat to evaluate conventional and intensive N management in the area. Additionally, a N source study was carried out in the latter year to compare ammonium nitrate and urea. Soil N supply for winter wheat ranged from 52 to 151 kg N/ha through the two years of field experiments at five sites. Available N in the 0-50 cm soil depth varied from 10 to 100 kg N/ha through the growing season in the different treatments. An accurate estimate of N behavior involves N accumulation in the crop. During the early spring until harvest, the crop dry matter yield and N uptake patterns were plotted. The grain yields ranged from 4 to 9 t/ha for the conventional management (75 kg N/ha), and from 4 to 11 t/ha for the intensive crop management (I.CM. 225 kg N/ha) system. Between the conventional and I.CM., there was no significant difference in grain yield but there was in quality, specifically grain protein. Grain protein ranged from 8.2 to 9.7% for the conventional and from 10 to 13.7% for the I.CM. treatment. Also, there was no difference in grain yield or quality between ammonium nitrate and urea fertilized plots at final harvest. However, in the early stage at GS31, crop took up more N from ammonium nitrate (97 kg N/ha) than from urea (75 kg N/ha) and soil mineral N levels with urea were higher than with ammonium nitrate. / Land and Food Systems, Faculty of / Graduate

Replicated field experiments were conducted in 1981-82 and 1982-83 on a State loam soil to determine if split spring N applications have possible yield advantages over single N applications for soft red winter wheat (Triticum aestivum L.). Treatments included a single and various split applications of 89. 6 and 134. 4 kg N/ha. These were applied at specific stages of wheat development. A control treatment was included to determine the contribution of indigenous soil N to grain yield and nitrogen uptake. Grain yields were increased by a split application of 134.4 kg N/ha (67.2 at G.S. 3.0 and 67.2 at G.S. 10.5) in 1982. No differences between grain yield for single and split N applications occurred in 1983. Yield levels averaged 6.25 and 7.21 Mg/ha for 1982 and 1983, respectively. Single N applications at G.S. 3.0 induced excessive tillering which was reflected in the higher number of tillers per m². Excessive tillering also resulted in increased lodging occurrence and reduced the harvest index. Increases in grain yield with split applications were attributed to greater photosynthetic efficiency in lower tiller densities of head-bearing tillers. Split N applications also improved the nitrogen and phosphorous economy of winter wheat, which is shown by increases in the nitrogen and phosphorous harvest indices for split applications of 134.4 kg N/ha in 1983. This resulted from an increase uptake of these nutrients during post-floral grain development. Analysis of the wheat tissue for N content at G.S. 5.0 indicates that tissue N levels reflect the amount of N applied. This suggest that tissue N analysis may be used to diagnose N deficiencies. / M.S.

An experiment was conducted at the Eastern Virginia Research Station, Warsaw, comparing the effects of fall applications of nitrogen (N), (0, 28, 56 kg/ha) from fish-solubles (FS) and spring applications of N (0, 56 kg/ha) from NH₄NO₃ on yield and components of yield of four cultivars each of barley (Hordeum vulgare) and wheat (Triticum aestivum). Both barley and wheat expressed significant yield responses to FS. The NH₄NO₃ application increased yields in both crops, although the increase in wheat was not statistically significant. Interactions between the barley cultivars and N source or rates were nonexistent; however cultivar yield and thousand kernel weight (Mkw) did express interactions with the nitrogen levels and sources in wheat. Cultivars of both crops displayed significant differences for almost every analyzed trait. Both crops responded similarly in the effect of N rates and sources on components of yield, with the greatest response being an increase in spikes/61 cm as the N rates increase. In barley, the increasing rates of N caused a slight increase in kernels/spike, while there was very little effect in wheat. In wheat, the spring application of NH₄NO₃ decreased Mkw, but there was no such effect in barley. Samples of the ten best heads taken from the plots provided useful estimates of kernels/spike in wheat, Mkw in both crops, and of cultivar yield in barley. / Master of Science