Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)




Wheat is one of the principal cash crops in South Dakota, producing annually about 36,600,000 bushels on approximately 2,050,000 acres. Two of the major problems confronting wheat. Producers in this state are low yields and lodging. High yielding semi-dwarfs from the International Maize and Wheat Improvement Center in Mexico offer breeders and producers in South Dakota short straw and high yielding ability. The semi-dwarfs promise to be better suited for irrigated production than tall varieties. Their performance under natural rainfall is of interest as well for most wheat acreage in South Dakota will not be irrigated. The use of commercial fertilizers to increase yields of wheat has become an accepted practice in American agriculture. Nitrogen fertilizer increase returns, either in grain yields or in protein content, if it is to used profitably by wheat producers. Among nitrogenous fertilizers, ammonium nitrate possesses characteristics which make it suitable for use in mixed fertilizer and desirable for direct application to soils requiring only nitrogen. High yields results from high fertility, weed and insect control, disease prevention, and use of adapted varieties. Soil moisture conditions also play an important role in seed production as well as in the protein content of wheat. Wheat production in some areas of this state is depressed by an inadequate supply of available nitrogen and soil moisture. It is not enough to collect data from yield tests. They do not establish basic concepts. What happens in the test should be measured to reveal the basis for yield differences. The breeder is better able then to plan plant breeding programs. The purposes of this study were to determine the responses of selected tall and semi-dwarf varieties grown under conditions of natural rainfall or irrigation at five levels of nitrogen fertilization and a constant high level of phosphorus fertilization. The characteristics studied were, namely, grain and straw yields, per cent protein in whole grain, yield of protein, seeds per head, weight of 200 seeds, heads bearing seeds in 60 cm. of row, number of seedlings in 60 cm. of row, plant height, per cent lodging, per cent fertility of main florets, and harvest index.

Library of Congress Subject Headings

Wheat--South Dakota
Wheat -- Fertilizers and manures
Nitrogen fertilizers -- South Dakota




South Dakota State University