Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Plant Science

First Advisor

Lawrence Fine


Soybeans have recently increased in importance as an alternative crop throughout the corn belt and parts of the South. In South Dakota this has involved the expansion of soybean production into less well adapted cropping environments. Because of considerable interest in bean production under irrigation, a need for information on the management of irrigation water has developed, to assure high yields in these marginal areas. The increasing demand for limited supplied of irrigation water, the marginal or poor quality of many of these waters, and the increasing awareness of the energy cost of irrigating have all intensified the necessity to determine the optimum management of minimal irrigation water. The questions in the mind of irrigators are primarily (1) are there really critical periods during growth and development of the soybean for water adequacy? and, (2) what is the profit maximizing point on the yield – irrigation water curve? Inasmuch as only about 25 per cent of the total flowers produced by soybeans are carried to maturity; the impact of reproductive abortiveness and the conditioning effect of soil water on this phenomenon as a yield limitation in soybeans is apparent. However, sufficient variation occurs in these losses to account for significant differences in yield, indicating that some abortiveness may be a management consequence. It appears from other work that the flowering-pod set stages of reproduction may be the key periods and it was decided to investigate this proposition. My hypothesis was that a defined soil moisture deficit would exert an unfavorable moisture response in the plant which, if imposed at a reproductive critical period of development, would be reflected in increased levels of flower and/or pod abortion, and thus a reduced yield potential. The study reported in this thesis was initiated to determine water management for most efficient use of a limited water supply. I expanded the scope of the work to test effects of soil moisture deficits during selected stages of plant development on plant stress, reproductive activity, yield, and yield components.

Library of Congress Subject Headings

Soil moisture



Number of Pages



South Dakota State University