Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Plant Science

First Advisor

D. B. Shank


One of the major objectives of commercial and publicly supported plant breeding programs is the selection of corn lines which exhibit superior yielding ability under stress conditions. To accomplish such a goal, various plant characteristics have been examined. For example, strong, high volume root systems have been selected to increase resistance or tolerance to corn rootworm feeding and root rot. Large tussels are also selected, whether consciously or not, to maintain good pollen production over a long period of time under dry or adverse conditions. Similarly, many researchers stress selection of lines which exhibit a short period of time between the onset of pollen shed and the appearance of the silks (silk delay). By changing these plant characteristics, will we counteract our goal? For example, by selecting for a stronger, higher volume root system for the plant to maintain can it still produce a superior yield? In effect, is there an optimum root size beyond which the trait may serve to reduce yields? This point becomes particularly important when the plant is subjected to stress conditions. Recent research has not attempted to deal with this question. In light of the continuing selection for increased root volume and tassel size, we should further investigate the effects of such selection pressures on our goal of yield. The objective of this experiment is to investigate the relationships which exist among root volume (as attached by root-pulling resistance), tassel size, silk delay, and yield, particularly when the plant is subjected to stress.

Library of Congress Subject Headings

Hybrid corn
Crop yields



Number of Pages



South Dakota State University