Document Type

Thesis - Open Access

Award Date

1954

Degree Name

Master of Science (MS)

Department

Agronomy

Abstract

The wealth of scientific data that are available on the subject of drought gives an indication of the interest that this problem has prompted in investigators. It is not the purpose of this paper to review all available material, but several pertinent aspects will be considered. The drought chamber was an important innovation in the study of plant reactions to conditions of high temperature, low relative humidity, and low soil moisture. Because it is difficult, if not impossible, in most areas to study drought under uncontrolled, natural conditions, this type of special equipment is a necessity for determining the inherent ability of a plant to develop under adverse moisture and heat conditions. Probably one of the first machines of this type was built by Maedmov and described by Aemodt (1), who later constructed a larger and improved chamber, which in turn was modified by Kenway and Peto (14). Spring wheat varieties tested in the latter two machines reacted similarly to their known behavior under natural drought conditions. Other workers who have successfully used a drought chamber of one form or another on a variety of plant species are Shirley (22), Mueller and Weaver (19), Coffman (5), Mcallister (17), Rayles et al. (2), McCrory (18), Haber (8), Chisholm (4), and Dirks (7). Hunter et al. (11) first described the effects of artificial drought on corn in a study of inbred seedlings. He found that the relative resistance of corn seedlings was essentially the same as was noted for plants in the field. A significant point to be considered in reviewing the work of these individuals is their conclusion, where correlation studies were undertaken, that artificial drought tests at the seedling stage reveal results similar to the effects of natural drought. Seedlings which were resistant to wilting were generally resistant to wilting at later stages of growth. The importance of resistance to wilting and leaf firing is brought out by Lonnquist and Jugenheimer (16) who reported that inbred lines of corn, as well as the single crosses among them, which were resistant, set more seed throughout the life of the silks and remained receptive longer than did susceptible lines and crosses. Only a small portion of the data on drought resistance is concerned with the complex manner in which it is inherited. Jenkins and Riehey (13) crossed Dark Green Lancaster, an inbred line of corn which had shown definite resistant characteristics during the drought of 1930, with ten other inbred lines. Rene of the single crosses showed burning of top leaves and only 12.6% showed burned tassels. On the other hand Krug variety, which was the best of 12 commercial varieties, revealed 37% of the plants with burned top leaves and 13.4% with burned tassels. Since some of the lines which were crossed with Dark Green Lancaster were drought susceptible, it indicated that resistance was transmitted as a dominant characteristic. In a similar study by Jenldne (12), ten crosses of a resistant inbred line, L317B2, were completely free from leaf burning while another line which appeared to be susceptible showed a variability of damage according to the resistance of the other parent. This indicated that in his study resistance acted as a dominant character. Observations of a group of pure lines of corn and their hybrids by Sayre (21) indicated that lines which were injured by drought transmitted their susceptibility to the hybrids in which they occurred. A genetic study by Heyne and Brunson (9) showed tolerance of corn to heat and drought to be intermediate to dominate in its inheritance. Also their work indicated that hybrid viger in itself does not make a cross resistant to drought.

Library of Congress Subject Headings

Corn -- Water requirements

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

45

Publisher

South Dakota State University

Rights

No Copyright - Non-Commercial Use Only
http://rightsstatements.org/vocab/NoC-NC/1.0/

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