Master's Theses

Date of Award

Summer 1963

Degree Name

Master of Science (MS)

Department

Biology

Advisor

Floyd E. Kisinger

Abstract

Stems of sunflower (Helianthus annuus L.) seedlings were exposed to localized, acute X-irradiation in an effort to determine effects of such treatment upon the vascular tissues. Exposed stem sections received 1500, 3000, or 9000 r in initial testing. Treated plants containing anthoc, yanin pigmentation in irradiated zone displayed a non-pigmented band within 4 to 5 days following exposure of a sufficient dosage. The diameter of irradiated zone soon became noticeably smaller than surrounding sections following the appearance of chlorosis. By the end of the fourth week, root papules were observed developing from the swollen region located above the site of irradiation. Anatomical studies of irradiated region showed that the vascular system failed to develop. Only a thin layer of xylary and phloic tissue extended through the irradiated zone. Vascularization which occurred generally was disorganized or located in isolated strands within the original vascular bundles. Transverse sections from above and below the irradiated zone showed that vascularization was indirectly affected as a result of changes in the exposed zone. Analyses indicated that the exposed zone contained fewer carbohydrates than the zone above, but not always less than tissues below exposed zone. In general the evidence obtained seemed to warrant the conclusion that sane movement of soluble carbohydrates into the irradiated zone occurred.

Rights

Copyright 1963 Rex E. Kerstetter

Comments

Notice: This material may be protected by copyright law (Title 17 U.S. Code).

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