HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Dunlap, J. R. Articles by Morgan, P. W. Search for Related Content PubMed Articles by Dunlap, J. R. Articles by Morgan, P. W. Agricola Articles by Dunlap, J. R. Articles by Morgan, P. W.

Preflowering Levels of Phytohormones in Sorghum II. Quantitation of Preflowering Internal Levels¹

Levels of free and bound indole-3-acetic acid (IAA), abscisic acid (ABA), and gibberellin-like (GA-like) compounds were determined over a 25-day period prior to flowering in the above ground portions of an intermediate (60M) and a late (90M) maturing genetic line of Sorghum bicolor (L.) Moench.This was an initial effort to learn something about the hormone status of these lines on a whole shoot basis and there is no specific inference to the mechanism of photoperiodism. Following purification of the plant extract, IAA and ABA were analyzed with high performance liquid chromatography (HPLC); GA-like substances were assayed with the lettuce hypocotyl elongation bioassay. The preflowering levels of GA-like activity did not differ significantly between the two sorghum genotypes; however, the preflowering levels of both free IAA and ABA consistently increased with age in the later maturing genotype (90M). Increasing levels of free IAA and ABA relative to GA-like activity may partially account for the delayed flowering characteristic of 90M. The differences in phytohormone levels in closely related genotypes differing in photoperiod requirement for floral initiation suggest the need for a detailed examination of the phytohormone status of the sorghum maturity genotypes relative to the mechanism of photoperiodism.

Key Words: Plant hormones • Maturity genotypes • Flowering • Photoperiodism

² Formerly graduate assistant (presently production technology manager, Weyerhaeuser Company, Hot Springs, AR 71901), and professor of plant physiology.

Received for publication September 4, 1980.