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 Palmer, A. F. E. Articles by Musgrave, R. B. Search for Related Content PubMed Articles by Palmer, A. F. E. Articles by Musgrave, R. B. Agricola Articles by Palmer, A. F. E. Articles by Musgrave, R. B.

Patterns of Translocation, Respiratory Loss, and Redistribution of ¹⁴c in Maize Labeled after Flowering¹

Maize (Zea mays L.) growing in the field was labeled with ¹⁴CO₂ at four leaf positions 15 to 18 days after flowering. On four occasions after labeling, entire plants were harvested and ¹⁴C in several plant fractions was analyzed by liquid scintillation spectroscopy to reveal patterns of translocation within the plants, losses of ¹⁴C by respiration, and patterns of mobilization and redistribution of ¹⁴C among and within organs. The first and third leaf blades above the ear (+1 and +3, respectively), and the first blade below the ear (_*1), exported ¹⁴C mainly kernels of the developing ear. Among these three leaf blades, the extent of export of ¹⁴C was more rapid from upper positions than from lower ones. Movement of ¹⁴C from the fifth leaf blade (_*5) below the ear was much slower than that from the upper three blades, but kernels of the developing ear ultimately became the principle sink for ¹⁴C exported by this blade. Compared with the upper three leaf blade positions, however, appreciable label from _*5 accumulated in the lower stem and roots. Labeling plants bearing partly-fertilized ears caused a large accumulation of ¹⁴C in the stem, roots and to a lesser extent, husks, compared with completely-fertillzed controls. About 20% of the ¹⁴C assimilated by the +1, +3, and _*1 blades was lost by respiration in the 5 weeks following labeling. During the same interval, nearly 70% of the ¹⁴C assimilated by the _*5 blade was lost by respiration. Approximately half of the carbon assimilated by +3, +1, and _*1 blades was translocated directly to kernels within 24 hr after assimilation. A similar quantity of label assimilated by +3, +1, and _*1 blades was deposited in cobs and husks within 24 hr after assimilation. Estimates of redistribution of label within the plants suggest that 60 to 80% of the ¹⁴C accumulated in kernels between days 1 and 35 following labeling was derived from ¹⁴C originating in upper leaves and deposited in the cob and husk within 24 hr.

Key Words: Growth • Dry matter distribution • Carbon balance • Source-sink relations

² Research and Production Agronomist, CIMMYT (presently at The Ford Foundation, P.O. Box 1043, Islamabad, Pakistan); Associate Plant Physiologist, Connecticut Agricultural Experiment Station; and Professor of Agronomny, Cornell University, respectively.

Received for publication December 4, 1972.