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 Wolf, D. D. Articles by Blaser, R. E. Search for Related Content PubMed Articles by Wolf, D. D. Articles by Blaser, R. E. Agricola Articles by Wolf, D. D. Articles by Blaser, R. E.

Photosynthesis of Plant Parts of Alfalfa Canopies¹

Radioactive carbon from CO₂ assimilated by upper leaves of alfalfa, Medicago sativa L., was not detected later in lower leaves. This suggests that the old leaves in dense canopies (low light intensity) were not parasitic. Net carbon exchange (NCE) and specific leaf weight (SLW) were highest for upper leaves and lowest for bottom leaves. NCE of petioles and stipules contributed 0.6 and 0.9% of total NCE of an alfalfa canopy. The upper steur under normal light conditions was near light compensation, while 8% of the photosynthate from leaves appeared to be respired by the lower stem tissue. The data suggest that models for predicting plant growth may need to include respiration from stems of plants in late growth stages. The data do not support the concept that respiration is a linear function of increased leaf area index.

Key Words: Leaves • Petioles • Specific leaf area • Growth models

² Associate Professor of Agronomy and Professor of Agronomy, respectively.

Received for publication July 7, 1970.