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Photosynthesis of Plant Parts of Alfalfa Canopies 1
Author(s) -
Wolf D. D.,
Blaser R. E.
Publication year - 1971
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1971.0011183x001100010018x
Subject(s) - biology , photosynthesis , stipule , respiration , medicago sativa , canopy , botany , leaf area index , agronomy
Radioactive carbon from CO 2 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.