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Measuring Heterotroph‐Induced Source‐Sink Relationships in Panicum Coloratum with ^1^1C Technology
Author(s) -
Dyer M. I.,
Coleman D. C.,
Freckman D. W.,
McNaughton S. J.
Publication year - 1993
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.2307/1942098
Subject(s) - biology , sink (geography) , agronomy , principal component analysis , panicum , transplanting , botany , mathematics , seedling , statistics , cartography , geography
We report a synthesis from three series of experiments on source‐sink relationships in Panicum coloratum L., a C"4 tropical grass obtained from the Serengeti grasslands of Africa. Studies on ^1^1C real‐time analyses of P. coloratum to determine aboveground effects of grasshopper grazing and belowground effects of mycorrhizal inoculation and nematode feeding provided the database. A series of multi‐ and univariate statistical investigations of all available experimental data described responses of leaves, stems, and roots to these biological stresses. From a principal components analysis we have shown differences in distribution of C source‐sink locations along three principal component axes, which accounted for 84% of the experimental variance. The first and second components (62% of variance) described C allocation to leaf, stem, and root sinks. The third component (22% of variance) showed a metabolic dichotomy between leaf starch sinks and labile carbon pools throughout the plant. We use the three principal components from a ^1^1C three‐compartment model describing leaf, stem, and root C source and sink variables to present patterns, or fingerprints, of responses to the experiments. Time of day, treatment class, number of days since transplanting, and ecotype controlled a large amount of the overall variation in plant C fixation and reallocation. A comparison of ^1^2C leaf carbon exchange rates (CER) measured with an infrared gas analyzer and ^1^1C rates showed a high positive correlation. Slopes for grasshopper grazing, mycorrhizal inoculation experiments, and nematode feeding showed almost identical results; however, differences in the intercept developed as a function of ecotype. We noted a significantly lower intercept in morning studies, but no differences in the slope for morning compared to afternoon studies. CER and all ^1^1C variables for grasshopper and nematode experiments showed a lower coefficient of ^1^1C variables and higher for CER. We conclude that ^1^1C experiments provide the base for developing laboratory, field, modeling studies to incorporate aggregations of real‐time C transfers within plants responding to biological stresses, including those of heterotrophs.