Abstract
Endogenous factors which determine the photosynthetic capacity of the leaf were studied in the fully expanded, primary leaves of young seedings of bean (cv. Bulgarian). Following removal of the shoot above the primary leaf node and excision of all axillary buds, the primary leaves increased in area and thickness, in chlorophyll content, in levels of soluble protein, and in the specific activity of ribulose-1,5-bisphosphate carboxylase. Plants in which phloem continuity was disrupted by heat-girdling of the stem, between the shoot above the primary leaf node and the organs below, did not exhibit similar increases, whereas the shoot above the girdle continued to grow for several days. Plants in which all developing trifoliate leaves were excised as soon as they became macroscopic exhibited an increase in their photosynthetic activity, area, and thickness, while their main stem and (leafless) branches made considerable growth. Transpiration from the primary leaves was the same in decapitated plants as in the heat-girdled ones, although in the latter it accounted for only about 30% of total transpiration.
The photosynthetic capacity of the primary leaves is not controlled by source/sink relationship of photosynthates, but rather by the pattern of distribution of factors carried from the roots to the leaves in the transpiration stream.
Full text
PDF



Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- Treharne K. J., Stoddart J. L., Pughe J., Paranjothy K., Wareing P. F. Effects of gibberellin and cytokinins on the activity of photosynthetic enzymes and plastid ribosomal RNA synthesis in Phaseolus vulgaris L. Nature. 1970 Oct 10;228(5267):129–131. doi: 10.1038/228129a0. [DOI] [PubMed] [Google Scholar]
- Wareing P. F., Khalifa M. M., Treharne K. J. Rate-limiting processes in photosynthesis at saturating light intensities. Nature. 1968 Nov 2;220(5166):453–457. doi: 10.1038/220453a0. [DOI] [PubMed] [Google Scholar]
- Weiss C., Vaadia Y. Kinetin-like activity in root apices of sunflower plants. Life Sci. 1965 Jul;4(13):1323–1326. doi: 10.1016/0024-3205(65)90084-6. [DOI] [PubMed] [Google Scholar]
- Woolhouse H. W. The nature of senescence in plants. Symp Soc Exp Biol. 1967;21:179–213. [PubMed] [Google Scholar]