A quantitative analysis of the growth of Helianthus annuus . Part I.—The respiration of the plant and of its parts throughout the life cycle

Abstract

By means of a quantitative analysis of plant growth we attempt to apportion the external and internal influences that determine the course of a plant’s development. The former can be analysed as various recognised environmental factors, the latter at present may be grouped together as the “internal” factor for growth. The general methods formulated for such an analysis have been outlined in a previous paper (8). In the present series of papers, of which this is the first, an account is given of such an analysis of growth of Helianthus annuus. The present paper is mainly confined to an account of the results obtained in an experimental study of the respiration of Helianthus annuus throughout its life cycle. As far as the authors are aware such a study of the respiration of a plant throughout its life cycle has not before been carried out. The method has been to determine at frequent intervals throughout the life cycle, the respiration at a given constant temperature of a representative plant of a corp. From these results it is possible to estimate the respiration of a mean plant of the corp at the recorded fluctuating temperature of the field and so to obtain a measure of the rate of loss in dry-weight of the plant under field conditions. In addition, the results afford information as to the affect of age upon respiration. Furthermore, its is thus possible to compare the effect of progressing age upon the rate of respiration with the effect of age upon the relative of increase in dry-weight.