Temperature Coefficients of Cell Enlargement

Abstract

Cell elongation was studied in sections of the scapes of Taraxacum officinale growing in sucrose-indoleacetic acid solns., in nearly grown leaves of Ricinus communis, and in the hypocotyls of Phaseo-lus vulgaris seedlings. Over the temp. ranges 0-20[degree]C for the dandelion scapes, and 10 to about 25[degree]C for the castor bean leaves and bean hypocotyls, the temp. response of cell elongation was that of an enzymic chemical reaction with Q10 values of 2-10 or more. Cell enlargement was checked when seedlings were grown in sand and resumed when a nutrient soln. was added. In young dandelion scape cells, protein synthesis was proportional to cell enlargement. In the 2d phase of growth, however, rapid enlargement was accompanied by a decrease of protein N per unit of cell length. It seems probable that cell enlargment is limited under usual conditions by protoplasmic reactions responsible for the production of new cell wall substances.