Effects of (2 Chloro-Ethyl) Trimethlammonium Chloride on Plant Growth, Leaf Area, and Net Assimilation Rate

Abstract

Both under glasshouse conditions and in a constant environment with light from fluorescent tubes, mustard plants' treatment with (2 chloro-ethyl) trimethylammonium chloride (CCC) responded by an increase in total leaf area. In the glasshouse the increase was due to the production of more lateral leaves, and in the growth chambers to the enlargement of stem leaves, since lateral branches did not form. Despite the increase in area, the net assimilation rate fell; this may be attributable to an effect of CCC on the photosynthetic mechanism or to an increase in the mutual shading of leaves, but it is more probable that the inhibition of stem growth also caused by CCC decreases the demand for photosynthate and leaves photosynthesise less. The leaf area of mustard (a long-day plant) is increased also by short-day treatment, and here again there is a concomitant shortening of the stem. Chlorophyll content, both per leaf and per unit area, and total dry matter per unit area, were increased in tobacco plants grown in culture solutions containing CCC. The treatment affected the distribution of nitrogen, increasing the amount per leaf and decreasing it per stem.