EFFECTS OF SOIL APPLICATIONS OF (2-CHLOROETHYL)-TRIMETHYLAMMONIUM CHLORIDE ON LEAF AREA AND DRY MATTER PRODUCTION BY BRUSSELS SPROUT PLANT

When (2-chloro-ethyl)-trimethylammonium chloride (CCC) was applied as a soil drench to plants of Brassica oleracea L. grown in pots, stem height and mean internode length were reduced. Although leaf area at harvest was significantly increased at the 1% level of application, total plant dry weight was less at all levels. Of the components of total dry weight, stem and root weights were significantly reduced while leaf weights were only significantly reduced at the 2% level of application. Leaf weight as a proportion of total weight increased, apparently at the expense of roots, while the stem proportion remained relatively constant with increasing dosages of CCC. Leaf-area ratio was also increased. The mechanisms by which the dry-weight differences might have arisen are discussed. It appeared that the reduction in root weight might have been caused by applying CCC to the soil rather than to the leaves. The number of stomata per unit area of the leaf surface was also reduced by CCC treatment and this response could have affected the rate of diffusion of carbon dioxide into the leaf and the rate of water loss from the leaf, thus reducing total dry weight and contributing to the drought tolerance of treated plants reported in the literature. Other factors which could have contributed to drought tolerance were an increase in leaf thickness and an increase in the percentage moisture content of both leaves and stems. Leaves were also retained for a longer period on the treated plants.