Influence of Temperature and Daylength on Growth and Sugar Content of Sugar Cane Following Auxin Treatment of Cuttings

Abstract

1. Stem cuttings of a commercial variety of sugar cane, C.P. (Canal Point) 36/13, were treated by soaking in aqueous solutions of several synthetic auxins: indoleacetic acid (IAA), indolebutyric acid (IBA), sodium naphthaleneacetate (NAA), and the amine salt of alpha-or-tho-chlorophenoxypropionic acid (a-O-CPA). Different concentrations and combinations of auxins were employed. 2. The effects of such auxin treatment on the growth and sugar content of plants were correlated with temperature and supplementary illumination during their development to maturity. Their response was compared with that of plants produced from untreated cuttings. Under normal conditions auxin treatment increased the height of the main axis, stimulated tillering, and increased sucrose but decreased reducing sugars. The number of green leaves produced was not significantly different in treated and untreated plants. The rate of stem elongation and tillering increased rapidly as the seasonal temperatures increased, especially tillering in auxin-treated plants. 3. Plants produced from auxin-treated cuttings and exposed to 4 hours of additional illumination daily were taller, developed more leaves, and contained more reducing sugars, but produced fewer tillers and less sucrose than did similarly treated plants kept under natural-day conditions.