( 2 -Chloroethyl) Trimethylammonium Chloride and Related Compounds as Plant Growth Substances. II. Effect on Growth of Wheat

Abstract

In this series of publications, the action of (2-chloroethyl)trimethylammonium chloride and certain other compounds structurally related to the quaternary ammonium cation, (CH3) 3N + CH,-CH,X, are described as a class of plant growth substances. In the first paper (1), compounds were examined for biological activity by an assay with wheat seedlings which involved the measurement of the distance between the bases of the first two leaf blades. Three very active and closely related compounds were discovered in which X was a chloro, bromo or =CH. group, namely, (2-chloroethyl) trimethylammonium chloride, (2-bromoethyl) trimethylammonium bro-mi(le ancl (2,3-n-propylene) trimethylammonium bro-mi(le.3 The growth of wheat plants after various treatments with the three most active derivatives is described in this paper. The most characteristic growth change was a reduction in height of plants accompanied by an increase in stem diameter. In most respects the growth alterations after treatment with derivatives related to (2-chloroethyl) trimethylam-monium chloride were the opposite from that obtained with gibberellin, and in addition, these effects were reversed by gibberellin. In fact, the actions of gib-berellin and (2-chloroethyl) trimletlhylammonium chlo-ri(le on the growth of plants have been found to be mutually antagonistic. MATERIALS AND METHODS The three quaternary ammoniunm salts used in the present investigation were synthesized by the reaction of trimethylamine with the corresponding dibalide, i.e., 1,2-dibromoethane for preparing (2-bromoethyl)-trimethylammonium bromide (1). For routine experiments 15 to 18 wheat seedlings I Received August 19, 1959. 2 Published with approval of the Director of the Michi-gan Agricultural Experiment Station as Journal Article No. 2478. 3 In the literature these compounds have also been referred to as derivatives of choline. Thus, (2-bromoethyl)-trimethylammonium bromide has been called bromocholine bromide and (2-chloroethyl)trimethylammonium chloride would be called chlorocholine chloride. (Triticumi, vldgare of variety Thatcher unless otherwise specified) were grown in 8 in. pots with a sand(I and loamii soil mlixture. Greenhouse temperatures were 560 F + 3 at night and 600 to 70° F during the day except as indicated otherwise. All data were obtained from experiments which were conducted during the winter and spring when light intensity in the greenhouse was low. Supplementary light from 500() watt incandescent bulbs extended the day length to 16 hours. Since the chemicals were neutral salts, aqueous solutions were used in the tests. Seedling plants were treated once at 11 days after planting the seed, at which time the second leaf was emerging. For soil treatments. 500 ml of a designate(d molarity of chemical was poured onto the soil. For spray treatments, solutions containing about 0.01 % aerosol' OT as wetting agent were sprayed onto the leaves of the seedlings until the leaves were wet. Seed treatment consisted of placing seedIs overnight on filter paper moistened w\ith a solution of the chemical and' then planting them immediately in untreated soil. Gibberellin1 wN-as applied only by spray treatmiient to the leaves of seedlling plants. Two w eeks after the soil or spray treatlmielnt. the distance from the base of the first leaf bla(le to the base of the second leaf blade for each planit was meas-ure(l in millimiieters. The data are average values from measuremiients on at least 15 plants. The distance betwveen the secondI and third leaf bla(les at the time of the first measurement was rapidly increasing, and thus, this length was not consistent even in the controls. Therefore, four weeks after treatnmeilt, the total stem height of the plants from the soil to the base of the uppermost leaf blade was also recorde(d in some experiments. Plants from a few treatments were kept to mila-turity to observe later growth patterns an(l yield of grain. Tn these cases. 12 in pots were used anid Hoag-land nutrient solution was applied about every ten (lays. RESULTS AND DISCuSSION TREATIMENTS AND GENERAL EFFECT ON GROWTII: When wheat plants were treated once with either (2-chloroethyl) trimethylammonium chlorile, (2-bro-moethyl) trimethylammonium bromide or (2,3-n-propylene) trimethylammonium chloride or bromide, the major growth difference was the developmnent of 380