An Analysis of the Response of Winter Wheat (Triticum aestivum) Components to Cycocel (Chlormequat) Application

Field-grown winter wheat (Triticum aestivum cv. Avalon) plants were treated with a formulation of 1.25 % Cycocel (2-Chloroethyl trimethylammonium chloride) and 0.5% LI-700 (acidified soya lecithin) at the beginning of stem extension in order to identify the component parts that are most affected and on which an assessment of the effectiveness of Cycocel formulations can be based. Cycocel consistently reduced culm length due to the reduction of the lengths of the first three basal internodes by 43, 37 and 15 % respectively. In absolute terms, the second internode contributed most to stem reduction, a feature retained up till maturity. There was evidence of relative dry matter redistribution from the stem to the leaves, while growth rate was slowed down such that treated plants matured later than the controls. The youngest fully opened leaf at the time of Cycocel application showed a transient reduction in length, area and dry weight, while total leaf area was largely unchanged. From the results, measurement of the lengths of the first two internodes proved to be the most sensitive indicator of effective Cycocel uptake.