| Abstract: | The robustness of a leaf elongation bioassay was evaluated byconducting trials with detached shoots of wheat at several differenttemperatures. Leaf elongation rate (LER) was monitored for shootsfed either an artificial xylem solution or xylem solution plus10–3mol m–3 abscisic acid (ABA). Consistent resultswere obtained when periodic ruler measurements of many shootswere made and compared with simultaneous measurements on a singleshoot made with a linearly variable displacement transducer(LVDT). ABA treatment consistently inhibited leaf growth; however,the magnitude of the inhibition was dependent on the temperatureat which the assay was conducted. Interpretation of resultsfrom such bioas-says in terms of ABA concentration suppliedto the detached shoots is complicated by this observation sincethere is no unique relationship between leaf growth inhibitionand ABA concentration. The results are discussed in terms ofchemical signalling affecting the growth rate of plants in dryingsoil. Key words: ABA, leaf growth, temperature, leaf elongation bioassay |
