Water-use adaption via the barley circadian clock

This thesis compromises work related to measuring physiological growth and water uptake traits in four early maturing mutants and the parental line of Hordeum vulgar cultivar Bowman alongside a winter cultivar Antonella using simply hydroponic systems on young plants. The aim of the project was to evaluate evidence of difference water regulation in response to artificially limited water availability. Plants were tested under warm night conditions and cold night conditions with cold nights substantially improving responses to osmotic stress by decreasing the severity of responses in severe osmotic stress but inhibiting growth. In all barley lines, cold night temperatures (4°C) reduced growth and water uptake. Results are inconclusive if mutations in evening complex circadian-clock genes influence water regulation in barley; however there were small differences in physiology, likely related to early maturing plants accelerated growth. Cold nights reduced growth and development in all barley lines while spring cultivar growth and water uptake physiology become more like winter cultivars. Environmental influences of water availability and night temperatures have strong effects on barley physiology and this work is further evidence that the circadian clock in barley has less of an influence on the plants survival fitness compared to Arabidopsis.