Growth-Regulating Substances and the Growth of Tiller Buds in Barley; Effects of IAA and GA3

Application of cytokinin to barley seedlings grown without mineralnutrients leads to rapid growth of coleoptile and first leaftiller buds. IAA and GA₃ cannot substitute for cytokinin inthis effect and applications of TIBA and CCC are also ineffectiveon bud growth. However, when bud growth was promoted, eitherby application of cytokinins or by supplying plants with mineralnutrients, IAA and GA₃ applications caused enhanced tiller growthindicating that these compounds can stimulate growth of activelygrowing buds. The results are compatible with an interpretationwhich stresses the importance of cytokinin availability in determiningtiller bud growth.