The early growth of tiller buds in barley is determined by application of mineral nutrient solution to the growing medium. The aim of this research was to determine whether the effect of mineral nutrient supply is exerted through an effect on the levels of endogenous growth regulators, particularly cytokinins. Three approaches were used to examine the problem, namely to determine the effects of exogenously applied growth substances on growth of tiller buds, to observe bud growth under treatment expected to modify the levels of endogenous cytokinina, and to measure the cytokinin activity in plants supplied with minerals. Exogenously applied cytokinins not only increased lateral bud growth in plants supplied with minerals but also promoted growth of buds arrested by mineral nutrient stress. Application of auxin or gibberellin increased dry matter in buds released from apical dominance by either mineral nutrient or cytokinin application, but had no effect on arrested buds. Root removal treatments, expected to modify levels of endogenous cytokinins, released growth of tiller buds under conditions of lack of mineral supply. Both root removal experiments and treatments with exogenous growth regulators confirmed the idea of an important role for growth substances, particularly cytokinins in the release of buds from apical dominance. Preliminary results thowed the presence of a high level of a cytokinin-like substance in plants given minerals nutrient solution, which was absent in the deficient condition, also favouring the initial idea. It is proposed that growth of exillary buds in vegetative barley plants is controlled by interactions between nutritional factors and endogenous growth substances. It is considered that mineral nutrient availability determines the levels of endogenous cytokinin which in turn determines whether or not buds are released. Mineral nutrients, other metabolites and growth substances are important in controlling subsequent growth of the tiller bud.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:661326 |
| Date | January 1979 |
| Creators | Rocha, Rosely de Franca |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11326 |
Page generated in 0.0024 seconds