ECOLOGICAL ASPECTS OF GROWTH AND DEVELOPMENT OF JERUSALEM ARTICHOKE (HELIANTHUS TUBEROSUS L.)

Jerusalem artichoke (Helianthus tuberosus L.) is a perennial species capable of reproduction by seed and of clonal growth from rhizomes and tubers. Natural populations are frequently found in highly unstable habitats, principally river and stream banks, man-disturbed waste areas and cultivated fields. It was postulated that variation among populations from different habitats, the allocation of resources within the plant during its life cycle and the regenerative potential of rhizomes and tubers from different soil depths may contribute to its ability to survive in a variety of habitats. Field and laboratory studies were conducted in 1982, 1983 and 1984 at the Plant Sciences Research Station, University of Western Ontario, London.;Jerusalem artichoke was able to allocate resources for growth of leaves, rhizomes and tubers even under conditions of severe defoliation. The annual allocation pattern of resources was characterized by a relatively large commitment of stored resources from overwintered rhizomes and tubers to structural increases in height, leaf number and lateral spread by rhizomes and tubers.;A comparison of two populations of Jerusalem artichoke indicated seasonal variations in ability to mobilize resources for the regeneration of shoots from buried rhizomes and tubers. The regenerative capacity for both populations was least for rhizomes and tubers removed from the maternal plants at the time of rapid flower and bud development.;The maintenance of genetic variability between populations and the ability to mobilize resources for vegetative and clonal growth, reproduction and regeneration does account for the ability of Jerusalem artichoke to survive in varying habitats.;Populations of Jerusalem artichoke collected from different habitats showed considerable morphological variation when grown in a common garden. Leaf number and dry weight of tubers produced per plant accounted for the greatest variation between populations. Morphological differences in leaf number, rhizome length and tuber yield appeared to be correlated to habitat.