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Populations of Dactylis glomerata from Norway and from Portugal were grown in pure stands and in 50:50 mixtures under natural conditions in Aberystwyth. Stands were sown at monthly intervals between September 1969 and September 1970. Monthly harvests from each sowing were taken either from stands which were defoliated regularly or from stands with uninterrupted growth from sowing. In both managements the environmental conditions during establishment of the stands had a major influence on the subsequent relative competitive abilities of the two populations. This was most pronounced for the September sowings in which the Portuguese population was more aggressive initially and this aggressiveness was maintained throughout the following summer even though environmental conditions at that time did not favour this population. Similarly, the Norwegian population was more aggressive in stands sown in May and June. Again this aggressiveness often was maintained throughout the series of harvests even though this population was dormant during the winter. In other monthly sowings the initial competitive relationships were modified by the effect of the subsequent environmental conditions on the seasonal patterns of growth in the two populations. These reversals of aggressiveness were more marked in stands which were defoliated regularly than in those with uninterrupted growth. [ABSTRACT FROM AUTHOR]

Miscanthus, a C4 perennial grass native to Eastern Asia, is being bred to provide biomass for bioenergy and biorenewable products. Commercial expansion with the clonal hybrid M. × giganteus is limited by low multiplication rates, high establishment costs and drought sensitivity. These limitations can be overcome by breeding more resilient Miscanthus hybrids propagated by seed. Naturally occurring fast growing indigenous Miscanthus species are found in diverse environments across Eastern Asia. The natural diversity provides for plant breeders, the genetic resources to improve yield, quality, and resilience for a wide range of climates and adverse abiotic stresses. The challenge for Miscanthus breeding is to harness the diversity through selections of outstanding wild types, parents, and progenies over a short time frame to deploy hybrids that make a significant contribution to a world less dependent on fossil resources. Here are described the strategies taken by the Miscanthus breeding programme at Aberystwyth, UK and its partners. The programme built up one of the largest Miscanthus germplasm collections outside Asia. We describe the initial strategies to exploit the available genetic diversity to develop varieties. We illustrate the success of combining diverse Miscanthus germplasm and the selection criteria applied across different environments to identify promising hybrids and to develop these into commercial varieties. We discuss the potential for molecular selections to streamline the breeding process. [ABSTRACT FROM AUTHOR]