The effect of seed weight and coleoptile tiller development on seedling vigour in tall fescue, Festuca arundinaceaSchreb.
SummaryTwo characters, previously shown to influence the rate of seedling growth in tall fescue, were studied in detail in three distinct populations as part of a programme to improve seedling vigour in the species. The effect of seed weight was found to be confined to the very early stages of growth and was apparent in seedling dry matter yield but not in tiller number. The development of a tiller in the axil of the coleoptile, which varied significantly between populations, had a far greater and more permanent effect both in terms of dry matter yield and tiller number. The increase in tiller number attributable to the coleoptile tiller and its derivatives increased geometrically in step with the total tiller number, so that the intitial difference of 28% in the first harvest remained practically unchanged in the subsequent three harvests. Similarly, the percentage difference in dry matter yield between plants with and without a coleoptile tiller remained more or less constant at about 22% from the second harvest onwards.It is concluded that the development of a coleoptile tiller may prove to be a useful selection criterion in the breeding of this species.
DIFFERENTIAL SURVIVAL OF CULTIVARS OF LOLIUM, DACTYLIS AND PHLEUM
A study of plant establishment showed that a considerable depletion in the size of the grass poptilation occurred during the first few months after sowing. In this experiment, two months after reseeding, the surviving grass seedlings amounted to about 20% of the viable seed sown; this figure was further reduced to about 10% before the swards were twelve months old. 
 
 
 
In swards based on several cultivars within a species the casualty rate varied from cultivar to cultivar, and may be further modifted by manuring and management. 
 
 
 
Evidence from older swards indicated that within a period of six years one cultivar could suppress another almost completely. 
 
 
 
The data suggest that not only is there a strong selection pressure within a sward during its early life, but also that the environment (produced in this case by manuring and management) eternities the relative persistency and aggressiveness of the individual cultivars. This illustrates how a sward originally composed of several plant types eventually settles to a narrow range, provided the management is not varied.
Hydrogen-rich gas production from biomass air and oxygen/steam gasification in a downdraft gasifier
Biomass gasification is an important method to obtain renewable hydrogen. However, this technology still stagnates in a laboratory scale because of its high-energy consumption. In order to get maximum hydrogen yield and decrease energy consumption, this study applies a self-heated downdraft gasifier as the reactor and uses char as the catalyst to study the characteristics of hydrogen production from biomass gasification. Air and oxygen/steam are utilized as the gasifying agents. The experimental results indicate that compared to biomass air gasification, biomass oxygen/steam gasification improves hydrogen yield depending on the volume of downdraft gasifier, and also nearly doubles the heating value of fuel gas. The maximum lower heating value of fuel gas reaches 11.11MJ/Nm3 for biomass oxygen/steam gasification. Over the ranges of operating conditions examined, the maximum hydrogen yield reaches 45.16gH2/kg biomass. For biomass oxygen/steam gasification, the content of H2 and CO reaches 63.27–72.56%, while the content of H2 and CO gets to 52.19–63.31% for biomass air gasification. The ratio of H2/CO for biomass oxygen/steam gasification reaches 0.70–0.90, which is lower than that of biomass air gasification, 1.06–1.27. The experimental and comparison results prove that biomass oxygen/steam gasification in a downdraft gasifier is an effective, relatively low energy consumption technology for hydrogen-rich gas production.