tailieunhanh - Báo cáo lâm nghiệp:"Seedling root growth of six broadleaved tree species grown in competition with grass under irrigated nursery conditions"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài:"Seedling root growth of six broadleaved tree species grown in competition with grass under irrigated nursery conditions" | Ann. For. Sci. 60 2003 601-608 INRA EDP Sciences 2004 DOI forest 2003052 601 Original article Seedling root growth of six broadleaved tree species grown in competition with grass under irrigated nursery conditions Ralph Harmer Malcolm Robertson Forest Research Alice Holt Lodge Wrecclesham Farnham Surrey GU10 4LH UK Received 24 June 2002 accepted 10 March 2003 Abstract - Pre-treated seeds of ash silver birch field maple hawthorn rowan and sycamore were sown into open nursery beds half of which were then over-sown with grass seed. After germination most species were harvested at approximately weekly intervals. Height dry weights lengths of roots and numbers of lateral roots and root tips of tree seedlings were assessed. Overall competition with grass had little effect on seedling size but appeared to reduce development of the lateral root system. However results were very variable both within and between species and differences observed were often only indicative and not statistically significant. Competition tended to increase allocation of biomass to roots and the length of the tap-root but reduced total length of the root system. In general on a length basis competition with grass had no effect on the number of 1st order laterals on the tap-root but the total number of root tips on the root system declined. The response to competition varied with species but differences could not be related simply to competitive ability. The small effects of grass competition may be related to the short duration of the experiment and the irrigation regime used. grass competition root seedling tree Résumé - Croissance racinaire de semis de six essences feuillues se développant en concurrence avec des graminées en pépinière irriguée. Des graines prétraitées de frêne bouleau verruqueux érable champêtre aubépine monogyne sorbier des oiseleurs et d erable sycomore ont été semées sur des planches de pépinières à ciel ouvert puis sur la moitié d entre elles on a effectué un semis