Genotypic variation of cut chrysanthemum response to high CO sub 2 /sub concentration: growth, time to flowering and visual quality.

摘要

In this study sixteen cut chrysanthemum cultivars were used to evaluate the effects of high CO₂ concentration (1500 micro mol mol-1) on growth, time to flowering and visual quality as compared to the concentration used in commercial greenhouses (600 micro mol mol-1). CO₂ enrichment increased light use efficiency (11-41%) and total plant dry mass (TDM) (5-40%) in a cultivar dependent manner. This TDM increase was a result of: (i) higher relative growth rate during the long day period (i.e., 0 to 2 weeks; LD); and (ii) higher absolute growth rate both during the period between 2 to 6 weeks (SD₁), and 6 weeks to final harvest (SD₂). Cultivar differences in TDM at flowering between the two CO₂ concentrations could be explained by differences in growth rate during the LD and SD₂ periods. Furthermore, growing at high CO₂ regime enhanced the number of flowers and flower buds per plant (NoF, 4-48%). Interestingly, the cultivars that showed the highest percentage of TDM increase, with CO₂ enrichment, were not the ones that had the highest increase in the percentage of NoF. In contrast, high CO₂ concentration had only a minor or no effect on the number of internodes on the main stem and on the reaction time in all the cultivars examined. From this research it is concluded that there is a large variation in the response of cut chrysanthemum cultivars to CO₂ enrichment, in terms of TDM and NoF, which gives possibilities for breeding.