SummaryThe effect of CO2 enrichment on Phalaenopsis cut flower production was examined for 30 months throughout five flowering cycles. The plant was cultured in three greenhouses with different CO2 levels of (A): control, daily mean of ambient air=438 ppm; (B): 700 ppm; and (C): 1000 ppm. 1. The fresh weight of cut flowers, the numbers of inflorescence and flowers per 20 plants varied, depending on the CO2 concentration for each flowering cycle.2. The preservability (vase life) of cut flowers always improved under higher CO2 levels. Organic acid contents of plants were also higher under higher CO2 levels.

No abstract

: The waterchestnut (Trapa natans var. japonica Nakai) has been dominating the entire in Lake North Inbanuma, Chiba Prefecture, Japan. In order to investigate the seasonal variation of its surface coverage area, photographic recording of surface areas occupied by waterchestnuts in ten quadrats carried out from a boat every two weeks over a period of two years. In addition, the waterchestnuts were sampled to determine the dry weight of each part of them.The seasonal variation of waterchestnut coverage area in all quadrats appears to be bimodal ; there are two peaks which occurred at the end of June and at the beginning of September. During this period, the total biomass estimated from the laboratory measurements of the dry weight of each part of the waterchestnuts is 320g/m2.The geographical distribution of waterchestnuts over the whole lake can be mapped on the basis of the Landsat TM data. The combination of remotely sensed infestation areas with the directly determined coverage areas and dry weight of waterchestnuts allows us to estimate the total biomass in each component of the waterchestnuts in the whole lake. IntroductionThe