21世紀前半には世界の人口は100億人に達すると予想されている。これだけの人口を養っていけるだけの食糧を今後、地球で生産することができるのであろうか。現在ヨーロッパでは口蹄疫や狂牛病などの問題が盛んに叫ばれている。食糧問題は、100億人を越える人間がこの地球上に住んでいくことができなくなってしまう深刻な問題である。農薬生産は、牧畜業も含めて根本は穀物である。そこでこの穀物生産をさらに増やすためには、農業技術の一層の推進と農地の拡大が必要となるであろう。これに比べて海洋は、まだ生産力が衰えてはいないが、捕鯨などについては海外から強い非難が集まっている。海洋における食糧生産性を高めるためには、どうしても富栄養化問題を避けて通るわけにはいかない。しかしながらいったん富栄養化してしまうと、これを元に戻すことは至難の業である。環境を保全しながら食程増産に尽くす道は陸上でも、海上でもはなはだ困難である。我々のCELSS学会は基本的には地球上の限られた空間内での食糧生産を増加する道を探ることができると期待している。

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We have developed a new image instrumentation system of chlorophyll a fluorescence with an optical microscope, capable of in situ analysis at the cellular level. With this system we analyzed the effects of DCMU on photosynthetic activity of green alga Closterium navicula. The fluorescence parameters qP, qN and NPQ, and Yield, which represent photochemical quenching, non-photochemical quenching, and photosystem II photochemical efficiency, were calculated from images taken under actinic and saturating illumination. Chlorophyll fluorescence (F and F'_m) intensity of alga whose photosystem inhibited by DCMU was higher than healthy alga. The qN and NPQ was reduced greatly throughout injured alga. These results indicated the inhibition by DCMU eliminated non-photochemical quenching. In contrast, qP and Yield were not very different from healthy alga. These results showed that photochemical quenching occurred ordinarily, but Yield could not be applied as an indicator of CO₂ fixation rate in such a case. It is necessary to choose the experimental condition to determine the validity of Yield.

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In order to obtain background data of volatile organic compounds (VOCs) in plant growth chambers without plant present, VOCs in Closed Ecology Experiment Facility (CEEF) were analyzed. In the chamber without cultivation materials, VOCs such as alkanes (C2-C7), alkenes (C2-C4), cycloalkanes (C5-C7), alkylbenzenes (C6-C8), siloxanes, trichloromonofluoromethane, 2-butanone, methylisobutylketone, 2-methylpropylacetate, phenol, and tetrahydrofuran were accumulated. The highest concentrations were observed in alkylbenzenes (C6-C8), whose concentrations increased by 50-200 ppbv for 7 days closure. Concentrations of ethylene, 1, 2-dimethylcyclopropane, methylisobutylketone, and butyl acetate were greater in the chamber where cultivation materials were installed. Terpenes, isoprene, some kinds of aldehides, C9-C11 alkanes, carbon disulfide and dimethyl sulfide, which are known as biogenic VOCs, were not accumulated. This result indicates that biogenic emissions of VOCs except for ethylene can be measured in the closed chambers of CEEF. The result also suggests that a trace gas removal system should be operated to remove toxic VOCs such as alkylbenzenes.

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