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  • Author or Editor: H. Biesinger x
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The objectives of this research were to mimic the gradient irradiances to which wheat (Triticum aestivum L. cv. SuperDwarf) plants were exposed aboard the Russian space station Mir, and to determine whether these irradiances inhibit growth and floral development. SuperDwarf wheat plants were exposed to irradiances of 20–40, 60–80, 100–120, and 140–180 (PPF = μmol·cm–2·s–1) and grown to maturity. Twenty plants were randomly selected from each irradiance level and chlorophyll, total leaf area, shoot biomass, and total soluble leaf and plasma membrane (PM) proteins were recorded. Irradiance at increasing levels of intensity increased the fresh biomass, leaf area, chlorophyll content, and the total soluble PM and leaf proteins of wheat tissue. There were significant differences between the abaxial and adaxial sides of the wheat leaves in stomatal density, stomatal index, stomatal length and width, and number of stomata along 1-mm length of leaf. These data may be uniquely valuable for further studies of relationships between chlorophyll content, photosynthetic rate, and productivity of wheat grown aboard the Russian space station Mir, space missions of long duration, or future manned space stations to generate oxygen, purify water, remove carbon dioxide, produce food and recycle waste materials. (Supported by NASA Grant NCC 2-831 and the Utah Agr. Expt. Station.)

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Our objectives were to ascertain whether wheat (Triticum aestivum L. cv. SuperDwarf) plants, grown aboard the Russian space station Mir in the microgravity of space, exhibited any plant structure and histochemical changes compared with those ground-based plants grown in Moscow, Russia, and Logan, Utah. Plants were harvested at stages of ontogeny corresponding to day 6, 14, 25, 35, and 55 post-emergence and placed in 4% formaldehyde: 1% glutaraldehyde (4F: 1G) fixative, adjusted to pH 7.2, and stored in Aclam plastic bags. Upon return to earth, samples were dehydrated and embedded in Spurr's resin. Use of differential chromophores on semi-thin sections (1 μm) suggests no major artifacts in cellular structure. Enzyme localizations for lignin, carbohydrate, starch, alkaline and acid phosphatase indicate that plants grown aboard Mir appeared to have less lignin than ground control plants. (Supported by NASA Grant NCC 2-831 and the Utah Agr. Expt. Station.)

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