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CHARGE NUMBER: Project 11716 PROJECT TITLE: Tobacco Microstructure PROJECT LEADER: Mary Ellen Counts PERIOD COVERED: July 1-31, 1981 DATE OF REPORT: July 31, 1981 L. C AUTORADIOGRAPHY WITH CA45 (M. E. Counts, S. E. Taylor). Bright 319 seedlings were transplanted to hydroponic culturing containers. The plants are being fed with a nutrient solution modified by R. Bass (Project 2506) for P.M. greenhouse plants. Four plants are being fed Ca45 C1 at increments during the growth period. Two plants received the totaf amount of isotope to be used in whole-plant labeling shortly after transplant. These plants should be ready for harvesting and Ca45 autoradiography studies in 6-8 weeks. Work also continued in optimization of photographic processes for autoradiography. Studies were done in preparation of leaf tissu samples for scintillator counting determinations of relative Ca49 1 bel activity in leaves of different stalk positions from plants fed Ca4~ at the various periods of growth. These scintillation data will be used to supplement whole leaf autoradiography techniques: Various types of film are now being evaluated for whole leaf label distribution determinations. RATOONED TOBACCO (M. E. Counts, S. E. Taylor) Ratooned greenhouse 411 Bright plants have been harvested, and leaf morphology with stalk position is now being evaluated with SEM. Bright 319 plants were ratooned also and are doing well. Similar studies of surface cell morphology were made for these plants. Samples of expanded field-grown Bright 319 plants of various stalk positions and fertilization applications ratooned by G. Nixon (Project 1901) have been examined. Cell size morphology data are now being collected for these samples. When data collection is complete, comparisons of cell size surface morphology with stalk position for the various tobacco types (411, 319, greenhouse, field-grown, controls) will be made and evaluated. DENITRIFICATION (I. L. Uydess) Investigations of the microbial aspects of the denitrification process continued. Several experiments were done to further understanding of the relationship between temperature, microbial growth and nitrite influence on denitrification of SEL. In one experiment, three bacterial isolates from the mixed bacterial population present in

-2- SEL were tested for growth at 50°C and 60°C, with and without the presence of nitrate. OnTy one of these isolates grew significantly at 60'C, the second grew marginally and the third did'not exhibit any growth at the elevated temperature. Two isolates appeared to grow better in the presence of nitrate. With the mixed nature of the bacteria in SEL and the widely variable substrates, it is expected that substrate influence on bacterial growth would vary and that these influences would' be different for the different organisms present. Work continues on SEL organism identification. In another experiment, the effect of nitrite (N02) levels on growth of and denitrification by SEL mixed bacterial cultures. It was found that bacterial growth was limited by elevated levels of nitrite (>600 ppm). Bacterial cultures in the presence of low nitrite levels reduced nitrate levels to about the same extent as contro1cultures witfi no nitrite present. Higher nitrite levels greatly retarded nitrate removal by the bacterial cultures. These experiments, although performed in laboratory environments, give valuable clues to best pilot plant operation parameters. /t 1 v 1-M.E.ecrUMIZI /l I v