Increased levels of nitrogen in liquid growth medium bring about increased growth and a delay in extracellular polysaccharide production by Chlamydomonas mexicana Lewin on a per‐cell basis. Addition of nitrogen to stationary phase cultures causes renewed growth and a temporary lag in polysaccharide synthesis until growth again ceases. Removal of nitrogen terminates growth, causing an immediate increase in polysaccharide synthesis. Phosphate‐starved cells show a response similar to nitrogen‐starved cells, indicating that the beginning of stationary phase and not nitrogen depletion causes the stimulation in extracellular polysaccharide synthesis. As similar results are assumed to occur on soil, the significance of this response is discussed.
Church-related small private liberal arts baccalaureate minority-serving institutions like Wesley College have modest endowments, are heavily tuition-dependent, and have large numbers of financially-challenged students. In order to sustain the level of academic excellence and to continue to build student demographic diversity in its accessible robust Science and Mathematics (STEM) programs, the faculty sought federal and state funds to implement a coordinated program of curriculum enhancements and student support programs that will increase the number of students choosing STEM majors, increase their academic success, and improve retention.
Eight tomato (Lycopersicon esculentum) cultivars were grown for 16 weeks in greenhouses enriched for an average of 8.1 hours daily to 1000 μl CO /liter of air or in greenhouses maintained at ambient CO. Carbon dioxide enrichment significantly decreased the mean number of greenhouse whiteflies [Trialeurodes vaporariorum (Westward), Homoptera: Aleyrodidae] as measured by counts from commercial yellow sticky traps. The number of whiteflies present was negatively correlated with both seasonal foliar C: N ratio and percent C but positively correlated with percent N in the foliage. Thus, CO enrichment apparently alters plant composition in such a way as to reduce significantly the population growth of greenhouse whiteflies.
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