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Stress Variances Among Informal Hospice Caregivers

Description: Article on stress variances among informal hospice caregivers.
Date: August 2012
Creator: Wittenberg-Lyles, Elaine; Demiris, George; Oliver, Debra Parker; Washington, Karla T.; Burt, Stephanie & Shaunfield, Sara
Partner: UNT College of Arts and Sciences

Root adaptations at stress levels of nitrate, phosphate, or both simultaneously

Description: Sunflowers in flowing hydroponic culture show reduced growth rates at nitrate levels below 10 ..mu..M nitrate or phosphate levels below 0.3 ..mu..F. At least for phosphate, this level is a very small fraction (0.003) of the K/sub m/ for the uptake systems. We have quantified four major adaptations that enable high growth rates under incipient stress: increased root:shoot ratio; increased uptake capacity (V/sub max/) per unit root mass; nocturnal uptake of nutrients; and (only partially adaptive) reduced tissue concentrations of nutrients. We show that capital energy costs (in root growth) for acquiring nutrients can exceed direct or operational costs of internal metabolism (nitrate reduction, e.g.,); this has implications for the plant-controlled trade-off of NO/sub 3//sup -/-NH/sub 4//sup +/ - N/sub 2/ as N sources for legumes and other plant types. We outline needed further research and suggest guidelines for breeding plants for tolerating nutritional stresses; we also suggest that some measures of nutrient-use efficiency may be misleading. 6 references, 2 figures, 2 tables.
Date: August 1, 1984
Creator: Gutschick, V.P. & Kay, L.E.
Partner: UNT Libraries Government Documents Department