Physiological and storage problems number     

H. S. Yohe  Wm. Stuart  C. O. Appleman  John Bushnell  Julian A. Dimock  J. T. Rosa  Earl S. Johnston  E. P. Miller  Freeman Weiss 《American Journal of Potato Research》1925,2(9):343-382

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Structural and physiological studies of paraquat-resistant Conyza     

Kevin C. Vaughn  E.Patrick Fuerst 《Pesticide biochemistry and physiology》1985,24(1):86-94

Structural and physiological studies were conducted with a population of Conyza bonariensis (L.) Cronq. that segregates into paraquat-resistant and -susceptible biotypes. Leaf disks from resistant seedlings, when incubated on 10 μM paraquat for 24 hr, exhibited little difference from the control disks incubated on H₂O as measured by conductivity change, malondialdehyde formation, or plastid ultrastructure. Leaf disks from the susceptible seedlings incubated on 10^?5M paraquat for 24 hr were uniformly bleached, had elevated malondialdehyde content, and leaked more electrolytes than control disks. Plastids of the susceptible biotype incubated on 10^?5M paraquat for 24 hr were swollen organelles with gross rearrangements of the lamella system. Most of the chloroplasts from the central area of the leaf disk of the resistant biotype incubated on a paraquat solution were structurally normal. Swollen plastids and plastids with twisted lamellae were also noted, although much less frequently. Plastids from the edges of the leaf disks of paraquat-resistant clones were structurally similar to those found throughout the leaf disks in susceptible seedlings. When the size of the leaf disk was increased, paraquat-resistant clones exhibited more “resistance” toward paraquat compared to similar-sized leaf disks of the susceptible seedlings. These data are consistent with the hypothesis that the paraquat-resistant seedlings have an altered uptake and/or compartmentalization of paraquat. Superoxide dismutase isozymes, which were previously considered to be related to paraquat resistance in Conyza, did not correlate with the segregation of paraquat resistance in this population.  相似文献   

Foreword     

W. M. Stuart 《American Journal of Potato Research》1923,1(1):1-1

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Cutting the costs of potato production     

Wm. Stuart 《American Journal of Potato Research》1929,6(1):15-18

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Mild to moderate overweight in dogs: is there an impact on routine hematological and biochemical profiles,echocardiographic parameters and cardiac autonomic modulation?     

Vieira  Aline Bomfim  Restrepo  Mariana Alvarez  Auzenne  Danielle  Molina  Kevin  O’Sullivan  Meghan  Machado  Marcus Vinicius  Cavanaugh  Sarah Marie 《Veterinary research communications》2022,46(2):527-535

Veterinary Research Communications - Obesity is considered the most common nutritional disease of dogs. Even though overt obesity is more likely to impair health, even moderately overweight dogs...  相似文献   

Stocking control concepts in uneven-aged silviculture   总被引：2，自引：0，他引：2  

O'Hara  Kevin L.; Gersonde  Rolf F. 《Forestry》2004,77(2):131-143

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Leaf respiration at different canopy positions in sweetgum (Liquidambar styraciflua) grown in ambient and elevated concentrations of carbon dioxide in the field     

Tissue DT  Lewis JD  Wullschleger SD  Amthor JS  Griffin KL  Anderson OR 《Tree physiology》2002,22(15-16):1157-1166

Trees exposed to elevated CO2 partial pressure ([CO2]) generally show increased rates of photosynthesis and growth, but effects on leaf respiration are more variable. The causes of this variable response are unresolved. We grew 12-year-old sweetgum trees (Liquidambar styraciflua L.) in a Free-Air CO2 Enrichment (FACE) facility in ambient [CO2] (37/44 Pa daytime/nighttime) and elevated [CO2] (57/65 Pa daytime/nighttime) in native soil at Oak Ridge National Environmental Research Park. Nighttime respiration (R(N)) was measured on leaves in the upper and lower canopy in the second (1999) and third (2000) growing seasons of CO2 fumigation. Leaf respiration in the light (R(L)) was estimated by the technique of Brooks and Farquhar (1985) in the upper canopy during the third growing season. There were no significant short-term effects of elevated [CO2] on R(N) or long-term effects on R(N) or R(L), when expressed on an area, mass or nitrogen (N) basis. Upper-canopy leaves had 54% higher R(N) (area basis) than lower-canopy leaves, but this relationship was unaffected by CO2 growth treatment. In August 2000, R(L) was about 40% of R(N) in the upper canopy. Elevated [CO(2)] significantly increased the number of leaf mitochondria (62%), leaf mass per unit area (LMA; 9%), and leaf starch (31%) compared with leaves in ambient [CO(2)]. Upper-canopy leaves had a significantly higher number of mitochondria (73%), N (53%), LMA (38%), sugar (117%) and starch (23%) than lower-canopy leaves. Growth in elevated [CO2] did not affect the relationships (i.e., intercept and slope) between R(N) and the measured leaf characteristics. Although no factor explained more than 45% of the variation in R(N), leaf N and LMA were the best predictors for R(N). Therefore, the response of RN to CO2 treatment and canopy position was largely dependent on the magnitude of the effect of elevated [CO2] or canopy position on these characteristics. Because elevated [CO2] had little or no effect on N or LMA, there was no effect on R(N). Canopy position had large effects on these leaf characteristics, however, such that upper-canopy leaves exhibited higher R(N) than lower-canopy leaves. We conclude that elevated [CO2] does not directly impact leaf respiration in sweetgum and that barring changes in leaf nitrogen or leaf chemical composition, long-term effects of elevated [CO2] on respiration in this species will be minimal.  相似文献   

The impact of shade on morphology,growth and biomass allocation in <Emphasis Type="Italic">Picea sitchensis</Emphasis>, <Emphasis Type="Italic">Larix</Emphasis> × <Emphasis Type="Italic">eurolepis</Emphasis> and <Emphasis Type="Italic">Thuja plicata</Emphasis>     

Seamus Kennedy  Kevin Black  Conor O’Reilly  Áine Ní Dhubháin 《New Forests》2007,33(2):139-153

To determine the effect of shade on morphology, growth and biomass allocation in Picea sitchensis, Larix × eurolepis and Thuja plicata, seedlings were grown in the open or under shadehouses providing 25%, 50% and 75% reductions of full-light for two growing seasons. For most of the characteristics assessed there was no significant interaction between species and shade indicating that the morphological responses to changing shade treatments were not species-dependent. After two growing seasons the mean height increment for the three species was significantly greater in 25% (76.1 cm) and 50% shade (74.9 cm) than in the open (69.5 cm). Root collar diameter increment, shoot, root and total biomass declined significantly with increasing shade while the opposite was true for the height:diameter ratio. In both western red cedar and hybrid larch the shoot:root ratio was significantly greater in the shade while in Sitka spruce this characteristic was not influenced by shade. While all species had significantly greater specific shoot areas in 75% shade than in 0% shade, this trend was particularly pronounced in hybrid larch. In hybrid larch and western red cedar, the normalised specific projected shoot area increased significantly with increasing shade. The opposite trend was observed for Sitka spruce. We conclude that in the main the species studied demonstrated similar shade acclimation responses despite their reported differences in shade tolerance.  相似文献   

Emergence timing affects root-collar diameter and mortality in loblolly pine seedbeds     

James N. Boyer  Stuart E. Duba  David B. South 《New Forests》1987,1(2):135-140

Eight half-sib families of loblolly pine (Pinus taeda L.) were sown in a nursery. Total germination, speed and uniformity of germination, root-collar diameters, mortality, and percent cull were recorded by family. Families which germinated quickest attained the greatest average diameters at the end of the growing season. Low variability in date of emergence led to correspondingly low variability in seedling diameter. When data for all families were combined, seedlings which emerged earliest experienced the lowest mortality, had the largest diameters, and produced the fewest culls.  相似文献   

Examination of stand structure on quail plantations in the Red Hills region of Georgia and Florida managed by the Stoddard-Neel system: an example for forest managers   总被引：1，自引：0，他引：1  

Moser  W. Keith; Jackson  Stuart M.; Podrazsky  Vilem; Larsen  David R. 《Forestry》2002,75(4):443-449

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