Evidence for red:far red signaling and photomorphogenic growth response in Douglas-fir (Pseudotsuga menziesii) seedlings     

Ritchie GA 《Tree physiology》1997,17(3):161-168

In a greenhouse experiment, potted coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were grown in miniature "Nelder" (Nelder 1962) plots where growing space varied from 265 to 2555 cm(2) per plant. After thirty weeks, mean plant height, crown biomass and branch number increased significantly (P = 0.0141) with decreasing growing space (increasing plant density). Differences in height growth became apparent about six weeks after sowing. Furthermore, horizontally reflected radiation measured within the Nelder plots showed a decrease in red:far-red ratio (R:FR) from 1.2 at the lowest density to 0.71 at the highest. Plant height was strongly inversely correlated with estimated phytochrome photoequilibrium values (r(2) = 0.893). Field measurements made in a three-year-old variable density plantation also showed a decrease in R:FR with increasing planting density from 300 to 3,000 trees ha(-1). These results support the hypothesis that young Douglas-fir seedlings are able to detect, through the phytochrome system, the presence of nearby seedlings owing to the depletion of R relative to FR in the spectra reflected by the foliage of the adjacent plants. They then adjust their growth allometry in a way that reduces the possibility of being over topped by these future competitors.  相似文献   

Field survival and early height growth of Douglas-fir rooted cuttings: relationship to stem diameter and root system quality     

Gary A. Ritchie  Yasuomi Tanaka  Rod Meade  Steven D. Duke 《Forest Ecology and Management》1993,60(3-4):237-256

In 1990, three studies involving 11 half-sib families of Douglas-fir rooted cuttings were established at three sites in western Washington State (USA): two with low regeneration difficulty (RD) and one with high RD. Grading and cull studies were installed on each site and a root number study on one site. The grading study compared the performance of nine classes of rooted cuttings based on stem diameter and root system quality. The cull study evaluated five different types of putative culls. The root number study determined the correlation between the number of initial roots and field performance.

In the grading study survival and height growth reflected stem diameter and relative root quality on all three sites. Mean survival by treatment was in the range 92–100%, 82–97% and 66–87% across the three sites. First year height growth varied from approximately 10 cm to 20 cm and was greatest on the low RD sites. Second year height growth was from three to four times greater than first year height growth on the low RD sites and two to three times greater on the high RD site. Plants with larger diameter had higher survival and better growth than those with smaller diameter. Within each diameter class, plants with good or fair root systems outperformed those with poor root systems. Performance of seedlings and transplants was nearly identical to that of rooted cuttings with corresponding diameter and root system quality.

In the cull study only trees with stem diameter < 4 mm were deemed true culls owing to significantly reduced survival and height growth. In the root number study, rooted cuttings generally increased in size in the nursery in proportion to root number. However, after 2 years in the field, root number was a very poor predictor of survival and height growth.  相似文献   

Dirofilarial hemoptytic expectoration in 5 dogs - an uncommon manifestation of canine heartworm disease     

Rishniw M  Hess A  Rojas R  Ritchie C  Laws AG  Staudt T  Bowman D 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2012,26(4):1061-1063

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A prospective longitudinal study of naturally infected horses to evaluate the performance characteristics of rapid diagnostic tests for equine influenza virus     

Read AJ  Arzey KE  Finlaison DS  Gu X  Davis RJ  Ritchie L  Kirkland PD 《Veterinary microbiology》2012,156(3-4):246-255

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Carlyle newton clayton, 1912 to 1998     

Sutton TB  Ritchie DF 《Phytopathology》1999,89(7):532

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Persistent viral shedding during asymptomatic Aleutian mink disease parvoviral infection in a ferret.     

Kate E Pennick  Mary Ann M Stevenson  Kenneth S Latimer  Branson W Ritchie  Christopher R Gregory 《Journal of veterinary diagnostic investigation》2005,17(6):594-597

A 2-year-old domestic ferret that appeared clinically healthy was repeatedly seropositive for Aleutian mink disease parvovirus (ADV) over a 2-year observation period. Antibody titers, determined by counter-immunoelectrophoresis, ranged from 1024 to 4096. Viral DNA also was identified in serum, urine, feces, and blood cell fractions by polymerase chain reaction analysis. Ultimately, DNA in situ hybridization revealed ADV DNA in histologic sections of various tissues and organs. These data indicate that this asymptomatic ferret was persistently infected with ADV.  相似文献   

Assessment of Molasses–Urea Blocks for Goat and Sheep Production in the Sultanate of Oman: Intake and Growth Studies     

Forsberg NE  al-Maqbaly R  al-Halhali A  Ritchie A  Srikandakumar A 《Tropical animal health and production》2002,34(3):231-239

The goal of this study was to develop a molasses–urea block (MUB) for purposes of supplementing trace minerals to domestic ruminant livestock in Oman. To accomplish this, the utility of molasses and date syrup as fermentable energy sources, of straw, date flakes and wheat bran as fibre sources, and of cement and lime as binders were evaluated. The proportion of cement needed for adequate hardening of the block was also studied. Molasses- and date syrup-based blocks hardened equally well. However, the higher cost of date syrup precluded its use. Wheat straw yielded a low-density block that hardened slowly. Date fibre retained moisture and hardened extremely slowly. Wheat bran-based blocks hardened quickly and yielded dense blocks. Hence, wheat bran was judged to be the superior source of fibre. Lime did not effectively bind the blocks. A cement content of 15% allowed hardening of the blocks within 2–3 weeks. A level of 10% cement in the block reduced the hardening rate by about 50%. Sheep and goats consumed both the straw- and wheat bran-based blocks but at different rates. Consumption of the straw-based block by sheep ranged from 50 to 179 g/head per day, whereas the denser wheat bran-based block was consumed at a rate of 8–20 g/head per day. Consumption of the straw-based block by goats was low (8 g/head per day) compared to that of wheat bran-based blocks (16–24 g/head per day). On the basis of the intake of the bran-based block by sheep, a block was designed that would provide approximately 50% of an animal's trace mineral requirements per day. This block consisted of 45% molasses, 10% urea, 5% trace minerals, 2.5% NaCl, 22.5% wheat bran and 15% cement. Sheep consuming this block gained more weight than sheep fed a conventional mineral block or sheep receiving no mineral supplementation. MUBs are inexpensive (9.5 US cents/kg). We conclude that MUBs have utility for providing trace elements in ruminant diets.  相似文献   

The write stuff     

JT FARAGHER 《Australian veterinary journal》1998,76(2):108-109

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Investigation of parrot papillomavirus in cloacal and oral papillomas of psittacine birds     

Latimer KS  Niagro FD  Rakich PM  Campagnoli RP  Ritchie BW  McGee ED 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》1997,26(4):158-163

Cloacal and oral papillomas from 27 psittacine birds of various species were examined for the presence of parrot papillomavirus by DNA in situ hybridization, DNA in situ polymerase chain reaction, and nested polymerase chain reaction. Parrot papillomavirus was detected in one oral papilloma from an African grey parrot by all three techniques. In addition, rare basophilic intranuclear inclusions were observed by light microscopy in tissue sections of the oral papilloma from this parrot. The remaining lesions were negative for parrot papillomavirus DNA. This study suggests that parrot papillomavirus may be involved in the development of papillomas in African grey parrots, but apparently is not responsible for development of similar lesions in unrelated species of psittacine birds.  相似文献   

Soil and residue management effects on arable cropping conditions and nitrous oxide fluxes under controlled traffic in Scotland 1. Soil and crop responses     

B. C. Ball  R. M. Ritchie 《Soil & Tillage Research》1999,52(3-4):177-189

Soil compaction can affect crop growth and greenhouse gas emission and information is required of how both these aspects are affected by compaction intensity and weather. In this paper we describe treatments of compaction intensity and their effects on soil physical conditions and crop growth in loam to sandy loam cambisol soils. Soil conditions and crop performance were measured over three seasons in a field experiment on soil compacted by wheels on freshly ploughed seedbeds. Ploughing buried the chopped residues of the previous crop. After ploughing, traffic was controlled such that the experimental plots received wheel traffic only as treatments. The overall objective was to discover how the intensity and distribution of soil compaction just before sowing influenced crop performance, soil conditions and emissions of nitrous oxide. Compaction treatments were zero, light compaction by roller (up to 1 Mg m⁻¹) and heavy compaction by loaded tractor, (up to 4.2 Mg). The experiment was located at Boghall, near Edinburgh (860 mm average annual rainfall) for the first two seasons under spring and winter barley (Hordeum vulgare L.) and in a drier area at North Berwick (610 mm average annual rainfall) for the third season under winter oil-seed rape (Brassica napus L.). Heavy compaction in dry soil conditions had little effect on crop growth. However, in wet conditions heavy compaction reduced air porosity, air permeability and gas diffusivity, increased cone resistance and limited winter barley growth and grain yield. Heavy compaction in wet conditions reduced winter barley yields to 7.1 Mg ha⁻¹, in comparison to 8.8 Mg ha⁻¹ in the zero compaction treatment. The compaction status of the top 15 cm of soil seemed to be particularly important. Loosening of the top 10 cm of soil immediately after heavy compaction restored soil conditions for crop growth. However, zero seed bed compaction gave patchy and uneven crop emergence in dry conditions. Both zero and light compaction to a target depth of 10 cm gave similar crop productivity. Maintenance of a correct compaction level near the soil surface is particularly important for establishment and overwintering of barley and oil seed rape.  相似文献