INFLUENCE OF A MYCORRHIZAL FUNGUS AND/OR RHIZOBIUM ON GROWTH AND BIOMASS PARTITIONING OF SUBTERRANEAN CLOVER EXPOSED TO OZONE

The influence of soilborne symbionts such as rhizobia or mycorrhizal fungi on plant response to ozone (O₃) has not been well defined. Leguminous plants in the field are infected by both types of organisms, which influence plant nutrition and growth. We studied the effects of infection with Rhizobium leguminosarum biovar trifolii and/or Gigaspora margarita on response of subterranean clover (Trifolium subterraneum L. cv Mt. Barker) to O₃. Exposures were conducted in greenhouse CSTR chambers using four O₃ concentrations [charcoal-filtered (CF), 50, 100, or 150 ppb; 6 h day^-1, 5 day wk^-1 for 12 weeks] as main plots (replicated). Four inoculum types were subplot treatments, i.e., inoculated with one, both, or neither microorganisms. At 2-wk intervals, plants were exposed to ¹⁴CO₂ and harvested 24 h later for determination of biomass and ¹⁴C content of shoots and roots. Ozone at 100 or 150 ppb suppressed clover growth during the experiment. Inoculation with G. margarita alone suppressed clover growth by the last two harvests, whereas R. leguminosarum alone enhanced growth during this time period. When both symbionts were present, the plants grew similarly to the noninoculated controls. Shoot/root ratios were increased by 100 or 150 ppb O₃ compared to that for CF-treated plants. Shoot/root ratios were greater for all inoculated plants compared to noninoculated controls. Under low O₃ stress (CF or 50 ppb), plants inoculated with both R. leguminosarum and G. margarita transported a greater proportion of recent photosynthate (¹⁴C) to roots than did noninoculated plants; we attribute this to metabolic requirements of the microorganisms. At the highest level of O₃ stress (150 ppb), this did not occur, probably because little photosynthate was available and the shoots retained most of it for repair of injury. Statistically significant interactions occurred between O₃ and inoculum types for shoot and total biomass. When averaged across harvests, 50 ppb O₃ suppressed biomass in the plants inoculated with G. margarita alone. Apparently, the mycorrhizal fungus is such a significant C drain that even a small amount of O₃ stress suppresses plant growth under these conditions.     

生物炭及生物炭-矿物复合物对菌根侵染、小麦和高粱营养的影响

The high price of synthetic fertilisers and the price barrier for biochar as a soil amendment have encouraged the exploration of using biochar in fertiliser replacement formulations. Biochars coupled with fertilisers can be applied at lower application rates to achieve benefits in plant growth and nutrition, as well as soil biological fertility.~It is necessary to evaluate the use of biochar as a fertiliser substitute.~Therefore, this study investigated the comparative influences of biochars, including {\it Acacia saligna} (AS), Simcoa jarrah (SJ) and Wundowie jarrah (WJ), mineral fertiliser with microbes (MF + M), biochar-mineral complex (BMC) and their combination on mycorrhizal colonisation, growth and nutrition of wheat in a glasshouse experiment and sorghum in field conditions. BMC + MF + M treatment produced higher mycorrhizal colonisation than MF + M alone, indicating that BMC had a significant role in increasing mycorrhizal colonisation.~SJ (treated with acetic acid) and MF + M treatments, as well as AS + MF + M application, showed si\-milar effects on mycorrhizal colonisation, but lower colonisation than the BMC~+~MF~+~M treatment.~Overall, the BMC + MF + M treatment supported the maximum shoot, root and total plant dry weight followed by AS + MF + M and WJ + MF + M. The~MF + M treatment had the maximum shoot N and K concentrations, while BMC + MF + M application had the maximum shoot P concentration. AS + MF + M and WJ + MF + M treatments supported the maximum N uptake by wheat shoots, while BMC + MF + M supported the maximum P uptake.~The results showed that biochars and BMCs could increase mycorrhizal colonisation, plant growth and nutrient uptake of wheat, particularly N, P, K, S and Zn. The field experiment confirmed that BMC application at a rate of 300 kg ha$^{-1}$ could increase the yield of irrigated sorghum on a loam soil and provide better applied P use efficiency compared to a water-soluble fertiliser alone. These results indicated that biochar-based fertilisers might increase the resilience and sustainability of dryland cropping in environments such as in Western Australia and warrant further field evaluation.     

Effect of Distal Femoral Growth Plate Fusion on Femoral-Tibial Length

Unilateral distal femoral epiphysiodesis in seven 10 week old crossbred Doberman Pinscher littermates resulted in a significant (p less than or equal to 0.0001) femoral length deficit of 23.5% without clinically detectable alterations in gait up to 42 weeks after surgery. In addition to compensatory hyperextension of the stifle joint, the ipsilateral tibia showed significant (p less than or equal to 0.0001) acceleration in longitudinal growth. The combined femoral-tibial length at necropsy was still significantly shorter (p less than or equal to 0.0001) in the treated leg than in the control leg despite the increased tibial growth. Unlike other species, neither of the other two femoral growth plates produced any significant compensatory increase in length after fusion of the distal growth plate. The femoral condyles of the treated legs rotated caudally and degenerative joint disease developed in all stifle joints of the treated legs. No contralateral limb abnormalities were evident radiographically.     

Bypass Surgery for the Treatment of Small Intestinal Ileus in the Horse A Report of Three Cases

The medical management of three horses with simple and strangulating small intestinal obstructions was unsuccessful and was therefore supported by surgical bypasses. Jejunocecostomies were used to treat horses with postoperative paralytic ileus that was unresponsive to medical management. These horses had abdominal pain, gastric distention, heart rate elevations greater than 60/minute, and small intestinal distention on rectal palpation. Two horses experienced weight loss which responded to bypass removal. The bypass effectively decreased the need for intravenous fluid administration and repeated nasogastric intubation.     

State Employment Growth: The Impact of Taxes and Economic Development Agency Spending

ABSTRACT The results of this study confirm the expected positive relationship between economic development agency spending and employment growth among the states. Furthermore, it is concluded that past studies, by failing to control for state economic development agency spending in estimated regression equations, have underestimated the negative impact of personal taxes on employment growth.     

The Effect of Long-Term Bone Plate Application for Fixation of Radial Fractures in Dogs

This study was divided into two phases. In the in vitro phase, a stainless steel bone plate was applied to the cranial surface of the radius in 14 canine limbs. The effect of the presence of a bone plate on bone density analysis using radiographic photodensitometry (RP) was evaluated by comparing the density measurement of the unplated limb to the density measurement of the plated limb. The optical density of the plated bones was 12% greater than that of the unplated bones. This information was used as a correction factor for the in vivo study. In the in vivo phase, 23 dogs with radial and ulnar fractures were examined for complications associated with the long-term application of a stainless steel plate applied to the cranial surface of the radius. In 14 dogs, RP analysis was used to compare the plated limb with the normal, contralateral limb. No significant differences in radial cortical bone density existed between the plated limb and the contralateral limb after taking into account the effect a bone plate had on photodensitometry readings. There was no significant correlation between the change in radial cortical density and the duration of bone plate application, suggesting that a steady state between bone loss and bone production occurs after long-term plate fixation of the fractured canine radius. The majority (87%) of the dogs with a plate applied to the radius greater than 1 year had normal limb usage when standing, walking, or running.     

Silicone Elastomer Sling for Fecal Incontinence in Dogs

Fecal incontinence was created by bilateral pudendal neurectomy in 12 dogs. In six dogs, the fecal incontinence was treated by implantation of a polyester-impregnated silicone elastomer sling to form an artificial external anal sphincter. Six dogs underwent the same operative procedure without the implant to serve as controls. Five dogs regained total continence and one dog regained partial continence after implantation of the sling. Four control dogs remained incontinent and two control dogs regained partial continence. The difference between the dogs with slings and the controls was statistically significant (P less than 0.01). The only complication was infection in one dog, which was treated successfully. Histologic reaction to the implant was confined to a zone of fibrosis 1 to 3 mm surrounding the implant. The sling was well tolerated clinically and appeared to offer a successful method for correction of fecal incontinence in dogs.