Dry matter production,nutrient uptake,and growth of cotton as affected by potassium fertilization

Insufficient potassium (K) nutrition produces detrimental effects on cotton (Gossypium hirsutum L.) lint yield and fiber quality. To further understand the deleterious effects caused by K deficiency, a 2‐yr (1991 and 1992) field study was conducted to determine how dry matter partitioning and nutrient concentrations of various plant tissues for the cotton genotypes, ‘DES 119’ and ‘MD 51 ne’, were altered by varying the application rate of fertilizer K and nitrogen (N). All plots received a preplant application of 112 kg N ha^‐1, and half of the plots were later sidedressed with an additional 38 kg N ha^‐1. Within each N treatment, half the plots received 112 kg K ha^‐1, preplant incorporated, with the remaining plots not receiving any fertilizer K. Dry matter harvests were taken three times in 1991 and two times in 1992. At cutout (slowing of vegetative growth and flowering), plants that received K fertilization had a 14% more leaf area index (LAI), a 3% increase in the number of main stem nodes, and a 2% increase in plant height. However, those plants had a 12% lower specific leaf weight (SLW) than plants receiving no K fertilization. By the end of season, the of K fertilization had resulted in more stem (21%), bur (13%), seed (19%), and lint weight (20%), but harvest index was not affected. Varying the level of N fertilization did not affect any of these dry matter parameters at any harvest. In general, the larger plants produced under K fertilization had reduced concentrations of N, phosphorus (P), magnesium (Mg), and sodium (Na) in the various plant parts. While N uptake efficiency was not affected by K fertility, plants that received K fertilization had increased efficiency of fertilizer N use and of N utilization within the plant. The smaller LAI of the K deficient plants probably reduced the photosynthetic capacity per plant. A reduced assimilation capacity could explain the inefficiency of N use, lint yield reductions, and poorer fiber quality often associated with K deficiencies.     

Risk frames on shark diving websites: implications for global shark conservation

• 1. Decision‐makers can leverage understanding about the human dimensions (HD) of shark conservation to inform more effective conservation action. Characterizing risk frames on shark diving websites can provide insight about the HD of shark conservation and deepen understanding of the role of risk in influencing human relationships with wildlife.
• 2. The objectives of the current study were to: (1) describe risk frames (e.g. victim, perpetrator) found on shark diving websites; (2) explore themes among and between risk frames; and (3) synthesize implications for conservation.
• 3. Content among 53 websites was analysed in December 2008; 15% used only a perpetrator frame, 21% used only a victim frame, 36% used both frames and 28% used neither frame.
• 4. Websites with a conservation link were more likely to use a victim frame (T = 0.283, P<0.05). The occurrence of both frames on study websites speaks to the relevancy of applying risk‐related thinking to shark conservation.
• 5. This research highlights how risk frames are contextualized on selected shark diving websites. Integrated with understanding of the ecological processes surrounding sharks and their conservation, HD information such as that presented here can contribute to more effective shark conservation. Copyright © 2011 John Wiley & Sons, Ltd.

     

Relative effects of mammal herbivory and plant spacing on seedling recruitment following fire and mining

Background  

There is much debate concerning which ecological constraints are the most limiting factors to seedling recruitment in disturbed communities. We provide the first comparison between selective herbivory and plant competition effects among two post-mined forest ecosystems (primary succession) and one post-fire woodland ecosystem (secondary succession). Animal exclosure assessments of nine common species across eight sites were performed for comparison within three locations separated by up to 200 km. Additionally, we asked whether pre-browsed plants differed in nutrient content between or within species in the separate systems.     

Retrospective study of 108 foals with septic osteomyelitis

Objective   To determine the clinical characteristics, short-term outcome and future athletic performance of foals with septic osteomyelitis.
Design   Retrospective clinical study of 108 Thoroughbred foals with radiographic evidence of bone infection that were presented at the Scone Veterinary Hospital between August 1995 and December 2001. Medical records were reviewed and information concerning signalment, the clinical, laboratory and radiographic findings, treatment and outcome was obtained. Racing records were obtained and evaluated for surviving foals that had reached racing age.
Results   Mean age of foals at initial evaluation was 39 days (range 1–180 days); 21 foals had multiple radiographic bone lesions (19.4%), and 76 had concurrent septic arthritis (70.4%). The most frequently affected bones were the femur, tibia and distal phalanx. In total, 87 foals were discharged from the hospital (80.6%), 79 survived long-term to reach racing age and 52 raced (65.8%). Overall, 48% (52/108) of the foals treated for osteomyelitis raced. Foals less than 30 days of age at the time of diagnosis, critically ill foals and those with multiple bones or joints affected were significantly less likely to be discharged from hospital. Multiple septic joints, but not multiple bone involvement, had an unfavourable prognosis for racing.
Conclusions   The prognosis for survival of foals with septic osteomyelitis or osteitis is favourable. Multiple bone or joint involvement is an important short-term prognostic indicator; however, the involvement of multiple joints, but not multiple infected bones, is associated with an unfavourable prognosis for racing.     

The suitability of a rolled BHK21 monolayer system for the production of vaccines against the SAT types of foot-and-mouth disease virus. I. Adaptation of virus isolates to the system, immunogen yields achieved and assessment of subtype cross reactivity

In an examination of 34 southern African SAT-type foot-and-mouth disease viruses, all but 1 attained satisfactory levels of infectivity within 6 passages in rolled BHK21 monolayer cell cultures. However, there were marked differences between adapted viruses with respect to the mass of immunogen (146S material) produced. Several isolates which consistently produced levels greater than or equal to 2 micrograms/ml were identified. In cross neutralization tests using post-vaccinal sera, SAT-1 and SAT-2 isolates showed considerable diversity and none of the viruses tested would be expected to produce a broad-spectrum response if incorporated into a vaccine. On the other hand, when 2 of the SAT-2 isolates were incorporated into the same vaccine a distinctly broader response resulted.