Root morphology and acid phosphatase activity in tomato plants during development of and recovery from phosphorus stress

Changes in root morphology and acid phosphatase activity (APA) were followed during the developent of P‐deficiency in tomato plants grown for 7, 14, and 21 days in 0.16 P well aereated nutrient solutions, followed by a period of sufficiency (recovery) in 1 mM P. Plants were harvested weekly for APA, dry weight, and P concentration in roots, stems and leaves, and every 2 weeks for root morphology determinations. APA was highly correlated to development and recovery from P stress. Mixmium values were attained during growth under deficiency and decreased to that of the control plants after a period of recovery in 1 mM P nutrient solutions. Total root weight and average root diameter decreased under P‐stress and root surface area per unit dry weight increased. Efficiency of P utilization (g dry weight/mg absorbed P) was much higher at the end of the stress period but approached that of the controls as P‐supply was restored to sufficiency levels. The implications of these results in developing rapid and reliable screening technigues to detect successful plant performance under P‐stress is discussed.     

Damping-off of soybean in southern Brazil can be associated with different species of Globisporangium spp. and Pythium spp.

Damping-off of soybean is a common problem in some fields in southern Brazil. Frequently, Phytophthora sojae has been pointed out as the main causal agent. However, questions were raised as to whether other oomycetes could also be present. Hence, the objectives of this study were to isolate, identify, and determine the pathogenicity and aggressiveness of oomycetes isolated from soybean seedlings. Thirty-three isolates were obtained from 13 fields. Isolates were identified based on morphology and molecular methods. Nine species were recovered: Pythium conidiophorum (n = 14, 42.4%), Globisporangium rostratifingens (n = 7, 21.2%), G. irregulare (n = 2, 6.1%), G. spinosum (n = 1, 3.0%), G. ultimum var. sporangiiferum (n = 2, 6.1%), Pythium acanthicum (n = 2, 6.1%), P. deliense (n = 1, 3.0%), P. inflatum (n = 1, 3.0%), and P. torulosum (n = 3, 9.1%). Pathogenicity and aggressiveness were determined with two soybean cultivars (DM57i52 and NEO530) in a seed rot assay and a root rot assay. All isolates were pathogenic to soybean with variable levels of aggressiveness in both assays. The range of seed disease severity index varied from 7.5 to 100 for DM57i52 and from 23.1 to 100 for NEO530. The mean root disease severity index of the soybean cultivars ranged from 29.4 to 92.8. This is the first official report of G. irregulare, G. rostratifingens, G. spinosum, G. ultimum var. sporangiiferum, P. acanthicum, P. conidiophorum, P. deliense, P. inflatum, and P. torulosum causing damping-off of soybean in the state of Rio Grande do Sul in southern Brazil.     

First record and new hosts of Coccophagus shillongensis Hayat and Singh, 1989 (Hymenoptera: Aphelinidae) in Serbia

Phytoparasitica - During a study on soft scales (Hemiptera: Coccomorpha: Coccidae) and their natural enemies in Serbia, the parasitoid Coccophagus shillongensis Hayat and Singh 1989 (Hymenoptera:...     

Epidural myelolipoma in a Husky-cross: a case report

Epidural spinal myelolipoma was diagnosed in an 11.5-year-old castrated male Husky-cross that was evaluated at the veterinary teaching hospital due to progressive thoracolumbar spinal hyperaesthesia and mild proprioceptive pelvic limb ataxia. A focal, ill-defined mildly inhomogenous extradural mass lesion was detected by MRI. The dog was euthanized. At necropsy an extradurally located reddish mass of about 2.5 cm in diameter was present in the vertebral canal. The mass was identified histopathologically as an epidural myelolipoma.     

BILATERAL ELBOW MALFORMATION IN A CAT CAUSED BY RADIO-ULNAR SYNOSTOSIS

A 9-month-old neutered male cat was referred because of left forelimb lameness. Physical examination, laboratory analysis, and radiographic examination of the entire skeleton were performed. The radiographic diagnosis was bilateral radio-ulnar synostosis with secondary elbow malformation. A comparison between clinical and radiographic findings of the cat and those described in children affected by radio-ulnar synostosis is reported. Correlations and differences are discussed.     

Modified hardwood sawdust as adsorbent of heavy metal ions from water

The sawdust of oak and black locust hardwood was found to have good adsorption capacities for heavy metal ions. The leaching of coloured organic matters during the adsorption can be prevented by each of the following pre-treatments of adsorbents: with formaldehyde in acidic medium, with sodium hydroxide solution after formaldehyde treatment, or with sodium hydroxide only. The studies indicated that the leaching of coloured matters from modified hardwood sawdust was less than that from unmodified hardwood sawdust, namely between 70 and 94%, dependent on wood species and the method of modification. At the same time, adsorption capacities of modified adsorbents were higher than unmodified adsorbents when sodium hydroxide was applied for modification. When formaldehyde was applied for modification, the adsorption capacities of adsorbents remained unchanged. Only the application of sodium hydroxide was recommended for modification of hardwood sawdust.     

Effect of fluoride pollution on genetic variability of <Emphasis Type="Italic">Larix gmelinii</Emphasis> (Pinaceae) in East Siberia

The genetic variability of four natural populations of Larix gmelinii from East Siberia was determined and compared by RAPD analysis. Comparison of the RAPD profiles provided an estimation of variability in 193 RAPD fragments. More than 89% of these fragments were found to be polymorphic. The main genetic variability parameters of the two populations from Central Yakutia, a region free of fluoride pollution, had considerably higher values than those from East Transbaikalia, a region potentially affected by fluoride pollution (FLU, near a fluorite quarry growing on soils with a high natural content of fluorides). AMOVA revealed that 72.94% of the variation was within populations, while only 7.05% of the variation was between populations within geographical regions. The genetic diversity of the FLU fluoride-tolerant population was the lowest, but only slightly lower than that of a fluoride non-tolerant population from Chita, 50 km distant from FLU. Although this study demonstrates the absence of fundamental alterations of genetic structure within the populations of L. gmelinii growing on soils with a high content of fluorides, it is presumed that the reduction of genetic diversity was the genetic response of the FLU population to such an environmental stress as a constantly high concentration of fluorides within the soil.