基于SHAW模型的内蒙古河套灌区秋浇节水灌溉制度

根据内蒙古河套灌区秋浇节水与土壤盐渍化防治的需要,利用SHAW模型模拟确定了不同盐渍化土壤合理的秋浇节水灌溉制度。结果表明：对于轻度盐渍化土壤,秋浇定额一般为142～183 mm,秋浇时间为9月28日－10月23日;对于中度盐渍化土壤,定额应该为180～200 mm,时间在10月14日－18日;对于重度盐渍化土壤,一般不种小麦,而种葵花等耐盐作物,定额为200～225 mm。因此,对于该灌区应该根据不同的土壤盐渍化程度,合理地安排秋浇。     

Phosphate absorption of intact komatsuna plants as influenced by phosphite

Phosphite (     ; Pi) uptake in cell suspension culture, information on how Phi affects the Pi uptake of intact plants remains to be determined. The present study was conducted to investigate the effect of Phi on Pi absorption of intact komatsuna plants ( Brassica rapa var. peruviridis cv. Ajisai) in hydroponic culture. Phosphite markedly decreased Pi absorption of the intact komatsuna plants under both low (0.05 mmol L⁻¹ ) and high (0.5 mmol L⁻¹) Pi supply, although the growth (both shoots and roots) and water uptake of the high Pi-supplied plants was not affected by Phi. The inhibiting effect of Phi was small at 0.2 mmol L⁻¹, but became large at 2 mmol L⁻¹. Using relatively large seedlings (28 days old) to better assess the influence of Phi on Pi absorption early in the treatment, the results indicated that there was an immediate decrease in Pi absorption within the first 2-day period of Phi treatment when the water absorption of the plants was not affected. Taken together, the results suggested that there was a strong inhibiting effect of Phi on Pi uptake of intact komatsuna plants and this effect is exerted most likely by competition between Phi and Pi at uptake level. We speculate that the application of Phi to plant roots in an environment that is unfavorable for Phi-to-Pi conversion (e.g. hydroponic culture) may need to increase the amount of required Pi fertilization of plants to compensate for the reduction in Pi uptake by Phi. Further research is needed to confirm our results.     

Genetic characterization of rabies viruses isolated from frugivorous bat (Artibeus spp.) in Brazil

In Latin America, rabies cases related to frugivorous bats have been reported since 1930's. Recently, two viruses isolated from Artibeus lituratus were proved to be vampire bat variants by monoclonal antibodies panels [2], but their genetic information is not well known. In this report, four rabies viruses were isolated from frugivorous bats (Artibeus spp.) in Brazil and their nucleoprotein gene sequences were determined. These isolates were found to be genotype 1 of lyssavirus and showed the maximum nucleotide sequence homology of 97.6-99.4% with vampire bat-related viruses in Brazil [6]. These results indicate that the Brazilian frugivorous bat rabies viruses in this study are closely related to vampire bat-related viruses that play a main role in rabies virus transmission to livestock in Brazil.     

Prevalence of dogs with intestinal parasites in Tochigi, Japan in 1979, 1991 and 2002

A total of 772 canine fecal specimens were collected in Tochigi in 1979, 1991 and 2001. The frequency of dogs that were kept indoor in 2002 (72.8%) was significantly higher than that for 1979 (21.2%, P < 0.001) and 1991 (40.6%, P < 0.01). The frequency of parasitized dogs in 2002 (18.8%) was significantly lower than that for 1979 (41.9%, P < 0.01). The findings of this study confirm the declining trend in Japan in the prevalence of helminth parasites in dogs, particularly Ancylostoma caninum and Trichuris vulpis. The reduction in the frequency of dogs with helminths may be mainly a result of the improvement in the environment and the routine use of filaricides.     

管道进口空气吸入的临界水深试验研究

制作1∶3比尺的大小水槽模型,试验研究了灌溉管道进口空气吸入的形式及临界水深与管道流速的关系,得出空气吸入的形式及临界水深与水槽内水流的紊动状态有关,且临界水深随流速的增加而增加的结论。相似性分析表明,临界水深在流速较小时大致符合0.2次方准则,而当流速较大时接近流速一致准则。此外,还根据试验结果对日本有关最小水深标准值进行了讨论     

Genetic variation in barley landraces from Bhutan

Summary In Bhutan, barley is usually grown in mountainous regions over 2,000 m elevation. The barleys investigated were six-rowed naked, and classified into three groups by spike and awn characters; lax spike and long awn, dense spike and long awn, and dense spike and elevated hood. They also varied in spike color; yellow, purple and black. For isozymes, there was no variation at Aat2 and Aat3 loci for aspartate aminotransferase in the Bhutanese barley.However, allelic variations at Est1, Est2 and Est4 loci for esterase were detected, and three genotypes consisting of their allelic combinations were found. Most of the collections were heterogeneous for these features. Combinations between spike-awn types and esterase genotypes were not at random, indicating that genetic diversities resulted from mechanical mixtures of different types. These types were distributed with geographical regularity in Bhutan. In comparing the spike-awn type and esterase genotype in barley collections from other regions of the Himalayas, the Bhutanese barleys were s-imilar to the Tibetan ones, but were much different from the Nepalese barleys. This suggests that the Bhutanese barleys had been introduced from Tibet.     

Soil-plant nutrition studies on tropical rice V. Yield components as affected by the timing of top-dressing of nitrogen in the Bangkhen paddy field

A number of factors may be involved in the effect of nitrogen top-dressing applied during the stage of panicle primordia development on yield components of rice plants, such as varietal difference, climate condition, and soil fertility.