Effects of entrance design on catch efficiency of arabesque greenling traps: a field experiment in Matsumae, Hokkaido

ABSTRACT:   A field experiment was conducted in the Matsumae area of Hokkaido, Japan, during June and July 2002, to investigate the effects of different entrance designs on the catch efficiency of fish traps by fishing with commercial traps (entrance inclination angle [α] = 37°; funnel length of entrance [ L _f ] = 22 cm) and experimental traps. The experimental traps were of the same size and similar design as commercial traps, with different entrance inclination angles (trap E1: α = 46°; E2: α = 27°; E3: α = 0°; all L _f  = 22 cm) or funnel lengths (E4: α = 37°, L _f  = 8 cm). In total, 2200 fish during 200 trap hauls were captured. The catch was significantly higher using both traps E2 and the commercial trap than with trap E3 ( P  < 0.05), and the catch of trap E2 was higher than that of the commercial trap. There were no significant differences in mean fish body length or the frequency distributions of body length among trap types (E1, E2, E3 and commercial). The funnel length of the entrance also affected the catch of traps. Trap E4 had significantly higher catches than the commercial trap ( P  = 0.04) when traps were deployed for a 1-day soak time. Fish body length frequency distributions did not differ between trap E4 and the commercial trap. The results showed that catch can be greatly affected by trap entrance designs.     

不同腔长下调Q激光器输出脉冲特性研究

从Nd3+:YAG脉冲激光器调Q技术出发,研究了不同腔长条件下电光调Q激光器输出脉冲的宽度、能量和峰值功率特征,得到了不同腔长的调Q激光器输出脉冲特性曲线。研究结果表明,激光器腔长的改变能较好地调节脉冲的输出特性,对脉冲激光器的灵活应用具有一定的指导意义。     

Descriptive field symbols for inped soil macropores

Abstract

A short hand notation for depicting inped soil macropores is presented. By utilizing symbols for macropore diameter, facial shape, pore length, inped shape and pore orientation; it is possible to quickly portray inped field macropores. Circles, ellipses, and triangles of differing dimensions are used to symbolize round, elliptical, and irregular facial shaped pores of different diameters. The pore length and orientation are symbolized by line length and line direction. The inped shapes (spherical, tubular, and elongated) are respectively represented by one line, two parallel lines, or three parallel lines within or intersecting the pore shape symbols. Field application of this methodology saves time and is valuable when numerous inped pores need to be depicted.     

Morphological Basis of Resistance in Cotton to the WhiteflyBemisia Tabaci

The morphological basis of resistance to the whiteflyBemisia tabaci Genn. (Aleyrodidae: Hemiptera) was studied. The plant characters examined were leaf area, thickness of leaf lamina, hair density, hair length, angle of insertion of leaf hair, and density of gossypol glands. Hair density and leaf thickness were positively correlated with the population ofB. tabaci, and a positive correlation was obtained between the adult whitefly population and gossypol glands on stem internodes. Cotton genotype USA-22 (sparsely hairy) was found to be more tolerant toB. tabaci than was genotype USA-13 (velvety hairy). The use of thinner and glabrous leaved cotton varieties is suggested to minimize the whitefly menace in cotton.     

Association of aster yellows subgroup 16SrI-B phytoplasmas with a disease of Rehmannia glutinosa var. purpurea

A new phytoplasma disease of Rehmannia glutinosa var. purpurea was observed in the Czech Republic in 1998. Infected plants showing severely proliferating shoots, leaves reduced in size with vein clearing and chlorosis, shortened internodes and virescent petals died in advanced stages of the disease. Electron microscopy examination of the ultra-thin sections revealed the presence of numerous polymorphic bodies in phloem tissue of leaf midribs and petioles. The disease was successfully transmitted from infected plant via a dodder bridge into periwinkle ( Catharanthus roseus ). The phytoplasma aetiology of this disease was further confirmed by polymerase chain reaction (PCR) using universal primers R16F2/R16R2. Restriction fragment length polymorphism (RFLP) analysis of amplification products indicated the presence of aster yellows related phytoplasmas (16SrI-B) in naturally infected samples of R. glutinosa var . purpurea and in symptomatic periwinkle after dodder transmission of the agent. A comparison of the amplified sequence with 17 sequences available in the GenBank confirmed the classification of the phytoplasma in the subgroup 16SrI-B. This is the first report of natural occurrence of phytoplasma-associated disease in R. glutinosa var. purpurea.     

Interacting effects of temperature integration and light intensity on growth and development of single-stemmed cut rose plants

Energy conservation in horticulture can be achieved by allowing temperatures to fluctuate within predefined bandwidths instead of using rigid set points for heating and ventilation. In temperature integration, plants are supposed to compensate effects of temporarily deviations of the average temperature some time later by deviations in the opposite direction. However, little is still known on the effects of integration periods exceeding 1 day. In this study, effects of temperature integration on growth and development of single-stemmed cut rose plants were determined. Pruned rose shoots were placed in climate chambers in which light levels switched daily (2 days integration period) or weekly (14 days integration period) from high light intensity (300 μmol m⁻² s⁻¹) to low light (150 μmol m⁻² s⁻¹). Temperatures were kept continuously at 20 °C (control) or changed with the light intensity (phase, high temperature at high light intensity, low temperature at low light intensity) or changed opposite to the light intensity (counter phase). Bandwidths of temperature integration were 0, 6 or 10 °C. Under these conditions, buds grew out to harvestable shoots in approximately 45 days. At both integration periods, shoot length was significantly reduced with increasing bandwidths of temperature integration. Shoot dry weights were reduced when a bandwidth of 10 °C was applied. At both integration periods, rates of photosynthesis were primarily determined by light intensity. However, in the counter phase treatments, photosynthesis rate at high light and low temperature was reduced compared to the high light condition of the control. Under these conditions, starch content increased to approximately 10%, suggesting a feedback inhibition of the rate of photosynthesis. However, this did not (yet) affect plant growth or development.     

不同钠盐胁迫对高冰草种子萌发的影响

通过对高冰草种子在不同钠盐(NaCl、NaHCO3、Na2CO3)溶液中萌发情况的研究,旨在探明高冰草种子在不同盐胁迫下的萌发特性。结果表明:碱性盐(NaHCO3、Na2CO3)胁迫较中性盐(NaCl)胁迫显著降低了高冰草的发芽率。高冰草种子在NaCl浓度150mmol/L、NaHCO3浓度100mmol/L和Na2CO3浓度50mmol/L时萌发受到明显抑制。不同钠盐胁迫下高冰草种子胚根和胚芽的受抑制大小顺序为,中性盐NaCl胁迫:胚根<胚芽;碱性盐NaHCO3和Na2CO3胁迫:胚根>胚芽。     

坡长对径流及侵蚀的影响

张家口市水保试验站坡长小区五年观测资料表明,降雨强度影响径流量、侵蚀量随坡长的变化。降雨强度较小时,径流量不能用坡长与降雨强度的乘积代替,侵蚀量随坡长增加较慢。降雨强度较大时,径流量可用坡长与降雨强度的乘积代替,侵蚀量方程中坡长指数较大。     

莱芜猪肌肉组织学特性与肉质关系的研究

本研究采用二因子多水平有重复的试验方法,对１４头育肥莱芜猪不同屠宰体重及不同解剖部位肌肉的组织结构和肌纤维的组织学特性及肉质性状进行研究。结果表明：随屠宰体重的提高,肌肉纤维直径（ＤＭＦ）,密度（ＭＦＤ）和宰后僵直肌工降度（ＳＬ）没有发生显著变化（Ｐ〉０．０５）,组织学显示的肌肉３种构成分在不同体重组间差异也不显著,但除ｐＨ外,其他各测定性状在不同部位肌肉都存在极显著的差异（Ｐ〈０．０１）,研究下     

高等级公路测量基准面的确定及长度变形分析

分析了高等级公路平面控制网导线边投影长度变形与测区平均高程及投影带宽度的关系．根据长度变形是否满足国家标准GB50026－93要求（≤2．5cm／1km）而确定坐标系统．给出了不同坐标系统之间的换算关系．文中算例表明：用简单算法能达到公路工程测量的精度要求．