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。     

Response of Maize and Cowpea Grown Sequentially to Application of Phosphate Rock in the Humid Tropics

Field trials were conducted at the Institute of Agricultural Research and Training Ibadan in 2000 and 2001 cropping seasons to evaluate the efficiency of some phosphorus (P) sources, rates, and frequency of application on grain yields of maize and cowpea grown sequentially. The experiment was laid out in a split–split plot arrangement using randomized complete block design, with three replications. The main plot was frequency of fertilizer application (seasonal and annual). Source of P [single superphosphate (SSP: 18% P₂O₅)]; Ogun rock phosphate (OPR: 20.21% P₂O₅), and crystallizer super (CS: 31.4% P₂O₅) constituted the subplots. The P rates (0, 20, 40, and 60 kg P ha^?1) were the sub-subplots. An early maize cropping followed by a late-season cowpea was the sequential cropping, while an early maize followed by a late-season maize was the continuous cropping. The croppings were repeated the second year. Frequency of P application and source of P were significantly different while rates of application were not. Maize and cowpea grain yields from the control treatment were significantly less than yields from P-treated plots. Maize grain yields were slightly greater in plots alternated with cowpea, compared to continuous maize. Relative agronomic efficiency (RAE) values of OPR and CS were 67% and 75%, respectively, in annual application and 140% and 134% in seasonal applications, respectively, in 2000. In 2001, the trend was almost similar to 2000 except that there was a decline in RAE values of cowpea. Each Naira invested in the annual application returned about ?3.12 while about ?2.13 was returned with the seasonal application (?125.00 is the equivalent of USD$1.00). The OPR and CS can serve as alternatives to water-soluble sources such as SSP.     

几种苹果矮化砧木的抗寒性研究

以71-3-150、GM256、SH6及M9 4种苹果(Malus)矮化砧木的1年生枝条为试材,进行-20℃、-25℃、-30℃、-35℃、-40℃低温处理,用电导法配合Logistic方程,求得拐点温度(LT50)即半致死温度,并对其电导率、可溶性蛋白含量和POD酶活性等指标进行了测定比较。结果表明:测得的电解质渗出率呈典型的S型曲线,与相应的低温呈极显著负相关;71-3-150、GM256、SH6及M9的半致死温度分别为-40.63℃、-39.29℃、-34.10℃、-30.10℃;抗寒性强的71-3-150和GM256能保持较高的可溶性蛋白含量和POD酶活性。     

Developmental Dynamics and Early Growth Vigour in Rice. I. Relationship Between Development Rate (1/Phyllochron) and Growth

Achieving early vigour, that is, rapid dry matter accumulation, is a priority in rice crop improvement, but this trait is complex and not well understood genetically and physiologically. This study tested the hypothesis that the development rate (DR) contributes to early vigour. Two diversity panels were phenotyped during vegetative stage for traits constituting early vigour (shoot dry weight, SDW; relative growth rate, RGR) or contributing to early vigour (tillering, leaf size, DR). The first panel comprised 169 genotypes from all major genetic groups of Oryza sativa and was phenotyped under irrigated upland conditions in the field (Philippines, Exp1). The second panel with 190 genotypes representing the diversity of the tropical japonica group was phenotyped in pots in a greenhouse (Montpellier, France, Exp2). Results from field and pot experiment pointed out that DR, tillering and leaf size were positively correlated with RGR and SDW, although the contribution of leaf size was small. DR was positively correlated with tillering but both were negatively correlated with leaf size. DR vs. RGR correlation was conserved in subsets of genotypes with similar leaf size and tillering, suggesting an effect of DR on RGR independent of the other traits. DR is a promising, still underexploited trait contributing to rice early vigour, requiring further genetic and physiological characterization.     

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.     

高效凝胶过滤色谱法测定肽的相对分子量分布

采用高效凝胶过滤色谱法,对肽粉、酵母核苷酸和自溶酵母粉三种肽类产品的相对分子量大小及分布进行了测定。结果表明,此三种产品的相对分子量分布范围集中在2000Da以下,寡肽含量丰富,其中含有一定量的游离氨基酸和氨基酸残基。该方法简便快捷、准确性高、重复性好,适合肽类产品分子量(<1 0KD)分布的分析检测。     

妊娠早期蒙古绵羊子宫内膜enJSRV及IFN-τ基因表达水平的分析

本研究旨在检测内源性绵羊肺腺瘤反转录病毒(enJSRV)与干扰素-τ(IFN-τ)在妊娠早期蒙古绵羊子宫内膜组织的表达以及enJSRV的表达与外周血孕酮水平变化的关系。运用TaqMan实时荧光定量PCR技术和电化学发光法对enJSRV和IFN-τ在妊娠早期蒙古绵羊子宫内膜组织相对表达及孕酮水平进行了测定。实时荧光定量PCR结果显示,enJSRV和IFN-τmRNA在妊娠早期绵羊子宫内膜组织有不同程度的表达。SAS统计学软件分析得出,子宫内膜组织中enJSRV mRNA在妊娠12～14d(交配日为0d)表达较高,2～10、16～30d的表达均低于前者。IFN-τmRNA仅在妊娠12～25d表达,14d达其峰值,30d就不能检出,且差异都极显著(P<0.01)。电化学发光法结果显示,孕酮水平在妊娠2d为0.4ng·mL-1,以后升高,妊娠8～16d维持在8.3ng·mL-1左右,在妊娠19～30d孕酮水平有所下降,30d为2.5ng·mL-1。以上结果提示,子宫内膜组织中enJSRV mRNA的表达与外周血孕酮含量及IFN-τ的变化高度相关,且enJSRV在胎盘的形态发生及生殖生物学方面发挥重要作用。     

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.     

Simulation of pressure caused by multiplication and swelling of Erwinia amylovora in intercellular space of host tissue

WhenErwinia amylovora grows, in an intercellular space of a host, and fills this space, further multiplication or swelling may create a pressure, and may cause tearing of host tissue. Theoretically, this bacterial pressure equals the actual water potential of the host tissue minus the water potential at which the bacterial biomass would completely fill the intercellular space, but without exerting pressure.Simulation runs indicate that, when the pressure increases, the extracellular slime ofE. amylovora shrinks by releasing water, thus allowing further production of bacterial dry matter. The slime remains around the bacterial cells as a dense substance, low in water content, having a strong capacity to swell when the pressure induces tearing apart of the host tissue. Simulation runs show that the pressure attains its highest values at evening and night.Some fire blight symptoms that illustrate the evidence of bacterial pressure are discussed.     

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.