Research on the inheritance of fasciation in lettuce (Lactuca sativa L.)

Summary Inheritance of fasciation was investigated in reciprocal crosses between two lettuce varieties: Suzan (non-fasciated) and Noran (fasciated). In glasshouses parental plants, F₁, F₂, and F₃ populations were assessed for fasciation according to a scale from 0 (non-fasciated)-9 (extremely fasciated).The observed environmental variation for fasciation of the homozygous parents was very low or absent, but the environmental variation for the F₁ populations was large. On the basis of this large variation of the heterozygous F₁ plants we supposed that such a variation also occurred in F₂ and F₃ populations.Considerable mortality was observed in all generations, which supposedly occurred at random in parents and F₁ but was non-random in the segregating F₂ and F₃ populations. So, means and variances of F₂ populations will be biased and therefore they were not used for genetical analyses of fasciation.From F₁ and F₃ populations and from some F₂ populations it appeared that no differences occurred between reciprocals. The differences for fasciation between reciprocal F₂ populations in the 1977 A experiment may result from non-random plant survival. A regression of F₃-means on the values for fasciation of parental F₂ plants, adjusted for their inbreeding, resulted in a realized h²-narrow of 0.4. This indicates that in the surviving plants of the F₂ populations still additive genetic variation was present to select successfully for non-fasciated plants.     

Analysis of generation means and components of variance for parthenocarpy in cucumber (Cucumis sativus L.)

Parthenocarpy (seedless fruit) has potential for increasing yield in cucumber (Cucumis sativus var. sativus L.). To determine the inheritance of parthenocarpy in gynoecious cucumber, P₁, P₂, F₁, F₂, BC₁P₁, and BC₁P₂ generations derived from crossing two non‐parthenocarpic gynoecious inbred lines [Gy8 (P₂; processing type) and ‘Marketmore 80’ (P₂; MM, fresh market type)] with a highly parthenocarpic inbred line [2A (P₁; processing type)] were evaluated for fruit number in a greenhouse at Arlington, Wisc. in 1999 (designated 2A × Gy8 1999) and in the open‐field at Hancock, Wisc. in 2000 (designated 2A × Gy8 2000 and 2A × MM 2000). There were significant location and location × generation interaction effects, and therefore generation means analyses were conducted separately for each location. The minimum numbers of effective factors controlling parthenocarpy were estimated to be at least one (2A × Gy8 1999), two (2A × Gy8 2000) and four (2A × MM 2000). Results suggest that selection for parthenocarpy for multiple hand harvest operations will likely be more effective than that for once‐over machine harvest operations. However, the selection efficiency will likely vary across different populations and environments.     

The inheritance of resistance to head blight caused by Fusarium culmorum in winter wheat

Summary Crosses were made among ten winter wheat genotypes representing different levels of resistance to Fusarium head blight to obtain F₁ and F₂ generations. Parents, F₁ and F₂ were inoculated with one strain of Fusarium culmorum. Data on incidence of head blight 21 days after first inoculation were analyzed. Broad-sense heritabilities averaged 0.39 and ranged from 0.05 to 0.89 in the individual F₂ families. The joint-scaling test indicated that the inheritance of Fusarium head blight resistance was adequately described by the additive-dominance model, with additive gene action being the most important factor of resistance. With respect to the non-additive effects, dominance of resistance predominated over recessiveness. The number of segregating genes governing resistance in the studied populations was estimated to vary between one and six. It was demonstrated that resistance genes differed between parents and affected resistance differently.     

Inheritance of Carbon Isotope Discrimination in Bread Wheat (Triticum Aestivum L.)

Summary Reliable selection of families with increased grain yield is difficult in breeding programs targeting water-limited environments. Carbon isotope discrimination (Δ) is negatively correlated with transpiration efficiency, and low Δ is being used for indirect selection of high wheat yield in rainfed environments. Yet little is known of genetic control and opportunities for improving selection efficiency of Δ in wheat. Half-diallel and generation means mating designs were undertaken to provide estimates of the size and nature of gene action for Δ in a range of wheat genotypes varying for this trait. Significant (P < 0.01) differences were observed for leaf tissue Δ among parents (19.3 to 20.7‰) and F₁ progeny (19.4 to 20.9‰) in the half-diallel. General (GCA) and specific combining ability (SCA) effects were significant (P < 0.05), while Baker's GCA/SCA variance ratio of 0.89 was close to unity, indicating largely additive gene effects. GCA effects varied from −0.38 to + 0.34‰ for low and high Δ genotypes `Quarrion' and `Gutha', respectively. GCA effects and parental means were strongly correlated (r = 0.95, P < 0.01) while directional dominance and epistasis contributed to small, non-additive gene action for Δ. Smaller Δ in F₁ progeny was associated with accumulation of recessive alleles from the low Δ parent. Narrow-sense heritability was high (0.86) on a single-plant basis. Generation means analysis was undertaken on crosses between low Δ genotype Quarrion and two higher Δ genotypes `Genaro M81' and `Hartog'. The F₁, F₂ and midparent means were not statistically (P > 0.05) different, whereas backcrossing significantly changed Δ toward the mean of the recurrent parent. Gene action was largely additive with evidence for additive × additive epistasis in one cross. Narrow-sense heritabilities were moderate in size (0.29 to 0.43) on a single-plant basis. Genetic gain for Δ in wheat should be readily achieved in selection among inbred or partially inbred families during the later stages of population development.     

Generation means analysis of plant architectural traits and fruit yield in melon

Unique architectural phenotypes have the potential for increasing yield in commercial melon (Cucumis melo L.). Therefore, a generation means analysis was conducted to investigate the inheritance of architectural traits (days to anthesis, primary branch number, fruit number and weight, and average weight per fruit). Progeny (F₁, F₂, BC₁P₁ and BC₁P₂) from a cross between US Department of Agriculture (USDA) line, USDA 846‐1 (P₁) and ‘TopMark’ (P₂) were evaluated at Arlington (AR) and Hancock (HCK), Wisconsin in 2001. Significant (P ≤ 0.05) environment effects and genotype × environment interactions (G × E) analyses necessitated analysis by location. Significant differences (P ≤ 0.05) among parents and generations were observed for all traits, and the two parental lines differed significantly for primary branch number, fruit number and average weight per fruit. Additive gene effects were most important in governing primary branch number and fruit number per plant, while dominance and epistatic genetic effects mainly controlled days to anthesis, fruit weight per plant and average weight per fruit. Narrow‐sense heritabilities were 0.62 (AR) for days to anthesis, 0.71 (AR) and 0.76 (HCK) for primary branch number, 0.68 (AR) and 0.70 (HCK) for fruit weight per plant, 0.33 (AR) and 0.45 (HCK) for fruit weight per plant, and 0.06 (AR) and 0.79 (HCK) for average weight per fruit. Estimations of the least number of effective factors for primary branch number were relatively consistent at both AR (approx. 4) and HCK (approx. 2). Results suggest that introgression of yield‐related genes from highly branched melon types (e.g. USDA 846‐1) into US Western Shipping germplasm may aid in the development of high‐yielding cultivars with concentrated fruit set suitable for machine and/or hand‐harvesting operations.     

红豆杉属植物的化学成分及药理作用研究进展

红豆杉属植物是提取抗癌新药物紫杉醇(Taxol)的原料植物。本文综述了国产红豆杉属植物的种类及分布、化学成分研究、药理作用及临床应用等方面的研究,并提出了存在的问题及今后发展的方向。     

Evaluation of the adequacy of diflubenzuron and dechlorane in toxic baits for leaf-cutting ants (Hymenoptera: Formicidae) based on formicidal activity

Studies assessing the characteristics of active ingredients (AIs) of toxic baits for leaf-cutting ants are still scarce, although the need for a delayed action of these compounds on adult workers has been well accepted (mortality ≤15% at 24 h and ≥90% at 21 days). Therefore, we determined the insecticidal action of two AIs used in commercial baits, diflubenzuron and dechlorane, over time in workers, and discussed the control of colonies in relation to the existing literature. Dechlorane presented excellent insecticidal activity with a delayed action at all concentrations tested, although its commercial use has been prohibited due to its organochlorine nature. In contrast, diflubenzuron did not cause significant mortality or symptoms of intoxication, indicating that the successful cases reported with the use of baits containing this AI were in fact due to an accidental contamination with dechlorane. We comment about the ineffectiveness of diflubenzuron on alternative targets, i.e., young forms and the mutualistic fungus, supporting the concept that the AI needs to a have a delayed action on adult workers.     

Conflicts management,social capital and adoption of agroforestry technologies: empirical findings from the highlands of southwestern Uganda

In the highland ecosystems where actions by some individuals or groups often generate off-site effects among a wide range of social actors and stakeholders, the use and management of natural resources are susceptible to multiple forms of conflicts. This paper examines the hypothesis that conflicts constrain the adoption of agroforestry technologies. Using empirical data from 243 households in Kabale-Uganda, the study identified over 780 different cases of conflicts, and found positive relationships between certain types of conflicts and adoption of agroforestry technologies. The results of this paper challenge the conventional wisdom that conflicts are pervasive, and that the prevalence of conflicts is a major barrier to the adoption of NRM technologies. On the contrary, they seem to suggest that conflicts may have some positive outcomes; they provide incentives for the adoption of NRM technologies, and can be a potential force for positive social change. Conflicts are an essential feature of NRM in the highland systems and cannot therefore be ignored. What matters is the ways such conflicts are managed and resolved, and transformed into a force for positive change. We found that three dimensions of social capital (collective action, byelaws implementation and linking with local government structures) have increased the ability of communities to manage and transform conflicts into opportunities for collective action. These findings suggest new areas for further investigation to improve understanding of adoption decisions and building local capacity for scaling up the impacts of agroforestry innovations.     

超声波提取中药有效成分及竹醋液的抑菌活性研究

研究了超声波在中药有效成分提取中的频率、时间和中药剂量的使用对抑茵效果影响；以灰霉菌为供试茵，通过抑茵实验来进行验证，证明超声波作用于药物提取具有提取率高、可靠性强、操作简便、大大缩短提取时间等优点；与传统超声波提取中药相比，使用竹醋液为溶剂提取中药进行抑茵，可以不用将其分离，从而节省了大量的人力、物力；确定以竹醋液与中药丁香、苦豆子、高良姜、黄连等辅配，然后用超声波提取这些中药的有效成份。结果表明：竹醋液不仅本身有很强的抑茵作用，而且分别与丁香、高良姜、黄连辅配，用超声波提取后能够产生明显的增效作用。     

金钗石斛的研究及在西双版纳仿野生栽培简况

简述了近年来在金钗石斛的性状、药理作用、化学成分、组培快繁和栽培试验方面的研究工作及在西双版纳的仿野生栽培概况。