Influence of Ammoniacal Copper Quaternary treatments on mechanical properties of blue-stained Lodgepole Pine wood

Three concentrations （2.8%, 2.0%, 1.2%） of Ammoniacal Copper Quaternary （ACQ） was selected to treat Lodgepole pine wood for evaluating ACQ treatment on mechanical properties of blue-stained wood. The bending modules of elasticity （MOE）, modules of rupture （MOR）, toughness and shearing strength parallel to grain on tangential surface, are tested according to the criteria GB1927-1943-91. Non-treated sample were also tested according to the same procedure. The results showed that the three groups specimen impregnated by different concentrations of ACQ solution met the AWPA standard 2003 of America （UC4A 6.4g/cm^3）. There were significant difference of toughness between treated wood and non-treated wood （p=0.01）, but there were no statistically significant differences among three concentrations in terms of toughness, and toughness of treated wood was approximately 20% lower than non-treated. MOR, MOE as well as sheafing strength parallel to grain were found to be not significantly different between treated wood and non-treated one, and there were no statistically significant difference among three concentrations of ACQ too. Toughness, MOR, MOE and sheafing strength parallel to grain increased with decrease of concentration of ACQ, but they were hardly affected by ACQ preservatives.     

对我国南方双季稻主产区粮食生产结构调整的思考

本文在区域比较优势分析的基础上,结合资源禀赋和市场需求,提出了一些新的粮食生产结构调整的建议.     

亚麻籽胶对面团流变性质的影响及其在面条加工中的应用

该文重点研究了添加亚麻籽胶对面粉的粉质特性、面团的流变性质以及面条品质的影响。粉质特性的结果表明,添加亚麻籽胶使面团的吸水率增加,面团的形成时间和稳定时间延长,弱化度降低,使面团的稳定性更好。动态流变性质和超微结构的显微观察表明,添加亚麻籽胶后,亚麻籽胶的网络结构加固了面筋蛋白的网络结构,因而面团的稳定时间和粘弹性均能提高。质构分析的结果表明,添加亚麻籽胶使面条烹煮后的硬度和咀嚼度提高,并具有较好的弹性和拉伸性能,面条的烹煮损失和面汤浊度降低,因而亚麻籽胶可用于面制品中以改善其食用品质。     

Farm Forestry Prospects Among Some Local Communities in Rachuonyo District,Kenya

Deforestation and degradation of productive lands are serious threats to the sustainability of forestry/agricultural practices in Kenya. In the last two decades farm forestry (FF) has been promoted through pilot projects among local communities as an example of sustainable land use. However adoption of FF is limited outside the project locations because FF improvement measures focused mainly on biological (e.g. succession, biodiversity and traditional industrial timber production) and technical concerns (e.g. material input delivery such as providing free tree seedlings for field planting) rather than local values, and interests and the constraints facing farmers. This study examined the local farm priorities and constraints and the prospects for the wider implementation of farm-level tree planting in four communities in Rachuonyo District. Using interviews with 597 randomly selected household heads, the study assessed farmer’s production assets and activities, land tenure, priority tree species and the constraints to growing trees on farms. Results show that farm labour is represented by a young population, 56.3% under the age of forty. They are mainly engaged in small-scale mixed cropping integrated with multipurpose trees and some livestock. Tree products contribute about 32% to household cash income, more than any other source (agricultural products, labour sales, etc). Females were more often household heads and had considerable influence over productive activities, making them an important target group in FF development. Farmers preferred exotic tree species due to their ability to provide short-term cash income, fuel and shade. Farmers’ concerns included population pressure on limited farmlands and the problem of credit for agricultural inputs. Given the feeling of secured tenure arrangement and influence of tree products on the household economy, farmers are likely to invest more in efficient land uses such as FF if consideration is given to local priorities.     

Using leaf tip necrosis as a phenotypic marker to predict the presence of durable rust resistance gene pair <Emphasis Type="Italic">Lr34</Emphasis>/<Emphasis Type="Italic">Yr18</Emphasis> in wheat

Fifty wheat varieties along with Jupateco-73 and Morocco were studied for the expression of leaf tip necrosis (LTN), a trait linked with the durable rust resistance gene pair Lr34/Yr18. LTN was frequent (i.e., ≥6) in nine replications of a field experiment over 3 years in 17 genotypes, and the varieties were considered positive for LTN. In molecular analyses of these varieties, having relative severity values up to 78 for yellow rust and 45 for leaf rust, the 150-bp Lr34/Yr18-linked allele was consistently amplified. Expression of LTN in six of nine replications is an appropriate threshold for predicting the presence of Lr34/Yr18 gene pair, and genotypes can be selected using this trait.     

不同保鲜处理对即食菠萝质量变化的影响

新鲜菠萝经机械削皮、去果眼、切分和清洗后用４种保鲜方法处理,分虽在４～５和１４～１５℃下贮存,并测定菠萝的呼吸强度、可溶性固形物和可滴定酸含量,菌落总数、大肠菌群、霉菌和酵母及致病菌,进同时行色、香、味和质地等的感官评定。试验结果表明,含０．２～０．４ｇ／１００ｍＬ食盐、８～１２ｇ／１００ｍＬ蔗糖和０．３～０．５ｇ／１００ｍＬ柠檬酸的溶液于６６～７５℃处理３～６ｍｉｎ能使菠萝的生命活动维持在较低水平,保持菠萝原有的新鲜状况,且产品的各项微生物指标均符合即食产品的卫生要求。产品贮存在１４～１５℃下７ｄ或４～４℃下１４ｄ均无明显的质量变化。据此提出了即食菠萝产品的质量指标和要求。     

菊属7个种的人工种间杂交试验

该文选择菊属（Ｄｅｎｄｒａｎｔｈｅｍａ（ＤＣ）ＤｅｓＭｏｕｌ．）７个野生种进行了正交设计的人工种间杂交试验，对各种间杂交结实率及杂种Ｆ１植株的形态变异进行了分析，研究结果表明：染色体倍性相同或相近的种间杂交结实率较高；毛华菊（Ｄ．ｖｅｓｔｉｔｕｍ）与野菊（Ｄ．ｉｎｄｉｃｕｍ）种间杂交较易成功，且能获得较多具明显形态变异的Ｆ１植株，而以紫花野菊（Ｄ．ｚａｗａｄｓｋｉｉ）为亲本的杂交组合结实率低且仅有较少具变异形态的杂种苗，此外，还对种间杂交在菊属植物进化中的作用进行了讨论，旨在为探讨菊花起源奠定基础。     

美洲黑杨基因资源收存及其遗传评价的研究

从１７个国家引进３３１个黑杨派无性系（其中５２个美洲黑杨无性系）,在山东省长清县营建我国第一个黑杨派无性系基因库。连续１０年对基因库内美洲黑杨无性系进行了多性状系统研究,结果表明各无性系间在物候期、生长、生根、抗寒和抗病虫等方面均存在着显著的差异,遗传变异丰富;系间的主要性状与无性系起源纬度及各性状间存在一定相关性。主要材料性状变异的研究结果表明,３８个８年生美洲黑杨无性系在木材基本密度、纤维长度无性系间变异达到极显著水平;木材密度和纤维长度与树高和胸径呈一定相关性;木材密度和纤维长度这两个性状在遗传上相互独立,受不同遗传机制控制。利用分子遗传标记ＲＡＰＤ技术研究库内美洲黑杨无性系ＤＮＡ多态性,结果表明本库美洲黑杨ＤＮＡ多态率为８６％,再次证明本库美洲黑杨遗传多样性高,可为我国杨树改良提供丰富的育种材料。     

沙棘木蠹蛾蛹的发育起点温度和有效积温研究

通过室外变温和室内恒温 2种不同的方法对沙棘木蠹蛾蛹的有效积温和发育起点温度进行了测定 ,结果表明 :变温条件下蛹的发育起点温度为 15.4 81°C,有效积温为 2 0 2 .356± 13.0 57日度 ;恒温条件下蛹的发育起点温度为 12 .0 55°C,有效积温为 2 95.2 0 3± 4 .0 94日度。蛹发育的最适温度为 2 1°C