光合细菌在虾病防治中的作用研究

本文着重研究光合细菌(PSB)在虾病防治中的作用,结果表明:对虾养殖池施用光合细菌后,随PSB浓度的增加水质、底泥中弧菌和异养细菌数量而逐渐减少,表明了PSB具有调节和改善养殖的微生态环境的作用。PSB还能降低底泥中的有机质和硫化物含量,降低COD含量,并提高养殖水体的溶解氧,改善水生环境。本文还分析了PSB在长毛对虾幼体培育中的应用效果,光合细菌的营养通过食物链的传递,促进对虾生长,增强对虾抗病能力,降低发病率和死亡率。     

Aesthetic preferences of non-farmers and farmers for different land-use types and proportions of ecological compensation areas in the Swiss lowlands

Beyond its traditional function of food production, agricultural land offers public amenities such as the protection of natural resources and landscape scenery. This study investigates the preferences of non-farmers and farmers for nine landscape scenarios in the Swiss lowlands. The nine landscapes were the result of a photo editing process combining three land-use types (arable crops, grassland and a mixture of both) and three proportions of ecological compensation areas (0%, 10% and 30%). The landscape photographs were randomly arranged on one page of a paper-based questionnaire which was sent to a random sample of 4000 Swiss households (non-farmers) and 500 farmers. The respondents (1376 non-farmers and 276 farmers) rated each landscape by attractiveness. Both non-farmers and farmers preferred a mixed land-use type or one dominated by arable crops over one dominated by grassland. Non-farmers’ preference ratings were highly influenced by the proportion of ecological compensation areas (ECAs) in the rated landscape: Non-farmers rated a landscape with a mixed land-use type and 30% ECAs highest, whereas farmers rated a landscape dominated by arable crops and 10% ECAs highest. The results indicate that heterogeneous landscapes (mixed land use, high proportion of ECAs) influence scenic beauty positively. Thus, farming practices and agro-environment schemes such as ECAs can have an impact on the visual attractiveness of a landscape.     

Are meadows with high ecological and patrimonial value endangered by heathland invasion in the French central Pyrenees?

Due to their high ecological and patrimonial value Festuca eskia and Nardus stricta meadows and Rhododendron ferrugineum heathlands need to be locally preserved in the Pyrenees. This could pose dilemmas to conservation managers if heathlands invade and replace the meadows. However, studies showing that the heathlands do actually invade meadows are lacking in the Pyrenees and the invasion hypothesis therefore remains to be proved. So, vegetation pattern changes in a particularly vulnerable site from the central Pyrenees was investigated by two means: (i) interpretation of stereo pairs of aerial photographs and (ii) analysis of the demography of Rhododendron populations in ten 150 m² experimental plots. The main results from photo interpretation indicated that, during the period between 1954 and 1995, 15% of a 17 ha meadow area shifted to heathland. This corresponded with a 592 m² year⁻¹ colonization rate and to an overall front progression of heathland over meadows of 3-60 m. Demographic data showed that meadow colonization by heathland passed through successive phases but appeared to be a rather slow process that can take as long as 120-320 years. During the process the cover rate over the 150 m² plots varied between 1 and 0.4 m² year⁻¹. Heathland extension does not seem to have been favored by the decrease in grazing pressure. Despite this, the progression of heathlands over meadows seems endangering the meadows. Finally we propose practices locally to limit the progression of Rhododendron.     

螺旋藻工厂化培养条件优化及营养成分比较

[目的]对螺旋藻工厂化的培养条件进行优化,并对其营养成分的含量进行比较。[方法]在以采光板作顶棚的封闭式车间内,采用4种不同直径的光生物反应器对春季螺旋藻进行培养,并对不同直径的光生物反应器所能达到的最大细胞密度及各种主要营养成分的含量进行比较。[结果]在20 cm的光生物反应器所能达到的最大细胞密度最大,为1.52 g/L。20 cm的光生物反应器培养的螺旋藻所含蛋白质和藻蓝蛋白含量最高;蛋白质含量最高可以达到61.2%,藻蓝蛋白含量最高可以达到10.9%。10 cm的光生物反应器培养的螺旋藻所含的粗脂肪、多糖和叶绿素a的含量最高、粗脂肪的含量最高可以达到7.48%,多糖最高可以达到8.2%,叶绿素a可以达到1.3 mg/g。[结论]该方法优化了螺旋藻工厂化的培养条件,为螺旋藻的开发利用提供了理论依据。     

小麦温光敏核不育系的育性提纯研究

最大限度控制育性的遗传漂移 ,是小麦温光敏核不育系提纯中要解决的主要问题。本研究通过对小麦温光敏核不育系 C4 9S- 87进行连续三年五代的育性提纯 ,初步建立了一套株系选择与冬、夏播育性连续鉴定相结合的不育系育性提纯方法 ,并获得了保持原不育系生物学特性、株间育性差异更小、完全不育株率和不育度均显著提高的 3个株系。本文还对育性遗传漂移的产生原因及控制对策进行了探讨     

旋LED照明应用

LED照明市场前景广大,在装饰照明、汽车照明、交通信号灯等方面都有巨大的潜力。作为一项全新的照明技术,LED因其节能、环保、寿命长、启动快等特点被普遍看好,并将逐步取代传统的照明。     

大豆光钝感种质创新与光周期育种途径的研究

通过选育光钝感品种来扩大品种种植区域.按着杜维广(1997)年选育广适应性种质程序和方法的设想,通过改进选育光钝感、具有良好综合农艺性状新种质NPSL-1和NPSL-2佐证了该设想的可靠性,并依据本试验结果提出大豆光周期育种途径.     

密度对不同株型玉米群体结构的调控效应

不同供试品种的茎叶夹角与株型特征密切相关,随着株型紧凑型增强,该参数值增大;在生育后期,不同株型玉米品种LAI各密度下大体表现为GY115较高,ND108次之,ZD958较低。随着密度增加,各品种LAI增大,紧凑型ZD958植株下位叶片的衰老速率相对减慢。供试品种群体中、下部1 d内各测定时期光截获的数量随密度增加明显减少,不同株型品种相比减小的幅度依数值大小依次为GY115,ND108和ZD958。随密度增大单株干物重降低,但以ZD958降低幅度较小,ND108次之,GY115较大。不同株型品种产量对密度的反应不同,获得高产的适宜密度存在明显差异。     

图书馆数码照片档案管理探究——以吉林省图书馆为例

随着数码相机成为吉林省图书馆各业务部门记录各类活动的拍摄主体后,为数众多的数码照片如何保存和利用成为一大问题。作者结合工作实际,以吉林省图书馆照片数据库建设为例,对数码照片的收集整理和后期管理提出了几点想法。     

育性敏感期低温对水稻光温敏不育系生理指标的影响

利用生产上常用的5个水稻光温敏不育系材料,在育性敏感期置于人工气候室内进行低温处理,分析低温对供试材料生理指标的影响以及耐冷性差异与生理指标变化之间的联系。低温设置为17.5℃、10 d,对照为21℃、10 d的可育温度,考察处理5,10 d以及返回大田生长5 d时的生理变化指标。结果表明,相比不耐冷的不育系,耐冷型不育系在低温处理前期SPAD值与对照相比变化不显著,SOD、POD活性略有增强,MDA含量、相对电导率有所增加;随着处理时间的延长,SPAD值、Pn值、Tr值、SOD、POD活性均开始下降,但下降幅度较不耐冷的小,MDA含量、相对电导率的持续增加也要慢于不耐冷不育系。