低盐水体南美白对虾与鲢鳙鱼混养的试验

在6口低盐淡水(盐度2～10)池塘中放养体长0 8～1 0cm的南美白对虾(Penaeusvan namei)(30万尾/hm2),其中三口塘再放养鲢(Hypophthalmichthysmolitrix)、鳙(Aristichthysno bilis)夏花(体长2 0～3 0cm)(1500尾/hm2,鲢:鳙=1:1)。鱼、虾分别精养90d和60d。混养池塘中对虾的成活率(24 6%)为单养池(9 1%)的2 7倍,产量(800 0±86 7)kg/hm2为单养池的3 2倍;鱼产量为(93 9±7 9)kg/hm2,鳙的出塘规格大于鲢,产量高于鲢。混养池塘水中氨氮、亚硝态氮和溶解氧含量低;透明度和活性磷含量高;pH值波动幅度小。     

采用白腐菌对难降解有机污染物的生物净化

白腐菌对难降解污染物的生物降解作用已引起世界范围内的普遍关注，它可通过其分泌的特殊的降解酶系或其他机制将各种难降解的有机污染物彻底降解为CO₂和H₂O。该文介绍了白腐真菌的生物学特性及其分泌的酶系，阐述了白腐菌所分泌的酶在降解各种难降解有机物中的作用机制，分析了提高白腐菌降解能力的方法，总结了白腐菌在治理环境污染方面的应用现状与研究进展，探讨了白腐菌在实际应用方面的不足以及今后的研究方向，对白腐菌在解决环境污染方面的问题具有实际意义。     

高密度二氧化碳对蛋清液中沙门氏菌和大肠杆菌杀菌效果和杀菌动力学的研究

研究了不同温度、压力和时间条件下,高密度二氧化碳(DPCD)处理对蛋清液中沙门氏菌和大肠杆菌的杀菌效果,并对DPCD处理蛋清液中大肠杆菌的杀菌动力学进行了分析。结果表明,在15 MPa,45℃下DPCD处理60 min,沙门氏菌和大肠杆菌分别降低了4.46和5.57个对数值,其中大肠杆菌对DPCD处理较沙门氏菌敏感。30 MPa,45℃,DPCD处理30 min,可以完全杀灭蛋清液中的大肠杆菌。线性模型能较好地拟合DPCD对大肠杆菌的杀菌效果,其中30 MPa,45℃下D值最小为5.830。     

Genetic variation in a Norwegian germplasm collection of white clover (Trifolium repens L.)

Phenotypic (r_p), genotypic (r_g), genotype × location (r_gl) and error (r_e)correlations for important agronomic characters were estimated for eleven Norwegian populations of white clover (Trifolium repens L.), originating from between 58^°52′N and 69^°30′N latitude, and from altitudes of 10 to 450 m a.s.l. The populations were evaluated in monoculture clonal field plots for two years at two locations in Norway. All pairwise correlations between foliage height, leaflet length, dry matter yield (DMY) and general performance were positive and significant. Winter survival was positively correlated with general performance, spring growth and DMY, but negatively associated with internode length, while seed yield showed a small positive genotypic correlation with foliage height. Considerable differences were, however, revealed among populations with regard to sign and magnitude of the estimated correlations. Within-population estimates of r_g were consistently positive between DMY, general performance and most other characters; between foliage height on the one hand and leaflet length, winter survival and seed yield on the other hand, and between internode length and leaflet length, indicating pleiotropy. Correlations involving other character-combinations varied substantially among populations, and imply presence of linkage and/or coadaptation. Path coefficient analysis was used to partition the genotypic correlations between some of the characters into direct and indirect effects. Path coefficients revealed that foliage height had the highest positive direct effect on DMY, followed by winter survival and internode length. Leaflet length, which showed a positive, significant simple correlation with DMY, exhibited a negligible direct influence, counterbalanced nearly completely by the positive indirect effect on DMY via foliage height. Positive indirect effects on DMY via foliage height were also found for winter survival and internode length. The coastal populations from North and Middle Norway, and a southern highland population showed the largest expected responses to phenotypic selection for most of the characters. The results demonstrate that there is enough genetic variation in adapted local populations to develop new improved cultivars adapted to high-latitude environments that combine upright growth habit with sufficient winter-hardiness and persistency. This revised version was published online in July 2006 with corrections to the Cover Date.     

Competition of infectious hypodermal and haematopoietic necrosis virus (IHHNV) with white spot syndrome virus (WSSV) for binding to shrimp cellular membrane

Infectious hypodermal and haematopoietic necrosis virus (IHHNV) and white spot syndrome virus (WSSV) are two widespread shrimp viruses. The interference of IHHNV on WSSV was the first reported case of viral interference that involved crustacean viruses and has been subsequently confirmed. However, the mechanisms underlying the induction of WSSV resistance through IHHNV infection are practically unknown. In this study, the interference mechanisms between IHHNV and WSSV were studied using a competitive ELISA. The binding of WSSV and IHHNV to cellular membrane of Litopenaeus vannamei was examined. The results suggested that there existed a mutual competition between IHHNV and WSSV for binding to receptors present on cellular membrane of L. vannamei and that the inhibitory effects of WSSV towards IHHNV were more distinct than those of IHHNV towards WSSV.     

无机磷溶解菌RW8的筛选、鉴定及对白三叶促生效果研究

从白三叶根际分离筛选9株溶磷微生物,并对挑选菌株进行形态、细胞以及种属鉴定,并分析其对白三叶的促生效果。通过分析溶磷圈与溶磷菌落直径的大小与比值获得溶磷量与持续溶磷能力较强的RW8菌株。通过形态与扫描电镜观察发现RW8是具有鞭毛的短杆菌,其菌落形态表面光滑,不透明;将RW8 16S rDNA序列比对NCBI数据库发现其与阴沟肠杆菌属(Enterobacter sp.)的同源性高达99.5%,Biolog鉴定其与阴沟肠杆菌(Enterobacter cloacae ss dissolvens)的相似性为0.610。RW8溶磷量达424.85 μg/mL,溶磷能力可能与RW8的产酸性能(12.30 μg/mL)密切相关。RW8对白三叶根系与幼苗的生物产量的分配有显著影响,接种RW8后能抑制白三叶根系伸长,根系鲜重与干重有下降趋势,但差异不显著;而幼苗的生物产量(干重与鲜重)均显著高于对照(P<0.05),并且该现象与植物生长激素IAA无关,其具体的作用机制还有待于进一步研究。     

景宁县白茶品系性状品质比较研究

白茶是我国特有的茶树品种资源。通过对景宁白茶6个品系性状特征观测比较,春茶生化品质检测和加工产品感官评审,为该县茶叶品质提升和白茶开发利用提供基础资料。     

白桦林“维他”机制研究(13)——边缘效应与增产机制和多样性的关系

分别在白桦幼林、中龄林和成熟林的林缘和林内设置样地２０块、样方１６０个，研究边缘效应与增产机制和多样性的关系。结果表明：①边缘效应可使白桦林树高增产１９％～４１％，胸径增产８％～１１％；其中，幼林高效应４．４８，径效应１．０７，中龄林高效应２．８１，径效应－１．１８，成林高效应１．１１，径效应－０．１９。②边缘效应表现显著的树种有红松、白桦、山杨和黑桦。③边缘效应可增加植物多样性１．３～１．６倍。④通过定义容他量和容他面积，说明了白桦林从幼龄到成龄是一个由自稳态经扩大领域态到自解体态的过程；其中处于扩大领域态的白桦中龄林的容乔量为０．２种／ｍ２、容灌量为０．２种／ｍ２、容草量为０．９种／ｍ２、容红量为０．２７株／ｍ２。     

New Varieties of Populus tomentosa Carr. and Breeding Techniques

The main morphological characteristics, producing area and growth characteristics of sixteen new varieties of Chinese white poplar (Populus to-mentoso Carr. ) are reported, aiming at providing referernce for breeding and extension of new varieties.     

大棚畦床栽培蘑菇高产的实践与体会

根据一定规模的实践，研究总结出一套成功的大棚畦床栽培蘑茹高产高效技术，具体介绍了大棚构建、畦床制作、堆料配制、适宜播期、优良品种、营养液、相对湿度、棚温和料温管理等的操作关键。文中还就适宜播期、种植方式、保湿越冬和适时补充营养液等关键技术进行了讨论。