北碚榕（FicusbeipeiensisS. SChang）形态特征与花部显微特征研究

北碚榕（Ficus beipeiensis S.S Chang）雌雄异株,仅分布在重庆市北碚区北温泉附近的石灰岩壁上,目前调查仅发现5株野生植株．本文主要采用形态学、解剖学及生态学方法对北碚榕及其近缘种（大果榕、苹果榕）的形态特点进行比较研究．结果表明：①雌雄植株在形态结构上差异显著,雄株：叶呈卵圆形,纸质,平均直径约为3.90 cm ,圆盘形;雌株：叶呈长椭圆形,硬纸质,平均直径约为1.51 cm ,梨形;在叶的形态结构上北碚榕雄株类似于大果榕;雌株叶形与两种榕树不相同．雄株花序形态结构上,近似于两者而雌株花序与其相比差异较大．②雌花只存在于雌性隐头花序内,在雌花期时发育成熟,雌花花柱呈棒状,子房球形;雄花序内有瘿花和雄花,瘿花于间花期成熟,雄花于雄花期发育成熟;瘿花花柱呈喇叭状,子房倒卵形;雄花具雄蕊2枚,分布在苞片周围,并不散生在花序内;三种花的形态结构特点与传粉小蜂的行为密切相关．     

江苏省杂交棉花品种性状研究及育种思路

研究2001-2013年江苏省农作物品种审定委员会审定通过的杂交棉花品种的性状表现,为杂交棉育种提供参考.根据区域试验数据,采用Excel等统计方法分析杂交棉花品种的亲本来源、产量表现、纤维品质及抗性等性状.结果表明：杂交棉品种亲本多为苏审常规棉与‘GK19’;不同阶段育成品种产量稳步提高,但增产幅度有降低趋势;单株铃数有渐近增加的趋势;30个白色杂交棉品种中,衣分均高于39.5％,铃重5.9 g以上的品种占60％;纤维品质达Ⅲ型以上品种占93.5％;近50％品种对枯、黄萎病的抗性达耐病级别;抗虫性有待提高.近期杂交棉育种以改进纤维品质与抗性为主,稳步提高产量;思路上注重种质资源创新,充分利用生物技术,研究“三系”杂交棉;重点开展病虫抗性和品质研究.     

春季栽培甜玉米品种鄂甜玉6号的种植密度筛选试验

为了研究春季栽培时,不同定植密度对甜玉米品种鄂甜玉6号主要农艺性状、产量及品质的影响,对2800、3200、3500、4000株／667m^2 4个种植密度进行了比较试验,结果显示,春季栽培时3200～3500株／667m^2为鄂甜玉6号最适宜的种植密度．其产量较高。     

三疣梭子蟹分级养殖技术

在浙江沿海地区,三疣梭子蟹已经逐步发展成为水产养殖的主导品种之一。笔者在总结多年三疣梭子蟹养殖生产技术与经验的基础上提出三疣梭子蟹分级养殖技术,通过指导养殖生产获得了较好的成效。三疣梭子蟹分级养殖技术是根据三疣梭子蟹生长发育的生物学特性和养殖生态要求,将三疣梭子蟹养殖全过程划分为种蟹培育期、苗种繁育期、中间培育期、养成生长期、膏蟹培育期等5个阶段,在养成期结合浙江地区的气候特点又细分为生长期、高温期、交配期等3个管理阶段,各个阶段采取相应的养殖技术和管理措施,开展养殖工作的一种方法。     

2株猪繁殖与呼吸综合征病毒的分离、鉴定及遗传进化分析

Two strains of porcine reproductive and respiratory syndrome viruses (PRRSV) were isolated from serum of some pig farms in Guangdong province and showed PRRSV positive in RT-PCR testing. The two viruses could passage stably and cause typical cenotaphic effect, they were named as LZ-GD and LB-GD. The analysis of variable region sequences of ORF5 and Nsp2 of the two viruses showed that LZ-GD and LB-GD strains were far to Europe strain Lelystad, the homology of nuclear nucleotide sequence were 63.5% and 63.8%, respectively, with classic American strain VR-2332 were 88.7% and 89.1%, respectively, and that with highly pathogenic JXA-1 strain were 99.2% and 99.3%, respectively. There were 30 amino acids deletion in Nsp2. It shared the deletion with JXA-1, HUN4 and other pathogenic variant. Thus, the two strains of PRRSV belonged to highly pathogenic American type.     

Characterization of the DNA nucleotide sequences in the genome of red sea bream iridoviruses isolated in Korea

The nucleotide sequences of DNA fragments amplified by polymerase chain reaction (PCR) from four different genomic regions of nine red sea bream iridoviruses (RSIVs) isolated from different species of fish, different areas and in different years in Korea were compared with the reported reference sequences. One isolate, RSIV Namhae, showed 100% homology to the reference sequences, while the other eight isolates, which appeared to contain identical nucleotide sequences, showed 96.6–98.9% homology with reference sequences depending upon the target regions of PCR gene amplification. However, differences in nucleotide sequences were not apparent between the RSIVs isolated in different locations, in different years or in different host species. We also cloned and sequenced the 3′ end flanking region (K1) of the DNA polymerase (DPOL) gene using the cassette ligation-mediated PCR method. This sequence was 4436-bp long and possessed two open reading frames (ORF-1 and ORF-2) oriented in opposite directions. The putative proteins encoded by these two ORFs could not be characterized by comparison with the proteins of other species in the data banks. The presence of the ribonucleotide reductase small subunit (RNRS) gene at the 3′ end of the K1 region allowed us to determine that these two genes, RNRS and DPOL, are separated 5508 bp and oriented in the same direction in the genome of RSIV. Moreover, it is of interest that a PstI-restriction fragment, of which the sequence but not the location within the RSIV genome had previously been reported, is located at nucleotide positions from 1096 to 2054, extending from within the ORF-1 region, spanning the intervening sequence between ORF-1 and ORF-2, and extending into the ORF-2 region. Various repeating sequences up to 86 bp were present at the 3′ ends of ORFs, especially within the nucleotide sequences at the 3′ terminus of ORF-2. No similarities were detected when the DNA sequences of the K1 region were compared to the DNA sequences of a repetitive element in the genome of other iridoviruses.     

超声波在水产养殖中的应用

超声波具有机械传质、加热和空化作用。高强度的超声会破碎生物的细胞,降低酶活性等;合适的低强度超声波可以促进鱼卵孵化,提高鱼类的生长速度,去除有害藻类,并能增强鱼类的免疫功能,有利于鱼病防治。     

The Yangtze River dolphin or baiji (Lipotes vexillifer): population status and conservation issues in the Yangtze River,China

• 1. Baiji were sighted 17 times during three recent simultaneous multi‐vessel surveys in the Yangtze River, China (November 4–10, 1997; December 4–9, 1998; October 31–November 5, 1999). There were 11 sightings in 1997 (consisting of 17 animals), five in 1998 (seven animals), and two in 1999 (four animals). It was concluded that 13 individuals could be considered as a minimum number of the baiji currently in the Yangtze River.
• 2. An annual rate of population decrease was roughly estimated as 10%. From the body sizes observed, the proportions of old, adult and immature individuals were approximately estimated at 57, 26, and 17% respectively.
• 3. Baiji showed a significant attraction to confluences and sand bars with large eddies. The present distribution range of the baiji is less than 1400 km in length in the Yangtze main river. Distances between the two nearest groups of baiji appear to be increasing.
• 4. Two typical sightings are described, in which surfacing and movements of baiji were recorded. Baiji were often found swimming together with finless porpoise. In the surveys they occurred in the same group in 63% of occurrences. Interactions between baiji and finless porpoise are described and discussed.
• 5. Human activities are the main threats to the baiji. Illegal electrical fishing accounted for 40% of known mortalities during the 1990s. Engineering explosions for maintaining navigation channels have become another main cause of baiji deaths. The last hope of saving the species may be to translocate the remaining baiji into a semi‐captive reserve, known as the ‘Baiji Semi‐natural Reserve’.

Copyright © 2003 John Wiley & Sons, Ltd.     

中棉所49在西北内陆棉区的稳定性与丰产性分析

利用AMMI模型及其双标图分析了中棉所49在2002-2003年和2008-2013年共8年西北内陆棉区国家棉花区域试验中的稳定性表现。结果表明：（1）2002年西北内陆国家棉花区试早中熟组各参试品种的稳定性优劣顺序依次为：中棉所49〉98—60〉K31〉中棉所35〉9—2005〉E3—8—12〉新创1号〉SGK9688〉SGK1779。（2）中棉所49在8年区域试验中的稳定性表现为：在5年试验中表现居第一位、1年试验中表现居第二位、2年试验中居第三位,其稳定性综合表现优良。（3）中棉所49的皮棉产量水平在8年区域试验中总体上稳中有升,体现了较好的丰产性能。可见,中棉所49在西北内陆早中熟棉区具有很强的推广应用价值。     

高温胁迫对玉米自交系父本花粉生活力的影响

以中种集团提供的10份骨干玉米自交系父本花粉为试验材料,通过TTC染色法和离体培养法,研究不同胁迫温度对花粉生活力的影响。结果表明,玉米花粉不易储藏,高温胁迫会导致花粉生活力显著下降,在35℃胁迫处理6 h之后花粉生活力全部丧失;在40℃胁迫处理4 h之后有8个自交系的花粉丧失生活力。TTC染色法和离体培养法均能有效测定玉米花粉生活力,离体培养法测得的花粉生活力低于用TTC法测得的水平。