Long photoperiod delayed spawning and increased somatic growth in gilthead seabream (Sparus aurata)

The effects of extended photoperiods, mimicking the longest day of the year, were studied in 1- and 2-year seabream. The photoperiod regimes started in late July, 36 and 39 days after the summer solstice and continued for 11 months, well beyond the natural reproductive season of December–March. Regime 1 (long day, 15.5L:8.5D), which used natural and fluorescent light, reduced the incidence of maturity in both year classes and females did not spawn although some gonadal development was observed. Among all 1-year sampled fish of regime 1, a maximum of 5% became spermiating males (March) and 5% reached the yolk granule stage of vitellogenesis (VO3; 250–400 μm diameter) by May. Among 2-year sampled fish of regime 1, 45% became spermiating males and 25% were females, which reached the advanced vitellogenesis stage (VO4; 400–600 μm) by April. Regime 2 (skeleton photoperiod), consisting of natural light and a 1.5-h pulse of fluorescent light during the period 14–15.5 h after sunrise, postponed gonadal development and spawning for up to 3 months. In this regime, a maximum of 80% of 1-year sampled fish were spermiating males in February and a maximum of 10% were VO3 stage females in March. In the sampled 2-year fish, the maximum levels were 50% spermiating males in February and 25% VO3 stage females in March. Control fish, which were exposed to the natural photoperiod (29°34′N), spawned during their natural season. The maximum levels for 1-year sampled control fish were 95% spermiating males and no females in December, while among 2-year sampled fish, maxima of 75% males in February and 45% VO4 stage females in November. Final average weights of photoperiod treated fish (1-year=430 g—regime 1, 400 g—regime 2; 2-year=582 g—regime 1, 518 g—regime 2) were significantly greater (p<0.05) than control fish (1-year=341 g; 2-year=476 g). Daily feed consumption (g/100 g fish) dropped from an average of 1.83 to 0.93 g for 1-year fish during August–December and from 0.88 to 0.54 g for 2-year fish during the same period. This was correlated with reduced autumn and winter water temperatures (26–20°C summer to winter change) and increased fish weight in all treatments. Daily feed consumption was also affected by the onset of spawning in the control and regime 2 (skeleton photoperiod) treatments of both 1- and 2-year fish. The efficiency of feed utilization (FCR) and protein and energy retention were all affected by the photoperiod regimes and followed the same pattern of decrease as weight gain, regime 1 (long day)>regime 2 (skeleton photoperiod)>control.     

鼠尾藻的有性繁殖过程和幼苗培育技术研究

重点研究了鼠尾藻的有性繁殖特性和规律,系统观察了鼠尾藻的成熟季节,雌、雄生殖托的成熟、排卵、排精、受精卵的细胞分裂、假根的形成、幼孢子体的构建和生长特征。并在实验室进行采苗和苗种培育试验,获得理想结果,该培育技术可以应用到生产中。     

Growth and reproductive performance of broodstock shrimp reared in a biosecure recirculating aquaculture system versus a flow-through pond

Over the past decade, viral pathogens have caused mass mortalities of farmed shrimp throughout the major shrimp farming regions of the world. In addition, the global shrimp farming industry has been criticized for negatively impacting coastal environments. These issues have raised concerns about the sustainability of traditional shrimp farming practices, and have prompted farmers and researchers to develop biosecure technologies that promote a sustainable industry. Current technologies include the use of specific pathogen free (SPF) shrimp that are grown to market size in recirculating systems that rely on pathogen exclusion. Inherent in this approach is the need to produce SPF broodstock under biosecure conditions. However, there is a paucity of information on broodstock growth and reproductive performance when they are reared in recirculating systems. The present investigation compares shrimp growth and reproductive performance in two trials where shrimp were cultured from market size (20 g) to broodstock size (40–60 g) in a recirculating aquaculture system (RAS) versus a flow-through earthen pond (EP). In trial 1, mean growth rates of males and females in the RAS were 0.83 and 1.33 g/week, respectively. In the EP, males and females grew 1.07 and 1.48 g/week, respectively. In trial 2, mean growth rates of males and females in the RAS were 0.90 and 1.53 g/week, respectively, whereas in the EP, males and females grew and 1.24 and 1.78 g/week. Slower growth rates in the RAS may be attributed to the lack of natural productivity, which provides supplemental nutrition to the shrimp. In addition to growth rates, reproductive performance of broodstock reared in the RAS was compared with historical reproductive performance of broodstock reared in the EP. Data on spawning success and production of viable nauplii revealed no significant differences (P>0.05) between broodstock shrimp reared in these two systems. These results indicate that broodstock shrimp can be cultured in a biosecure RAS while maintaining good growth and high survival. In addition, reproductive performance of broodstock shrimp reared in a RAS is not compromised when compared with broodstock shrimp reared in a conventional, flow-through pond.     

自然及养殖水体河蟹性成熟和性早熟的研究

在长江流域的自然水体中，进行生殖洄游的河蟹以二秋龄种群为主体，当年性早熟的个体约占5％－10％，大多数河在青春蜕壳后由黄为绿蟹的时间集中在秋分前后，此后性腺发育进入高速增长期，而在人工养殖的条件下，河蟹的当年性成熟率甚至可达到近似100％，盐度、温度和是促使河蟹当年性早熟的因素，也是控制性成熟的技术关键。     

沙棘的花芽分化及花器发育进程研究

利用光学显微镜对中国沙棘花芽分化及花器发育进程进行观察研究,结果表明:沙棘花芽分化分为花芽分化开始期、花序分化期、花蕾分化期、花萼分化期、雄蕊分化期、雌蕊分化期。花粉性细胞的发育经过花粉母细胞、二分体、四分休、单核花粉粒、双核花粉粒几个阶段。胚囊发育包括孢原阶段、四分孢子、经减数分裂,形成成熟胚囊等几个阶段。该研究为合理制定沙棘的栽培技术措施和培育新品种提供了科学依据。     

不同出雏时间雏鸡性比例规律的探讨

本试验研究了出雏不同时间雏鸡性比例的变化规律。试验从入孵满２０ｄ开始，到２１ｄ１５ｈ扫盘结束，期间共拣雏１２次，每次拣雏完毕后，随即鉴别公母。结果表明：出雏的不同时间，雏鸡性比例存在显著（Ｐ＜０．０５）、极显著（Ｐ＜０．０１）的差异，并呈现明显的规律性。２０ｄ时，母鸡最多，公母比值为０．３５０±０．０３０。其后，公鸡的比例增加，到２１ｄ３ｈ，公鸡达到最多，公母比值为１．７９２±０．０８０。此后，母鸡的比例增加，扫盘出雏结束时，公母比值为１．３３０±０．０５０。     

从芍药的花芽分化试论芍药,牡丹的花型形成和演化

本文研究了芍药的花芽结构和性质,并对花芽分化进程作了系统的观察研究。确定了雄蕊原基伸长呈圆柱形是瓣化的临界点。雌蕊原基的腹缝线开裂,心皮伸展、扩大而成花瓣。观察认为雄蕊原基的产生是同步的,而遗传性的表现可以是整体的、局部的和个体的。花型分类的多样性与雄蕊原基的遗传变异的多样性密切相关。根据观察把重瓣花的花瓣定性为有性的和无性的两类。雄蕊离心瓣化形成“楼子类”花型;而向心瓣化形成“千层类”花型。花瓣自然增加不能形成高级重瓣花型。     

小麦条锈菌ZS有性与无性菌系毒性差异初步分析

小麦条锈病是小麦生产上最主要的病害,条锈菌毒性不断变异是造成小麦条锈病频繁发生和小麦品种抗病性丧失的主要原因。对小麦条锈菌新菌系开展品种抗病性评价,并探明条锈菌有性菌系、无性菌系间的毒性差异,为科学、超前指导小麦抗病育种和抗病品种的合理布局应用提供技术支撑。2017 — 2021年从454个小麦条锈菌有性菌系和1 728个无性菌系中,获得ZS有性菌系35个和无性菌系167个,占比分别为7.71%和9.66%;其中已归类ZS-1、ZS-18、ZS-52类型中有有性菌系14个、无性菌系72个,占比分别为3.08%和4.17%。2022年选择ZS有性与无性菌系重要类型混合菌,对76个甘肃省内小麦生产品种进行苗期、成株期接种鉴定,结果发现,有性ZS菌系与无性ZS菌系对供试小麦品种苗期致病力分别为97.37%、92.11%,相对寄生适合度分别为0.353 0、0.248 7;成株期致病力分别为 72.37%、71.05%,相对寄生适合度分别为0.362 7、0.184 0。表明有性菌系致病性和寄生适合度均高于无性菌系。建议在陇南越夏区,及早调整小麦抗病育种目标,以持续控制条锈病的发生流行,保障粮食安全。     

现代百合品种培育的技术途径及其杂交特殊现象的机制

为了减少百合(Lilium)育种的盲目性,提高育种效率,本文主要以作者在百合育种工作中的结果和经验为基础,对现代百合品种与野生种的关系、百合组内杂交和组间杂交的差异、现代百合品种的育种途径、非整倍体百合的培育以及百合杂交中特殊现象的机制与新假说(即:百合倍性间杂交的胚乳中含有5个或以上相同基因组是其发育和杂交成功之关键)等方面进行了概述,为百合育种工作者提供有益的参考资料。     

稻瘟病菌有性世代初步研究

 本文首次报道用来自我国10个省市(区)水稻的52个稻瘟病菌株与国际水稻所提供的4个标准菌株进行杂交,在培养基上形成了有性世代(产生子囊壳)。有性世代形成能力于菌株之间有很大差异,而了囊壳的产生和数量与配对标准菌株的交配型有关。同时还发现,供试菌株中存在着两种交配型(即A和a),但极大多数的菌株为交配型A,仅其中1个来自云南的菌株为交配型a。