Heterosis, direct and maternal genetic effects on semen quality traits of rabbits

A complete diallel cross involving two rabbit sire lines (C and R) was carried out to estimate the crossbreeding genetic parameters of seminal traits. 2140 ejaculates from 153 males were analyzed. The traits studied were: presence of gel plugs (G), urine (U), and calcium carbonate deposits (CC), number of useful ejaculates (UE), pH, volume (V), mass and individual motility (Mm, Mi), useful Mi (UM), concentration (Cn), number of spermatozoa per ejaculate (TSE), percentage of viable spermatozoa (Vi), spermatozoa with normal apical ridge (NAR), normal spermatozoa (Nr), spermatozoa with morphological abnormalities of head (H), neck-midpiece (Nm), and tail (T), presence of proximal and distal cytoplasmic droplet (Dp, Dd).

Estimates of heterosis, direct and maternal genetic effects were obtained from the solutions of the mixed model. There were major differences in direct genetic effects between lines, which were favourable to line C for Cn and TSE, and unfavourable for CC, Nm and Dp. Smaller differences were also observed in Vi and NAR favourable to line R. Differences between lines with respect to the maternal genetic effects were relevant and favourable to line C for V and to line R for U, UM, Cn, TSE, Nm, Mi, and Mm. Individual heterosis was high for Dp and Dd.     

Low temperature storage and in vitro germination of cherimoya (Annona cherimola Mill.) pollen

Due to the protogynous dichogamy of cherimoya and to the absence of proper pollinating vectors, hand-pollination with fresh pollen is a common practice for cherimoya commercial production. In order to optimize the process of hand-pollination, in this work we have studied the conservation of cherimoya pollen at −20, −80 and −196 °C for up to 3 months. In vitro pollen germination of fresh pollen was 57.1% and it was progressively reduced with conservation time at the three temperatures studied reaching a minimum after 3 months of storage of 10.4%, 14.2% and 13.6% at −20, −80 and −196 °C, respectively. Differences in germination among temperatures were only significant during the first 2 weeks of storage. Field pollinations with pollen stored for up to 3 months at the three temperatures show no yield differences compared to pollinations performed with fresh pollen. The results indicate that pollen collected and stored at sub-zero temperatures at the beginning of the cherimoya blooming season can be used along the whole blooming season avoiding the need of collecting fresh pollen daily.     

Extinction risk of wood-living model species in forest landscapes as related to forest history and conservation strategy

Dead wood is a critical resource for biodiversity in boreal forests. We analysed the persistence of five model species inhabiting dead wood. By parameterising a metapopulation model (the incidence function model), the model species were all assigned characteristics that makes it likely that they have disappeared from some (20%) forest landscapes with a long history of forest management. In the metapopulation model, a forest stand (5 ha) was regarded as a habitat patch. The amount of habitat in each patch was obtained from models of dead wood dynamics of Norway spruce in central Sweden. Dead wood generated by altered management over the entire landscape was found to be less efficient in reducing extinction risks in comparison to the same amount of dead wood generated by protecting reserves. Because generation of dead wood by altered management is often less expensive than setting aside reserves, it is difficult to determine which conservation measure is most cost-efficient. In a landscape subjected to forestry for the first time, it was better to preserve a few large reserves than many small ones. However, in a managed, highly fragmented forest landscape it was better to set aside many small reserves. The reason for this was that small plots with high habitat quality could be selected, while large reserves originally contained habitats both of high and low quality, and the rate of habitat quality increase was low. A strategy for biodiversity conservation in a managed forest landscape should include information about the history of the landscape, the current amount and spatial distribution of forest habitats, and the potential for rapid restoration of forest habitats, both on managed and unmanaged forest land.     

安哥拉山羊级进杂交后代生活力初步观察

对安哥拉山羊及其级进杂交后代的生长发育、繁殖力、抗病性、采食习性等进行初步观察研究，结果表明：在试验场良好的饲养条件下，各代杂种羊生长发育正常，但繁殖力、抗病性、采食能力随级进杂交代数的增加有降低的趋势。据此，笔者认为，在陕北特定的生态经济条件下，培育毛用山羊新品种，级进杂交代数不宜太高，到Ｆ３代应停止级进，进行横交固定，而且在整个育种中，应始终注意饲养问题，以保证新品种培育成功。     

贮藏条件对郁金香花粉生命力的影响

以花粉萌发率为指标,研究了6种贮藏条件对4个品种的郁金香花粉生命力的影响.结果表明:不同品种的郁金香花粉生命力不同.贮藏温度对郁金香花粉生命力有很大影响,-18℃ 冷冻条件有利于保持郁金香花粉生命力,0～2℃冷藏条件次之,20～25℃常温条件最差.贮藏湿度对郁金香花粉也有影响,在常温和冷藏条件下,干燥条件比非干燥条件更有利于郁金香花粉生命力的保持.     

桂花花粉活力测定与''''晚籽银''''桂柱头可授性分析

采用TTC、无机酸和离体萌发等方法测定了不同桂花品种的花粉活力,用联苯胺一过氧化氢法测定柱头可授性,用扫描电镜观察了'晚籽银'桂柱头的分泌物.结果表明TTC、无机酸法不适合用于桂花花粉活力的测定,而用一定浓度的蔗糖、硼酸制成的固体培养基则能较好地测定花粉活力.桂花的不同品种和不同的开花期其花粉活力均具有显著差异.'晚籽银'桂的柱头为湿型柱头,在整个花期中均具有较强的可授性.'晚籽银'桂属雌蕊先熟型,其花粉活力与柱头可授性有4-5 d的相遇期.     

Viability retention of seeds of shisham (Dalbergia sissoo Roxb.) on the trees after maturity

In 1991 and 1992 studies on Dalbergia sissoo Roxb. showed the availability of ample amount of viable seed from November to May. Viability of seeds collected from December to March was more than 90 per cent. There was a slight but significant decrease in germination from March to may. Again germination per cent was slightly and significantly decreased from May to July. Thereafter, seed availability and viability were got drastically reduced. Sufficient viable seed of Dalbergia sissoo Roxb. can be collected at any time from November to July.     

Advances in the Research and Application of Artificial Insemination to Equids in China: 1935–2012

China was one of the first countries to use artificial insemination (AI) in equids, and it achieved international recognition for its widespread application of AI to commercial horse breeding. This article reviews the history of equine AI in China. The technique originated from the high demand for horses to be used in agriculture, transportation, and the military. Artificial insemination was identified as an ideal tool for Chinese horse breeding to improve the productivity of native horses, especially during 1950-1970. Presently, AI is still practiced commonly in China, and it includes the use of fresh semen and transported cooled semen. The use of frozen semen has also been resumed to broaden the range of elite Sporthorse stallions and to preserve threatened or endangered native breeds. Accurate prediction of the optimum time for insemination depended mainly on transrectal palpation of the mare's ovaries. In addition to controlled methods of insemination, factors like volume and number of spermatozoa in the inseminate and timing and frequency of insemination were optimized to accomplish high fertility rates in the field. Production of hinnies and mules for agricultural labor and donkeys for meat and hide gelatin stimulated a nationwide upsurge of research into the reproductive physiology of and AI technology in donkeys. In the future, there will be further increases in the use of traditional and modern AI techniques in the breeding of Chinese equids.     

不同贮藏时间及花瓣张开角度对番茄花粉活力的影响

为了研究不同贮藏时间及花瓣张开角度对花粉活力的影响,采用I2-KI染色法和蔗糖培养基培养法对花瓣张开角度为A(0°~45°)、B(45°~90°)和C(90°~180°)的番茄花粉活力及花粉管长度进行测定。试验结果表明,不同贮藏时间及花瓣张开不同角度间的花粉活力存在显著差异。花瓣张开角度A的花粉活力随着贮藏时间增加呈先升高后降低的趋势,以室温贮藏3 d的花粉染色率最高。花瓣张开角度B和C则以采摘当天活力最强,5 d后所有花粉活力均低于5%,基本丧失萌发能力。新采摘的有活力花粉散落于蔗糖15 g/L+H3BO30.03 g/L+CaCl20.02 g/L+琼脂6 g/L的培养基表面,1~2 min即开始萌动,20 min时,花粉管长度已达到花粉粒直径的2.75倍,60 min时达到7.5倍。花粉管在培养基上相互接触会出现相互作用,抑制部分花粉管生长。