Germination and storage characteristics of Prunus africana seeds

Prunus africana, from the moist highlands of sub-Saharan Africa, is subject to great exploitation because its bark is used in the treatment of prostate-related diseases. A better understanding of the biology of its seed could help the ex situ and in situ conservation of the species. Fifty per cent of fresh seeds (46.8% MC) from mature purple fruits harvested in Kenya germinated after 10 days incubation at 25°C. The germination rate was linearly related to constant temperature, giving a prediction for the minimum temperature for germination at ca. 0.6°C. All seeds germinated at 5°C during 4 months fully hydrated storage. P. africana seed is, thus, neither dormant nor chilling sensitive. The relationship between equilibrium moisture content and relative humidity was used to construct a sorption isotherm, against which seed desiccation and storage responses were assessed. Seventy six per cent of mature seeds survived drying to 4.5% MC (22% RH) compared to 17% of seeds from immature purple-green fruits. Although, 25–45% of mature seeds survived at 8–12% MC after 2 months, only 10% remained viable after 6-month storage at 5°C. This study proposes optimum conditions for the artificial regeneration of P. africana seeds and highlights the need for further experiments storing dry seeds at sub-zero temperatures.     

稻种资源低温贮藏生活力跟踪监测与种质更新

对广西农业科学院种质库贮藏保存的水稻种质资源、不同贮藏年限的发芽率（生活力）情况进行跟踪研究和预警分析，并对相关种质进行及时更新补充入库。     

西门塔尔公牛精液品质季节性变化的分析

本文通过对８头西门塔尔公牛三年精液品质指标的统计，对其精液品质随季节变化的规律作了分析，并对变化的原车和生产实践中的有关问题进行了初步探讨。     

Effects of microwaves on fungal pathogens of wheat seed

An investigation into the effect of microwaves on the fungal pathogens of winter wheat was undertaken. This was achieved by microwaving seed at 0, 15, 30 and 45 s. Agar plate tests and DNA analysis were then used to assess pathogen loads and germination, emergence and tetrazolium tests used to investigate seed viability after treatment. Throughout all treatment times, microwaving significantly reduced levels of contamination on seed and was particularly effective at controlling Fusarium spp. and Microdochium nivale. Conventional seed survived microwave treatment better than organic seed. Subsequent analysis and experimentation revealed that seed moisture content was inherently linked to losses in seed vigour upon exposure to microwaves. Seed levels of fungal DNA did not decrease with the observed loss of culturable fungal propagules, thus fungal death was attributed to heat and desiccation rather than denaturing DNA. Microwave treatment of wheat seed may offer a method to significantly reduce fungal loads on both conventional and organic wheat seed.     

Hydatidosis of slaughtered animals in Bahir Dar Abattoir,Northwestern Ethiopia

The study was conducted from May 2005 to December 2006 in Bahir Dar Abattoir to assess the current status of hydatidosis in cattle and sheep. Hydatid cyst count and characterization were conducted based on routine meat inspection. Of the total 420 cattle and 340 sheep slaughtered in Bahir Dar Abattoir 143 (34.05%) and 36 (10.6%) animals were found harboring hydatid cysts respectively. Thorough meat inspection in the abattoir revealed that 202 and 54 visceral organs were found harboring one or more hydatid cysts in cattle and sheep respectively. Differences in prevalence rates between the two species of animals were highly significant (P < 0.001). The infection of the lung, liver, kidney, spleen and heart were found to be 57.9% , 36.6% , 3% , 1.5% , 1% in cattle and 50%, 48.1% and 1.9% in sheep respectively. From the total of 864 in cattle and 138 in sheep hydatid cysts counted 315 (36.4%), 268 (31.0%), 65 (7.5%), 216 (25.0%) in cattle and 92 (66.7%), 20 (14.5%), 1 (0.7%), 25 (18.1%) in sheep were found to be small, medium, large and calcified cysts respectively and 484 (56.0%), 164 (18.9%), 216 (25%) in cattle and 35 (25.4%), 78 (56.5%), 25 (18.1%) in sheep were sterile, fertile and calcified cysts respectively. Viability rates of 62.2% in cattle and 78.2% in sheep were observed. The rate of cyst calcification was higher in the liver than in the lung while fertility rate was higher among the cysts of the lung for both cattle and sheep.     

黑莓花粉含水量与贮藏特性的研究

用硅胶对黑莓花粉进行干燥,发现干燥4 h时花粉的含水量降为14.13%,生活力为39.16%,在该含水量下花粉的耐贮藏性最好,在-20℃贮藏120 d后,仍能保存20.35%的花粉生活力。     

马尾松种子生活力与发芽指标相关性的初步研究

马尾松(pinus massoniana)种子实验室发芽率与生活力之间存在线性相关,其数学表达式为y~(-1)=1.0756x~(-1)-0.000826。场圃发芽率与实验室发芽率、生活力之间也存在着线性相关,场圃发芽率与生活力之间存在着y~(-1)=1.144x~(-1)+0.0002375的关系。场圃发芽率与实验室发芽率存在着y~(-1)=1.2499x~(-1)-0.00189的关系。     

The implications of poaching for giant panda conservation

Poaching giant pandas (Ailuropoda melanoleuca) for their skins is a serious threat to the persistence of wild giant panda populations in China. An individual-based, age-structured stochastic simulation model was constructed to give a quantitative analysis of the effects of poaching. The model takes a total wild population of 1216 individuals divided among 16 ‘patches’. The model treats individual populations as being completely independent, with no dispersal, and density-dependence only enters into the model through local carrying capacity of patches. The model simulates three types of poaching: deterministic (constant) poaching, stochastic poaching with normal distribution and stochastic poaching with observed distribution. Results showed that, with a given initial population, poaching adult females produces lower average population size and higher average percentage extinction than poaching adult males or young. At the same poaching intensity, all three poaching simulations predicted a similar probability of extinction. However, they predicted different average population size and percentage extinction because of differences in the parameters in the three models. These results should therefore be treated with caution when constant poaching simulation or stochastic poaching with assumed normal distribution is used as a simplification of realistic poaching. Nevertheless, the results imply that giant pandas are threatened by any reduction in natural populations. Effective measures are essential to reduce poaching. It is also important to limit the capturing of wild animals for zoos or breeding facilities as this also has a serious effect on the total population.     

Storability of onion seeds and effects of packaging and storage conditions on viability and vigour

Fresh onion seeds desiccated to 6.0% seed moisture content (SMC) were stored in various packaging materials under different storage conditions. Seeds packed in aluminum-laminated pouches beside those stored with silica gel at 25 °C maintained satisfactory germinability and vigour after 12 months. Desiccated seeds stored in moisture impervious containers produced more vigourous seedlings. Germination potential of onion seeds increased with reduced SMC besides storage in moisture impervious packets along with desiccants as physiological and biochemical attributes are regulated. Seed viability and vigour decreased with accelerated ageing due to increased lipid peroxidation, decreased activities of several free radical and peroxide scavenging enzymes. Electrical conductance of seed leachates also increased with ageing. Thus, adoption of appropriate storage temperature and moisture control techniques would significantly affect onion seed quality, which was due to minimum accumulation of free peroxide radicals and enhanced activity of free radical scavenging enzymes.     

君子兰（Clivia miniata Regel）的贮藏花粉时间与受精过程

 利用花粉低温冷藏技术与常规石蜡制片技术研究了大花君子兰的贮藏花粉寿命以及受精过程，为其杂交育种提供基础资料。结果如下：新鲜花粉结籽率为35%；-21℃贮藏70 d的花粉结籽率为22%；贮藏140 d的花粉结籽率为4%；贮藏180 d的花粉结籽率为0。两个精细胞具有二型性。成熟胚囊里次生核位于反足细胞端。胚珠发育不同步，胚珠没有受精与胚珠败育成为结籽率低的内部原因。君子兰受精过程经历时间为：人工异花授粉2 h左右花粉萌发；花粉管在花柱中生长26 h左右；花粉管在子房腔内生长12 h左右；授粉后42～50 h雌雄性细胞融合；授粉后44～46 h初生胚乳核分裂；授粉后的第6～7 d，合子进行分裂，合子休眠期为4～5 d。