X射线水衬比法测定华山松种子生活力的研究

通过研究,运用Ｘ射线摄影技术,经浸种、培养、干燥、射线摄影,在４天内即可准确判断出华山松种子的潜在发芽能力———生活力。制作了射线判图的标准图片,确定了最佳判图条件是：２５℃浸种４８ｈ,２５℃培养４８ｈ,４０℃干燥５ｈ;判图标准是：有生活力的种子,胚及胚乳之间界线模糊不清,胚隐约可见,胚乳亮度均匀。证明了华山松种子生活力强弱与其本身干燥后失水量关系极大,发芽种子的平均失水量为１４４％,死亡种子的平均失水量是２５６％。     

Establishment of reliable methods of in vitro pollen germination and pollen preservation of Brassica rapa (syn. B. campestris)

A simple and reliable method for evaluating the viability of Brassica pollen was established in which the in vitro germination rate of pollen was adopted as the index of the viability of pollen grains. Pollen grains were preincubated in an atmosphere in which the relative humidity (RH) was fixed to 52% or 66% at 20 °C for 5 hours. They were cultured for 16 hours at 25 °C in a liquid Kwack's medium (1964) supplemented with 20% sucrose, and the pH was adjusted to 8.0. They were then observed under a microscope and the number of germinating and unchanged pollen grains were counted. The germination rate of pollen was improved and stabilized by preincubation and the use of a high pH medium. More than 90% of the freshly harvested pollen grains of Brassica rapa (syn. B. campestris) germinated constantly in these conditions Undehisced anthers were collected from flowers at anthesis and dehydrated by incubation at 20 °C for 16–24 hours in an atmosphere where the RH was fixed to 15% or 32%. They were put into a plastic vial and preserved in a freezer at -20 °C. The germination percentage of the preserved pollen was scored at intervals during preservation. The germination rate of the pollen grains preserved at -20°C for 1 year was higher than 50% and the pollen proved to be efficient for seed set. Most of the seeds germinated normally. This revised version was published online in August 2006 with corrections to the Cover Date.     

用过氧化氢法快速测定林木种子生活力的研究

本文采用过氧化氢法快速测定杉林、马尾松、火炬松种子的生活力。结果表明,用该法测定杉木、马尾松种子的生活力,所得结果与标准发芽测定所得发芽率之间没有显著差异;但火炬松不宜用该法测定生活力。过氧化氢法的优点是操作简便,成本低,适于基层单位应用。     

Effect of temperature and humidity on the longevity of Orobanche seeds

The effects of moisture and temperature on seed longevity were studied over periods of up to 426 days in three species of Orobanche . Saturated salt solutions were used to achieve equilibrium relative humidities (e.r.h.) between 11% and 85% at temperatures of 20–60 °C. The viability equation describing loss of viability in these conditions applied to the three species such that the lower the temperature and lower the equilibrium relative humidity the greater the longevity. The initial viability differed between species with the seed lot of Orobanche crenata having the lowest viability. However, the relative effect of temperature on longevity and the relative sensitivity of seed longevity to changes in equilibrium relative humidity were the same in all species. Longevity, estimated by the standard deviation of the seed survival curves was greater in Orobanche aegyptiaca and O. crenata than in Orobanche minor , being for example about 100, 103 and 49 days, respectively, at 40 °C, 50% e.r.h. Accurate prediction of longevity is necessary to understand and quantify the population dynamics of weeds and will help the farmer to optimize control measures such as solarization. Taken in conjunction with published data on loss of viability of imbibed seeds, the annual loss of viability on a typical Eritrean farm is predicted to be about 38%.     

杂交稻早夏季制繁种种子生活力和活力低的原因分析

杂交稻在早夏季制繁种收获时正值全年最高温度期,晴天中间水泥地晒种,造成种子损伤,使 发芽势、发芽率、发芽指数降低,同时晴天收割后闷种又使种子在高温、高湿的条件下加速老化,破坏了 细胞膜的完整性,脱氢酶活性降低,导致种子的发芽力下降,发芽指数降低。而阴天午间水泥地晒种和闷 种的影响则较小,早夏季制繁种种子收获进仓后比夏季制繁种要多经过一段时间的炎热夏季,在常温库 条件下,受高温的影响更大,从而加速活力的下降,低温库有利于早夏季制繁种种子生活力和活力的保 持。早夏季制繁种种子的裂颖率、柱头夹持率高于夏季制繁种种子,降低了种被的保护作用,其发芽力、 发芽指数、细胞膜的完整性均较差,早夏季制繁种的种子千粒重低于夏季制繁种的种子,千粒重低的种 子活力也低。     

A fluorescence‐based assay for in vitro screening of Saprolegnia inhibitors

The incidence of fish pathogenic oomycetes, Saprolegnia, has increased significantly in aquaculture since the ban of malachite green. For the efficient characterization of anti‐Saprolegnia therapeutics, simple accurate methods are required. However, the current screening methods are limited by time, and none of them are confirming the viability of treated spores or hyphae. In this study, a modified fluorescence‐based assay for the in vitro screening of Saprolegnia inhibitors has been developed. This method involves the use of FUN‐1 viability dye combined with calcofluor white M2R, and is based on the formation of orange‐red cylindrical intravacuolar structures (CIVS) in metabolically active spores, hyphae and biofilms. Heat‐killed and bronopol‐treated Saprolegnia spores, hyphae and biofilms exhibited diffuse bright green fluorescence which confirms complete loss of viability. For boric acid‐treated spores, no germination was observed. However, tiny CIVS were observed in 50% of treated spores which indicated reduction in their viability. Our results proved that FUN‐1 dye is an efficient tool to distinguish between live and dead Saprolegnia spores, hyphae and biofilms and to monitor the change in Saprolegnia viability during qualitative evaluation of potential anti‐Saprolegnia compounds.     

Survival rates for a declining population of bottlenose dolphins in Doubtful Sound,New Zealand: an information theoretic approach to assessing the role of human impacts

• 1. The bottlenose dolphins of Doubtful Sound, New Zealand are a declining population at the southern limit of the species' range, exposed to impacts from tourism and habitat modification. Patterns in apparent annual survival were analysed from photographic resightings of naturally marked adults (1990 to 2008) and calves within the first year of life (1994 to 2008) using capture‐recapture models.
• 2. The most parsimonious model for adults provided a time‐invariant, sex‐invariant estimate of survival (?_{a(1990–2008)}=0.9374; 95% CI: 0.9170–0.9530), marginally lower than prior estimates for wild bottlenose dolphins.
• 3. The most parsimonious model for calves indicated a significant time‐variant decline in survival from an estimate similar to other populations (?_{c(1994–2001)}=0.8621; 95% CI: 0.6851–0.9473) to a current estimate that is, to our knowledge, the lowest recorded for free‐ranging bottlenose dolphins (?_{c(2002–2008)}=0.3750; 95% CI: 0.2080–0.5782).
• 4. Information theoretic evidence ratios suggested that observed patterns in calf survival were 22 times more likely to be explained by a decline coincident with the opening of a second tailrace tunnel for a hydroelectric power station than by a decline in any other year or across multiple years.
• 5. Projections using an age‐structured stochastic population model indicated that the current level of calf survival was unsustainable (population decline: 100% of model runs; population extinction: 41.5% of model runs) and was a key factor in the observed population decline in Doubtful Sound.

Copyright © 2008 John Wiley & Sons, Ltd.     

Ecoviability for ecosystem‐based fisheries management

Reconciling food security, economic development and biodiversity conservation is a key challenge, especially in the face of the demographic transition characterizing many countries in the world. Fisheries and marine ecosystems constitute a difficult application of this bio‐economic challenge. Many experts and scientists advocate an ecosystem approach to manage marine socio‐ecosystems for their sustainability and resilience. However, the ways by which to operationalize ecosystem‐based fisheries management (EBFM) remain poorly specified. We propose a specific methodological framework—viability modelling—to do so. We show how viability modelling can be applied using four contrasted case‐studies: two small‐scale fisheries in South America and Pacific and two larger‐scale fisheries in Europe and Australia. The four fisheries are analysed using the same modelling framework, structured around a set of common methods, indicators and scenarios. The calibrated models are dynamic, multispecies and multifleet and account for various sources of uncertainty. A multicriteria evaluation is used to assess the scenarios’ outcomes over a long time horizon with different constraints based on ecological, social and economic reference points. Results show to what extent the bio‐economic and ecosystem risks associated with the adoption of status quo strategies are relatively high and challenge the implementation of EBFM. In contrast, strategies called ecoviability or co‐viability strategies, that aim at satisfying the viability constraints, reduce significantly these ecological and economic risks and promote EBFM. The gains associated with those ecoviability strategies, however, decrease with the intensity of regulations imposed on these fisheries.