不同成熟度花生种子发芽率及活力差异性研究

本文以8130花生品种为材料,研究了不同成熟度花生种子的发芽率、活力情况及差异性.结果表明,不同成熟度的花生种子的发芽率、活力差异极大,成熟度高的种子发芽迅速整齐,种子活力强;成熟度越低的种子发芽率和幼苗干重明显降低,种子活力低.     

The sustainability of the common crane (Grus grus) flock breeding in Norfolk: insights from simulation modelling

VORTEX computer simulations were used to assess the viability of a small breeding flock of common cranes, recently established in Norfolk. Investigations were also conducted on the relative impact of various management options. Raising the carrying capacity of the site had little influence on the survival of the flock. However, great improvements were associated with increases in the size of the founder flock and reductions in the mortality rates of chicks and adults. Regularly supplementing the population increased flock survival times: for a fixed total number of birds added, frequently supplementing with few birds produced the best results. Immigration from the population in continental Europe also increased persistence of the flock, and it is possible that immigration rates will improve as the British flock expands. Strategies including captive breeding, and regular supplementation of the flock, may be the most effective means of ensuring the viability of the Norfolk cranes. The potential value of simulation models in guiding management of small populations is discussed.     

The roles of carrying capacity, immigration, and population synchrony on persistence of stream-resident cutthroat trout

Like many other species, cutthroat trout (Oncorhynchus clarki) have declined substantially relative to historic conditions, and many existing populations are isolated. To inform conservation and restoration efforts for stream-resident cutthroat trout, I built a stage-structured stochastic simulation model to explore the dynamics of populations in isolation or connected by immigration. Relatively small increases in carrying capacity substantially reduced extinction risk in small, isolated populations. In the sensitivity matrix, the two most important elements affecting population growth rate were the survival of subadults that became reproductively mature the next year and the survival of young-of-the-year fish. Increasing either of these should allow populations to recover more rapidly from disturbances and reduce extinction risk. When populations were allowed to interact with one another, relatively low immigration rates (=7 individuals/year) between populations substantially reduced extinction risk to those populations without sufficient space to maintain persistence when isolated. However, higher immigration rates were required to maintain persistence the more synchronous the dynamics of interacting populations became. The results highlight the importance of maintaining adequate space or increasing habitat capacity for isolated populations and the importance of connectivity and large population cores if remnant populations are to be maintained.     

Bacteria and protozoa in soil microhabitats as affected by earthworms

The effects of incorporation of elm leaves (Ulmus glabra) into an agricultural sandy loam soil by earthworms (Lumbricus festivus) on the bacterial and protozoan populations were investigated. Three model systems consisting of soil, soil with leaves, and soil with leaves and earthworms, respectively, were compared. The total, viable, and culturable number of bacteria, the metabolic potentials of bacterial populations, and the number of protozoa and nematodes were determined in soil size fractions. Significant differences between soil fractions were shown by all assays. The highest number of microorganisms was found in microaggregates of 2–53 μm and the lowest in the <0.2μm fraction. A major part of the bacteria in the latter fraction was viable, but non-culturable, while a relatively higher number of culturable bacteria was found in the macroaggregates. The number of colony-forming units and 5-cyano-2,3-ditolyl tetrazolim chloride (CTC)-reducing bacteria explained a major part of the variation in the number of protozoa. High protozoan activity and predation thus coincided with high bacterial activity. In soil with elm leaves, fungal growth is assumed to inhibit bacterial and protozoan activity. In soil with elm leaves and earthworms, earthworm activity led to increased culturability of bacteria, activity of protozoa, number of nematodes, changed metabolic potentials of the bacteria, and decreased differences in metabolic potentials between bacterial populations in the soil fractions. The effects of earthworms can be mediated by mechanical mixing of the soil constituents and incorporation of organic matter into the soil, but as the earthworms have only consumed a minor part of the soil, priming effects are believed partly to explain the increased microbial activity. Received: 7 January 1996     

种子热风干燥发芽率的预测

根据谷物种子发芽率损失速率的正态分布理论，建立了种子热风干燥发芽率预测的数学模型。谷物种类包括大麦、小麦、玉米、高梁和大豆。以玉米为例，重点讨论了热风温度与种子初始水分对干燥过程中种子发芽率损失速率的影响。模拟结果表明，随着热风温度的升高和种子初始水分的增大，种子发芽率损失速率将增大。     

影响大豆疫霉菌Phytophthora sojae卵孢子生活力和萌发的因素

研究的目的是寻找一种能够促使大豆疫霉菌卵孢子在短时间内大量萌发的方法。结果表明，卵孢子菌龄、预处理温度、化学物质及其浓度在某种程度上均影响大豆疫霉菌卵孢子的生活力。胡萝卜琼脂平板上24℃密封培养条件下，30d菌龄的卵孢子中只有10.56％处于萌动状态，但经0.4%的KMnO4处理20min 或35℃处理5d后，萌动率分别提高到58.49％和83.55％，但并不萌发。以3ml大豆感病品种Sloan的根系分泌物为培养液，26℃黑暗或光照培养7d即可获得80％以上的卵孢子萌发率。     

Biology and management of Phalaris minor in rice–wheat system

Phalaris minor Retz. (Littleseed canarygrass) is a pernicious weed, which infests several crops during the winter season, particularly the wheat crops in rice–wheat sequence. Considering the limitations of cultural and chemical methods of weed control, the understanding of its biology with respect to different environmental, edaphic and management factors may offer a useful key to strengthen weed management strategies. This review considers various aspects on dormancy, viability and agro-ecology with emphasis on management practices in host and succeeding crops. Due attention has been given to the approaches required to manage the resistant biotypes under present conditions and hence to avoid further escalation of the epidemic. The various studies indicate that P. minor utilizes beneficially the prevailing environmental and management conditions of both the wheat and succeeding rice crop in rice–wheat system for its survival and growth. Its seed is highly sensitive to variable moisture and temperature regimes for germination and exhibits tolerance to anoxia during anaerobic respiration in rice. Tillage options, residue management, spatial–temporal considerations and other factors influence the seed dynamics, pattern and depth of emergence and growth of P. minor. A comprehensive and conceptual understanding of these aspects may provide useful guidelines in formulating cautious and opportunistic weed management strategies.     

千年桐花粉萌发条件筛选及储存研究

[目的]为千年桐花粉萌发及储存提供理论依据。[方法]采用单因素随机试验设计,探讨蔗糖浓度、硼酸浓度、CaCl2以及pH对花粉萌发率的影响,设计4种花粉储存的方法,研究不同方法的储存效果。[结果]在花粉萌发培养基里添加15%～20%的蔗糖、20～30mg/L的硼酸及0.05%～0.10%的CaCl2,并把pH调整到6.0～6.5有利于千年桐花粉萌发;-20℃冷冻干燥贮藏是较好的储存方法,保存10 d后的萌发率仍有25.36%。[结论]该试验解决了千年桐花粉离体萌发和储存的关键问题,具有一定的现实意义。     

大花百子莲的花粉活力与柱头可授性1）

以引种植物大花百子莲为对象,对其在引种地的花粉活力、柱头可授性进行了研究,探讨了两者与授粉成功的关系。结果表明：大花百子莲花粉萌发的最佳培养基为10％蔗糖＋0．1％ H3 BO3＋0．2 g? L-1 Ca（NO3）2;随着开花进程的不断深入,花粉活力不断下降,始花期的花粉活力接近80％,末花期花粉活力只有3％左右;花粉在4℃条件下存活时间约为7 d,25℃条件下存活时间为5 d,而在35℃条件下存活时间只有2 d;大花百子莲花粉在开花当天已具有萌发能力,而柱头在开花第2天具有可授性,因此大花百子莲存在雌雄异熟现象。     

不同稀释液对猪精液4℃保存效果的影响研究

[目的]利用改进的BF-5稀释液（命名为naBF5）,开发一种4℃液态保存猪精子的方法。[方法]把猪精子在LEN、BF5和mBF5这3种稀释液中4℃条件下保存5d,按照保存天数分别检测精子的活力、顶体形态、活率和ATP浓度并进行比较。[结果]在4℃条件下保存的1～2d,精子的活率在3种稀释液中没有显著的差异;但是第3天开始,3种稀释液中的精子活率有显著差异,在mBF5中保存的精子活率显著地高于在LEN和BF5中保存的精子。第1～5天,在mBF5和B巧稀释液中保存的精子正常顶体的百分率高于LEN稀释液中保存的精予;并且,在4℃保存5d后,在mBF5稀释液中保存的精子正常顶体的百分率要高于在BF5中保存的精子。在4℃条件下保存的第1～5天,mBF5稀释液中的精子活力百分率高于LEN和BF5稀释液保存的精子活力。在3种稀释液中,保存的第1～5天,精子活力的百分率都持续地降低。保存的第1～5天,mBF5稀释液中保存的精子ATP浓度比LEN和BF5稀释液中保存的高。保存5d之后3种稀释液中精子ATP浓度都迅速下降。[结论]在4℃条件下保存5d,与LEN和BF5稀释液相比,保存在mBF5稀释液中的精子表现出较高的活力、正常的顶体百分率、活率和ATP浓度。