花椒园棉蚜及其捕食性天敌动态的模糊聚类分析

为了了解花椒园棉蚜捕食性天敌对棉蚜的控制作用,采用模糊聚类方法对花椒园棉蚜及其捕食性天敌种群的动态进行分析。结果表明,对不同时期的棉蚜及其捕食性天敌的种群进行模糊聚类得出结果,棉蚜种群的17次调查结果可以聚为7类,λ=0.8300;其捕食性天敌的调查结果同样聚为7类,λ=0.9400。聚类结果阐明了花椒园中棉蚜及其捕食性天敌随季节变化的差异;同时反映了棉蚜的种群消长与其捕食性天敌的数量密切相关,是抑制花椒园棉蚜种群消长的主要因素之一。     

黑穗醋粟(Ribes nigum L.)苗端结构的研究

本文对黑穗醋栗的苗端结构进行了研究,其结果表明,黑穗醋栗不同品种(厚皮、薄皮)的营养苗端结构相似,呈分区图样,包括原套、亚外套、中央母细胞区及肋状分生组织区。黑穗醋栗不同品种的生殖苗端结构及分化过程相似,但时序不同;薄皮品种的分化进程早于厚皮品种。     

马铃薯茎尖脱毒培养关键因子分析

对马铃薯茎尖脱毒培养关键因子方面进行了分析,综合论述了马铃薯茎尖培养脱毒的原理,影响马铃薯茎尖培养脱毒的因素和培养条件的控制,并针对脱毒难的问题提出了提高脱毒率诸如结合化学处理等的有效措施,指出了茎尖培养脱毒中尚存在的一些问题以及相应对策。     

Prey depletion caused by overfishing and the decline of marine megafauna in eastern Ionian Sea coastal waters (central Mediterranean)

Surveys primarily aimed at determining dolphin encounter rates were conducted from small inflatable craft in eastern Ionian Sea coastal waters between 1997 and 2004. During 633 surveys totalling 21,276 km of effort, observations of cetaceans and other marine species spotted in a study area of 480 km² were systematically recorded. Common dolphin encounter rates declined 25-fold across the study period, steadily decreasing from 2.18 encounters/100 km in 1997 to 0.09 encounters/100 km in 2004. Encounter rates of tuna also declined significantly. Swordfish encounter rates dropped from 1.03 encounters/100 km in 1997 to 0-0.12 in 1998-2004. Encounter rates of bottlenose dolphins did not show significant trends. The decline of high-order marine predators feeding on epipelagic prey was consistent with the hypothesis of prey depletion, likely resulting from intensive exploitation of local fish stocks, particularly anchovies and sardines. The catholic feeding habits and opportunistic behaviour of bottlenose dolphins may allow them to withstand the effects of overfishing at their present low density.     

高粱茎尖再生体系及其遗传转化影响因子的研究

本文对高粱茎尖再生体系及其转化影响因子进行了研究。不同基因型的茎尖再生频率有很大差异,说明基因型是影响茎尖再生的一个重要因素。在9种不同的激素组合中,以0.25MG/L KT、0.5MG/LBAP和0.25MG/L IAA对茎尖的再生效果最好。在MS培养基的基础上,采用B5培养基维生素并添加200MG/L L-ASN,10MG/L抗坏血酸和100MG/L PVP可提高茎尖再生频率。对农杆菌介导高粱茎尖转化的因子进行了优化,获得较高转化频率的条件为:茎尖预培养时间3D,在OD600值为0.5农杆菌菌液中感染10MIN,共培养3D。     

氮肥施用时期对小麦不同茎蘖位顶端发育的调控效应

氮素营养是影响小麦顶端发育的重要因子。本研究表明 ,分别于护颖原基分化期、雌雄蕊原基分化期和药隔分化期施用氮肥 ,尽管均未影响到主茎叶原基数 ,以及主茎 (MS)和T1、T2分蘖 (主茎第 1、2分蘖 )的总小穗数 ,但是明显加快了主茎的出叶速率 ,减少了各主要茎蘖 (MS、T1、T2、T3)不孕小穗数。此外 ,护颖和雌雄蕊原基分化期施用氮肥 ,能够促进上述主要茎蘖小花原基的分化 ,增加其总小花数 ;而护颖至药隔分化期施用氮肥则明显促进了MS、T1、T2和T3的小花结实。研究结果为高产小麦栽培调控和生长模拟提供了依据。     

Impacts of ski-development on ptarmigan (Lagopus mutus) at Cairn Gorm, Scotland

This paper reports adverse impacts on numbers and breeding success of ptarmigan (Lagopus mutus) in 1967-1996 at a ski area in the Cairngorms massif, where ptarmigan normally show 10-year population cycles. An influx of carrion crows (Corvus corone), generalist predators, followed the development. On the most developed area near the main car park, ptarmigan occurred at high density but then lost nests to frequent crows, reared abnormally few broods, died flying into ski-lift wires and declined until none bred for many summers. On a nearby higher area with fewer wires, ptarmigan lost nests to frequent crows and reared abnormally few broods, but seldom died on wires. Adult numbers declined and then became unusually steady for over two decades, with no significant cycle. On a third area further from the car park, ptarmigan lost fewer nests to the less frequent crows but bred more poorly than in the massif’s centre, and showed cycles of lower amplitude than there. On a fourth area yet further away, with few or no crows, ptarmigan bred as well as in the massif’s centre and showed cycles of the same amplitude as there.     

Variation in developmental patterns of wild barley (Hordeum spontaneum L.) and cultivated barley (H. vulgare L.)

Summary Six wild barley (Hordeum spontaneum) accessions, from a diverse range of habitats, and two spring-cultivated barleys, were examined for variation in durations of development phases. The durations of the leaf initiation and spikelet initiation phases were longer and spikelet growth phases shorter, in wild than in cultivated barley. Across all wild and cultivated barleys the rate and duration of spikelet initiation were negatively correlated, but neither was related to the number of spikelets per spike. The number of spikelets was positively correlated with the number of leaves and the ratio of the number of spikelets to the number of leaves declined with increasing time to anthesis, indicating that each successive leaf was associated with a diminishing increase in the number of spikelets. The duration of culm elongation and final culm length were shorter in accessions of cultivated barley compared with wild barley. This paper also discusses the feasibility for increasing the number of spikelets per spike through breeding for genetic changes in lengths of pre-anthesis phases of development.Abbreviations ANOVA Analysis of variance - HV Hordeum vulgare - CE Culm elongation - DR Double ridge - HS Hordeum spontaneu - ° Cd Degree days     

黄秋葵子叶离体再生体系的建立

以带子叶和部分下胚轴的顶芽为外植体,建立再生体系。结果表明,下胚轴长度为2 mm时有利于不定芽的形 成,7-10 d苗龄的外植体最易诱导出不定芽,芽分化和生长的最适温度为25±1℃。6-BA<1 mg／L不定芽难以发 生,6-BA 6+NAA 0.1有利于不定芽形成;CA3 2.0可以提高不定芽的诱导率。