孕穗期低温对冬小麦生理生化特性和产量的影响

为明确孕穗期低温对小麦生理生化特性和产量的影响,以‘小偃22’等5个冬小麦品种为材料,对其在低温（2±1） ℃胁迫下叶片中超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性、丙二醛(MDA)含量、相对电导率、可溶性糖含量、脯氨酸含量和可溶性蛋白含量等生理指标进行测定,并测定单株产量。结果表明:（1）与对照相比,低温胁迫24 h和48 h后,供试品种叶片SOD活性、POD活性、CAT活性、MDA含量、相对电导率、可溶性糖含量和脯氨酸含量均显著增加,而可溶性蛋白含量显著降低。（2）低温胁迫使各品种单株籽粒产量和单株穗粒数显著下降,但对小穗数和千粒重的影响不大。（3）经隶属函数分析,‘小偃22’、‘矮抗58’和‘西农509’属于抗寒性较强的品种,而‘郑麦9023’和‘郑麦366’为抗寒性较弱的品种,这与它们在试验中的籽粒产量表现相符。研究发现,与抗寒性弱的小麦品种相比,抗寒性强的品种在相同低温下具有相对较高的保护酶活性、较强的渗透调节物质积累能力和较低的质膜破坏程度,这是其在低温胁迫后能维持较高产量的生理基础。     

新疆野核桃种质对低温胁迫的生理响应

以新疆巩留野核桃林37份新疆野核桃种质资源的1年生枝条为材料,6份核桃楸为对照,利用人工气候箱模拟春季低温,分别于-20 ℃和4 ℃处理12 h,测定其相对电导率、游离脯氨酸、可溶性糖、丙二醛含量、过氧化物酶活性等生理生化指标,并进行相关分析。采用隶属函数和主成分分析综合评价核桃种质对低温的生理响应。结果表明: 低温胁迫下,新疆野核桃相对电导率、游离脯氨酸含量、可溶性糖含量、丙二醛含量和过氧化物酶活性均呈上升趋势。综合评价其低温抗性与生境相关:巩留野核桃林中沟>东沟>西沟>主沟。新疆野核桃表现出比核桃楸更为耐低温的特性。本研究从37份新疆野核桃种质中筛选出7份耐低温种质,为改良核桃品种和提高核桃耐倒春寒等生长期的突然天气变化的能力提供科学参考。     

低温胁迫下菠萝幼苗生长与生理特性变化

以国内外10个菠萝品种幼苗为材料,研究了它们在低温胁迫下的生长及其渗透调节物质、细胞膜透性的变化特征,并综合评价它们的耐寒性.结果表明:(1) 随低温处理时间的延续,各品种幼苗单株干重虽然均呈逐渐增加趋势,但不同品种生物量增加幅度存在显著差异.(2) 随着低温处理时间的延长,各品种叶片脯氨酸含量和细胞膜相对透性逐渐升高;可溶性蛋白含量总体上初期升高后期降低,而‘巴厘'、‘珍珠'、‘台农17号'、‘台农19号'和‘MD-2'的可溶性蛋白在处理末期又有所上升;可溶性糖含量变化趋势复杂.(3) 低温胁迫处理9 d后,各菠萝品种叶片中的脯氨酸和可溶性蛋白含量及细胞膜相对透性均增加;可溶性糖含量除‘珍珠'略有减少外,其余均增加.(4)经过各指标赋分分级综合评价后认为,‘MD-2'和‘巴厘'品种耐寒性最强;‘台农17号'、‘台农16号'、‘巴厘突变体'、‘台农13号'、‘台农19号'和‘无刺卡因'耐寒性中等;‘珍珠'和‘台农6号'耐寒性最弱.研究发现,菠萝耐寒性强弱可根据干物质积累结合其它生理指标来综合评判.     

不同福禄考品种对低温胁迫的生理响应及抗寒性综合评价

通过对14个福禄考品种在低温胁迫下相关生理指标进行分析,结果表明:可溶性糖含量随处理温度降低呈"升降升降"的变化趋势;可溶性蛋白含量随处理温度降低呈"降升降降"的变化趋势;不同品种脯氨酸、叶绿素、丙二醛含量和超氧化物歧化酶活性变化趋势不同,差异达到显著水平。运用主成分分析法和聚类分析法对14个福禄考品种进行抗寒性排序,将其分为3个抗寒等级:强抗寒品种为‘Sub-05’、‘Sub-Ja-03’和‘Sub-Ja-04’;中抗寒品种为‘Sub-Ja-01’、‘Sub-Ja-02’、‘Sub-06’、‘Sub-07’、‘Pan-02’和‘Pan-Ru-07’;弱抗寒品种为‘Pan-01’、‘Pan-Ru-06’、‘Pan-05’、‘Pan-04’和‘Pan-03’。丛生福禄考品种抗寒性优于锥花品种,与露地越冬观察的结果基本一致。     

Na2CO3胁迫对黄瓜幼苗生长及生理指标的影响

以‘津优一号’和‘春四’黄瓜为实验材料,采用砂培法研究了Na2CO3胁迫对黄瓜幼苗生长及生理指标的影响。结果显示,随着Na2CO3浓度的增大,两个黄瓜品种的幼苗根冠比逐渐下降,叶绿素含量先上升后下降,可溶性糖含量、脯氨酸含量、SOD活性逐渐上升;‘津优一号’的相对电导率和丙二醛含量随Na2CO3浓度的增大逐渐增加,而‘春四’的相对电导率和丙二醛含量在20 mmol.L-1时最低,此后逐渐上升。主成分分析结果显示,丙二醛含量、SOD活性、可溶性糖含量、脯氨酸含量、叶绿素b,这5项指标在评价黄瓜幼苗的Na2CO3耐性方面是比较重要的。结合这5项指标综合分析,发现‘津优一号’较‘春四’有较强的耐碱性。     

水分和氯化钙胁迫对麦冬抗逆性生理指标的影响

为研究麦冬在水分胁迫和盐分胁迫条件下一些抗逆性生理指标的变化,本文以盆栽后以正常浇水处理为对照,设置了不同程度人工水分胁迫和钙离子胁迫处理研究可溶性糖含量、脯氨酸含量及丙二醛含量的变化情况.结果显示,轻度水分胁迫使可溶性总糖和游离脯氨酸含量减低.但随着时间的推移,胁迫程度加剧,可溶性总糖和游离脯氨酸含量开始回升,而MDA含量无显著变化.表明水分胁迫下.麦冬可积累可溶性糖和游离脯氨酸等渗透调节物质,从而改善自身水分状况,保护细胞膜及生理代谢过程,膜脂过氧化程度减轻.钙盐胁迫也可使可溶性总糖和游离脯氨酸含量升高.     

火龙果幼苗对低温胁迫的生理响应及其抗寒性综合评价

以野生火龙果量天尺和贵州主栽品种‘紫红龙’、‘晶红龙’、‘粉红龙’扦插幼苗为试材,人工控温进行抗寒锻炼、低温冷害处理及恢复生长,以未处理作对照,测定不同处理下幼苗的电解质渗出率(REC)、可溶性糖、可溶性蛋白、游离脯氨酸和丙二醛(MDA)含量的变化。结果表明,电解质渗出率随温度降低逐渐增加,恢复生长后电解质渗出率与对照之间没有显著差别。幼苗中的可溶性糖、可溶性蛋白、脯氨酸及丙二醛含量在抗寒锻炼和低温处理后升高,恢复生长后降低。可溶性糖和脯氨酸含量随不同处理变幅较大,MDA和可溶性蛋白随不同处理变幅较小。运用Fuzzy数学中隶属函数法进行抗寒性综合评价,得出火龙果抗寒性强弱表现为量天尺>‘晶红龙’>‘粉红龙’>‘紫红龙’,与恢复生长的试验结果基本一致。     

甜瓜幼苗叶片内源一氧化氮和蔗糖代谢对低温胁迫的响应

以低温敏感型甜瓜品种‘XL-1’和耐低温型品种‘红优’为试材,采用6℃低温处理0、1、3、6、12、24h及3d、5d和7d,研究低温胁迫下甜瓜幼苗叶片中NO合成和蔗糖代谢的变化特征。结果表明:(1)低温胁迫能提高甜瓜幼苗叶片中硝酸还原酶(NR)活性,诱导促进NO生成,其中耐低温型甜瓜‘红优’中NO对低温的响应时间更早,变化幅度更大。(2)与对照相比,低温胁迫处理提高了2种甜瓜幼苗叶片中蔗糖、果糖和葡萄糖含量,增加了蔗糖磷酸合成酶(SPS)、蔗糖合成酶(SS)、酸性转化酶(AI)和中性转化酶(NI)活性,降低了淀粉含量。(3)低温胁迫处理使2种甜瓜叶片中渗透调节物质可溶性糖、可溶性蛋白、脯氨酸的含量上升。研究发现,低温胁迫通过增加甜瓜体内NO合成酶的活性刺激体内NO合成,通过促进蔗糖代谢相关酶的活性,提高蔗糖、果糖和葡萄糖的含量,从而响应低温胁迫,且低温胁迫诱导的糖分物质积累时间晚于NO的产生时间。     

高温和干旱胁迫对鳞叶藓游离脯氨酸和可溶性糖含量的影响

研究了高温和干旱胁迫对鳞叶藓 (Taxiphyllumtaxirameum)游离脯氨酸和可溶性糖含量的影响。结果显示 ,高温和干旱均能诱导植物体内可溶性糖的积累。在 60℃高温胁迫下处理 ,可溶性糖含量随处理时间的延长而增加 ,最高值比对照增加了 2倍。PEG 60 0 0胁迫下处理可使可溶性糖含量分别增加 2 .4倍。经统计学检验 ,逆境条件与游离脯氨酸含量变化无关     

不同红小豆品种幼苗对干旱胁迫的生理响应

为筛选红小豆（Phaseolus angularis Linn.）幼苗抗旱性鉴定指标,采用盆栽控水方法,对红小豆3个品种‘保红947’、‘东北大红袍’、‘晋小豆5号’进行了苗期形态特征及根系生理生化特性的研究。结果表明：干旱胁迫抑制了红小豆3个品种植株的生长;重度干旱胁迫下,3个品种光系统Ⅱ（PSⅡ）的潜在活性（可变荧光/初始荧光,Fv/Fo）、最大光化学效率（可变荧光/最大荧光产量,Fv/Fm）、株高、叶面积、茎粗、根鲜重、根系活力、可溶性蛋白质含量等指标均随干旱胁迫强度的增加呈明显下降趋势,根冠比、根系脯氨酸（Pro）含量、可溶性糖含量、SOD活性、POD活性、MDA含量等指标随着干旱胁迫强度的增加呈明显上升趋势。综合各项生理指标,‘东北大红袍’在干旱胁迫下能保持相对较优的生理状态,抗旱性最强。通过主成分分析表明,株高、叶面积、茎粗、主根长、根鲜重、最大光化学效率、根系活力、可溶性糖含量、可溶性蛋白质含量、SOD活性、MDA含量等生理生化特性可作为鉴定红小豆苗期抗旱性的指标。     

Foreign exploration for Scirtothrips perseae Nakahara (Thysanoptera: Thripidae) and associated natural enemies on avocado (Persea americana Miller)

Scirtothrips perseae Nakahara was discovered attacking avocados in California, USA, in 1996. Host plant surveys in California indicated that S. perseae has a highly restricted host range with larvae being found only on avocados, while adults were collected from 11 different plant species. As part of a management program for this pest, a “classical” biological control program was initiated and foreign exploration was conducted to delineate the home range of S. perseae, to survey for associated natural enemies and inventory other species of phytophagous thrips on avocados grown in Mexico, Guatemala, Costa Rica, the Dominican Republic, Trinidad, and Brazil. Foreign exploration efforts indicate that S. perseae occurs on avocados grown at high altitudes (>1500 m) from Uruapan in Mexico south to areas around Guatemala City in Guatemala. In Costa Rica, S. perseae is replaced by an undescribed congener as the dominant phytophagous thrips on avocados grown at high altitudes (>1300 m). No species of Scirtothrips were found on avocados in the Dominican Republic, Trinidad, or Brazil. In total, 2136 phytophagous thrips were collected and identified, representing over 47 identified species from at least 19 genera. The significance of these species records is discussed. Of collected material 4% were potential thrips biological control agents. Natural enemies were dominated by six genera of predatory thrips (Aeolothrips, Aleurodothrips, Franklinothrips, Leptothrips, Scolothrips, and Karnyothrips). One genus each of parasitoid (Ceranisus) and predatory mite (Balaustium) were found. Based on the results of our sampling techniques, prospects for the importation of thrips natural enemies for use in a “classical” biological control program in California against S. perseae are not promising.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

Biological control of three floating water weeds,<Emphasis Type="Italic">Eichhornia crassipes,Pistia stratiotes</Emphasis>, and <Emphasis Type="Italic">Salviniamolesta</Emphasis> in the Republic of Congo

Since 1999, four specific weevils (Coleoptera, Curculionidae) were released in the Republic of Congo against three exotic floating water weeds: Neochetina eichhorniae Warner and N. bruchi Hustache against water hyacinth, Neohydronomus affinis Hustache against water lettuce, and Cyrtobagous salviniae Calder and Sands against water fern. Recoveries of exotic weevils were made from all 24 release sites except one, and all four species have established and spread (up to 800 km for water hyacinth weevils). Within a few years of releases, control of water fern and water lettuce was such that fishing and navigation could be resumed, while reductions of water hyacinth populations were only beginning.     

A molecular phylogeny of Hebeloma species from Europe

In order to widen the scope of existing phylogenies of the ectomycorrhizal agaric genus Hebeloma a total of 53 new rDNA ITS sequences from that genus was generated, augmented by sequences retrieved from GenBank, and analysed using Bayesian, strict consensus and neighbour joining methods. The lignicolous Hebelomina neerlandica, Gymnopilus penetrans, and two species of Galerina served as outgroup taxa. Anamika indica, as well as representatives of the genera Hymenogaster and Naucoria, were included to test the monophyly of Hebeloma, which is confirmed by the results. Hebeloma, Naucoria, Hymenogaster and Anamika indica cluster in a strongly supported monophyletic hebelomatoid clade. All trees largely reflect the current infrageneric classification within Hebeloma, and divide the genus into mostly well-supported monophyletic groups surrounding H. crustuliniforme, H. velutipes, H. sacchariolens, H. sinapizans, and H. radicosum, with H. sarcophyllum being shown at an independent position; however this is not well supported. The section Indusiata divides with strong support into three groups, the position of the pleurocystidiate Hebeloma cistophilum suggests the possible existence of a third subsection within sect. Indusiata. Subsection Sacchariolentia is raised to the rank of section.     

Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Die GattungKarschia — Bindeglied zwischen bitunicaten Ascomyceten und lecanoralen Flechtenpilzen?

The genusKarschia, in the earlier sense, including saprophytes and parasites on lichens, has been thought to be a non-lichenized parallel genus of the lichen genusBuellia. Modern workers included it on the one hand inBuellia, on the other hand combined it with bitunicate ascomycetes. It is now proved thatKarschia is heterogeneous and contains but superficially similar members both of the genusBuellia of theLecanorales and of typical or masked bitunicateAscomycetes. Therefore, it can not be regarded as a link betweenLecanorales andDothideales. The type species ofKarschia belongs to theDothideales.

     

Demographic characteristics of an intertidal bay goby (Lepidogobius lepidus)

Synopsis In a fourteen month study (May 1976 – June 1977) I examined the following characteristics of an intertidal bay goby (Lepidogobius lepidus) in Morro Bay, California, U.S.A.: annual and seasonal patterns of abundance, age composition and growth rates, survivorship and mortality patterns, and the reproductive cycle for female gobies. Fishes were collected with the aid of quinaldine and otoliths and ovaries removed. Age and growth rates were estimated from otolith annuli using a back calculation formula and a Brody-Bertalanffy growth curve. Mortality rates were derived using the methods of Heincke (1913), Robson & Chapman (1960), mean age, and a catch curve (Ricker 1975). A gonad index was used to describe the annual reproductive cycle. Results indicated that abundance fluctuated seasonally and that these fluctuations appeared to be caused by reproductive emigrations. Bay gobies reached an age of 7+ and a standard length of 87 mm. Growth was relatively constant (6 mm yr⁻¹) until age 5, at which point it began to decline. The mean rates of survivorship, mortality, and instantaneous mortality were 0.75, 0.25, and 0.29 respectively. Mortality rates for individual age classes ranged from 0.13 to 0.51 and increased with age. This stock appears to reproduce mainly during the winter.     

Systematic significance of mature embryo of bamboos

The mature embryo of seven species belonging to five genera of Indian bamboos is described. In all these the basic pattern of embryo organisation is same: the scutellar and coleoptilar bundles are not separated by an internode, the epiblast is absent, the lower portion of the scutellum and the coleorhiza are separated by a cleft and the margins of embryonic leaves overlap. The features unique to fleshy fruited bamboos are: presence of a massive scutellum, the juxtaposition of plumule and radicle and the occurrence of a bud in the axil of the coleoptile. The fleshy fruit bearing bamboos should be classified into one group, the tribeMelocanneae. Evidence is provided to recognise additional groups in the subfamilyBambusoideae.