遮阴对南山茶与红皮糙果茶幼苗生长及生理特性的影响

以2年生南山茶Camellia semiserrata、红皮糙果茶C. crapnelliana实生苗为试材，研究全光照(CK)、30%遮阴、50%遮阴和70%遮阴等处理对其生长、生物量分配及叶片部分生理生化指标的影响。结果表明，30%遮阴可显著增加南山茶幼苗株高净生长量、总生物量，其叶绿素a、叶绿素b显著增加，SOD、CAT酶活性及Pro含量均与CK组无显著差异，MDA含量则显著降低；红皮糙果茶幼苗则在30%遮阴下显著增加株高和地径，叶绿素a、叶绿素b含量及SOD酶活性、Pro含量与CK组无差异，MDA含量显著下降。说明两种山茶属植物幼苗较适宜的光照条件为遮阴30%。此外，红皮糙果茶幼苗在50%遮阴条件下与CK组比较，虽然地径生长受抑制，但株高生长无显著差异，且叶绿素a、叶绿素b含量与CAT酶活性显著增加，Pro、MDA含量显著下降，表明红皮糙果茶幼苗能通过调节叶绿素含量、CAT酶活性和Pro含量积极应对50%遮阴的弱光环境，进行适应性生长。因此生产上及绿化应用中，南山茶幼苗对光照的需求更为严格，遮阴控制在30%；红皮糙果茶幼苗则可适应更加荫蔽的环境(50%遮阴)。     

遮阴对闽楠叶绿素含量和光合特性的影响

为探讨闽楠对不同光环境的光合适应机制,以2年生闽楠幼苗为材料,设置3个光照处理(全光照、遮光率50%和遮光率78%),适应6个月后,测定其叶绿素含量、气体交换和叶绿素荧光同步数据,研究不同光环境处理对闽楠叶片叶绿素含量、叶绿素荧光参数和光合特性的影响.结果表明: 3种光照处理下,闽楠叶片叶绿素a、叶绿素b、叶绿素(a+b)和类胡萝卜素含量大小次序为78%遮光率>50%遮光率>全光照,但不同光照处理对闽楠叶绿素a/b值没有显著影响.遮阴条件下,闽楠叶片光补偿点(LCP)降低,光饱和点(LSP)和表观量子效率(AQY)升高,说明遮阴条件下闽楠叶片对弱光和强光的利用能力均有所提高;最大净光合速率(P_{n max})、光下暗呼吸速率(R_d)和最大电子传递速率(J_max)均增大.在不同处理间,闽楠叶片净光合速率(P_n)、CO₂气孔导度(g_sc)、胞间CO₂浓度(C_i)和叶肉导度(g_m)均存在显著差异.P_n和g_m的大小顺序为: 78%遮光率>50%遮光率>全光照.78%遮光率处理下g_sc显著大于全光照.50%遮光率条件和78%遮光率条件下C_i均显著小于全光照.78%遮光率条件下PSⅡ实际光量子产量(F_v′/F_m′)、PSⅡ光化学效率(Φ_PSⅡ)和电子传递速率(J)均显著大于50%遮光率条件和全光照.由此可知,在遮阴条件下闽楠可以通过增加叶绿素含量、AQY、J、g_sc和g_m来增大光合能力.     

不同遮阴环境下木奶果幼苗生长与生理生化的响应

木奶果是一种在幼苗期和成熟期对光适应性不同的热带乔木树种。研究不同遮阴环境下木奶果幼苗的生长及生理响应机制,以明确木奶果幼苗生长的适宜光照环境范围,对木奶果的苗木栽培及生态应用意义重大。本试验设置了5个处理,即CK(无遮阴),S3(遮光率45.3%)、S4(遮光率69.2%)、S6(遮光率80.0%)和S8(遮光率90.2%),观测停扣山和谢鞋山种源的木奶果幼苗4个月后的生长生理变化情况。结果显示:随着遮阴强度的加大,木奶果幼苗的叶面积与光合色素含量一直上升;叶绿素a/b值和过氧化氢酶(CAT)活性一直下降;丙二醛含量在S6前先呈下降趋势,而后稍有上升;株高和地径增长量先升后降,相对电导率、脯氨酸(Pro)与可溶性糖(Ss)含量则表现为先降后升。强光环境下,木奶果幼苗通过增加类胡萝卜素相对含量与CAT活性,以减缓膜脂过氧化损害;弱光环境下,木奶果幼苗通过增加叶面积与光合色素含量提高光能利用率。Pro与Ss则作为综合调节物,调节渗透压,以减轻强光与弱光带来的细胞膜胁迫压力。其中,停扣山与谢鞋山种源分别在S6与S4处理下Pro与Ss含量达最低值且株高与地径增长量达最高值。表明幼苗期的木奶果具有阴生植物的特性,强光或重度遮阴都会在一定程度上抑制其生长。停扣山种源木奶果幼苗比谢鞋山种源更耐阴,反映了其种源地长期光强环境差异的影响。     

遮阴对四季桂生理生态特性的影响

为了解遮阴对四季桂(Osmanthus fragrans)生长的影响,研究了成都地区夏季遮阴处理下四季桂扦插苗生理生态特性的变化。结果表明,随遮光率增加,比叶重下降;叶绿素b(Chl b)含量增加,Chl a/b降低。遮阴下叶片可溶性糖、可溶性蛋白含量降低,以80%遮光率下降的最显著;随遮光率上升,叶片丙二醛(MDA)含量下降,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性降低,以55%、80%遮光率的MDA含量下降显著。遮阴处理下,叶片光饱和点(LSP)、光补偿点(LCP)、最大净光合速率(Pmax)、暗呼吸速率(Rd)均下降,而表观量子速率(AQE)增大;瞬时光能利用率(LUE)升高,净光合速率(Pn)、气孔导度(Gs)、气孔限制值(Ls)均降低,胞间CO_2浓度(Ci)升高。四季桂幼苗主要通过提高Pn和抗氧化酶活性来适应强光环境;降低SLW、LSP、LCP和Rd,提高Chl和Ci含量,增大AQE和LUE提高弱光利用能力,中度遮阴(25%、55%遮光率)有利于幼苗在夏季的生长。     

滤光膜对喜树幼苗叶片生长和喜树碱含量的影响

喜树 (Camptotheca acuminata)为中国特有树种 ,因其次生代谢产物喜树碱具有抗癌作用而闻名。通过用黄色、红色、蓝色 3种滤光膜对温室栽培的喜树幼苗进行遮光处理 ,研究了不同光照环境下喜树幼苗叶片生物量、叶绿素含量、光合作用和喜树碱含量的差异。结果表明在 30 d的遮光过程中 ,红膜和蓝膜遮光明显导致幼苗叶片生物量降低 ,黄膜遮光下幼苗叶片生物量在处理后 2 5 d才表现明显降低。不同滤光膜下幼苗叶片叶绿素含量先降低然后升高 ,遮光幼苗的叶绿素 a/ b明显低于日光幼苗。幼苗日最大净光合速率的顺序是 :日光 >黄膜 >红膜 >蓝膜。处理后第 2 0天 ,不同滤光膜下幼苗的光饱和光合速率 (Amax)、光饱和点 (Is)、光补偿点 (Ic)、最大表观量子效率 (AQYmax)都不同程度的低于日光幼苗。处理后第 10天至第 30天 ,遮光幼苗叶片喜树碱含量均显著高于日光下幼苗 ,以蓝膜下幼苗的喜树碱含量最高。蓝膜和黄膜下幼苗的喜树碱产量在后期处理中显著高于日光下幼苗 ,蓝膜下幼苗喜树碱产量在第 30天最高 ,是日光下幼苗的 2 .4 9倍。红膜下幼苗的喜树碱产量在第 10天后与日光下幼苗差异不显著。通过滤光膜遮光促进喜树碱在幼苗叶片中的积累 ,提高了叶片喜树碱产量 ,对喜树碱的生产实践有一定的意义     

遮光对臭牡丹生长和光合特性的影响

对全光照(遮光率0％,对照)以及遮光率25％ 、50％和75％条件下臭牡丹(Clerodendrum bungei Steud.)生长和光合特性的变化进行了研究.结果表明:随遮光率的提高臭牡丹枝长生长量和比叶面积逐渐增加、枝条直径生长量和比叶质量逐渐减小,叶面积呈波动变化,其中在遮光率25％条件下叶面积最小.在遮光条件下叶片以及栅栏组织和海绵组织厚度差异不显著,但均显著小于对照.在遮光条件下叶片叶绿素a和总叶绿素含量以及叶绿素a/b值总体上随遮光率提高逐渐增加且均高于对照,仅在遮光率25％条件下叶绿素b以及总叶绿素含量低于对照.在遮光率25％和75％条件下叶片净光合速率(Pn)有明显“午休”现象,Pn日变化曲线近似于“双峰型”;而在对照和遮光率50％条件下Pn无“午休”现象,日变化曲线近似于“单峰型”;4个处理组Pn峰值的大小以及峰值出现时间有差异.在上午9:00,在遮光率25％和50％条件下叶片气孔导度(Gs)略有降低,而在对照和遮光率75％条件下Gs明显升高;此后随时间的延长各处理的Gs总体上呈逐渐下降的趋势.各处理组叶片胞间CO2浓度(Ci)的日变化曲线基本一致,均呈早晚略高、中午略低的趋势,谷值均出现在13:00.在对照及遮光率25％和75％条件下,叶片蒸腾速率(Tr)的日变化曲线均呈“双峰型”;而在遮光率50％的条件下Tr呈逐渐降低的趋势,日变化曲线近似于“单峰型”.总体上看,4个处理组叶片的Pn、Gs、Ci和Tr日平均值均无显著差异;且在遮光率25％、50％和75％条件下臭牡丹叶片的Pn与Tr间有显著或极显著相关性.综合分析结果表明:臭牡丹是偏阴生植物,在栽培中适度遮光有利于臭牡丹的生长发育.     

光照和水分对四季米仔兰幼苗生长的影响

四季米仔兰栽培历史悠久,是重要的造景树种。以1年生四季米仔兰幼苗为研究对象,设置3个光照处理(透光度为70%、50%、30%)和3个水分处理(田间持水量为70%、50%、30%),以透光度90%、田间持水量90%为对照,分析不同环境条件下四季米仔兰幼苗的生长状况和光合生理指标。结果表明：干旱胁迫和遮光抑制四季米仔兰幼苗的生长,且干旱胁迫的影响大于遮光。随着土壤水分的减少,株高增量、地径增量、净光合速率、蒸腾速率、气孔导度和叶绿素含量均显著降低,最大降幅分别为71.4%、81.2%、93.2%、71.5%、70.6%、30.4%;适当遮光(透光度50%)可缓解严重水分亏缺(田间持水量30%)对四季米仔兰幼苗生长的不利影响。透光度70%和田间持水量70%条件下株高增量、叶面积、净光合速率、蒸腾速率和气孔导度最大。最大荧光、可变荧光、PSⅡ潜在活性、PSⅡ最大光能转化效率随着水分减少呈先上升后下降趋势。四季米仔兰幼苗能够通过调整生长、提高叶绿素含量和调节光合系统来维持光合作用以适应胁迫环境。透光度70%和田间持水量70%有利于四季米仔兰幼苗光合作用的发挥,对其生长有积极影响。     

光强和施肥对杜鹃红山茶成花品质的影响

杜鹃红山茶(Camellia azalea)为我国特有的珍稀濒危植物, 因四季都能开花且花色鲜艳, 具有较高的观赏价值,目前还没有影响其花观赏品质的研究。研究光照和施肥对杜鹃红山茶花瓣花青素含量和花芽数的影响。研究发现, 光照强度导致花芽数量改变, 但高光照(全光照和 80%自然光照)和过低光照环境(20%自然光照)均不利于其花瓣中花青素的积累, 50%自然光照下花青素含量显著高于其他光照环境下花青素含量。 施肥能促进杜鹃红山茶开花, 但对花色没有显著影响。研究指出, 为提高杜鹃红山茶的观赏品质, 其生长环境可参考 50%自然光照,并适当施肥。     

种子大小和干旱胁迫对辽东栎幼苗生长和生理特性的影响

在温室内遮阴条件下,设置80%、60%、40%和20%田间持水量(对照、轻度、中度和重度干旱)4个处理,研究种子大小和干旱胁迫对盆栽辽东栎幼苗生长和生理特性的影响。结果表明: 大种子(3.05±0.38 g)幼苗的单株叶面积、总干质量和根冠比在所有处理均显著大于小种子(1.46±0.27 g)幼苗,前者的株高、基径、叶片数、比叶面积、相对生长率和净同化率等生长参数在轻度、中度和重度干旱处理均不同程度大于后者。大种子幼苗叶片过氧化物酶(POD)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性均高于小种子幼苗,前者叶片丙二醛(MDA)、可溶性蛋白、游离脯氨酸含量和叶绿素总量在部分干旱处理显著大于后者。除根冠比外,其他生长参数均随干旱胁迫增强逐渐减小,重度干旱处理大、小种子幼苗总干质量分别比对照降低19.4%和20.0%。POD、CAT和SOD活性均随干旱胁迫增强先升后降,在中度干旱处理,大、小种子幼苗POD活性分别显著高于对照126.7%和142.1%,CAT活性分别显著高于对照170.0%和151.9%。在重度干旱处理,大、小种子幼苗MDA含量分别显著高于对照86.5%和68.9%。可溶性蛋白、游离脯氨酸含量和叶绿素总量均随干旱胁迫增强先升后降,在中度干旱处理,大、小种子幼苗可溶性蛋白含量分别显著高于对照320.7%和352.7%。辽东栎大种子幼苗可依赖其生长和生理方面的优势比小种子幼苗具有更强的干旱耐受性,在退化次生林人工辅助实生更新中应优先选用抗逆性更强的大种子幼苗。     

遮阴对绣球光合特性和叶绿素荧光参数的影响北大核心CSCD

为了从光合作用机制及叶片吸收光能分配的角度解释绣球(Hydrangea macrophylla)对不同光环境的适应机制,探讨绣球对光环境变化的生理响应和适应性,该文以盆栽的绣球品种‘无尽夏新娘’为材料,设置遮阴(遮光率为50%、75%)两种处理,并以全光照为对照,经过60天的处理,测定其光合-光响应曲线、气体交换参数、叶绿素荧光参数。结果表明:遮阴60天后,绣球的暗呼吸速率、光补偿点和光饱和点均有所下降,而表观量子效率(AQY)上升,说明绣球能够通过这些途径提高对弱光的利用能力并降低呼吸消耗,以维持植株正常生长,从而表现出了极强的适应能力;在50%的遮阴处理下,绣球叶片的净光合速率、胞间CO2浓度、蒸腾速率和水分利用效率均与其全光照和75%遮阴处理下差异显著;遮阴导致光系统II(PSII)最大光化学效率(Fv/Fm)增加,3种光照处理下呈显著差异,全光照下Fv/Fm低于50%遮阴处理,初始荧光水平高于50%遮阴处理,推断此条件下的绣球叶片发生了光抑制;而随着光照的减弱,非光化学淬灭系数在降低,说明遮阴降低了绣球叶片PSII天线色素吸收光能以热的形式耗散的比例,绣球叶片吸收的能量约70%用于热耗散,约20%用于非光化学反应,仅有4%的能量用于光化学反应,说明绣球处于饱和光环境下时,主要通过提高叶片吸收光能向热耗散等PSII调节性能量耗散途径的分配,削弱反应中心过量激发能的积累。     

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.     

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.     

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.     

Host plants of someRhinanthoideae (Scrophulariaceae) of eastern North America

Twenty three species in 11 genera were examined in the field to determine hosts. OnlyStriga asiatica andSeymeria cassioides have a narrow host range being restricted to grasses and pines, respectively. These are the only species which cause pronounced and sometimes serious host damage. The other species attach to a great diversity of hosts.     

Apoptotic Regulation of Caspase Activity

Intracellular cysteine aspartate-specific proteases (caspases) play both signaling and effector roles in realizing the program of cell death. Caspases function as proteolytic cascades unique for each cell type and signal triggering apoptosis. All parts of the proteolytic cascades are duplicated and controlled by feedback signals. Amplification cycles between pairs of caspases (the third and the sixth, the ninth and the third, the twelfth and the sixth, and others) help multiply the initial apoptotic signal. The presence of physiological inhibitors of apoptosis that directly interact with caspases creates a multilevel regulatory network of apoptosis in cell. The caspase proteolytic cascades are also regulated by sphingolipid secondary messengers, among them ceramide, sphingosine, and their phosphates. Moreover, an association of the caspase signaling with ubiquitin-dependent proteolysis is shown in cells. In particular, the use of extracellular activators and inhibitors of caspases allows irreversible activation of apoptosis in tumor cells or the prevention of apoptosis in cortical neurons under neurodegenerative diseases.     

Analysis of twin of eyeless regulation during early embryogenesis in Drosophila melanogaster

The Drosophila Pax6 homolog twin of eyeless (toy) is so far the first zygotically expressed gene involved in eye morphogenesis in Drosophila. The study of its expression during embryogenesis is therefore informative of the initial events of eye development in Drosophila. We have analyzed how the initial expression domain of toy at cellular blastoderm is regulated. We show that the three maternal patterning systems active in the cephalic region (the anterior, terminal and dorsal-ventral systems) cooperate with zygotically activated gap genes to shape the initial expression domain of toy. Whereas Bicoid, Dorsal and Torso signaling synergistically act as activators, Hunchback, Knirps and Decapentaplegic act as repressors.     

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.     

New species of Peruvian Orchidaceae III

Sixteen new species are proposed in the generaAckermania, Dressleria, Epidendrum, Maxillaria, Oncidium, Rodriguezia, Sigmatostalix, andTrigonidium. All new species are illustrated.Maxillaria vittariifolia L. O. Williams is newly recorded for Peru. A key is provided forTrigonidium of Peru.Trigonidium loretoense Schltr. andT. peruvianum Schltr. are lectotypified.     

Interaction of Synthetic Analogues of Natural Chalcones and Flavones with Guanidine

The reaction of chalcones and flavones with guanidine in ethanol results in 2-(2-aminopyrimidinyl-4)-phenols.