不同播期生态条件下燕麦叶片细胞形态的观察

用细胞离析法对春播和秋播燕麦各叶位叶片细胞形态的观察表明,春播时随叶位提高,具有多环的叶肉细胞比例增加,叶肉细胞变小,表皮气孔密度增加。而秋播有与春播相反的趋势,即随叶位提高,多环的叶肉细胞所占比例变化不大或略有下降,叶肉细胞变大,气孔密度降低。随秋播播期推迟,相同叶位叶片细胞的变化趋势,与秋播时随叶位提高的     

黑麦不同叶位叶片、叶鞘叶肉细胞形态及其功能的研究

以田间生长的两个黑麦品种为材料，对各叶位叶片、叶鞘的叶肉细胞形态进行了离析观测。黑麦各叶片叶肉细胞形态不一，从1环到10余环。冬前所生叶片叶肉细胞的形态各叶位间无明显的变化规律；春季伸长节间的叶片，随叶位的上升多环细胞所占比例渐增，旗叶尤其明显。越冬前后长出的叶片叶肉细胞的长、宽均较大，以前和此后伸出     

高粱叶片及其它营养器官细胞形态的初步观察

运用细胞离析法对高粱两个品种各叶位叶片细胞形态的观察表明,随叶位升高,三环以上的多环细胞所占的比例有增加趋势,但中部叶位的略有下降。叶肉细胞随叶位升高逐渐变小,但品种间叶肉细胞高度的变化趋势却有不同。冀杂6号叶片表皮气孔密度随叶位升高而增加,而y2203的却差异不大。高粱叶鞘薄壁细胞的形态与叶片细胞的显著     

大麦不同叶位叶鞘同化细胞形态结构的初步观察

研究材料为六棱食用大麦品种矮秆齐,二棱啤酒大麦品种76-22。针对2个品种不同叶位叶鞘同化细胞的形态结构作了初步的观察。结果发现:大麦叶鞘同化细胞的形态随叶位上升而逐渐趋于复杂化,主要表现为所谓的环状细胞和不规则的分枝状细胞比例随叶位上升而明显交小。此变化与叶片叶肉细胞的变化相一致。此外高位叶鞘的表皮细胞壁发生明显的波状加厚,而低位叶鞘表皮则无这种特征。     

“谷上谷”生育性状的观察——Ⅱ.不同叶位叶片解剖组织结构的观察

用“谷上谷”和“尺八量”两个谷子品种为材料,对不同叶位叶片的解剖结构进行了观察。结果表明:谷子叶片随叶位上升运输系统趋于优化,如叶片维管束数目、韧皮部和木质部面积随叶位上升而逐渐增多和增大。上述各种性状,“谷上谷”的叶片均优于普通谷“尺八量”的相应叶片。叶肉细胞形态的观察,谷子叶片叶肉细胞大多数为不分枝     

玉米不同叶位叶片的初步研究

用两个玉米品种,于春、夏两季播种,对玉米植株基部(第3叶)、下部(第7、9叶)、中部(果穗叶)和上部(倒二叶)四个叶位叶片,进行叶肉细胞的形态、气孔器的分布、维管束的数目、叶绿素的含量和光合强度的综合研究。趋势如下:叶肉细胞的形态具有多样性,果穗叶最复杂,四环以上细胞的比例最高,自果穗叶向上向下各叶渐趋简单。不同叶位叶片气孔器的密度,有随叶位上升而增加的趋势。在维管束的数目、导管粗度、叶绿素的含量和光合强度诸方面,果穗叶均高于其它叶位。综上所述,玉米不同叶位叶片的结构与功能的变化趋势是一致的,中部果穗叶片优于其它叶位。     

燕麦叶鞘和穗部的同化细胞形态及其光合功能的研究

运用细胞离析法观察表明,燕麦叶鞘及穗下节间、穗轴、颖壳和芒的同化细胞形态均与叶肉细胞类似,而且随叶位升高,叶鞘同化细胞形态逐渐复杂化的趋势也与叶肉细胞类似。与叶片一样,上述绿色器官也均具有同化CO2,进行光合作用的能力。     

玉米抽雄后不同叶位叶对籽粒产量的影响及其光合性能

在玉米抽雄后剪去玉米植株不同层次和不同叶位叶片,观察各层次和各叶位叶对玉米籽粒产量的效应。在去叶同时测定各层次和各叶位叶的光合强度、叶绿素含量,并向各叶位叶喂以³²P,观察其向果穗运输的情况。前后经过四年的实验,发现玉米抽雄后不同层次叶片对籽粒产量的效应是不同的,其作用大小顺序是中部叶片>上部     

新疆冬小麦品种更替与旗叶叶肉细胞变化的关系研究

本文报道新疆冬小麦品种更替中旗叶叶肉细胞变化趋势的研究结果。研究表明:1.品种更替中旗叶多环叶肉细胞的频率基本是按地方品种→引进品种→自育品种方向逐渐提高的。2.旗叶叶肉细胞形态变化的趋势表现为,细胞环数与细胞总宽之比值按品种演变顺序逐渐减小。细胞高而不宽,峰谷明显。说明可能是向增强光合作用能力方向发展。3     

2种观赏彩叶竹形态结构的观察与分析

为了探究彩叶观赏竹叶片结构与颜色之间的关系,以白纹阴阳竹(Hibanobambusa.tranquillans f. shiroshima H. Okaura)和白纹椎谷笹(Sasaella.glabra f. albo-striata Muroi)2种观赏竹的叶片为材料,制作叶表皮制片、叶片石蜡切片和超薄切片,通过光学显微镜和电子显微电镜对其形态结构进行观察。结果显示：2种竹子叶片表皮结构相似,均属于稻型叶,且二者叶片绿、白条带区域的表皮细胞之间无明显差异;而叶肉细胞则呈现不同程度的叶绿体变异（基粒片层降解、产生大量嗜锇颗粒等）。其中,叶色为浅绿色的条纹中有1层或2层叶肉细胞叶绿体发生变异;叶色为白色或浅黄色的细胞内叶绿体全部变异;而叶色为绿色的细胞中叶绿体结构均正常。表明叶肉细胞中叶绿体变异的程度可能是影响竹子叶片色度的重要原因之一,从而使叶片呈现不同的颜色。     

叶片的生理状态及添加物对大麦叶肉原生质体培养的影响

作为原生质体源的叶片的生理状态及培养基中的添加物对大麦叶肉原生质体培养均有明显的影响。试验中观察到叶片中、上段的原生质体比基部的具较强的感应力。叶片经黑暗预处理后，其原生质体培养时呈较好的稳定状态，并观察到添加１．０，２．０ｍｍｏｌ／Ｌ的抗坏血酸能提高原生质体的活力。在添加０．５ｍｇ／Ｌ２，４－Ｄ、１．０ｍｇ／ＬＮＡＡ及０．５ｍｇ／ＬＺＴ的ＲＭＳ培养基中，经微弱光照（１５０ｘ）诱导了细胞持续分裂并     

Programmed cell death begins earlier in the mesophyll cells of tulip petals than in the epidermal cells

Based on histological observations, the onset of programmed cell death (PCD) occurs earlier in the mesophyll cells of petals than in the epidermal cells, but few biochemical studies have addressed the onset of PCD in mesophyll cells. We sampled epidermal cells and, separately, mesophyll cells from tulip petals, and then used biochemical methods to examine the onset of PCD in the two different tissue types. DNA laddering and collapse of cells had begun in mesophyll cells before petals had visibly wilted, but DNA laddering was not evident in epidermal cells at that point. Changes in protein content and total proteinase activity during senescence also supported the conclusion that the onset of PCD occurred in mesophyll cells before it occurred in epidermal cells. This study is the first to use multiple biochemical methods of analysis, as well as microscopic observations, to demonstrate that PCD begins earlier in the mesophyll cells than in the epidermal cells of tulip petals.     

The barley mutant emr2 shows enhanced resistance against several fungal leaf pathogens

Homozygous mlo -barley plants are resistant to barley powdery mildew but hypersusceptible to the rice blast fungus Magnaporthe oryzae . A mutational analysis was performed in the barley back-cross line BCIngrid mlo5 which led to the identification of two mutants with enhanced capacity to resist infections by M. oryzae , referred to as enhanced M. oryzae resistance mutants emr1 and emr2 . Here, we report on the characterization of emr2 mutant plants which not only show an almost complete reduction in disease severity after inoculation with M. oryzae but are also resistant to the necrotrophic fungi Drechslera teres and Rhynchosporium secalis . Histological analysis revealed that resistance to M. oryzae was based mainly on the formation of papillae at sites of attempted penetration into epidermal cells. There was no progression of fungal growth into the mesophyll. Additionally, because of the presence of the mlo -allele, emr2 -plants retained resistance to powdery mildew. The emr2 -conditioned broad spectrum resistance was inherited as in a recessive manner. Monitoring of PR -gene expression and enzymatic activity of peroxidases revealed a constitutively activated defence in emr2 .     

Differential Response of Two Wheat Genotypes to Nitrogen Supply. II. Mesophyll Cell Characteristics and Photosynthesis of Laminae at Full Expansion

Two wheat genotypes, viz. Uniculm 'Gigas' (V1) and Kalyansona (V2) were raised to maturity under two levels of nitrogen supply @ 30 (N1) and 120 (N2) kg ha⁻¹, under pot culture conditions. Laminae numbering 1 to 8 on the shoot were examined for area, net photosynthetic rate ( P _n) and mesophyll cell characteristics, at full expansion. N1 resulted in greater reduction in the area of upper laminae in V1 than in V2. The flag and penultimate laminae maintained similar P _n rates at both N levels in V1 despite a large reduction in area at N1. However, V2 exhibited about 25% reduction in P _n rates of the flag laminae at N1 as compared with N2. Mesophyll cell number per unit area gradually increased with laminae order in the genotypes. The greater number of mesophyll cells in the upper laminae was essentially due to a reduction in cell size and surface area as a result of low N availability. The large differences in laminae size due to N treatments, particularly in V1, are attributed to mesophyll cell numbers. However, the maintenance of P _n rates in V1, even at low N supply, is a possible outcome of higher activity of the mesophyll cell constituents in this genotype.