Temperature drop, dry matter accumulation and cold resistance of young cucumber plants

The study aimed to provide information on the involvement of plant cold resistance in a whole cucumber (Cucumis sativus L.) plant response to temperature drop treatments. The main objective was to explain the effects of a temperature drop on dry matter production and plant morphogenesis. The experimental design included temperature drops to 12°C for 0, 1, 2, 4 and 6 hours at the beginning, in the middle and at the end of the night. The overall average temperature for all treatments was 20°C. A 2-hour temperature drop resulted in the most significant reduction in plant dry weight and leaf petiole length, but the highest degree of cold resistance. With the extension of a temperature drop duration to 4--6 hours, dry matter production was similar to that in the control plants, leaf petiole length increased, but not up to the control level and cold resistance was reduced, but was still higher compared to that of the control plants. Changes in dry matter production, leaf petiole length and cold resistance, depending on the duration of the temperature drop, were interrelated and their patterns varied little with the timing (position effect) of the temperature drop. It is concluded that plant cold resistance mechanisms play an important role in a whole plant response to temperature drop treatments. Thus, plant response to temperature drop treatments can be considered as a response to stress.     

Allometric relationships ofmalva parviflora growing in two different bioclimatic regions

A total of 660 individual plants ofMalva parviflora, a medicinal plant in many countries, growing in two bioclimatic regions were randomly collected with the aim of examining the differences in the allometry of this herbaceous plant growing in two bioclimatic regions. Allometric relationships were found in plant height, stem width, leaf area, leaf length, leaf width, petiole length, and leaf dry weight whereas no relationship was found between plant height or petiole length with specific leaf area. Plants growing in the cool bioclimatic region showed that plant height increases more than the increase in stem width, leaf length, leaf width, and petiole length while plants growing in the warm bioclimatic region showed that plant height increase was lower than that of stem width, leaf length, leaf width, and petiole length. Plant height relationship with root length indicated that in the cool region the plant height increase was less than the increase in the root length while the opposite occurred in the warm region. These differences can be explained by the effects of the different environmental conditions present in the two bioclimatic regions such as water scarcity and availability on the growth ofM. parviflora.     

Allometry ofUrtica urens in polluted and unpolluted habitats

The allometry ofUrtica urens (small nettle), an important medicinal plant in many countries, growing in an area near pollution sources and an area away from pollution sources was determined. The allometric coefficients were determined for nonlinear relationships between plant height, stem width, root length, petiole length, leaf dry weight, petiole dry weight, leaf length, leaf width, leaf area and specific leaf area. The slopes of the linear equations were determined for the above parameters. The results showed that there is a difference in the allometry of different parts ofU. urens growing in these two areas. Air pollutants reduced the plant height, stem width, root length and petiole length and increased leaf parameters. The same pattern of growth was reflected by comparing the slopes of the straight lines of the parts of the plants growing in the two areas.     

Variation in growth of overwintered stolons of contrasting white clover populations in response to temperature, photoperiod and spring environment

The response of overwintered stolons of nine contrasting white clover populations to temperature, photoperiod and natural conditions was studied in six environments during the spring. Rate of leaf appearance, leaflet length, petiole length, stolon internode length, dry matter distribution within the plant and total dry weight were measured on 15 plants of each population/environment combination. Most characters, except leaf size and proportion of dry matter allocated to leaf, responded positively to temperature in the range 10 – 20°C. A positive effect of photoperiod extension was also found for all characters except rate of leaf appearance, internode length and distribution of dry matter to leaf. Population differences in response to environment were found which were related to both leaf size classification and origin. Stolon dry weight was positively correlated with leaf length, petiole length and stolon internode length in most environments. The relationships between the eight characters were often complex and canonical variate analysis provided a convenient way to discriminate between the populations based on all eight characters.     

匍匐茎草本金戴戴对盐分梯度的表型可塑性

 研究了匍匐茎型克隆草本金戴戴(Halerpestes ruthenica) 4种基株（基因型）对不同盐分处理（0,85.5, 171.0, 256.5和342.0 mM NaCl）的表型可塑性。随着盐分浓度的增加,实验植物与生长相关的性状指标 (如植株干重、总叶面积、分株数和总匍匐茎长度) 显著减小。植株干重、总叶面积和总匍匐茎长度具有显著的基株间差异。实验植物与形态相关的性状指标 (如平均叶柄长和根冠比) 对盐分梯度具有可塑性并具有显著的基株间差异;而其它形态指标 (如平均节间长、比节间长和比叶柄长)     

Height convergence in response to neighbour growth: genotypic differences in the stoloniferous plant Potentilla reptans

Using a new experimental set up, the way in which height growth of stoloniferous plants is adjusted to that of their neighbours, as well as differences between genotypes in their ability to keep up with neighbour height growth were tested. Five Potentilla reptans genotypes inherently differing in petiole length were subjected to three experimental light gradients, involving light intensity and red : far-red ratio. Each plant was placed in a vertically adjustable cylinder of green foil, and the treatments differed in the speed of cylinder height increase and final height. Total weight of plants decreased from the 'Slow' to the 'Fast' treatment, while petiole length increased. Leaves reaching the top of the cylinder stopped petiole elongation, resulting in similar final heights for all genotypes in the 'Slow' treatment. In the 'Fast' treatment only the fastest-growing genotype maintained its position in the top of the cylinder and genotypes differed strongly in final height within the cylinders. Plants adjust their height growth to that of the surrounding vegetation, leading to height convergence in short light gradients that slowly increase. These adjustments and genotypic differences in ability to keep up with fast-growing neighbours can influence the outcome of competition for light.     

广西多穗柯叶片性状变异及幼苗生长量研究

多穗柯是一种珍贵天然野生药用植物,可以开发出保健食品色素和天然医用药品,广西的资源较丰富,该研究采集巴马、那坡、德保及田林等4个产地的多穗柯种子进行播种育苗,并跟踪调查测定一年生幼苗的叶片性状及幼苗生长量,并进行相关性分析。结果表明:(1)不同产地间叶片性状及幼苗生长指标均存在不同程度的差异,其中巴马与那坡、德保、田林在叶长、叶宽、叶面积、叶脉间距、叶鲜重、叶片干物质含量、叶片组织密度等叶片性状上的差异均达到显著水平,在株高、地径、单株干重、主根长、单株根干重及单株叶干重等生长指标上亦存在显著差异,且生长量是后3个产地的1~2倍;通过比较各产地的叶片保水力及植株净生长量,巴马的多穗柯植株耐旱性及生长速度优于其他三地。综合各性状表现,认为巴马的多穗柯苗期表现比较好,生长速度快,长势好,抗旱性较强,可作为多穗柯优良种源的初步选择。(2)8月份是多穗柯株高、地径的生长高峰期,建议此时应加强肥水管理,调节适宜的水肥光热条件,尽量延长幼苗的快速生长时间,以获得苗木的最大累积生长量。(3)叶片性状与幼苗生长量的相关性分析结果显示,叶面积与株高、地径、单株干重、单株根干重以及单株叶干重等呈极显著正相关,叶脉间距、叶绿素相对含量(SPAD)与株高、单株干重呈显著或极显著正相关,比叶面积与株高、地径呈显著负相关。因此,在以后的优株表型选择中,要优先考虑叶子大、叶脉间距宽、中老熟叶片叶色浓绿的植株。该研究结果为多穗柯优良种质资源的早期筛选提供了一定的依据。     

林缘和荒草坡不同草本层盖度小生境中积雪草的等级可塑性

为研究克隆植物在不同生境中对小生境的利用能力和对不同尺度异质性生境的等级可塑性及其格局差异,比较了林缘和荒草坡不同草本层盖度小生境中积雪草(Centella asiatica)分株种群、克隆片段和叶水平的形态和生理特征。在分株种群水平,林缘和荒草坡积雪草被测的分株种群特征差异均不显著,不同草本层盖度小生境间积雪草根冠比差异显著,即在盖度小的小生境中其根冠比显著大于盖度大的小生境。在克隆片段水平,林缘和荒草坡生境显著影响积雪草的根干重、花果干重、一级匍匐茎节间长和总匍匐茎节间长,而不同草本层盖度小生境则显著影响花果干重、根冠比、一级匍匐茎数、二级匍匐茎节间长和总匍匐茎节间长。荒草坡积雪草拥有更大的根干重和花果干重,但一级匍匐茎节间长和总匍匐茎节间长较短。草本层盖度小的小生境中积雪草的根冠比和一级匍匐茎数显著高于盖度大的小生境,而花果干重、二级匍匐茎节间长和总匍匐茎节间长则相反。在叶水平,荒草坡和草本层盖度大的小生境中,积雪草的叶片长、叶片宽和叶面积都较大,而草本层盖度大的小生境中积雪草叶柄长和比叶柄长都显著大于盖度小的小生境;林缘和荒草坡生境与不同草本层盖度小生境对4个叶绿素指标影响均不显著,林缘和荒草坡生境与不同草本层盖度小生境的交互作用对所有测量特征均无显著影响。上述结果表明,积雪草对不同生境和有草本层盖度差异的小生境的反应存在等级可塑性,但是二者的等级差异格局不同;等级反应格局的差异反映出积雪草对不同生境条件有不同的生态适应对策,且对生境小尺度异质性的可塑性强于对大尺度异质性的可塑性。     

Effect of simulated climate warming on the morphological and physiological traits of Elsholtzia haichowensis in copper contaminated soil

The aim of this study was to investigate the effects of temperature and Cu on the morphological and physiological traits of Elsholtzia haichowensis grown in soils amended with four Cu concentrations (0, 50, 500, and 1000 mg kg^?1) under ambient temperature and slight warming. At the same Cu concentration, the height, shoot dry weight, total plant dry weight, and root morphological parameters such as length, surface area and tip number of E. haichowensis increased due to the slight warming. The net photosynthetic rate, stomatal conductance, transpiration, light use efficiency were also higher under the slight warming than under ambient temperature. The increased Cu concentrations, total Cu uptake, bioaccumulation factors and tolerance indexes of shoots and roots were also observed at the slight warming. The shoot dry weight, root dry weight, total plant dry weight and the bioaccumulation factors of shoots and roots at 50 mg Cu kg^?1 were significantly higher than those at 500 and 1000 mg Cu kg^?1 under the slight warming. Therefore, the climate warming may improve the ability of E. haichowensis to phytoremediate Cu-contaminated soil, and the ability improvement greatly depended on the Cu concentrations in soils.     

Influence of Bemisia argentifolii (Homoptera: Aleyrodidae) infestation and squash silverleaf disorder on zucchini seedling growth

We investigated the effect of different levels of infestation by whiteflies, Bemisia argentifolii Bellows & Perring, on the growth and pigment concentrations of seedlings of zucchini, Cucurbita pepo L., that differed in their tolerance to squash silverleaf disorder. Genetically similar sister lines that were either tolerant (ZUC76-SLR) or susceptible (ZUC61) to silverleaf disorder exhibited reduced plant height, internode length, plant dry weight, and petiole length in response to whitefly feeding. Similar plant growth responses to whitefly feeding were observed despite that the foliage of ZUC61 silvered severely, whereas the foliage of ZUC76-SLR showed no silvering in a greenhouse experiment conducted in the spring and showed only minimal silvering in a similar greenhouse experiment conducted in the fall. In plants of both sister lines infested with 50 pairs of whiteflies and their progeny, petioles, but not the leaf blades, of uninfested leaves had reduced chlorophyll content. In another experiment, two different genetic sources of tolerance to silverleaf disorder (ZUC33-SLR/PMR and ZUC76-SLR) and a commercial silverleaf-susceptible zucchini hybrid ('Zucchini Elite') responded similarly to whitefly feeding, except the tolerant genotypes did not exhibit leaf silvering. All genotypes, silverleaf tolerant or not, had reduced dry weight, plant height, and internode length that became more pronounced as whitefly infestation increased. All genotypes had reduced levels of chlorophylls and carotenoids in uninfested young leaf blades and petioles from infested plants. Petioles, however, were more affected by feeding than leaf blades, showing a 66% reduction in chlorophylls a+b and carotenoids at the lowest infestation level (30 pairs of whitefly and their progeny), whereas pigments in leaf blades declined more slowly in response to whitefly feeding density, averaging 14-15% less at the highest infestation level (90 pairs of whitefly and their progeny). We conclude that tolerance to silverleaf disorder does not prevent stunting in zucchini seedlings nor does it protect against the systemic loss of photosynthetic and protoprotectant pigments induced by feeding of B. argentifolii whiteflies.     

Biomass Partitioning in Tomato Plants Infected with Meloidogyne incognita

Tomato plants were inoculated with Meloidogyne incognita at initial populations (Pi) of 0, 1, 10, 50, 100, and 200 (x 1,000) eggs per plant and maintained in a growth chamber for 40 days. Total fresh biomass (roots + shoots) at harvest was unchanged by nematode inoculation with Pi of 1 x 10⁵ eggs or less. Reductions in fresh shoot weight with increasing Pi coincided with increases in root weight. Total fresh biomass declined with Pi above 1 x 10⁵ eggs, whereas total dry biomass declined at Pi above 1 x 10⁴ eggs. The greatest reduction percentages in fresh shoot biomass induced by root-knot nematodes occurred in the stem tissue, followed by the petiole + rachis; the least weight loss occurred in the leaflets. Although biomass varied among shoot tissues, the relationship between biomass of various shoot tissues and Pi was described by quadratic equations. The linear and quadratic coefficients of the equations (stem, petiole + rachis, or leaflets on Pi) did not differ among tissues when calculations were based on standardized values. Meloidogyne incognita-infected plants had thinner leaves (leaf area/leaf weight) than did uninfected plants. Reductions in leaf weight and leaf area with nematode inoculation occurred at nodes 5-15 and 4, 6-14, respectively. Losses in plant height and mass due to nematodes reflected shorter internodes with less plant mass at each node.     

Clonal Plasticity in Response to Partial Neutral Shading in the Stoloniferous Herb Potentilla reptans var. sericophylla

Ramet-pairs of Potentilla reptans L. var.sericophylla Franch from forest gap and forest understory were subjected to unshading, shading and partial shading treatments in a pot experiment. The genet biomass, total length of stolons, number of ramets, specific stolon weight, petiole length and specific petiole weight of the plant species under the shaded condition were smaller than those under the unshaded condition. The stolon internode length did not respond to the various treatments. In the plants from the forest gap, the petiloes of ramet grown in the shaded patch were longer as connected to plant part in the unshaded patch than as connected to plant part under the same shaded condition. Such modification of local response of ramet petiole to shading due to physiological integration was not observed in the plants from the understory. There was no effect of connection to ramets in shaded patches on the local response of the rest ramet characters to the partial unshading.     

匍匐茎草本绢毛匍匐委陵菜对局部遮荫的克隆可塑性

采自林窗和林内生境的绢毛匍匐委陵菜 (PotentillareptansL .var.sericophyllaFranch)“分株对”(即由一匍匐茎节间相连着的两个分株 ,其一为“目标分株” ,另一为“相连分株”)在一户外实验中经历了全不遮荫、全部遮荫和局部遮荫处理。该植物的基株生物量、匍匐茎总长度、分株数、匍匐茎比节间重、叶柄长、比叶柄重在遮荫条件下较小。匍匐茎节间长度没有对遮荫处理发生反应。在局部遮荫处理 ,遮荫斑块的分株的叶柄长度由于连着未遮荫斑块中分株而变得更长。这种克隆整合对克隆形态可塑性的修饰作用只在林窗生境来源的实验植物中观察到。其他克隆生长和克隆形态特征的可塑性在不同生境来源的实验植物间没有差异。     

8种湿地植物不同苗龄植株的表型特征及相关性分析

对水葱(Scirpus validus Vahl)、香蒲(Typha orientalis Presl)、小香蒲(T.minima Funk.)、再力花(Thalia dealbata Fraser ex Roscoe)、黄菖蒲(Iris pseudacorus Linn.)、灯芯草(Juncus effusus Linn.)、梭鱼草(Pontederia cordata Linn.)和菖蒲(Acorus calamus Linn.)8种多年生湿地植物1年生和3年生植株的地上和地下部分干质量、株高(包括花序高和叶层高)、根长、根数和根粗进行了测定,并对各表型特征指标间以及苗龄与各表型特征指标间的相关性进行了分析。结果显示:8种湿地植物3年生植株的地上和地下部分干质量普遍高于1年生植株;从生长量分配情况看,除小香蒲外,其余种类3年生植株地下部分干质量所占比例均高于1年生植株。多数种类1年生和3年生植株的株高差异较小。从根系特征看,根数小于100、根粗1.0~2.0 cm的植株以1年生为主,而根数大于100、根粗1.0 cm以下和2.0~3.5 cm的植株以3年生为主;根长15~25 cm的植株以1年生所占比例较高(62.5%),而根长25~35 cm的植株1年生和3年生所占比例相等。相关性分析结果表明:1年生植株的地上部分干质量与株高、根长与根粗呈显著正相关(P<0.05),3年生植株的地下部分干质量与根粗也呈显著正相关;但不同苗龄植株的其他表型特征指标间的相关性均不显著。苗龄与植株地下部分干质量呈极显著正相关(P<0.01),但与地上部分干质量、株高、根长、根数和根粗的相关性不显著。总体而言,8种湿地植物3年生植株的表型特征优于1年生植株,更适用于污染水体及退化湿地生态系统的修复。     

茄子幼苗耐低温性生理机制研究

选择耐低温性不同的6份茄子高代自交系幼苗为材料,进行白天10℃/夜间7℃低温处理10d,调查其耐低温性、生长指标(株高、茎粗、鲜重、干重)、生理指标(POD、SOD、APX活性及脯氨酸含量),以探讨低温对茄子幼苗生长过程中的生长和生理指标的影响.结果显示:(1)各材料的上述性状在常温下均差异不显著,而在低温处理下差异极显著;与对照相比较,幼苗株高、茎粗、鲜重和干重下降,而POD、SOD、APX活性及脯氨酸含量上升.(2)各材料指标的升降幅度与其低温耐受性密切相关,耐低温性强的材料生长指标下降幅度较小,而生理指标提高幅度较大,耐低温性弱的材料则表现相反.(3)各指标间相比较,茄子耐低温性与株高、茎粗、干重、POD活性、SOD活性呈显著正相关,与其余性状的相关未达显著水平.研究表明,低温使茄子幼苗的生长受到一定程度的抑制,但耐低温材料能够通过调节自身的保护酶系统活性来减轻低温的伤害,维持植物体的正常生长及生理代谢功能.     

Rice cultivar evaluation for phosphorus use efficiency

Phosphorus deficiency is one of the most growth-limiting factors in acid soils in various parts of the world. The objective of this study was to screen 25 rice cultivars (Oryza sativa L.) at low, medium, and high levels of soil P. Number of tillers, root length, plant height, root dry weight and shoot dry weight were related to tissue P concentrations, P uptake and P-use efficiency. Shoot weight was found to be the plant parameter most sensitive to P deficiency. Significant cultivar differences in P use efficiency were found. Phosphorus use efficiency was higher in roots than shoots and decreased with increasing levels of soil P. Positive correlations were found among growth parameters such as plant height, tillers, root and shoot weight, and P content of roots and shoots. These results indicate selection of rice cultivars for satisfactory performance under low P availability can be carried out using shoot and root dry weight as criteria.     

Isolation of micropropagated strawberry endophytic bacteria and assessment of their potential for plant growth promotion

Twenty endophytic bacteria were isolated from the meristematic tissues of three varieties of strawberry cultivated in vitro, and further identified, by FAME profile, into the genera Bacillus and Sphingopyxis. The strains were also characterized according to indole acetic acid production, phosphate solubilization and potential for plant growth promotion. Results showed that 15 strains produced high levels of IAA and all 20 showed potential for solubilizing inorganic phosphate. Plant growth promotion evaluated under greenhouse conditions revealed the ability of the strains to enhance the root number, length and dry weight and also the leaf number, petiole length and dry weight of the aerial portion. Seven Bacillus spp. strains promoted root development and one strain of Sphingopyxis sp. promoted the development of plant shoots. The plant growth promotion showed to be correlated to IAA production and phosphate solubilization. The data also suggested that bacterial effects could potentially be harnessed to promote plant growth during seedling acclimatization in strawberry.     

Biocontrol Agent Talaromyces flavus Stimulates the Growth of Cotton and Potato

Beneficial plant-microbe interactions in the rhizosphere are primary determinants of plant health and soil fertility. Some antagonistic fungi have shown great effects toward the growth of plant crops. In this study, two major crops, cotton and potato, were selected to evaluate their growth promotion by the antagonistic fungus Talaromyces flavus. For each plant, five T. flavus isolates were selected from our fungal collection which had shown the highest antagonistic activities against the causal agent of wilt diseases on these plants. In the next step, for every crop, five isolates were used under greenhouse conditions. For evaluation of the plant growth promotion ability of T. flavus isolates, a split-plot trial was arranged in a randomized complete block design with four replications. The main factor was the method of application of T. flavus as a soil treatment, a seed treatment, and a combination of both methods. The subfactor was the use of different fungal isolates. Measured parameters were root length, crown length, plant height, plant fresh weight, and plant dry weight. Results showed that the maximum increase in the above parameters was mediated by the seed treatment method. The most effective isolate for cotton plants was TF-Co-M-23, which increased root length, plant height, plant fresh weight, and plant dry weight by 1.80-, 2.26-, 1.23-, and 1.19-fold, respectively. There were no significant differences among the various treatments affected by T. flavus in terms of crown length. The most effective isolate for potato plants was TF-Po-V-50, which increased root length, crown length, plant height, and plant dry weight by 1.71-, 1.09-, 1.45-, and 3.75-fold, respectively. The overall results of this study suggest that it may be possible to promote cotton and potato growth characteristics by using the antagonistic fungus T. flavus.     

Combined effects of chromium and arsenic on rice seedlings (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) growth in a solution culture supplied with or without P fertilizer

The growths of two rice genotypes (Jin23A and CDR22) under the coexistence of As and Cr in solution culture with and without P were investigated. The result showed that rice shoot dry weight decreased due to the complex contamination of As and Cr, however, the influences on plant height, root length and root dry weight were insignificant.     

大白菜部分形态性状的QTL定位与分析

应用352个标记位点的大白菜AFLP和RAPD图谱和一套栽培品种间杂交获得的重组自交系群体,采用复合区间作图的方法对大白菜9个形态性状进行QTL定位及遗传效应研究。在14个连锁群上检测到50个QTL:其中控制株型的QTL有5个;控制株高的QTL有6个;控制开展度的QTL有5个;控制最大叶长的QTL有7个;控制最大叶宽的QTL有4个;控制叶形指数的QTL有6个;控制中肋长的QTL有7个;控制中肋宽的QTL有4个;控制抽苔的QTL有6个。另外,估算了单个QTL的遗传贡献率和加性效应。这将为大白菜品种改良中形态性状的分子标记辅助选择提供理论依据。