Methylene Blue Stainability of Root-Tip Protoplasts as an Indicator of Aluminum Tolerance in a Wide Range of Plant Species,Cultivars and Lines

We previously developed a new simple technique of methylene blue (MB) staining for the discrimination of aluminum (Al)-tolerant protoplasts from 4 plant species (rice, oats, maize and pea). The objectives of the present study were to confirm the applicability of this technique to a wider range of plant species, cultivars and lines, and to identify a common strategy for the early stage of Al tolerance. A total of 10 plant species, two Brachiaria spp., two Oryza spp., buckwheat, maize, pea, triticale, wheat and barley, corresponding to 18 different plant samples (species, cultivars, and lines), were used. Al tolerance (relative net root elongation of the longest root), which was screened at 20 μM AICI₃ in 0.2 mM CaCl₂ (pH 4.9) for 24 h, ranged widely from 10 to 88. Among cultivars and lines within the same species, Al accumulation in the root tip portion was higher in Al-sensitive plants, corresponding to more severe permeabilization of the plasma membranes (PM). Protoplasts isolated mainly from the epidermis, and outer and central parts of the cortex were stained to different degrees by MB, and the blue color was observed both on the surface and inside the protoplasts. Color pictures obtained after staining for 3 min with 0.1% MB were analyzed by Image Hyper II. The ratio of the heavily stained area at threshold 95 to the entire area stained with MB at threshold 125 was defined as MB stainability. MB stainability was negatively correlated with Al tolerance (y= 48.6e^?0.02x , R ²= 0.676**) suggesting the common importance of permeation characteristics of PM, in addition to PM negativity for Al tolerance in a wide range of plant species, cultivars and lines. Analysis of the PM lipid composition was proposed as an important topic for future studies on the negativity and permeation of PM.     

干旱胁迫对豫楸1号嫁接苗的生理生化影响研究

以1年生豫楸1号四种砧木嫁接苗(金丝楸、豫楸1号、灰楸和梓树)为试验材料通过盆栽干旱胁迫以正常浇水处理为对照,研究了不同程度干旱胁迫对这四种不同砧木豫楸1号嫁接苗在保护酶活性、脂膜透性、过氧化物的反应物积累和细胞渗透调节性物质等方面的生理生化影响。结果表明:保护酶SOD活性先上升后下降,活性表现明显的是金丝楸嫁接苗;MDA的积累都有明显增加,金丝楸嫁接苗积累最少,增加较多的是梓树嫁接苗和灰楸嫁接苗;脂膜透性都有不同程度的上升,其中梓树嫁接苗和灰楸嫁接苗上升较快,金丝楸嫁接苗积累较少。可溶性蛋白的含量都有不同程度的上升,其中金丝楸嫁接苗积累较多。经过对几项生理指标的综合方差[1]分析,认为金丝楸嫁接苗相对于其他三个品种具有较强的抗旱能力。     

拖拉机旋流管式拔尘空滤系统设计

根据市场反馈的问题结合试验结果,对发动机空滤进气系统进行了改进设计,通过利用排气管废气压力,设计了使用旋流管式拔尘的进气结构,从而有效提高了空滤效果。对我公司TL拖拉机使用的该新型进气系统结构的设计进行简要介绍。     

芸苔链格孢菌毒素对白菜细胞膜透性、SOD酶和POD酶活性的影响

 本文以白菜幼苗为材料,研究了芸苔链格孢菌毒素(AB-毒素)对白菜叶片细胞膜透性及叶片内SOD酶、POD酶活性变化的影响。结果表明,白菜叶片用AB-毒素处理后,细胞膜透性增大,且随处理时间的延长和毒素浓度的增加而增高。不同白菜品种用毒素处理后膜透性的改变与病菌接种的发病程度呈正相关,即电导率大的白菜品种,叶片发病也重。试验结果还发现,芸苔链格孢菌及其毒素处理白菜后,体内SOD酶和POD酶活性的变化基本趋于一致,即处理后12 h内急剧下降,然后(12~48 h)活性上升。而对照处理基本变化不大。可见,芸苔链格孢菌毒素表现了与其病原菌一致的致病作用。     

Nodule phosphorus requirement and O2 uptake in common bean genotypes under phosphorus deficiency

Abstract

The effect of P deficiency on nodulation, nodule P content, nodule O₂ permeability and N fixation rates in Phaseolus vulgaris–rhizobia symbiosis was studied under glasshouse conditions. Four recombinant inbred lines (L34, L83, L115 and L147) and one variety cultivated in Morocco (Concesa) were inoculated with Rhizobium tropici CIAT 899 in hydroaeroponic culture. Two P levels i.e. 75 (deficient level) and 250 µmol plant^?1 week^?1 P (sufficient level) were applied and the trial was assessed 42 days after transplanting that coincide with plant flowering stage. Under P-deficiency, decrease of plant growth (18%) and nodule biomass (19%) was detected and significantly pronounced in the sensitive line L147 compared with the remaining genotypes. Additionally, under P-deficiency, the efficiency in use of rhizobial symbiosis, estimated by the slope of the regression model of shoot biomass as a function of nodule biomass, was significantly increased in the four lines. This constraint did not significantly influence nodule P content in Concesa, but it was 24 and 41% lower in the tolerant and in the sensitive lines, respectively. Nodule P content was positively correlated to nodule biomass, r=0.75, and shoot N, r=0.92. These genotypic variations were associated with variability in nodule O₂ permeability that was significantly affected by the P level-bean genotype interaction. Under P-deficiency, nodule O₂ permeability was significantly reduced in the tested genotypes and accompanied with a decrease in shoot N content, especially in the sensitive lines (35%). Moreover, the ratios plant N fixed: nodule P content and plant N fixed:nodule dry weight were affected under P-deficiency in four lines with an exception observed in Concesa. Depending on the observed data we concluded that N₂ fixation efficiency could be influenced by nodulation and level of nodule P requirement which depend on both bean genotypes and P level.     

季节性冻融区地下水位预测方法研究

为预测河套灌区冻融区全年地下水位变化过程,采用统计学方法,研究了冻融期地下水位与地表气温间的关系,建立了二者间的线性模型,结合非冻融期水量均衡模型,建立了改进型水量均衡模型,通过优化求解方法确定模型参数。结果表明,模型计算埋深与实测埋深拟合效果较好,提出的改进型水量均衡模型可较好地预测冻融区全年地下水位变化过程,解决了冻融期间地下水模拟难题,方法简单精确,具有很好的实用性。     

一种微波功率可调的热风微波耦合干燥装置

现有的微波发出功率多采用时间间断式控制,磁控管的发射功率恒定,通过改变磁控管的通断时间实现微波平均输出功率的调节,这种方式不能改变微波的瞬间功率,微波功率输出控制不精确,对物料品质影响较大。为此,设计了一种微波耦合干燥装置,通过改变磁控管高压回路的电容,使磁控管高压回路的阻抗发生改变,以达到微波发出功率的线性可调。以马铃薯为试验研究对象,在热风温度为60°C、电容值魏0、0.25、0.33、0.5、1!F)的条件下进行干燥对比试验,试验结果表明:热风微波耦合的干燥效率明显优于单一热风干燥,速度快、能耗低。热风微波耦合干燥是一种快速,高效和节能的干燥方式,在农产品和食品干燥中具有广阔的应用前景。     

Vitality rating of picea abies by defoliation class and other vigour indicators

The study was made to assess the relationship between visually estimated defoliation class and a number of other variables depicting the vitality of Norway spruce (n=50). Variables characterizing crown size and condition were determined on the standing trees. Electrical impedance (an indication of the physiological status of a tree) was measured in the inner bark tissue of the living trees. Shoot growth and needle variables were determined from the detached sample branches. Negative correlations were found between defoliation class and the growth parameters (5‐year height, radial and volume growth of the trunk). Positive correlations were observed between the needle loss class and the abundance of branch damage, secondary shoots and impedance values. 18 variables (defoliation excluded) describing tree size and vitality were summarized in a factor analysis incorporating 5 factors. These were interpreted as 1) vitality, 2) foliage discoloration, 3) tree size, 4) needle number and 5) needle size factors. The tree‐specific score values for the first factor were interpreted as “vitality indices”;. The rank correlation between these score values and defoliation degree was 0.835. This result suggests that the defoliation class and vitality parameters contributing to the first factor give a consistent estimate of the tree condition.     

Air layering and its potential in propagating Uapaca kirkiana: a fruit tree from the miombo woodland,Tanzania

The potential to propagate Uapaca kirkiana through air layering was investigated at Igumbilo forest, Tanzania. The objective was to determine the effect of time of setting air layers and use of indole-3-butyric acid (IBA) to promote rooting. Air layers were initiated on young shoots, 1-to 2-years old, growing on mature trees. After root initiation, they were detached, potted and reared at the nursery for a further three months. Thereafter they were harvested and assessed. Two factors were investigated: effect of time at which air layers were initiated (June, September and December), and influence of IBA at 50, 100 and 150 mg l^?1concentrations. Varied rooting successes were realised, being influenced by time at which air layers were initiated, IBA concentration or both. Optimal rooting of 82.5% was realised in June-initiated air layers treated with 50 mg l^?1 IBA. Air layers initiated in December and treated with the control had the poorest rooting (46.7%). Application of 100 mg l^?1 IBA during June significantly improved the number of roots, root length and root biomass produced. The increase in rooting ability during June is partly linked to better nutritive status, since most plants at this time have sufficient food reserves acquired during the active photosynthetic rainy period of January–May. The period is also associated with minimal plant developmental activities such as budding and flushing, which are usually antagonistic to rooting. Thus, air layering is a potential technique to propagate U. kirkiana, and can contribute effectively to capture desirable traits rapidly disappearing because of ongoing deforestation and maintain the desired fruit tree attributes once attained. Further studies are recommended to determine its cost effectiveness in relation to other vegetative techniques.