Interspecific variation of constitutive chemical compounds in <Emphasis Type="Italic">Pinus</Emphasis> spp. xylem and susceptibility to pinewood nematode (<Emphasis Type="Italic">Bursaphelenchus xylophilus</Emphasis>)

Pinewood nematode (PWN), Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD), was detected in Spain in 2008. This gives rise to serious concern, as the disease has caused severe environmental and economic losses in Portugal and in Asian countries. We studied interspecific variation in susceptibility to pine wilt disease and differences in constitutive chemical compounds in the xylem tissue of the seven pine species -P. canariensis, P. halepensis, P. pinaster, P. pinea, P. sylvestris, P. radiata and P. taeda. Two-year-old trees were inoculated with B. xylophilus. Water potential and nematode densities were measured for each species on specific dates; whereas, wilting symptoms were recorded weekly until the end of the assay. Chemical compounds in the xylem were determined prior to inoculation. Three different resistance groups can be established in terms of the pine species susceptibility to PWN: non- to slightly-susceptible (P. canariensis, P. halepensis, P. taeda and P. pinea), susceptible (P. pinaster and P. radiata), and highly-susceptible (P. sylvestris). Nematodes migrated downward to the roots in all seven species. Constitutive xylem nitrogen, total polyphenols, and marginally phosphorus were negatively correlated with mortality caused by PWN. The most susceptible species, Pinus sylvestris, presented high levels of constitutive lipid-soluble substances and low levels of manganese, pointing to a possible relation between these components and PWN susceptibility. The results suggest P. sylvestris, P. pinaster and P. radiata forests could be severely damaged by PWN in Spain and highlight how constitutive chemical compounds such as nitrogen might play a role in resistance mechanisms against PWN.     

The effect of application of organic manures and mineral fertilizers on the state of soil organic matter and nutrients in the long-term field experiment

Purpose

Soil organic matter (SOM) plays an important role in terrestrial ecosystems and agroecosystems. Changes in the agricultural sector in the Czech Republic within the past 25 years have had a negative impact on SOM content and contribute to gradual soil degradation. The aim of this study is to estimate the effect of long-term application of different mineral fertilizers (NPK) and organic manures (manure, cattle slurry) on soil chemical properties (quality of humus, available nutrients, and soil reaction).

Materials and methods

Soil samples were collected from Luvisol during two selected periods 1994–2003 and 2014–2016 from long-term field experiment carried out in Prague-Ruzyně (Czech Republic). Average annual temperature is 8.5 °C, and annual precipitations are 485 mm. Different fertilization regimes have been applied for 62 years. The crop rotation was as follows: cereals (45%), root crops (33%) and legumes (22%). Soil analysis—soil organic carbon (SOC) was determined by oxidimetric titration method. Short fractionation method for evaluation of humic substance (HS), humic acid (HA) and fulvic acid (FA) content was used. Absorbance of HS in UV-VIS spectral range was measured by Varian Carry 50 Probe UV-VIS spectrometer. Degree of humification (DH) and color index (Q_4/6) were calculated from fractional composition data. Soil reaction was measured by potentiometric method. Available nutrients (phosphorus, potassium, magnesium, calcium) were determined by Mehlich II and Mehlich I methods and by ICP-OES. For data analysis, the following are used: exploratory data analysis, ANOVA, and principal component analysis (PCA).

Results and discussion

PCA analysis differentiated fertilizers into two categories: (1) variant NPK (lower quality of humus)—higher acidity, lower SOC and HS content, predomination of FA, higher DH and lower content of available nutrients; (2) variants with organic manures (higher quality of humus)—lower acidity, higher SOC and HS content, predomination of HA, middle DH, and high content of available nutrients. The main result of presented study is to give a synthesis of effect of different type of fertilizers on a sustainable organic matter management in arable soils, with respect to yields, food security and adaptation to predict climate changes.

Conclusions

Long-term application of mineral fertilizers (NPK) without organic matter input can accelerate humus mineralization and soil quality degradation with all negative consequences such as (nitrogen leaching, higher availability of toxic element for plants, slow energy for soil microorganisms etc.). Application of organic fertilizers (manure and cattle slurry) helps to achieve the long-term stable yields while maintaining soil at optimum quality (long-term sustainable management with SOM). Principal component analysis is a useful tool for evaluation of soil quality changes.

     

枸杞瘿蚊预测预报研究

通过长期在托克托县五申乡的4个自然村蹲点观察记录,研究枸杞瘿蚊蛹的发育天数和温度的关系以及蛹的发育历期,预测枸杞瘿蚊成虫出现的始盛期基本在5月上旬。同时通过多年记录测算,得出有效积温（T）和发育天数（N）预测式为：N=14.2±10.1/T-（13.5±0.6）;越冬蛹（x）和翌年成虫数（y）的预测公式：y=4.48x-12.08,并通过实验验证,认为所得公式在实践中预测的比较准确。     

绿盲蝽为害对不同空间位置桃叶生理指标的影响

为明确绿盲蝽为害不同时期桃树的应激反应发生发展过程,采用生化测定方法分析了桃树上、中、下部不同受害程度叶片内的可溶性糖、蛋白质、游离氨基酸含量以及防御性酶活性的变化。结果表明,绿盲蝽为害后,随着时间的延长,受轻度为害的桃树叶片内可溶性糖含量由28.61 mg/g减少至19.21 mg/g,蛋白质含量由1.29 mg/g先增加至2.01 mg/g,后减少至1.66 mg/g,游离氨基酸含量由0.49 mg/g增加至0.72 mg/g;而受重度为害的叶片内可溶性糖和蛋白质的含量均先减少后增加,游离氨基酸含量则先增加后减少。防御性酶活性随绿盲蝽为害程度的加重也发生了不同程度的变化,随着时间的延长,受轻度为害的叶片内超氧化物歧化酶活性降低,过氧化物酶和过氧化氢酶活性有所升高;而受重度为害的叶片内超氧化物歧化酶活性先降低后升高,过氧化物酶活性升高,过氧化氢酶活性降低。说明不同位置桃树叶片对绿盲蝽的为害胁迫产生了应激反应,通过调整其体内各种防御性物质的含量,对绿盲蝽为害产生诱导抗性,且与为害程度有一定的相关性。     

快速、准确鉴别产几丁质酶菌株的新方法

使用几丁质平板法筛选具有几丁质酶活性的细菌时,由于几丁质平板本身趋于透明,而降解环也为透明色,不易观察到明显的抑菌圈,故在筛选几丁质降解菌时,其观察结果受人为因素影响较大。本文首次使用刚果红染色的方法,对几丁质平板进行染色,降解环为浅红色,而未降解部分为深红色;结果表明,降解环的直径大小随着接种时间的延长而逐步增大,且降解环的大小可反映酶活大小。因此,此法可以直观、清晰、准确地对具有几丁质酶活性的菌株进行筛选,在相关菌株的筛选中具有较大的潜在应用价值。     

Sporophyte induction studies in ferns in vitro

Sporophytes induction from spore-derived gametophytes and the morphogenic potential of homogenised sporophytes were performed in several ferns: Adiantum capillus-veneris, Asplenium adiantum-nigrum, Ceterach officinarum, Davallia canariensis, Dicksonia antarctica, Dryopteris dilatata, Dryopteris filix-mas, and Polypodium cambricum. The influence of growth rate, the formation of sexual organs, and the homogenisation of the gametophyte on sporophyte formation were studied. Gametophytic growth and sporophyte development were not antagonistic events and no correlation was found between the proportion of sexual phenotypes and rate of sporophyte formation. A pre-treatment of the rhizome with BAP exhibited swelling and upon transferral to Murashige and Skoog (MS) basal medium developed numerous fronds. Homogenised sporophytes of A. capillus-veneris, D. canariensis, and P. cambricum cultured on MS basal medium regenerated sporophytes while on MS with 4.4 μM BAP favoured formation of aposporous gametophytes and/or dedifferentiated cellular aggregates. In A. adiantum-nigrum, BAP induced either aposporous gametophytes or sporophytes.     

原木边部锯材的精确尺寸和相应规格的确定

确定了原木边部锯材宽度和厚度的理论值0.424d×0.1d,较目前通用的0.43d×0.1d和0.421d×0.1d均更精确。根据确定式计算的边部锯材出材率,平均为17.66％;边部规格锯材出材率为17.49％;而边部Ⅰ等钝棱锯材的出材率则达23.48％。     

原木周边部分的最大短锯材

对原木周边部分最大短锯材材积计算式和最佳锯剖位置探索的结果。最大短锯材材积计算式为: V=(43~(1/2)(R~2-a~2)~(3/2))/(R~2-r~2)(a-b)L最大短锯材外材面的最佳位置为: a=(3b±(9b~2+16R~2)~(1/2))/8     

森林可持续经营保障机制的探讨

在对森林可持续经营内涵认识的基础上指出,森林可持续经营目标的实现,需要有一套行之有效的综合保障体系去约束规范森林经营者的经营行为。文章重点从理论上探讨了构建中国森林可持续经营动力、激励和约束机制的内涵和关键措施     

对应分析方法的注记

本文说明了对应分析中变量的协方差阵是一个退化矩阵。阐述了要进行对应分析时,原始数据应满足的条件。通过讨论得出进行对应分析若需要对原始数据作标准化处理时,模标准化、最大值标准化和总和标准化总是可行的,应用极差标准化是有条件的;而中心化、离差标准化和标准差标准化则不可使用