真江蓠对氨氮去除效率与吸收动力学研究

以真江蓠(Gracilaria asiatica)为实验材料,在实验室水平上测定了真江蓠培养密度对NH4-N去除效率和吸收速率的影响,比较了真江蓠在氮半饥饿和氮饱和状态下的氨氮吸收动力学特征以及不同起始浓度NH4-N对其吸收速率的影响.结果表明:真江蓠密度为2～24 g·L-1时,5 h内随着藻体密度增大和实验时间延长,真江蓠去氨氮能力也增强.当藻体密度为24g·L-1时,真江蓠在5 h内去除氨氮效率最高,达到99.77%.各种藻体密度在起始阶段保持较高吸收速率(30～41 μmol·g-1·h-1),随后藻体密度与吸收速率呈反比关系,其最低藻体密度组(2 g·L-1)在3 h和5 h吸收速率最大,分别为28.33 μmol·g-1·h-1和18.85μmol·g-1·h-1.在起始浓度梯度实验中,氮半饥饿和氮饱和真江蓠吸收氨氮的最大吸收速率和半饱和常数在1 h均达到最高值,分别为116.47、159.40μmol·g-1·h-1和439.70、913.61 μmol·g-1·h-1.之后随着培养时间的延长而降低.氮半饥饿和氮饱和真江蓠对NH4-N的吸收差别不显著;当氨氮浓度为300～500μmol·L-1时,氮半饥饿的真江蓠在起始1 h内有一个快速吸收阶段(40.7～102.1μmol·g-1·h-1),吸收速率与NH4-N浓度几乎成正比,此时不符合米氏动力学饱和方程,而在低N浓度下(100～200μmol·L-1),藻体对NH4-N的吸收则没有出现这种现象;随着培养时间延长,直到NH4-N浓度达到一定限度时,吸收速率可达到一极大值而符合米氏动力学饱和方程.该研究结果为大规模栽培真江蓠净化水体和生态修复提供了理论依据.     

不同密度对江西车前产量及其构成因素的影响研究

研究不同密度对江西车前产量及其构成因素的影响以及产量与产量构成因素的相关性。结果表明,在8．0-13．6422万株／hm^2范围内,车前产量随着密度的增大而增加;超过13．6422万株／hm^2,则产量呈下降趋势。通过二次曲线拟合得出车前高产栽培最适密度为13．6422万株／hm^2。     

毛车前的花粉母细胞减数分裂及核型分析

采用压片法,对武汉地区野生毛车前的花粉母细胞减数分裂及体细胞核型进行了研究。结果表明,毛车前的绝大多数花粉母细胞减数分裂中染色体行为正常,终变期同源染色体配对后可形成12个二价体;仅在2.93%的花粉母细胞减数分裂中观察到染色体落后、染色体桥等异常行为,其减数分裂为同时型;花粉粒育性为96.88%。核型分析结果表明,毛车前的染色体数目为2n=24,核型公式为K(2n)=24=22m+2sm,其核型为"1B"型。     

基因枪作用下的外源GUS基因在四种红藻组织块中的瞬间表达

建立合适的外源基因转移系统是大型海藻基因工程的一个重要研究内容。外源基因在大型海藻组织中的瞬间表达可以确定外源基因是否导入海藻组织及研究影响导入的各种因素,以此来建立合适的ＤＮＡ导入系统。迄今,秦松等［１９９４］对海带的遗传转化进行了研究,用基因枪将...     

Mapping the drivers of parasitic weed abundance at a national scale: a new approach applied to Striga asiatica in the mid-west of Madagascar

The parasitic weed genus Striga causes huge losses to crop production in sub-Saharan Africa, estimated to be in excess of $7 billion per year. There is a paucity of reliable distribution data for Striga; however, such data are urgently needed to understand current drivers, better target control efforts, as well as to predict future risks. To address this, we developed a methodology to enable rapid, large-scale monitoring of Striga populations. We used this approach to uncover the factors that currently drive the abundance and distribution of Striga asiatica in Madagascar. Two long-distance transects were established across the middle-west region of Madagascar in which S. asiatica abundance in fields adjacent to the road was estimated. Management, crop structure and soil data were also collected. Analysis of the data suggests that crop variety, companion crop and previous crop were correlated with Striga density. A positive relationship between within-field Striga density and the density of the nearest neighbouring fields indicates that spatial configuration and connectivity of suitable habitats is also important in determining Striga spread. Our results demonstrate that we are able to capture distribution and management data for Striga density at a landscape scale and use this to understand the ecological and agronomic drivers of abundance. The importance of crop varieties and cropping patterns is significant, as these are key socio-economic elements of Malagasy cropping practices. Therefore, they have the potential to be promoted as readily available control options, rather than novel technologies requiring introduction.     

On the formulation of disulfide herbicides based on aminophenoxazinones: polymeric nanoparticle formulation and cyclodextrin complexation to combat crop yield losses

Background

The resistance of weeds to herbicides is a significant issue in ensuring future food supply. Specific examples are Plantago lanceolata, Portulaca oleracea and Lolium rigidum, which mainly infect rice, wheat, barley and pastures, and cause high yield losses every year. In this regard, natural products and their mimics have provided new hope as a result of their different modes-of-action, activity at low concentrations and reduced pollution effects relative to conventional herbicides. However, the poor water solubility and physicochemical properties of these compounds limit their broad application. These problems can be addressed by formulation techniques, and encapsulation appears to be of great interest.

Results

Disulfide herbicides inspired by aminophenoxazinones have been formulated with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), γ-CD and polymeric nanoparticles (NPs). In silico studies were employed to identify which complexes would be generated and complex formation was confirmed by nuclear magnetic resonance spectroscopy. Solubility diagrams were generated to assess any improvement in water solubility, which was enhanced 2–13-fold. Scanning electron microscopy and energy-dispersive X-ray spectra confirmed the success of the formulation process for the nanoparticles. Formulated compounds were evaluated in an in vitro wheat coleoptile bioassay, with almost 100% elongation inhibition achieved using only water for the bioassay. Specific in vitro testing on weed phytotoxicity showed that the application of core/shell NPs is highly effective in the fight against P. lanceolata seed germination.

Conclusions

The formulation of disulfide herbicides with CD complexes and NPs led to an enhancement in water solubility and bioactivity. These systems can be applied in pre-emergent mode against P. lanceolata, using only water to prepare the sample, and they showed better activity than the positive controls. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Phytochemical Constituents and Allelopathic Effects of Some Medicinal Plants Extract on the Soil Algal Diversity

Phytochemical constituents of the shoots and roots extract of chosen eight medicinal plants （Plantago major, Verbesina encelioides, Glinus lotoides, Helotropium supinum, Mentha microphylla, Euphorbia hirta, Juncus subulatus and Convolvulus arvensis） were estimated using standard qualitative analysis. The extract contained alkaloids, glycosides, saponins, phenols, tannins, f[avonoids and terpenoids in some medicinal plants while others contain some only of these phytochemical components. Allelopathic effect of the various concentrations of the extracts on the soil algal diversity was also investigated. Wollea saccata was the only algal species disappeared from all applied investigated plant extracts. Phormidium richardsii, Monoraphidium braunii, Eunotia verneris and Nitzschia bilobata were the highly sensitive algal species to all applied shoot and root extract from all tested plants, they disappeared from most of the studied plants. On the other hand, Phormidium animale and Chlorella neustonice were highly tolerant algal species to all applied extracts. Counts of Cyanophyceae, Chlorophyceae and Bacillariophyceae were decreased by addition of some investigated medicinal plants extracts such as Juncus subulatus, Convolvulus arvensis and Euphorbia hirta. So the authors can use these plants extracts in biocontrol of the nuisance of algal bloom or any other microorganisms. Also, these plants may be useful to recover eutrophic water which needs further investigation.     

Effect of Varying Nitrogen Regimes on Growth,Seed Yield,and Nutrient Accumulation in Isabgol

A greenhouse experiment was conducted to determine the optimum dose of nitrogen (N) fertilizer for attaining maximum yield of isabgol (Plantago ovata Forsk.). Sixty three-day-old plants were subjected to varying levels of N (0, 30, 60, and 90 kg N/ha) until seed harvesting. Maximum growth and seed yield occurred at 60 kg N/ha, whereas 90 kg/ha was inhibitory to isabgol growth. The growth and seed yield recorded at 30 or 60 kg N/ha did not differ much, and in view of the high cost to be incurred from applying 60 kg N/ha and the relatively low yield achieved at this level, 30 kg N/ha would be a much more suitable level for isabgol. Accumulation of N, potassium (K), and phosphorus (P) in shoots or roots of isabgol increased consistently under increasing levels of N, but this pattern of increase in the levels of three nutrients in plant tissues was negatively associated with the growth of the crop, particularly at the supra-optimal N level (90 kg N/ha).     

贵州不同产地苗药飞龙掌血中总生物碱和白屈菜红碱的含量测定

[目的]测定贵州不同产地苗药飞龙掌血中总生物碱和白屈菜红碱的含量。[方法]采用反滴定法测定总生物碱含量,并采用高效液相色谱法测定白屈菜红碱的含量,色谱柱为Diamonsil C18(250 mm×4.6 mm,5μm),流动相为乙腈-浓度0.1%磷酸水溶液(V/V,28∶72),检测波长为270 nm,流速为1.0 ml/min。[结果]总生物碱、白屈菜红碱的平均回收率分别为97.5%和99.8%;RSD分别为2.71%和0.40%。[结论]该分析方法准确、灵敏、可靠,可用于飞龙掌血中总生物碱和白屈菜红碱的含量测定。     

雾培对药用植物车前生长及品质的影响

文章以土壤栽培为对照,采用1/2日本园试营养液配方研究气雾栽培对车前生长、产量和品质的影响,探索适合药用植物车前高效种植的新途径。结果表明,和土培组相比,雾培组车前生长周期缩短82 d;株高、叶面积、根系体积、干重显著增加,分别提高了10.4%,148.3%,218.0%,250.3%;植株可溶性蛋白质、Vc含量、可溶性糖含量均高于土培组,分别是土培组的1.07,1.41,1.31倍;总黄酮、多糖和大车前苷含量均低于土培组,但仍达到药用质量标准。雾培有利于车前的生长,可缩短生长周期,提高生物量,改善营养品质,但不利于药用成分的积累。