The rates of maize growth and lignin biosynthesis change after root-applied chalcone

The effects of root-applied chalcone at 0.15 mmol L⁻¹ on the growth and lignin biosynthesis in maize were investigated. The contents of 4-coumarate: CoA ligase (4CL, EC 6.2.1.12) substrates in maize shoots were increased more rapidly in the samples with chalcone application than in the control and the increase occurred at ≤ 3 h after the application (HAA). The lignin content was reduced by chalcone at ≤ 6 HAA. The shoot growth was suppressed by chalcone at ≤ 9 HAA. Consequently, the results suggest that chalcone suppressed maize growth by inhibiting monolignol biosynthesis.     

Influence of Compost Addition to Soil on the Behaviour of Herbicides

The transformations of eight herbicides (atrazine, simazine, terbutryn, pendimethalin, carbetamide, 2,4-D, metsulfuron-methyl and dimefuron) in soil after compost addition were monitored during long-term laboratory incubations. The herbicides were applied to soil, compost and soil-compost mixtures. Herbicide sorption, their kinetics of mineralisation and the extractability of residues were compared in the different treatments. Compost addition to soil generally decreased herbicide mineralisation and favoured the stabilisation of herbicide residues. A fraction of the stabilised residues remained extractable and potentially available. However, most of them were unextractable and formed bound residues. Sorption could be at the origin of a kinetically limited biodegradation, mainly for the most highly-sorbed herbicides (atrazine, simazine, terbutryn, pendimethalin and dimefuron). Compost addition had little effects on the less sorbed herbicides (carbetamide, 2,4-D and metsulfuron- methyl). © 1997 SCI.     

Synthesis and Evaluation of New Ethyl 2,3- Dihydro-3-oxoisothiazolo[5,4-b]pyridine- 2-alkanoate Derivatives as Potential Herbicides

Several ethyl 2,3-dihydro-3-oxoisothiazolo[5,4-b]pyridine-2-alkanoate derivatives were synthesized as herbicides. Only 5-methyl derivatives inhibited both hypocotyl and root growth in the lettuce (Lactuca sativa L.) seedling test at 100 mg litre^-1. Only ethyl propionate and valerate derivatives showed significant inhibition at 0·1 mg litre^-1, whereas ethyl acetate or butyrate derivatives were inactive. Contrary to unoxidized derivatives, the inhibitory effect of 1-oxide and 1,1-dioxide derivatives was strongly dependent on concentration; ethyl 2,3-dihydro-5-methyl-3-oxoisothiazolo[5,4-b]pyridine-2-propionate 1,1-dioxide inhibited 100% of germination at 100 mg litre^-1 and 45% of lettuce seedling growth at 0·1 mg litre^-1. Quantitative structure–inhibition of growth relationship analysis carried out by adaptive least-squares (ALS) method gave a good correlation with small and hydrophobic 5-substituents as well as with odd carbon-chain ethyl alkanoates in position 2. Active compounds did not show auxin-like activity from 0·1 to 100 mg litre^-1. © 1997 SCI.     

Ovicidal,larvicidal and juvenilizing activity of a picolinephenoxyanilide against Cydia pomonella

N‐(4‐phenoxyphenyl)‐2‐pyridinecarboxamide (1) was synthesized from commercially available materials and its ovicidal and larvicidal activity against Cydia pomonella (L) was tested. The compound showed a LC₅₀ of 0.98 mg ml⁻¹ when eggs less than 24 h were sprayed using a Potter Tower, but it had no effect when eggs older than this were sprayed. The compound did not have larvicidal activity when larvae were treated with 1200 µg g⁻¹. However, the larval head capsules were smaller than those in the controls when treated at this concentration. To assess its possible juvenile‐hormone‐like activity, the compound was topically applied to young pupae of Tribolium confusum duVal, where it produced clear juvenilization effects, which were dependent on the applied dose. © 2000 Society of Chemical Industry     

Changes in wind activity from 1957 to 2011 and their possible influence on aeolian desertification in northern China

Wind activity is proved to have significant impacts on aeolian desertification. Clarifying the fluctuations and change trend of wind velocity is important for understanding their influence on aeolian desertification. In this study, we used a dataset of wind velocities collected from 93 meteorological stations across northern China from 1957 to 2011 to analyze the changes in wind activity during this period. We tested the monotonic and step(abrupt) trends for annual and seasonal data of mean wind velocity by using Mann-Kendall and Mann-Whitney tests, respectively. The results indicated that the annual mean wind velocity decreased by 0.83 m/s from 1957 to 2011. The decreasing trends were also significant(P<0.01) for each season. The magnitude of the decrease was smallest in the east of northern China and largest in the west of northern China, and the most remarkable decrease occurred in the northwest of northern China. Abrupt decreases in annual and seasonal mean wind velocities occurred in the mid-1980 s, which was consistent with the changes in aeolian desertification since the mid-1980 s in northern China. As revealed by our study, although both modern aeolian desertification and ecosystem rehabilitation are affected by human activities to some extent, they are also likely to be strongly controlled by climate change, especially by wind activity.     

Molecular cloning and characterization of the cinnamate 4‐hydroxylase gene from Eupatorium adenophorum

Cinnamate‐4‐hydroxylase (CA4H), a cytochrome P450‐dependent monooxygenase, plays crucial roles in phenylpropanoid metabolism and plant defense. Previously, the authors showed that the expression of CA4H was induced in response to an allelopathic substance in Eupatorium adenophorum. Here, the full‐length cDNA of EaCA4H was cloned by using rapid amplification of cDNA ends. The 1518 bp open reading frame of EaCA4H was deduced to encode a protein of 505 amino acid residues. Like other CA4H proteins, the predicted EaCA4H polypeptides contained conserved domains of cytochrome P450. A Southern blot analysis indicated that at least five copies of EaCA4H exists in the genome of E. adenophorum. Subcellular localization revealed nuclear‐localized EaCA4H–green fluorescent protein fusion protein in onion epidermal cells. Heterologous silencing of endogenous CA4H in tobacco by a conserved EaCA4H fragment resulted in reduced expressions of key enzymatic genes and the production of downstream flavonoids in the phenylpropanoid pathway. Intriguingly, similar effects were observed in transgenic tobacco plants overexpressing EaCA4H. Altogether, the results indicate that the disturbed expression of CA4H in plants leads to relatively low expression levels of key enzymatic genes and the accumulation of the flavonoids that are involved in phenylpropanoid metabolism.     

“新时代交互英语—视听说”与大学英语四级成绩的相关研究

2005年9月清远职业技术学院采用"新时代交互英语"进行听说课程教学改革。本文通过对04级和05级英语专业学生在使用该教材前后的英语语言技能成绩进行数据分析,发现该教材有助学生通过大学英语四级考试。     

Initiation of Setaria as a model plant

Model organisms such as Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa) have proven essential for efficient scientific discovery and development of new methods. With the diversity of plant lineages, some important processes such as C₄ photosynthesis are not found in either Arabidopsis or rice, so new model species are needed. Due to their small diploid genomes, short life cycles, self-pollination, small adult statures and prolific seed production, domesticated foxtail millet (Setaria italica) and its wild ancestor, green foxtail (S. viridis), have recently been proposed as novel model species for functional genomics of the Panicoideae, especially for study of C₄ photosynthesis. This review outlines the development of these species as model organisms, and discusses current challenges and future potential of a Setaria model.     

黄河滩区不同刈割期对热研4号王草生产性能和品质的影响

为了找到热研4号王草(Pennisrtum purpureumxp typhoidevm‘Reyan No.4’)在河南省黄河滩区营养和产量俱佳的刈割利用方式,从苗高80cm开始,在留茬15~20cm的情况下,采用每隔30d、40d、60d和全年1次性的刈割方式,研究不同刈割方式对王草生长、产量和营养水平的影响,为当地草食家畜的发展提供优质且稳定的饲草。研究表明:刈割会限制茎长,增加茎粗,有利于植株的分蘖及降低倒伏率;过频刈割会降低茎叶比(S/L ratio),叶面积指数(LAI)和生长速度,不利于饲草生产;适度的刈割有利于提高鲜干比(F/D ratio)、单株分蘖数和生长速度,有利于牧草的高产。另外,刈割次数对热研4号王草粗蛋白质和粗纤维含量有显著影响,而对粗脂肪、粗灰分和无氮浸出物含量影响不显著,多次刈割会提高粗蛋白质含量、降低粗纤维含量,每隔30d与40d刈割1次与1年仅割1次相比,粗蛋白质含量分别提高5.47%(P0.05)和2.80%,粗纤维含量分别降低6.67%(P0.05)和5.54%(P0.05),而每隔60d刈割1次和1年仅割1次相比,饲草营养没有显著差异。综合评价结果表明:每隔60d刈割1次,一年刈割2次,留茬15~20cm,牧草生长良好,粗蛋白质含量可达到13.01%,全年产草量达到29.83tDM·hm-2,均达到理想水平。     

由类分《我国石油企业劳动工资管理》一书想到的……

结合实际图书分类工作,依据《中国图书馆分类法》（第四版）,对F416,F426以及F129和F719等类目的设置提出了可行性建议。