Cutting weeds with a CO2 laser

Stems of Chenopodium album . and Sinapis arvensis . and leaves of Lolium perenne . were cut with a CO₂ laser or with a pair of scissors. Treatments were carried out on greenhouse-grown pot plants at three different growth stages and at two heights. Plant dry matter was measured 2 to 5 weeks after treatment. The relationship between dry weight and laser energy was analysed using a non-linear dose–response regression model. The regression parameters differed significantly between the weed species. At all growth stages and heights S. arvensis was more difficult to cut with a CO₂ laser than C. album . When stems were cut below the meristems, 0.9 and 2.3 J mm⁻¹ of CO₂ laser energy dose was sufficient to reduce by 90% the biomass of C. album and S. arvensis respectively. Regrowth appeared when dicotyledonous plant stems were cut above meristems, indicating that it is important to cut close to the soil surface to obtain a significant effect. When cutting L. perenne plants with 2-true leaves at a height of 2 cm from the soil surface with a laser, the biomass decreased significantly compared with plants cut by scissors, indicating a delay in regrowth. This delay was not observed for the dicotyledonous plants nor for the other growth stages of L. perenne .     

Chromosomal structural changes in Capsicum annuum L. and C. chinense Jacq.

Summary Wide hybridizations between M. arvensis and Brassica amphidiploid species (B. napus and B. juncea) were carried out in order to incorporate desirable traits of M. arvensis into Brassica crops. Crossing barriers between them were present without the use of in vitro techniques. F₁ hybrids have been produced through ovary culture, when M. arvensis were used as a female parent. Higher hybrid embryo productivity (3.07 embryos per pollination) was obtained in the cross of M. arvensis x B. napus than in that of M. arvensis x B. juncea (0.79 embryos). The hybridity was confirmed by morphology, cytology, isozyme and Southern analyses. The first backcrossing progenies and open pollinated ones were produced.     

Establishment and Identification of Cytoplasmic Male Sterility in Brassica napus by Intergeneric Somatic Hybridization

Exploitation of novel cytoplasmic male sterility(CMS)is a main approach for widening the cytoplasmic genetic background of hybrid oilseed rape and avoiding epidemic risk in oilseed rape production.In this study,symmetric somatic hybrids between Brassicanapus var.Zhongshuang4 and Sinapis arvensis(Yeyou18)were produced by protoplast fusion.Two of the six established hybrids were male sterile showing trace or no pollen release upon flowering with non-or slightly extended stamens.Using Zhongshuang4 as a recurrent parent to pollinate the male sterile plants,the ratio of male sterile plants increased with the number of backcrosses.As early as in BC3 generation,most of the sterile families had nearly 100%sterile plants.Up to BC4 generation,the male sterility became stable and no fertility segregation was observed.All F1 progenies from tested crosses using restorer and maintainer lines of Polima CMS were 100%sterile,indicating that the established CMS by somatic hybridization is different from Polima CMS.The origin of the cytoplasm and potential use of this hovel CMS in oilseed rape breeding were discussed.Key wotds:Oilseed rape,Protoplast fusion,Cytoplasmic male sterility,Sinapis arvensis     

温度对4种杂草种子萌发的影响

研究了20℃/15℃和25℃/20℃两种日波动温度对棒头草（Polypogon fugax Nees ex steud.）、大瓜草（Spergula arvensis L.）、红花月见草（Oenothera rosea L’Herit.ex Ait.）和紫茎泽兰（Eupatorium adenophorumSpreng.）种子的发芽率、发芽势和发芽指数的作用。结果表明,4种杂草种子萌发对两种波动温度的反应存在差异。前4 d高温有利于棒头草种子萌发,而3 d以后,种子在低温时的发芽率均高于高温处理。前3 d高温促进大瓜草种子的发芽势,而4 d后两种温度下种子的发芽率维持不变,且低温处理的发芽率比高温处理高10%左右。红花月见草和紫茎泽兰种子萌发对温度的反应很相似,即在种子萌发的早期高温和低温种子发芽率差异很大,随着发芽时间的进一步延长,两种温度处理的发芽率逐渐接近。     

In-vitro Fertilization of Ovules of Some Species of Brassicaceae*

The method of in-vitro fertilization of ovules can be successfully applied to various species of Brassincaceae. Mature embryos and plants were obtained after in-vitro pollinating the ovules of Arabis caucasica, Brassica napus, B. oleracea var. sabellica (kale), B. oleracea var. italica (broccoli), Diplotaxis tenuifolia, Moricandia arvensis and Sisymbrium Loeselli. In the case of Sinapis alba fertilization and embryo development did not occur. The same method has been successfully used for obtaining hybrid immature embryos at different stages of development from crosses between B. napus X D. tenuifolia, B. napus X M. arvensis, B. oleracea var. italica X D. tenuifolia, D. tenuifolia x B. napus, D. tenuifolia. X M. arvensis and D. tenuifolia X S. Loeselli. The present findings show that in-vitro pollination of ovules of various species of Brassicaceae makes it possible to (a) perform the whole process of fertilization and embryogenesis; and (b) obtain intergeneric hybrid embryos.     

Moricandia arvensis 与甘蓝型油菜属间杂种的获得及其生物学特性研究

以C_3作物甘蓝型油菜作父本与野生C_3—C_4中间型植物Moricandia arvensis作有性杂交,经子房培养和胚性芽挽救,获得了4个属间杂种,经腋芽繁殖使杂种群体增至数百株。RFLP分析结果显示,杂种核DNA具有两个亲本的特征指纹,而其细胞质中仅含母本Moricandia arvensis的线粒体DNA指纹。杂种多具33条染色体,为双亲配子染色体数之和。虽然杂种植株在大多数形态特征上表现为双亲的中间类型,但在某些性状上明显趋向某一亲本。杂种植株的一般特征是半匍匐性,浅裂叶,开浅黄花。其以CO_2补偿点很高,为C_3类型。花粉母细胞减数分裂不正常,有多价体产生。杂种雌雄性皆不育。用秋水仙素将杂种加倍为双二倍体后,仍然雄性不育。对进一步向芸薹属作物基因组中导入C_3-C_4基因的技术途径进行了讨论。     

国外关于Sinapis arvensis L．的一些研究

本文综合叙述了国外对ＳｉｎａｐｉｓａｒｖｅｎｓｉｓＬ．的研究结果，包括名称和类别、经济重要性、历史和地理分布、形态特征、生长发育、繁殖、细胞遗传学、ＳｉｎａｐｉｓａｒｖｅｎｓｉｓＬ．与Ｂｒａｓｓｉｃａ几个种的杂交、对某些寄生物及对除草剂和其他化学物质的反应等。     

Metal micronutrients relationships in crop,soil, and common weeds of two maize (Zea mays L.) fields

Deficiencies of metal micronutrients are common in some calcareous soils. Samples of aerial parts of maize and five common weeds and also soil beneath these plants were collected and analyzed to investigate the status and relationships of metal micronutrients in soil, crop, and common weeds of maize field trials at two sites. Results showed that Fe concentration in five studied weeds was higher than that of maize; the highest Fe concentration was found in Convolvolus arvensis and Echinochloa crus-galli (first site) and in Convolvolus arvensis tissues (second site). At both sites, the highest Mn concentration was observed in aboveground parts of Echinochloa crus-galli. The concentration of Mn (both sites) and Fe and Cu (second site) were remarkably higher in Echinochloa crus-galli tissues in comparison with maize. Also the concentrations of Fe (both sites) and Cu (second site) were considerably higher in Convolvolus arvensis tissues in comparison with maize. Available Fe was the highest in the soil beneath Convolvolus arvensis and Portulaca oleracea (first site) and beneath Convolvolus arvensis and Cenopodium album (second site). The high value of available Fe in the soil beneath Convolvolus arvensis may explain why Fe concentration was the highest in aerial parts of this weed species.     

Fumigant toxicity of volatile natural products from Korean spices and medicinal plants towards the rice weevil,Sitophilus oryzae (L)

The fumigant toxicity of various volatile constituents of essential oils extracted from sixteen Korean spices and medicinal plants towards the rice weevil, Sitophilus oryzae L (Coleoptera: Curculionidae), was determined. The most potent toxicity was found in the essential oil from Mentha arvensis L var piperascens (LC₅₀ = 45.5 µl litre^?1 air). GC–MS analysis of essential oil from M arvensis showed it to be rich in menthol (63.2%), menthone (13.1%) and limonene (1.5%), followed in abundance by β‐pinene (0.7%), α‐pinene (0.6%) and linalool (0.2%). Treatment of S oryzae with each of these terpenes showed menthone to be most active (LC₅₀ = 12.7 µl litre^?1 air) followed by linalool (LC₅₀ = 39.2 µl litre^?1 air) and α‐pinene (LC₅₀ = 54.9 µl litre^?1 air). Studies on inhibition of acetylcholinesterase activity of S oryzae showed menthone to have a nine‐fold lower inhibitory effect than menthol, despite menthone being 8.1‐fold more toxic than menthol to the rice weevil. Different modes of toxicity of these monoterpenes towards S oryzae are discussed. © 2001 Society of Chemical Industry     

Review of Field Bindweed,Convolvulus arvensis L., a Troublesome Weed in Cotton Fields

Field bindweed(Convolvulus arvensis L.), known as one of the ten most noxious weeds in the world, has a considerable ability to adapt to the environment and to reproduce and regenerate. In recent decades, field bindweed has increasingly become a problematic weed of cotton fields in China. This review summarizes research to-date on this weed, including morphological and taxonomic characteristics, distribution and habitat, life history, economic characteristics and control strategy. Based on the analysis of the occurrence and harmfulness of field bindweed in China, we suggest carrying out further research on the reproductive characteristics of perennial root systems, adaptability to regional environments and high-efficiency control technologies for field bindweed.