巨桉不同状态叶片浸提液对萝卜幼苗形态和抗性生理特性的影响

以珍珠岩作为基质,选择4年生巨桉(Eucalyptus grandis)嫩叶(T1)、老叶(T2)、表层凋落叶(T3)、腐解凋落叶(T4)4种状态的叶片,每种状态叶片设置3个浸提液浓度水平[分别称取风干叶片30g、15g和7.5g加入900mL蒸馏水进行浸提,以蒸馏水为对照(CK)],采用水培法研究了不同状态叶片浸提液对萝卜(Raphanus sativus)幼苗形态生长和抗性生理特性的影响。结果显示:(1)巨桉不同状态叶片浸提液显著抑制了萝卜幼苗的根长,其中嫩叶的抑制作用最强,腐解凋落叶抑制作用最弱。(2)各状态叶片浸提液处理后萝卜幼苗中过氧化氢酶(CAT)和过氧化物酶(POD)的活性均呈现升高趋势,嫩叶各浓度处理以及其他状态叶片的高浓度处理下超氧化物歧化酶(SOD)活性升高,而其余浓度处理的SOD活性降低。(3)各状态叶片浸提液处理萝卜幼苗的丙二醛(MDA)含量在低浓度处理时低于CK,其余处理下则高于CK。(4)嫩叶各浓度处理萝卜幼苗的可溶性糖(SS)含量显著高于CK,且随着老叶和表层凋落叶浸提液浓度的升高,幼苗SS含量先升后降,腐解凋落叶各浓度处理下则呈渐增的趋势;而可溶性蛋白(SP)含量则随浸提液浓度的增加而升高,且T2和T3两种状态叶片的各浓度处理与CK差异显著。研究表明,巨桉不同状态叶片浸提液对萝卜幼苗生长和抗性生理产生了强烈的抑制作用,其中以嫩叶最强,老叶和表层凋落叶次之,腐解凋落叶最弱。     

不同植物对小麦、黄瓜和萝卜幼苗化感作用潜力的初步评价

以小麦、黄瓜、萝卜为受体植物,用室内和田间生物测定方法,研究了甘肃省农区18种植物的化感作用.结果表明,黄花蒿、龙葵、曼陀罗植株茎叶的水抽提物对3种受体植物化感作用最强,其抑制综合效应(SE)分别为47.66%、32.89%和26.63%;其次是苍耳、马齿苋、刺儿菜、灰藜;其SE值分别为21.71%、20.93%、20.83%、20.2%.对受体植物化感作用较弱的是野豌豆(SE-3.5%)、狗尾草(SE2.2%)、鹅绒藤(SE1.97%);土荆芥(SE-103%)、丛枝蓼(SE-163%)、燕麦(SE-533%)对受体植物无明显化感作用.黄花蒿对受体萝卜、黄瓜、小麦、玉米的苗高、植株鲜重有显著影响,其SE值分别为54.07%、38.46%、33.35%、20.88%;黄花蒿对田间小麦植株生长抑制的综合效应为44.70%.可见黄花蒿具有一定的开发利用价值     

钙对萝卜幼苗抗寒性及某些生理指标的影响

研究结果表明钙能够提高萝卜幼苗的抗寒性, 同时与抗寒性有关某些生理指标也受到影响。在低温胁迫后及恢复生长后处理组的萝卜幼苗的超氧物歧化酶、过氧化物酶、抗坏血酸过氧化物酶、过氧化氢酶的活性都比对照组高;在低温胁迫后处理组的脯氨酸及抗坏血酸的含量均比对照组高, 但处理组萝卜幼苗的丙二醛含量却比对照组低。表明钙对萝卜幼苗抗寒性的影响可能与其防止膜脂过氧化有关。     

胡桃醌对小麦种子萌发及幼苗生长的化感效应

以小麦种子为试验材料,采用培养皿药膜法、生化分析法研究了胡桃醌对小麦种子萌发和幼苗生长的化感效应。结果显示:(1)与对照相比,低浓度胡桃醌(4和20μmol.L-1)处理能促进小麦种子萌发和幼苗生长,种子α-淀粉酶活性增大,幼苗中可溶性蛋白含量升高,丙二醛(MDA)含量减少,超氧化物歧化酶(SOD)活性无显著变化。(2)当胡桃醌浓度大于100μmol.L-1时,对小麦种子萌发和幼苗生长开始呈现抑制作用,种子α-淀粉酶活力降低,幼苗相对含水量、可溶性蛋白含量降低,MDA含量升高,SOD活性先增大后减小。(3)在最大浓度胡桃醌(1 250μmol.L-1)处理下,小麦幼根的细胞形状不规则,排列混乱,层次不分明,维管束模糊不清,幼苗细胞质壁分离,叶绿体萎缩坏死,细胞核变形。研究表明,高浓度胡桃醌通过抑制受体小麦保护酶活性,加重膜脂过氧化程度,导致幼根、幼苗细胞结构的破坏,从而产生化感效应,且化感效应随浓度的增加不断增强。     

毛竹浸提液对苦槠幼苗生长的化感效应

为探讨毛竹(Phyllostachys edulis)扩张过程中潜在的化感作用,选择苦槠(Castanopsis sclerophylla(Lindl)Schott)为研究对象。采用水浸提的方法,用毛竹茎叶、枯落物和土壤3部分浸提液浇灌苦槠幼苗,以蒸馏水处理作为对照,对比分析质量浓度分别为0.1、0.05、0.02 g/mL的3个浓度梯度浸提液处理下苦槠幼苗生长指标及各项光合生理指标的差异。结果表明,毛竹浸提液对苦槠幼苗苗高、地径和叶绿素相对含量的影响大体上呈现高浓度抑制低浓度促进的双重浓度效应。不同来源毛竹浸提液的化感效应不尽相同,土壤浸提液对苦槠幼苗生长和光合生理均呈现抑制作用,而茎叶、枯落物浸提液低浓度时为促进作用。毛竹潜在的化感作用,在其扩张过程中可能会干扰森林主要树种更新,从而对森林群落产生威胁。     

羽枝青藓和瘤柄匐灯藓对入侵植物种子萌发和幼苗生长的影响

入侵植物会通过化感作用等手段抑制本地种的生存繁衍,但本土植物尤其是地被层的藓类植物对入侵植物有何影响尚不清楚。本文以本土羽枝青藓和瘤柄匐灯藓为供体材料,以恶性入侵杂草稗草和野胡萝卜为受试材料,从藓丛结构特征和化感作用角度探究藓类植物对入侵植物种子萌发和幼苗生长的影响。结果表明: 2种入侵植物种子落入藓丛后其发芽率、发芽势和发芽指数均受到显著抑制,抑制效果为藓丛上部>藓丛下部>无藓丛。稗草种子落入藓丛下部会显著影响其根长和根芽比。施加藓类浸提液均显著降低2种入侵植物的发芽率、发芽势及发芽指数,但呈现不同的浓度效应。施加浸提液在一定程度上增加了稗草幼苗芽长、根长和根芽比,但对野胡萝卜无明显的规律性影响。藓类植物对2种入侵植物种子萌发和幼苗生长的化感综合效应均表现为抑制作用,其中,野胡萝卜的敏感性大于稗草,且高浓度下更加明显。可见,藓类植物对入侵植物种子萌发和幼苗生长具有一定抑制作用。     

林窗凋落物化感作用对格氏栲幼苗生长的影响

为探讨林窗凋落物化感作用对幼苗更新的影响,通过模拟林窗与非林窗光照强度,以林窗和非林窗凋落物水浸提液（浓度1 ： 10、1 ： 30、1 ： 50和1 ： 100）为化感物质的主要来源,阐述林窗、凋落物化感作用及二者协同效应对格氏栲幼苗高度、叶绿素荧光参数和渗透调节物质的影响。结果表明：（1）非林窗幼苗的叶绿素相对含量、PSⅡ潜在活力（F_v/F_o）、PSⅡ最大光化学效率（F_v/F_m）和可溶性糖含量高于其它林窗,后期幼苗高度和叶片初始荧光（F_o）低于其它林窗。（2）与对照处理相比,不同浓度凋落物浸提液均抑制了幼苗F_v/F_o,而浓度1 ： 50和1 ： 100提高了幼苗后期高度、可溶性蛋白含量和叶绿素相对含量。（3）不同浓度凋落物浸提液中,林窗存在总体上提高了幼苗高度,且小林窗和非林窗幼苗叶绿素相对含量、F_v/F_o和F_v/F_m值高于其它林窗。（4）熵值法结果表明,非林窗格氏栲幼苗生长的综合评价值高于其它林窗,凋落物浸提液浓度对幼苗生长的影响呈"低促高抑"效应,浓度1 ： 50下幼苗生长的综合评价值高于其它浓度。高浓度（1 ： 10和1 ： 30）浸提液下,中林窗幼苗生长的综合评价值高于其它林窗。综上,林窗与凋落物化感作用共同影响格氏栲幼苗,且中林窗（50-100 m²）减弱了高浓度凋落物化感作用对格氏栲幼苗生长的毒害作用。未来,通过人为干扰方式调节林窗面积,适当清理森林凋落物以促进格氏栲幼苗天然更新。     

加拿大一枝黄花根系和根际土壤水浸液对萝卜和白菜种子萌发及幼苗生长的影响

用加拿大一枝黄花根系及根际土壤水浸液对白菜和萝卜的化感作用进行了研究。结果表明,加拿大一枝黄花根系水浸液和根际土壤水浸液对白菜和萝卜种子的萌发具有抑制作用。根际土壤水浸液对白策和萝卜幼苗生长具有促进作用,而对其胚根的伸长生长则具有显著的抑制作用。0．05g／mL根系水浸液处理显著抑制萝卜幼根的伸长,但其它浓度对白菜和萝卜幼苗生长和根系伸长的影响不明显。实验还表明高浓度的根系水浸液和根际土壤水浸液明显抑制白菜和萝卜的根系脱氢酶活性和硝酸还原酶活性。     

紫茎泽兰叶片化感作用对10种草本植物种子萌发和幼苗生长的影响

化感作用在生物入侵过程中具有重要的意义,紫茎泽兰具有化感物质,它能抑制豌豆等一些对化感物质敏感的植物种子萌发,但它对入侵早期直接与之竞争的植物的影响以及化感作用与其入侵性的关系还知之甚少。以紫茎泽兰入侵早期直接与之竞争的草本植物和为替代控制紫茎泽兰引进的牧草为材料,利用培养皿滤纸法研究紫茎泽兰叶片提取液对种子萌发和幼苗生长的影响,探讨化感作用与其入侵性的关系,并为其替代控制提供依据。紫茎泽兰叶片提取液对10种受体植物种子萌发和幼苗生长均有化感作用,不同浓度的提取液对植物的化感作用强度不同,低浓度时较弱,高浓度时较强。高浓度的提取液能降低种子发芽率、发芽速率、胚轴和胚根长度,增加幼苗丙二醛含量,其中发芽速率更敏感,可能是衡量化感作用的最敏感指标。不同植物对紫茎泽兰化感作用的敏感程度不同,无芒虎尾草、白三叶、细叶苦荬和莎草砖子苗对紫茎泽兰化感作用较敏感,紫花苜蓿最不敏感。     

香草醛对杉木幼苗生长的影响

为了解杉木连栽土壤中有毒化感物质对杉木幼苗毒害作用 ,采用水培杉木幼苗方法 ,通过投加不同浓度香草醛 ,发现 1mg·kg- 1 香草醛显著抑制杉木种子胚根的伸长 (P<0 .0 5) ,只为对照的 70 % ;香草醛浓度达 1 0mg·kg- 1 时 ,叶绿素总量明显下降到对照的80 % ;超过 2 0mg·kg- 1 对杉木幼苗地径与高度生长产生明显抑制作用 ;50mg·kg- 1 以上将明显影响地上部分枝叶的正常生长发育 ,及至植株冠层的生长 ;超过 1 0 0mg·kg- 1 ,整个植株的生长受到显著抑制 .香草醛是连栽土壤中毒性较大的一种有毒化感物质 ,是杉木存活率低的重要原因之一 .     

Acylated anthocyanins from red radish (Raphanus sativus L.)

Twelve acylated anthocyanins were isolated from the red radish (Raphanus sativus L.) and their structures were determined by spectroscopic analyses. Six of these were identified as pelargonidin 3-O-[6-O-(E)-feruloyl-2-O-beta-D-glucopyranosyl]-(1-->2)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside), pelargonidin 3-O-[6-O-(E)-caffeoyl-2-O-(6-(E)-feruloyl-beta-D-glucopyranosyl)-(1-->2)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside), pelargonidin 3-O-[6-O-(E)-p-coumaroyl-2-O-(6-(E)-caffeoyl-beta-D-glucopyranosyl)-(1-->2)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside), pelargonidin 3-O-[6-O-(E)-feruloyl-2-O-(6-(E)-caffeoyl-beta-D-glucopyranosyl)-(1-->2)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside), pelargonidin 3-O-[6-O-(E)-p-coumaroyl-2-O-(6-(E)-feruloyl-beta-D-glucopyranosyl)-(1-->2)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside), and pelargonidin 3-O-[6-O-(E)-feruloyl-2-O-(2-(E)-feruloyl-beta-D-glucopyranosyl)-(1-->2)-beta-D-glucopyranoside]-5-O-(beta-D-glucopyranoside).     

Effect of salinity on growth,water use and nutrient use in radish (Raphanus sativus L.)

Radish (Raphanus sativus L.) plants were grown at five soil salinity levels (1, 2, 4, 9 and 13 dS m^-1) to analyse the effects on growth, dry matter partitioning, leaf expansion and water and nutrient use. Salinity was varied by proportionally changing the concentration of all macro nutrients. When the electrical conductivity (EC) of the soil solution increased from 1 to 13 dS m^-1, the influx concentration of the nutrients absorbed by the plants (the ratio between the uptakes of nutrients and water) increased only from 1.6 to 3.5 dS m^-1. The total nutrient uptake showed an optimum at an EC of the soil solution of about 4 dS m^-1. The data suggest that at low salinity level (≤ 2 dS m^-1) the nutrient uptake was limited by availability while at high salinity (>4 dS m^-1) it was limited by the growth of the plant. Total water use by the plants decreased and water use efficiency increased at high salinity. Plant growth was optimal at 2–4 dS m^-1. At salinities higher than 4 dS m^-1 total plant dry weight decreased 2.8% per dS m^-1. About 80% of the growth reduction at high salinity could be attributed to reduction of leaf area expansion and hence to reduction of light interception. The remaining 20% of the salinity effect on growth was most likely explained by a decrease in stomatal conductance. The small leaf area at high salinity was related to a reduced specific leaf area and increased tuber/shoot weight ratio. The latter could be attributed to tuber formation starting at a smaller plant size at high salinity. This revised version was published online in June 2006 with corrections to the Cover Date.     

QTL mapping of clubroot resistance in radish (Raphanus sativus L.)

A QTL analysis for clubroot resistance (CR) of radish was performed using an F₂ population derived from a crossing of a CR Japanese radish and a clubroot-susceptible (CS) Chinese radish. F₃ plants obtained by selfing of F₂ plants were used for the CR tests. The potted seedlings were inoculated and the symptom was evaluated 6 weeks thereafter. The mean disease indexes of the F₃ plants were used for the phenotype of the F₂. The results of two CR tests were analyzed for the presence of QTL. A linkage map was constructed using AFLP and SSR markers; it spanned 554 cM and contained 18 linkage groups. A CR locus was observed in the top region of linkage group 1 in two tests. Therefore, the present results suggest that a large part of radish CR is controlled by a single gene or closely linked genes in this radish population, although minor effects of other genomic areas cannot be ruled out. The CR locus was named Crs1. Markers linked to Crs1 showed sequence homology to the genomic region of the top of chromosome 3 of Arabidopsis, as in the case of Crr3, a CR locus in Brassica rapa. These markers should be useful for breeding CR cultivars of radish. As Japanese radishes are known to be highly resistant or immune to clubroot, these markers may also be useful in the introgression of this CR gene to Brassica crops.     

Interrelationship between chromocentres and chiasmata in radish (Raphanus sativus L.)

A comparative study of the number and distribution of chromocentres in interphase nuclei and mean chiasma frequency at diakinesis has been made in three varietal populations of radish (Raphanus sativus L.), Scarlet Globe, Japanese White and Chinese White. The study showed a significant difference between the varietal populations in mean chiasma frequency and number of chromocentres (P<0.001), indicating that these nuclear characters are genotypically controlled. The correlation analysis revealed a significant negative correlation between chromocentres and chiasma frequency (r= -0.87). It was concluded that an increase in the amount of constitutive heterochromatin, as inferred by chromocentre counts, adversely affects the chiasma frequency and, consequently, genetic recombination in radish.     

24-Epibrassinolide alleviated zinc-induced oxidative stress in radish (Raphanus sativus L.) seedlings by enhancing antioxidative system

This article encompasses the results on the effects of 24-epibrassinolide (EBR) on the changes in reactive oxygen species (ROS) and activities of antioxidative enzymes in radish (Raphanus sativus L.) seedlings subjected to zinc (Zn) stress. Zn toxicity resulted in significant enhancement in the level of membrane lipid peroxidation, protein oxidation, contents of hydrogen peroxide (H₂O₂) and hydroxyl radical (^·OH), the production rate of superoxide radicals (O ₂ ^·? ) and the activities of lipoxygenase and NADPH oxidase in radish seedlings indicating the induction of oxidative stress. However, Zn-mediated enhancement in indices of oxidative stress was considerably decreased by EBR treatment. EBR application enhanced the activities of catalase, superoxide dismutase, guaiacol peroxidase, glutathione peroxidase, and peroxidase in radish seedlings under Zn stress. EBR treatment reduced the activity of ascorbic acid oxidase in Zn stressed seedlings. Further, EBR application also enhanced the free proline and phenol levels under Zn stress. From the results obtained in this study, it can be inferred that EBR application alleviated oxidative damage caused by over production of ROS through the up regulation of antioxidative capacity in Zn stressed radish seedlings.     

Management of Alternaria blight of radish seed crop (Raphanus sativus L.)

Radish (Raphanus sativus L. var. Tasaki Mula) was used in this investigation. On foliar spray, among the three fungicides (Iprodione, Mancozeb and Carbendazim), Iprodione (0.25%) followed by Mancozeb (0.3%) provided the maximum control of Alternaria blight and increased seed yield during the first cropping season (2004–2005). The results in second cropping season (2005–2006), 10 December (early) transplanting with three sprays of Iprodione resulted lowest leaf area diseased, whereas plants in 25 December (normal) transplanting had the lower pod area diseased. In third cropping season (2006–2007), 25 October transplantation with BAU-Biofungicide (2.0%) and Iprodione (0.25%) foliar application showed significant effect in reducing Alternaria blight and increased seed yield by 120.45% and 97.73%, respectively over non-sprayed control. Bio-Biofungicide ranked second in reducing the disease, but ranked first in increasing seed yield. The cost benefit analysis of management practices for radish seed crop during 2005–2006 revealed that stickling transplanting in 25 December (normal) with two sprays of Iprodione (0.25%) yielded the highest return (BCR 3.27), whereas negative result (BCR ? 0.89) has been estimated in case of non-sprayed control plots in late transplanting (10 January). However, cost benefit analysis of cropping season 2006–2007 revealed that BAU-Biofungicide (2.0%) six sprays yielded the highest return (BCR 4.41) followed by six sprays of Iprodione (BCR 3.90). Finally, it may be concluded that Integration of early transplanting (25 October) with foliar sprays ofBAU-Biofungicide (2.0%) was found best for eco-friendly management of Alternaria blight of radish seed crop with significantly higher seed yield.     

Growth of radish (Raphanus sativus) seedlings in magnetic fields

Radish seedlings were grown in asymmetric magnetic fields. The number of seeds germinated and the dry weight of the plants were the two criteria by which possible effects were examined. Two experiments were done; in the first the plants were grown for an average of 7.7 days and in the second for 14.1 days. A statistical analysis of the results failed to reveal any significant difference between control plants grown in dummy magnets and those subjected to the magnetic influence.     

萝卜种质资源亲缘关系的RAPD分析

利用筛选出的12个随机引物,对来源于不同国家和地区的有代表性的56份萝卜种质资源遗传多样性进行了RAPD分析,共扩增出109条带,其中多态性带为72条,多态性带百分率为62.9%,种质平均期望杂合度为0.289.系统聚类分析将供试材料分为2大类、9组,主坐标分析将其分为3大类、7组,两种分类方法结果基本一致,后者能更为直观和清楚地反映群体之间的关系.