Characterization of novel inbred lines of white clover (Trifolium repens L.). I. Dynamics of plant growth and nodule development in flowing solution culture

Growth, dry matter partitioning between shoots and roots, and extent of nodulation were characterised in four novel self-fertile highly inbred lines (referred to as A, B, C and D) of white clover (Trifolium repens L.) thought to differ fundamentally in their nitrogen relations and therefore regarded as candidate material for genetic mapping. Plants were inoculated with a mixture of three strains of Rhizobium and grown in flowing nutrient solutions without N for 18 d. Half the plants were then supplied with 20 μM NO₃ ^- during a 36 d treatment period, the remaining plants acting as ‘controls’ solely dependent upon N₂ fixation for acquisition of N. Total dry matter production and shoot:root ratios were similar in all lines supplied with NO₃ ^- and in control plants of lines B and C. Growth was severely reduced in control plants of line D and to a lesser extent in control line A. These effects were attributed to a failure to develop effective N₂ fixation capacity after apparently normal infection. Mean nodule size, nodule numbers and nodule d.w. per plant were extremely low in line D compared with the other lines, irrespective of whether NO₃ ^- was supplied. Lines A, B and C differed in the severity with which NO₃ ^- decreased mean d.w. per nodule and total nodule d.w. per plant relative to corresponding control plants, with line C being least sensitive. Nitrate also decreased the total number of nodules per plant relative to control plants after day 14 in all lines except C, and most severely in line B. This revised version was published online in August 2006 with corrections to the Cover Date.     

三叶草作为 Sr、Cs 污染指示植物的效应研究

【目的】通过盆栽水培试验,探究三叶草(Trifolium pratense L.)对Sr、Cs的敏感性和生理特性。【方法】试验设置Sr、Cs和Sr+Cs 3种处理,每种处理设0、0.1、0.5、1、2 mg/L 5个浓度梯度。测定各浓度处理下三叶草植株冠径、单株叶面积和生物量等生长指标,叶片叶绿素含量和MDA含量等生理生化指标以及三叶草地上、地下部分对Sr、Cs吸收情况。通过对比不同处理间各指标的差异,研究三叶草对Sr、Cs的敏感特性。【结果】在Sr处理下,三叶草单株叶面积显著增加,叶片MDA含量随处理浓度升高而逐渐升高,其中1.0 mg/L Sr处理下的MDA含量显著高于对照。在Cs和Sr+Cs处理下,三叶草植株的生长和形态指标如植株冠径、单株叶面积、地上部生物量均受到严重抑制,分别降低28.0%～35.0%和29.5%～37.1%、31.6%～41.7%和16.8%～21.1%、44.0%～48.0%和47.0%～56.0%;三叶草叶片MDA含量随处理浓度的升高逐渐增加,叶片也逐渐黄化。同时,三叶草对Cs的吸收量远远大于对Sr的吸收,且Sr、Cs主要积累于地上部。【结论】三叶草对Cs敏感,在生理水平上表现为叶绿素含量降低,叶片MDA积累增加;在个体水平上表现为单株叶面积减小、生物量降低、生长受到抑制以及叶片出现特征性黄化现象,具有作为Cs污染指示植物的潜力。     

不同贮藏年限蒙农1号红三叶种子活力的研究

以不同贮藏年限蒙农1号红三叶种子为材料,通过标准发芽试验,对种子千粒重、硬实率、发芽率、发芽势、发芽指数和活力指数等指标进行测定,比较不同贮藏年限种子活力变化情况.结果表明:?18℃低温贮藏条件下,红三叶种子千粒重随着贮藏年限的增加有降低的趋势;红三叶种子当年收获和贮藏1年的硬实率高,贮藏2年的种子大部分已破除硬实,解...     

Productivity of two Douglas fir/subclover/sheep agroforests compared to pasture and forest monocultures

Resource sharing between tree and forage plant components in silvopastoral systems includes a complex set of facilitative and competitive interactions. To the extent that facilitation exceeds competition, agroforests are expected to outyield monocultures of their components. Pasture and Douglas fir (Pseudotsuga menziesii) tree production of young agroforests was compared to pasture and forest monocultures under both grid and cluster patterns of tree planting near Corvallis, Oregon, USA, during 1983–1987. The height and diameter growth of forest and agroforest trees was similar, regardless of tree planting pattern. Five-year average annual forage production was 6500, 5800, and 2800 kg ha^–1 on pasture, agroforest, and forest plots, respectively. The total cumulative 1982–1987 above-ground phytomass yield of forage plus trees was similar for pasture and conventional grid forest monocultures. The total productivity of agroforests, however, was over 30% greater than either pasture or forest components grown in monoculture. Approximately 1.6 ha (0.96 ha forest + 0.64 ha pasture) of monocultures would be needed to equal the productivity of 1 ha of agroforest.Oregon Agricultural Experiment Station Technical Paper No. 10, 825.     

白三叶叶片水浸提液对几种园林植物的化感作用

采用砂培法研究了不同质量浓度白三叶Trifolium repens叶片水浸提液对一串红Salvia splendens,香雪球Lobularia maritime,石竹Dianthus chinensis,高羊茅Festuca arundinacea和马蹄金Dichondra repens等幼苗生长、根系活力、叶绿素质量分数以及抗氧化保护酶活性的影响,并采用气相色谱-质谱(GC-MS)联用技术对白三叶叶片水浸提液化学成分进行了分析。结果表明:白三叶叶片水浸提液对一串红、香雪球、石竹、高羊茅和马蹄金幼苗生长有明显的影响,其中,50 g·L-1白三叶叶片水浸提液处理5种园林植物幼苗,对其生长指标有极显著的抑制作用(P<0.05),其幼苗根系活力分别降低了24.0%,42.8%,51.6%,16.1%和14.9%,幼苗叶绿素质量分数分别下降了13.6%,43.1%,30.5%,57.1%和13.8%。当处理质量浓度为25 g·L-1时,对5种园林植物幼苗体内过氧化物酶(POD),超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性有显著的促进作用(P<0.01);当白三叶叶片水浸提液质量浓度增加到50 g·L-1时,对5种园林植物幼苗体内POD,SOD和CAT活性有极显著抑制作用(P<0.01),同时使幼苗体内丙二醛(MDA)质量摩尔浓度极显著增加(P<0.01)。白三叶叶片水浸提液有42种化合物,主要成分是4-羟基-紫罗兰酮(16.4%),乙酸异戊酯(11.0%),二氢香豆酮(9.6%),乙烯基愈创木酚(7.4%),喇叭茶醇(6.4%),菖蒲酮(5.5%),麦芽酚(4.9%),紫罗兰酮环氧化物(4.7%)和2-羟基-6-甲基苯甲醛(4.2%),合计占到总量的70.1%。图7表2参31     

温度对10个白三叶品种种子萌发特性的影响

以Rivendel、Durana、Tribute、Tahora II、Prop、Barbzan、Haifa、Alice、Dutch White、Huia 10个白三叶品种的种子为试验材料,设置5个不同处理温度(30℃、25℃、20℃、15℃和10℃),测定其种子发芽势、发芽率、发芽指数和根尖长等指标,旨在揭示其种子萌发特性。结果表明:随处理温度的降低,Rivendel、Tahora II和Dutch White的种子发芽势、发芽率和发芽指数均呈下降趋势。Durana、Prop、Haifa和Alice在25℃时种子发芽势、发芽率和发芽指数均达最大值,而Barbzan和Huia在20℃时表现较好。Tribute在25℃时其种子发芽率和发芽指数达最大值。15℃时10个白三叶品种的种子发芽势、发芽率和发芽指数较20℃时有所降低且种子发芽指数和根尖长下降显著,10℃时降幅更为显著。10℃和15℃均不利于白三叶种子萌发。     

2种彩叶植物光合特性的研究

[目的]揭示2种彩叶植物光合作用的基本生理生态特征和规律,以科学指导植物造景中彩叶植物的配置。[方法]以3年生红花檀木与黄叶假连翘健壮植株各4株为试材,选取每株中部外围功能叶5片,应用美国LI—COR公司生产的LI-6400便携式光合测定系统,测定了2种彩叶植物的光合特性。[结果]红花檀木与黄叶假连翘的光补偿点分别为17．53和17．55μmol／（m^2·s）,光饱和点分别为1000和2000μmol／（m^2·s）;红花檀木的光合日变化呈双峰曲线,黄叶假连翘的光合日变化呈单峰曲线;黄叶假连翘的水分利用率超过红花檀木。[结论]2种植物对光的适应能力很强,红花檀木光补偿点较黄叶假连翘小,其耐阴性更强,固此在园林复层配置时可将其置于下层。     

洋竹草属———中国大陆新归化属

报道了中国大陆新归化记录属要要洋竹草属 Callisia Loefling 及新归化记录种要要洋竹草 Callisia repens (Jacq.) L.。标本采自福建厦门和广东潮州,生长于屋顶与墙头。洋竹草原产于热带美洲,已在中国的台湾、香港 归化,可用于垂直绿化、屋顶绿化等。介绍了洋竹草在中国大陆的分布信息,并进行了相关讨论。     

低温胁迫对马蹄金抗性生理生化指标的影响

在低温胁迫下，马蹄金叶片内游离脯氨酸含量，超氧化物歧化酶（SOD）活性和丙二醛含量均发生明显变化。低温处理过程中，随温度降低脯氨酸含量先增后减，在5℃和0℃时，脯氨酸含量处理48h比处理24h有所增加，在-5℃时，2种处理结果差异不明显，随温度降低SOD活性也呈先增后减趋势，在0℃和5℃时，SOD活性处理48h比处理24h高，而-5℃时结果相反，丙二醛含量随温度降低呈递增趋势。     

Effect of Agronomic Factors on Annual Leguminous Forage Crop in Mediterranean Environments

Dry matter and seed production of five annual leguminous species hairy vetch ( Vicia villosa Roth cv. Orsara) , crimson clover ( Trifolium incarnatum L. ecotype Campano) , squarrosum clover ( T. squarrosum L. ecotype Calabro) , persian clover ( T. resupinatum cv. Accadia) and fenugreek ( Trigonella foenum-graecum L. ecotype Maltese) was estimated in 1989–90 under two density and irrigation rates and with two cutting treatments. The experiments were done at the Forage Crops Institute of Foggia, which has a typical Mediterranean environment. The forage cut severely affected the regrowth of the plants in all species. The year and irrigation factors affect dry matter, seed production and seed yield components more than the plant density rates. The averages over the years, for dry matter and seed yield were 21.0 % and 20.5 % higher in the irrigated than the not irrigated ones. The lower plant density rate, for seed yield trait, gave better result in hairy vetch in irrigated and non-irrigated treatment. Whereas in the other species, the lower rate of planting gave greater yield under non-irrigated and the higher rate under irrigated growing condition. The seed yield components most influenced by irrigation were: thousand seed weight and seeds/pod in hairy vetch and heads/tiller and seeds/head in clovers species. Fenugreek was the earliest forage crop (cut at the beginning of March), followed by crimson and persian clovers (cut at the middle of April) and squarrosum clover and hairy vetch (cut in the middle-late of May). All the cultivars and ecotypes considered not regrowth after cut and could represent an important fresh forage resource for the period March–May for the Mediterranean regions.