模拟硫酸型、硝酸型及其混合型酸雨对油菜生理特性、生长和产量的影响

为了了解我国酸雨污染由硫酸型向硫-硝酸复合型转变所引起的环境效应,以油菜(Brassicanapus)为供试材料,在大田试验条件下,系统研究了模拟硫酸型(SAR)、硝酸型(NAR)及其混合型(MAR)酸雨对农作物生理特性、生长和产量的影响。结果表明,3种酸雨胁迫均能抑制油菜生理、生长和产量形成,但不同类型的酸雨间的抑制效应存在差异。当pH≤4.1时,SAR、NAR、MAR能破坏油菜叶质膜系统、降低光合色素含量及光合速率,从而抑制作物的光合作用;当pH≤3.1时,油菜叶面积减小,叶受害百分率明显增加。pH=4.1可作为酸雨对油菜产量的影响阈值。在pH=7.0–1.5的酸度范围内,油菜叶片膜透性、丙二醛含量、叶受害百分率表现为NARMARSAR,光合速率、光合色素含量、叶面积及产量则表现出SARMARNAR的变化特征。当pH4.1时,3种酸雨处理间差异均不明显,pH≤3.1时,3种酸雨间的胁迫效应差异显著增加(p0.05),且酸度越强,差异越大,其变化趋势为NARMARSAR。说明NAR和MAR胁迫对油菜生理、生长及产量的抑制较大。     

模拟酸雨对小黑麦种子萌发及幼苗生理特性的影响

以小黑麦品种中饲237为材料。在不同pH值的模拟酸雨条件下对种子萌发及幼苗生理特性进行了研究。分别测定了发芽率、发芽势、发芽指数、活力指数和种子脱氢酶含量、幼苗鲜重、幼苗叶片叶绿素含量、叶片电导率等指标。结果表明,种子的各项发芽指标及种子脱氢酶含量、幼苗鲜重、叶绿素含量等随酸雨pH值减小整体呈降低趋势,叶片电导率则随酸雨pH值减小而有增加趋势。     

模拟秋季酸雨对三角枫叶片光合生理特性的影响

以三角枫幼苗为材料,采用盆栽方法,研究了pH 5.6、pH 4.0、pH 3.0和pH 2.0酸度模拟酸雨胁迫对三角枫叶片光合生理特性的影响,以探讨酸雨胁迫下三角枫的光合生理响应机制。结果显示:(1)随着酸雨浓度的增加和胁迫时间的延长,三角枫叶片相对叶绿素含量下降幅度逐步增大;叶片丙二醛含量呈逐渐上升的趋势,且各处理均显著高于对照;叶片质膜透性和脯氨酸含量均呈先升高后降低的趋势,且pH 2.0处理的叶片质膜透性在试验20d时迅速增大,升高幅度最大(146.3%)。(2)叶片净光合速率、蒸腾速率、水分利用效率、表观光能利用效率以及表观CO2利用效率在胁迫下也均呈显著下降趋势,且以pH 3.0和pH 2.0处理降幅最大。研究表明,pH 4.0的模拟酸雨对三角枫叶片的光合生理指标无显著影响,而pH≤3.0的强酸雨胁迫使三角枫叶片叶绿素含量显著下降、膜保护系统受损、光合作用效率显著下降;三角枫能适应弱酸雨(pH≥4.0)环境,可作为酸雨地区的园林绿化树种。     

模拟酸雨对西洋杜鹃生理生态特性的影响

采用盆栽方法,研究了不同pH值条件下的模拟酸雨对西洋杜鹃生长及其叶片主要生理生化特征的影响。结果表明:在酸雨胁迫下,随着酸雨胁迫的增强,西洋杜鹃叶片受害程度逐渐加重;叶片丙二醛含量逐渐升高;可溶性蛋白含量先升后降;过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性均呈先升后降的单峰曲线变化,其中pH值为4.3的处理下西洋杜鹃叶片CAT和SOD活性最高,pH值为3.0的处理下其POD活性最高;其叶绿素含量逐渐下降;叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)及水分利用率(WUE)均呈先升后降的趋势,而胞间CO2浓度(Ci)则持续下降,pH值为4.3的处理下其Pn、Tr、Gs和WUE均达到最高。研究表明,大致可以认为pH值≤3.0是酸雨对西洋杜鹃造成隐形伤害的阀值,而酸雨灾害严重地区的降水pH值为2.0—4.0左右,说明西洋杜鹃可以在酸雨灾害较重的地区生长,可作为酸雨灾害严重地区园林绿化及植被构建的物种之一。     

模拟酸雨对绿豆、玉米生理生态特性的影响

探讨了模拟酸雨对绿豆、玉米的影响．结果表明,叶绿素含量、叶绿素ａ／ｂ值、叶片活力、叶汁ＰＨ、土壤ｐＨ与模拟酸雨ｐＨ值呈正相关;相对电导率、ＰＯＤ活性和脯氨酸含量与模拟酸雨ｐＨ呈负相关;ＳＯＤ活性随模拟酸雨ｐＨ减小而下降．     

模拟酸雨对大豆、花生生长和产量的影响

大豆(Glycine max)、花生(Arachis hy-pogaea)是我国主要油料作物,国内外均曾用大豆作为模拟酸雨的试验材料。本文对大豆作了较详细的观察。在大田中进行了花生试验,研究酸雨对其产量的影响。     

模拟酸雨胁迫对杨梅幼苗水分生理特性的影响

选择浙江省典型亚热带经济植物杨梅为对象,通过盆栽试验研究了重度酸雨(pH2.5)、中度酸雨(pH4.0)和对照(pH5.6)处理对杨梅幼苗水分生理特性的影响.结果表明:季节、年份和酸雨对杨梅幼苗的光合速率均有显著影响,各处理中,夏季的差异大于春、秋季,pH4.0处理对光合速率有促进作用;季节、年份、酸雨,季节-年份交互作用以及三者交互作用对气孔导度均有显著影响,各处理在夏季的差异大于春、秋季,酸雨对气孔导度有抑制作用;季节、年份、酸雨及季节-年份和季节-酸雨两两交互作用对蒸腾速率有显著影响,各处理夏季的差异大于春秋季,且pH2.5处理对蒸腾速率的抑制作用最强;酸雨、季节-年份和季节-酸雨交互作用对水分利用率有显著影响,且pH2.5处理对水分利用率有一定的促进作用.     

模拟酸雨对山核桃和杨梅光合生理特征的影响

通过盆栽模拟酸雨淋喷实验,比较了浙江省典型经济植物山核桃和杨梅幼苗光合特性的差异,研究了不同强度酸雨胁迫（pH 2.5、pH 4.0 和 pH 5.6（对照））对其光合生理生态特征的影响。结果表明,在无酸雨条件下,杨梅的最大净光合速率、暗呼吸速率、光饱和点和光补偿点明显高于山核桃。酸雨胁迫下,pH 4.0的酸雨胁迫使山核桃的最大净光合速率、光饱和点显著降低,使杨梅的表观量子效率显著升高,而pH 2.5的酸雨胁迫使山核桃的最大净光合速率、表观量子效率显著降低,使杨梅的光饱和点显著升高。从季节反应模式来看,酸雨对山核桃光合特性的影响在夏季较春季明显,而对杨梅的影响则春季较夏秋季明显。     

模拟酸雨对银杏雌雄幼苗生长及生理特性的影响

本试验采用盆栽方法,研究了4种pH值(5.6、5.0、4.0、3.0)条件下的模拟酸雨对银杏雌、雄幼苗生长及叶片主要生理生化特性的影响。结果表明,随着模拟酸雨pH值的不断降低,银杏雌、雄幼苗地上部分可见伤害逐渐出现,其叶片相对含水量、光合色素含量和抗氧化酶活性逐渐降低,而丙二醛、可溶性蛋白质和游离脯氨酸含量逐渐升高。与pH值为5.6的对照相比,pH值5.0和4.0的模拟酸雨对上述测定值的影响并不明显,而在pH值3.0的模拟酸雨处理后,大部分测定值的变化幅度达到了显著水平。尽管在上述4种处理条件下银杏雌、雄幼苗地上部分所表现出的可见伤害并无明显差异,但从叶片相对含水量、比叶面积、抗氧化酶活性、光合色素含量和各种生化物质含量的测定值进行分析发现,银杏雄株内部生理生化过程受到的干扰要大于雌株。由此推测,高浓度的酸雨(pH=3.0)会影响银杏雌、雄幼苗的正常生长,其耐酸阈值应在pH值4.0~3.0间,且银杏雌株幼苗在耐酸性方面强于雄株。     

酸雨胁迫条件下紫花苜蓿种子萌发和幼苗生理特性的变化

以紫花苜蓿种子皇冠（Phabulous）为材料,研究不同pH值的模拟酸雨对皇冠（Phabulous）种子萌发及幼苗生理特性的影响。分别测定了发芽率、发芽势、发芽指数、活力指数和种子脱氢酶含量、幼苗鲜重、幼苗干重、幼苗叶绿素含量、叶片导电率等指标。结果表明,种子的各项发芽指标及幼苗鲜重、脱氢酶活力、叶绿素含量等随酸雨pH值减小整体呈降低趋势,叶片浸泡液电导率则随酸雨pH值减小而呈增大趋势。     

Effects of simulated acid rain on oilseed rape (Brassica napus) physiological characteristics at flowering stage and yield

A pot experiment was conducted to study the effects of different acidity simulated acid rain on the physiological characteristics at flowering stage and yield of oilseed rape (B. napus cv. Qinyou 9). Comparing with the control (pH 6.0), weak acidity (pH = 4.0-5.0) simulated acid rain stimulated the rape growth to some extent, but had less effects on the plant biomass, leaf chlorophyll content, photosynthetic characteristics, and yield. With the further increase of acid rain acidity, the plant biomass, leaf chlorophyll content, photosynthetic rate, antioxidative enzyme activities, and non-enzyme antioxidant contents all decreased gradually, while the leaf malonyldialdehyde (MDA) content and relative conductivity increased significantly. As the results, the pod number per plant, seed number per pod, seed weight, and actual yield decreased. However, different yield components showed different sensitivity to simulated acid rain. With the increasing acidity of simulated acid rain, the pod number per plant and the seed number per pod decreased significantly, while the seed weight was less affected.     

Effects of dalapon and TCA on the growth and yield of oilseed rape (Brassica napus)

The tolerance of oilseed rape (Brassica napus cv. Jet Neuf) to the herbicides dalapon and TCA was studied in two series of 10 experiments over four years. TCA (7.6–30.4 kg a.i./ha) was applied pre-emergence and dalapon (2.9–11.6 kg a.i./ha) was sprayed post-emergence between September and November at two growth stages (2–5, 4–7 leaves). Dalapon at all doses caused the leaves to appear yellow-green in colour and at the higher rates (5.8–11.6 kg a.i./ha), especially when applied at the later of the two growth stages, scorched the leaf margins and stunted the plants. TCA also caused the leaves to appear yellow-green and was noted to affect the retention of water by the leaf surfaces. In general the visible effects of treatment with dalapon were more severe than those of TCA. The effects of these two herbicides on rape seed yields were variable, with some trials showing statistically significant reductions and others none. However by combining the results of trials with similar treatments some underlying trends were identified. In the overall analyses dalapon at 11.6 kg a.i./ha, applied at both growth stages and at 5.8 kg a.i./ha, applied at the later one, reduced yields significantly. TCA at 15.2, 22.8 and 30.4 kg a.i./ha also caused significant yield reductions in the combined analyses. Further statistical analysis questioned the safety of the lower rates of both herbicides, which were similar to those recommended by the manufacturers. The severity of the foliar damage caused by dalapon was well correlated with the risk of significant yield reductions but not with the actual percentage loss of yield. No such correlations were possible with TCA as the visual symptoms were similar on all sites and were unaffected by dose. Recent changes in agricultural practices and in crop cultivar do not appear to have altered the sensitivity of rape to dalapon and TCA appreciably.     

Effects of light leaf spot (Pyrenopeziza brassicae) on yield of winter oilseed rape (Brassica napus)

The relationship between development of light leaf spot and yield loss in winter oilseed rape was analysed, initially using data from three experiments at sites near Aberdeen in Scotland in the seasons 1991/92, 1992/93 and 1993/94, respectively. Over the three seasons, single-point models relating yield to light leaf spot incidence (% plants with leaves with light leaf spot) at GS 3.3 (flower buds visible) generally accounted for more of the variance than single-point models at earlier or later growth stages. Only in 1992/93, when a severe light leaf spot epidemic developed on leaves early in the season, did the single-point model for disease severity on leaves at GS 3.5/4.0 account for more of the variance than that for disease incidence at GS 3.3. In 1991/92 and 1992/3, when reasonably severe epidemics developed on stems, the single-point model for light leaf spot incidence (stems) at GS 6.3 accounted for as much of the variance. Two-point (disease severity at GS 3.3 and GS 4.0) and AUDPC models (disease incidence/severity) accounted for more of the variance than the single-point model based on disease incidence at GS 3.3 in 1992/93 but not in the other two seasons. Therefore, a simple model using the light leaf spot incidence at GS 3.3 (x) as the explanatory variable was selected as a predictive model to estimate % yield loss (y_r): y_r= 0.32x– 0.57. This model fitted all three data sets from Scotland, When data sets from Rothamsted, Rosemaund and Thurloxton in England were used to test it, this single-point predictive model generally fitted the data well, except when yield loss was clearly not related to occurrence of light leaf spot. However, the regression lines relating observed yield loss to light leaf spot incidence at GS 3.3 often had smaller slopes than the line produce, by the model based on Scottish data.     

Effects of mixtalol and paclobutrazol on photosynthesis and yield of rape (Brassica napus)

Photosynthetic and yield effects of paclobutrazol and mixtalol sprayed, respectively, on rape at the three-leaf stage and shoot or anthesis stages were examined. They significantly increased chlorophyll content and photosynthetic rates, prolonged leaf longevity, and increased green pod area. Paclobutrazol-treated plants were shorter, more branched, and produced more seeds. Foliar sprays of mixtalol increased podding percentage, pods per plant, and seeds per pod. A high seed yield of 1809.0 kg/ha was obtained with mixtalol sprayed at anthesis, while significant yields were also achieved with treatments of mixtalol at the shoot stage and paclobutrazol at the three-leaf stage. The photosynthetic and yield effects of mixtalol or paclobutrazol were reduced when both growth regulators were applied together, and this led to yield reductions. No adverse effects from mixtalol or paclobutrazol were observed on seed oil content, erucic acid, and glucosinolate content. The total rape oil production with mixtalol sprayed at anthesis and shoot stages and paclobutrazol at the three-leaf stage increased significantly by 20.9%, 14.4%, and 13.4%, respectively, over the controls.     

Changes in fatty acids contents and growth characteristics in transformed oilseed rape (Brassica napus)

Spring oilseed rapeBrassica napus L. ssp.oleifera cv. HM-81 was transformed with T_L-DNA of the Ri plasmid of the agropine strainAgrobacterium rhizogenes 15834. Selfed progenies (R₂ and R₃ generations) were studied for changes in values of growth characteristics and fatty acids contents. Transformants are ‘homozygous’ for T_L-DNA. Both generations of transformants differed significantly from the nontransformed control plants in reduced length, lower number of pods per plant, lower total mass of seeds and the higher number of branches. The contents of palmitic, linoleic and linolenic acids were significantly higher in transformants when compared with the control. On the contrary, the contents of both stearic and oleic acids were in most of transformants significantly lower. Only traces of erucic acid (less than 0.05 % ) were found, both in transformed and nontransformed plants.     

模拟酸雨对油菜(Brassica napus L.)生长、产量及品质的影响

以油菜为供试材料,通过田间试验方法研究了酸雨对农作物生长、产量及品质的胁迫效应.研究结果表明,模拟酸雨胁迫对油菜的生长发育有较大的影响,具体表现为株高、叶面积生长受抑,叶单面鲜重明显降低,且在pH3.1时开始出现外观上的可见伤害;产量的分析结果表明,pH4.1可作为酸雨对油菜产量的影响阈限;品质特征指标分析结果表明,酸雨胁迫会导致油菜粗脂肪含量降低,使可溶性糖含量减少,而且随着酸度增强,粗脂肪与可溶性糖降低幅度越大;酸雨胁迫对可溶性蛋白质的影响阈限在pH5.1与pH4.1之间,对游离氨基酸总量的影响阈限在pH4.1与pH3.1之间,而对还原性糖、总酸度的影响阈限则在pH3.1与pHl.5之间,但以上各指标的确切阈值及酸雨对其影响的具体机理还有待进一步研究.     

Viruses infecting winter oilseed rape (Brassica napus ssp. oleifera)

Turnip mosaic virus (TuMV) and cauliflower mosaic virus (CaMV) have been found infecting field crops of winter oilseed rape (Brassica napus ssp. oleifera) in South Warwickshire. Other viruses found include broccoli necrotic yellows virus (BNYV) and a member of the beet western yellows virus group. Systemic leaf symptoms caused by TuMV varied within and between cultivars; the three predominant reaction types were classified as necrotic, mosaic and immune. Some recently introduced cultivars of oilseed rape were more severely affected by TuMV infection than older cultivars. Reactions to CaMV were less varied and immunity was not found. The seed yield from TuMV and CaMV-infected plants was less than that of healthy control plants. This effect was due to infected plants producing either fewer seeds, smaller seeds or both. Germination of seeds from infected plants was unaffected if sown soon after harvest. After storage for one year the germination of seed from a virus infected plant was significantly less than that of seed from a virus-free plant. All commercial cultivars tested were experimentally susceptible to turnip yellow mosaic virus (TYMV) and some American strains of cucumber mosaic virus (CMV).     

Progressive introgression between Brassica napus (oilseed rape) and B. rapa

We have earlier shown extensive introgression between oilseed rape (Brassica napus) and B. rapa in a weedy population using AFLP markers specific for the nuclear genomes. In order to describe the progress of this introgression, we examined 117 offspring from 12 maternal plants from the introgressed population with the same AFLP-markers; AFLP data were supported by chromosome counting. We also analysed the offspring with a species-specific chloroplast marker and finally evaluated the reproductive system in selected maternal plants. Our results indicated a high outcrossing rate of the introgressed maternal plants. It seemed that B. rapa most often functioned as the maternal plant in the introgression process and that the amount of oilseed rape DNA was highly diminished in the offspring compared to their introgressed maternal plants. However, our analysis of plants from the weedy population indicated that introgression can lead to both (1) exchange of chloroplast DNA between species producing B. rapa-like plants with B. napus chloroplasts and (2) incorporation of B. napus C-genome DNA into the B. rapa genome. Therefore, we question whether it can be regarded as containment to position transgenes in the chloroplast or in specific parts of the nuclear genome of B. napus.