铅胁迫对杨梅生理特性的影响

通过水培试验,研究了不同浓度的铅胁迫对杨梅（Myrica rubra Sieb. et Zucc.）叶片的叶绿素含量、可溶性蛋白质含量、可溶性糖含量、超氧化物歧化酶（SOD）活性、过氧化物酶（POD）活性、丙二醛（MDA）含量以及根系活力的影响。结果表明,在2 mmol·L^-1低铅条件下,杨梅叶片叶绿素含量和可溶性蛋白质含量在30 d内与对照相比无显著性差异;叶片可溶性糖和MDA含量在2 mmol·L^-1低铅处理第10 d即比对照显著增加;根系活力在2 mmol·L^-1低铅胁迫处理20 d后比对照显著降低;叶片SOD和POD活性在2 mmol·L^-1低铅胁迫下活性随着处理时间的延长而呈先升后降的变化趋势,在低铅处理第20 d SOD 和POD活性达到最大。在6 mmol·L^-1高铅胁迫下,杨梅叶片的叶绿素含量、可溶性蛋白质含量、SOD活性、POD活性、MDA含量以及根系活力均随着处理时间的延长而不断降低;而叶片可溶性糖含量在高铅处理30 d时比对照有所增加。综上所述,杨梅在低铅条件下可诱导活性氧清除系统以及叶片可溶性糖含量增加以减少由于铅胁迫带来的活性氧代谢失衡和缺水对植株的伤害。     

甜菜碱对干旱胁迫下棉花幼苗生理特性的影响

以新疆广泛种植的棉花品种新陆早18号为试材,通过测定棉花幼苗体内脯氨酸、可溶性糖和丙二醛（MDA）的含量及抗氧化酶包括超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）的活性,研究叶面喷施不同浓度甜菜碱（Glycine betaine,GB）对干旱胁迫下棉花幼苗生理特性的影响。结果表明,干旱胁迫下,与对照相比,脯氨酸、可溶性糖、MDA含量及SOD和POD活性都显著提高,喷施甜菜碱后促进脯氨酸和可溶性糖含量进一步提高,酶活也显著升高,同时有效抑制了丙二醛含量的增加,CAT活性受干旱胁迫及甜菜碱的影响较小。研究表明喷施低浓度甜菜碱在一定程度上可以缓解干旱胁迫对棉花幼苗的伤害。     

暖季型草坪草对高温胁迫的生理响应

以沟叶结缕草(Zoysia matrella)与结缕草(Z.japonica)为材料, 测定了高温胁迫下两种暖季型草坪草叶片主要抗性生理指标的变化, 结果表明: 40 ℃高温处理下, 两种结缕草叶片渗透调节物质(可溶性糖、可溶性蛋白质、脯氨酸)和ABA、GA3、IAA、MDA含量均显著增加, SOD、POD与CAT酶活性都显著增强; 两种结缕草叶片的Chla、Chlb、Car含量以及Chla/Chlb的比值则出现了不同程度的下降.高温下, 沟叶结缕草渗透调节物质的积累量和ABA、GA3、IAA含量的增加均高于结缕草, SOD和CAT活性的增强也大于结缕草, 表现出更强的耐热特性.     

紫穗槐幼苗叶片对不同干旱梯度胁迫的生理生态响应

研究了长期不同干旱梯度胁迫条件下紫穗槐幼苗叶片各种生理生化指标变化.结果表明:轻度、中度、重度胁迫条件下SOD、POD活性明显高于对照,而且随着胁迫时间的延长而逐渐增高.重度胁迫下SOD、POD活性与轻度、中度差异显著.胁迫前期(1～60 d)SOD、POD活性变化具有波动现象,胁迫后期(60～120 d)SOD活性下降,POD活性上升.轻度、中度、重度胁迫条件下可溶性蛋白质、脯氨酸含量高于对照,而且随着胁迫时间的延长而增高.重度胁迫下可溶性蛋白质、脯氨酸含量与轻度、中度差异显著,轻度、中度胁迫条件下可溶性蛋白质、脯氨酸含量差异不显著;从第80天始脯氨酸含量下降,而可溶性蛋白质含量增高.轻度、中度、重度胁迫条件下,可溶性糖含量差异较小.轻度、中度、重度胁迫条件下MDA含量、细胞膜相对透性高于对照,且逐渐增高,重度与轻度、中度差异显著,细胞膜透性变化与MDA含量变化成明显的正相关,MDA含量变化与SOD活性变化成正相关.     

喷施脱落酸对镉富集植物繁缕生长及其镉积累的影响

盆栽试验研究了镉胁迫条件下喷施脱落酸(ABA)对富集植物繁缕(Stellaria media)生长及镉积累的影响。结果表明,喷施ABA提高了繁缕生物量及光合色素含量。随ABA喷施浓度的增加,繁缕的生物量及光合色素含量呈增加的趋势,但繁缕的镉含量、镉积累量、抗氧化酶(SOD、POD和CAT)活性、可溶性蛋白含量及可溶性糖含量呈先增后降的趋势,最大值出现在ABA浓度为15 mg L-1,此时,繁缕根系、地上部分及整株镉积累量均达到最大值,分别为94.54、235.93和330.47μg plant-1,较各自对照分别增加了19.07%(P0.05)、49.45%(P0.05)和39.28%(P0.05)。喷施ABA能够促进繁缕的生长,提高繁缕对镉的富集能力,以15 mg L-1的ABA浓度为最佳。     

KClO3诱导东魁杨梅成花的生理效应

研究不同KClO3浓度对6年生东魁杨梅成花过程生理生化的影响,结果表明:喷施KClO3后东魁杨梅叶片细胞受到伤害处于胁迫状态,丙二醛含量和电解质渗漏率显著增加.KClO3浓度低于1 500 mg·L-1时,叶绿素a、叶绿素b以及总叶绿素含量均显著增加,SOD、POD和CAT活性显著提高,导致叶片光合能力显著上升;生理分化期叶片蛋白质含量明显上升,可溶性糖含量降低;而形态分化期蛋白质含量下降,可溶性糖含量显著上升,可溶性糖/蛋白质比值显著增加,从而促进东魁杨梅的花芽分化.KClO3浓度高于1 500 mg·L-1时,叶绿素a、叶绿素b、总叶绿素和类胡萝卜素含量均降低;SOD、POD和CAT活性降低;导致叶片光合能力、可溶性糖含量以及可溶性糖/蛋白质比值显著下降,从而抑制东魁杨梅的花芽分化.结论是喷施1 000～ 1 500 mg·L-1 KClO3可显著提高东魁杨梅的成花率.     

籼稻2个杂种F1种子活力和劣变处理后生化性状的比较

为明确杂交稻种子在储藏过程中品种间抗老化能力的差异,采用人工老化方法研究了杂交籼稻“汕优63”F1;和“特优559”F1种子活力,比较了2品种劣变后9个生化性状的变化。结果表明：种子活力,SOD、POD、CAT、脱氢酶活性,可溶性蛋白含量随种子老化而降低,种子浸出液电导率、可溶性糖和MDA含量随种子老化增加。劣变后“特优559”的SOD、POD、CAT、脱氢酶活性降低程度及可溶性糖和MDA含量增加程度比“汕优63”低,说明“特优559”抗老化能力比“汕优63”强。SOD、POD、CAT、脱氢酶活性和可溶性蛋白含量与种子活力极显著正相关,电导率、可溶性糖、MDA含量与种子活力极显著负相关。     

调亏灌溉和施氮对玉米叶片保护系统的影响

通过盆栽试验,研究了不同生育期亏水和氮肥处理对春玉米叶片丙二醛(MDA)含量、可溶性糖(SS)含量、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性的影响.结果表明,调亏灌溉可使玉米叶片MDA和SS含量明显升高,而使POD和SOD活性有所降低.施氮处理能保证叶片在抽雄期前SS含量、SOD和POD活性处于较高水平.MDA含量与灌水和施氮水平呈负相关,拔节后期达最大值,之后减小.从苗期到拔节后期,调亏灌溉施氮处理的可溶性糖含量较高,而高氮持续亏水处理可导致可溶性糖含量降低.POD活性到拔节后期达到最大,抽雄期有所降低.亏水处理明显降低了叶片POD活性,复水后补偿效应明显.施氮可适当提高POD活性,但抽穗亏水和全生育期亏水高氮处理在抽雄期的酶活性降低.SOD活性的变化趋势和POD相似.苗期亏水处理在复水后各生理生化指标补偿效果较好,拔节期亏水处理次之.高氮处理不宜在抽雄期调亏灌溉.调亏灌溉和施氮的最佳处理组合为苗期调亏低氮处理.     

硝酸钙对厚皮甜瓜坐果节位叶片衰老及果实产量和品质的影响

以厚皮甜瓜迎春为试材,研究了叶面喷施不同浓度硝酸钙对坐果节位叶片衰老及果实生长和品质的影响。结果表明,坐果节位雌花开放后,叶面喷施10、 20、 30 mmol/L 的硝酸钙均可延缓坐果节位叶片叶绿素、 可溶性蛋白质含量的下降,提高叶片的净光合速率（ Pn ）和过氧化物酶（POD）、 超氧化物歧化酶（SOD）、 过氧化氢酶（CAT） 等抗氧化酶活性,降低丙二醛（MDA） 含量,提高果实的小区产量、 可溶性固形物和可溶性糖含量,其中20 mmol/L 的硝酸钙处理效果与对照差异显著。叶面喷施20 mmol/L 硝酸钙,可延缓厚皮甜瓜坐果节位叶片衰老,提高厚皮甜瓜的果实产量和品质。     

超级早稻结实期遭遇高温时喷施抗逆剂的缓解效果

以“安抗1号”和“有机钙博士”两种抗逆剂为材料,以喷清水为对照,在自然高温下进行水稻田间试验,测定剑叶生理指标、水稻产量和稻米品质指标,研究超级早稻灌浆结实期遭遇高温喷施抗逆剂的缓解效果。结果表明：高温发生时,喷施“安抗1号”（T2）和“有机钙博士”（T3）4d后,与喷清水（T1）相比,超级早稻剑叶抗氧化酶活性极显著（P＜0.01）增加,其中SOD活性分别增加17.10%、12.37%,POD活性分别增加13.54%、15.01%,CAT活性分别增加133.86%、87.46%;叶片渗透调节物含量极显著（P＜0.01）增加,其中可溶性蛋白含量分别增加33.58%、34.38%,可溶性糖含量分别增加23.74%,17.30%;MDA含量极显著（P＜0.01）降低28.34%、26.53%。喷施抗逆剂22d后,超级早稻剑叶SPAD衰减率T2、T3处理显著低于T1（P＜0.05）,分别降低3.40个百分点和4.24个百分点;T2、T3处理比T1剑叶SOD活性显著（P＜0.05）增加;POD活性差异不显著;CAT活性和可溶性糖含量均极显著（P＜0.01）增加;可溶性蛋白含量显著（P＜0.05）增加;MDA含量极显著（P＜0.01）降低。喷施抗逆剂处理显著（P＜0.05）提高结实率5.7个百分点,增产11.87%～13.77%。说明高温发生时,喷施抗逆剂能有效缓解高温对超级早稻灌浆结实的危害,改善超级早稻稻米的外观品质及加工品质。     

有机酸处理条件对玉米秸秆热解特性的影响

酸洗预处理能有效改善K^+对生物质热解的影响,该文利用热重分析仪和裂解-气相色谱质谱联用仪进行了玉米秸秆的热解试验,研究了不同有机酸酸洗浓度(3%、5%和7%)、酸洗温度(25、50和75℃)和酸洗时间(1、2和3 h)对玉米秸秆热解特性的影响。结果表明:酸洗能显著降低玉米秸秆内在K^+的含量;经过不同条件的有机酸洗预处理后,玉米秸秆的TG/DTG(thermogravimetry/differential thermogravimetry)曲线均向高温段移动,最大热解速率随着酸洗浓度和酸洗温度的增加逐渐增大,随着酸洗时间的增加先增大后降低,在酸洗温度为75℃时,最大热解速率达到最大值15.49%/min;与此同时,玉米秸秆热解主要产物为酚类、酮类和呋喃类化合物,酸洗后,其酚类物质产率明显增加,在酸洗浓度为7%时达到最大值16.75%,而酮类和呋喃类化合物产率减少,分别在酸洗时间为1 h和酸洗浓度为7%时达到最小值0.10%和7.13%。酸洗后,焦炭产率减少,在酸洗浓度为3%时达到最小值18.79%。通过研究不同处理条件下有机酸对玉米秸秆热解特性的影响,为生物质预处理中酸溶液的选择提供了参考。     

Endogenous organic acid variations in different chickpea (Cicer arietinum L.) genotypes

Abstract

Changes in cropping systems during the past century have led to selective pressure on weed flora. Species and ecotypes with characteristics enabling them to survive in high-input farmland have increased in numbers, at the cost of plants lacking these characters. Since the 1950s, the perennial weed species Cirsium arvense (L.) Scop. and Sonchus arvensis L. have mainly been controlled by the herbicide group synthetic auxins like MCPA. During recent decades, C. arvense seems to have become less susceptible to MCPA in both Europe and North America but the reasons are unclear.

To study the importance of selective pressure on weed ecotypes, both short- and long-term studies were carried out in Uppsala, Sweden. The first consisted of two growth-characteristic greenhouse experiments. The hypothesis was that ecotypes of C. arvense and S. arvensis from high-input farmland were different and displayed a more competitive growth pattern than did ecotypes from low-input farmland.

The second study was a field experiment with four ecotypes of C. arvense from low-input farmland to study if selective pressure was in force, over a period of six years. The four ecotypes had different growth characteristics and herbicide sensitivity and they were exposed to crop competition and MCPA treatments during the experimental period. The hypothesis was that ecotypes with a more competitive growth pattern and MCPA tolerance would survive to a greater extent than would other ecotypes. For C. arvense, the results from the growth-characteristic experiment showed that the growth pattern of ecotypes from high-input farmland differed, showing a more directly elongated growth pattern with fewer spines on the leaves compared with ecotypes from low-input farmland, which usually were of rosette-type. Results from the field experiment with C. arvense showed that after six years MCPA-sensitive and/or rosette-type ecotypes had almost disappeared while ecotypes with a more directly elongated growth pattern and less sensitive to MCPA survived to a much greater extent. The conclusion was therefore that when exposed to selective pressure like crop competition and herbicide treatments, ecotypes of C. arvense with a more directly elongated growth pattern and less sensitive to herbicide treatment survived to a greater extent compared with ecotypes missing these traits. Ecotypes from high-input farmland had generally fewer leaf spines than did ecotypes from low-input farmland. This may suggest a trade-off between spine formation and rapid competitive growth. In the growth-characteristic experiment with S. arvensis, no differences between ecotypes from high- and low-input farmland regarding growth characteristics or leaf spines could be detected. This might partly be due to a lower exposure of S. arvensis to selective pressure compared with C. arvense, since S. arvensis generally is less sensitive to MCPA.     

Interactive effects of organic acids in the rhizosphere

Organic acids released into the rhizosphere may perform many beneficial functions to the plant including metal detoxification and enhancement of nutrient acquisition. Typically, these organic acids are studied in isolation; however, roots simultaneously exude a cocktail of organic acids and other substances, and their combined impact on rhizosphere processes may be quite different. It has been hypothesized that some exudates may play secondary roles (e.g. inhibitors of microbial activity, blockage of sorption sites), which might enhance the longevity and nutrient-mobilization capacity of others. Here we investigated how the decomposition, sorption and P-solubilizing effects of citrate, malate and oxalate are affected by the presence of malonate and shikimate. We found that in a range of agricultural soils the decomposition of citrate, malate and oxalate was rapid, but not influenced by the presence of large quantities of shikimate or malonate. This suggests that the individual organic acids are taken up by different transport mechanisms or components of the microbial community. At large concentrations, malonate decreased sorption of citrate, malate and oxalate on the soil, whilst shikimate had little effect. The capacity of citrate, malate and oxalate to desorb P was significantly greater in cocktails containing malonate compared with the single organic acid; no effect was seen with shikimate. We conclude that neither malonate nor shikimate at realistic concentrations will significantly affect the biodegradation of citrate, malate or oxalate in the rhizosphere, and while malonate did enhance P desorption, this effect is additive rather than synergistic. Overall, we found little evidence that malonate and shikimate act as secondary regulators of citrate, malate and oxalate behavior in soil.     

Effect of humic acid and fulvic acid based liquid and foliar fertilizers on the yield of wheat crop

Abstract

An organic-mineral liquid fertigation fertilizer containing humic acid, nitrogen (N)–phosphorus (P)–potassium (K), zinc (Zn), sulfur (S), manganese (Mn) and a liquid foliar fertilizer consisting of fulvic acid and gibberellic acids were formulated and applied to wheat. The purpose of this study was to develop an efficient and cost effective liquid and foliar fertilizer and compare their potential with commercially available urea and DAP. The fulvic acid and humic acids were obtained by alkaline extraction of lignite coal. All the treatments were significant over the control. The application of the liquid fertigation fertilizer and liquid foliar fertilizer along with 50?kg of urea per acre showed the best results biological yield (grain plus straw yield). It was found that the highest yield was obtained in T₆ treatment and the second best results were obtained with T₂ treatment, but has a high cost, while treatment T₆ was the most significant economical and yielded a high income when compared to other treatments.     

Organic Acids and Diffusive Flux of Organic and Inorganic Phosphorus in Sandy-Loam and Clayey Latosols

This study evaluated the effects of organic acids on the diffusive flux of phosphorus (DFP) along time. Treatments were a factorial 2?×?2?×?2?×?2?×?5 design: two soils (clayey Red Latosol and a sandy-loam Red-Yellow Latosol), two organic acids (citric acid, CA, and humic acid, HA), and two phosphorus (P) sources [monopotassium phosphate (KH₂PO₄) and inositol hexaphosphate (IHP)] either with or without heating (100 °C) of the soil. The soil plus treatments, in all combinations, were placed in contact with an anion exchange resin and the P in the resin was measured after 2, 4, 6, 10, and 15 days. The DFP was greater when the soils were treated with CA than when treated with HA. Citric acid was more effective in increasing the DFP from KH₂PO₄, whereas HA was the organic ligand that promoted a larger DFP when the source was IHP.     

Low pH and aluminum tolerance of Bradyrhizobium strains isolated from acid soils in Indonesia

Sixty-seven strains of Bradyrhizobium isolated from soybean plants growing on acid soils in West Java and Sumatra, Indonesia, were examined for the effect of the pH and aluminum concentration on their growth in nutrient media, compared with 61 strains of Bradyrhizobium from soils in Japan. The results in this study indicated that the indigenous population of Bradyrhizobium in the soils of Indonesia showed a large difference in acid- and Al-tolerance from that of Japan. Eighty-five and 48% of the isolates from Japanese soils and Indonesian soils, respectively, were unable to grow in YEM broth at pH below 4.5. The acid-tolerance was correlated with AI-tolerance of the isolates on YEM agar plates at pH 4.4. Seventy-five percent of the isolates that grew in YEM broth at pH 4.5 were also resistant to 400 µM Al on the YEM plates. Acetylene reduction assay of the root nodules revealed that 3 of the acid- and Al-tolerant isolates from Indonesian soils showed a significantly high nitrogen fixation activity.     

不同来源腐殖酸的组成和性质的研究

本研究从三种有机物料草炭、褐煤、风化煤中提取腐殖酸,对其组成和性质进行了测定,同时对胡敏酸进行酒精沉淀分级。研究结果表明:褐煤胡敏酸氧化度和芳香度最高,其次为风化煤胡敏酸,最后是草炭胡敏酸;风化煤富里酸的氧化度和芳香度最高,其次为褐煤富里酸和草炭富里酸。胡敏酸各级分的回收率均随着级分数的升高而增加。回收率以风化煤胡敏酸最高,依次为褐煤胡敏酸、草炭胡敏酸。     

粘土矿物对土壤腐殖质化学性质的影响

Chemical characteristics of humic substances in soils with different mineralogical characteristics and under different utilization paterns in Zhangpu,Fujian Province,together with two pairs of cultivated soils in North China Plain were studied by chemical analysis,visible and IR spectroscopy and ^13C NMR spectrometry.For soils in Zhanpu the HA/FA ratio and both the aromaticity and the degree of humification of HA were higher in soils with montmorillonite as the predominant clay mineral than in those with kaolinite as the predominant clay mineral,provided these soils were under the same utilization pattern.While for each pair of soils with similar mineralogical characteristics the HA/FA ratio was higher and the C/H ratio and the contnet of carboxyl group of HA were lower in paddy soil than in upland soil.Among the upland soils(or paddy soils)studied the Ha/FA ratio of soil in Zhangpu with kaolinite as the predominant clay mineral was the lowest,and that of soil in Zhangpu with montmorillonite as the predominant clay mineral was the highest .the lowest.and that of soil in Zhangpu with montmorillonite as the predominant clay mineral was the highest It was concluded that the presence of montmorillonite favored the fromation and maturation of humic acid.     

Chemical Composition of Ten Blackcurrant (Ribes nigrum L.) Cultivars

Abstract

Ten blackcurrant cultivars were evaluated for some quality components. On average, the sugar content was 9.0%, of which fructose made up 45%, glucose 40% and sucrose 15%. Soluble solids were 15.4% as an average for the ten cultivars in three years. The acid content was 5.1% of fresh weight, 88% was citric acid and 12% malic acid. The ascorbic acid content varied from 67 mg per 100 g fresh fruit in Hedda, to 204 mg per 100 g in Blackdown. Except for Hedda and Øjebyn, which both had low values of ascorbic acid and colour properties, the quality components of the cultivars were found to be within an acceptable range.     

Plant defence inducers rapidly influence the diversity of bacterial communities in a potting mix

Plant hormones and their functional analogues are used in agriculture to combat plant diseases and pests. These chemicals are generally targeted at shoots, but soils inevitably receive a dose during application. In this study, we used 16S rRNA gene amplicon pyrosequencing to determine whether the diversity of bacterial communities in a potting mix (referred here as ‘model soil’) is influenced by exposure to salicylic acid (SA), methyl jasmonate (MeJA), ethylene (ET) and abscisic acid (ABA). The number of operational taxonomic units (OTUs; richness) and Simpson's Diversity Index values (evenness) associated with each sample was not influenced by the hormone treatments, but changes in community composition were observed. Relative to the control, all hormones more than doubled the abundance of a Limnobacter population, ABA led to a four-fold increase in a Cellvibrio population, ET led to a c. 70% decrease in an Algoriphagus population, and MeJA and ABA applications halved the abundance of a Massilia population. These changes may influence plant productivity.