Phytoaccumulation of Lead by Selected Wetland Plant Species

Several anthropogenic activities lead to the production of substantial amounts of aqueous effluents that contain various toxic trace and heavy metals and which pose potential threats to the wild habitat of wetlands. As a part of the remediation of heavy metals, it is necessary to identify some aquatic hyperaccumulator plants. To this end, a greenhouse study was conducted to investigate the phytotoxicity resulting from lead (Pb) and its accumulation in selected plant species. Lead was added from low to very high levels in a swell–shrink clayey soil (Typic Haplustert). Seven levels of Pb (0, 50, 100 200, 400, 600, and 800 mg kg^–1 soil) were applied. Typha angustifolia L. of Typhaceae and Behaya plant (Ipomoea carnea L.) of the Convolvulaceae family were taken as test plants. Lead was added at high and low concentrations to determine whether an increase in concentration would Pb to an increased toxicity to the plants. Recorded weight of the Typha crop was reduced (6%) at 600 mg Pb kg^–1 soil, and at greater doses of Pb, the dry-matter yield was inhibited considerably. In the case of Ipomoea, no growth retardation from Pb was observed. Most Pb accumulated in roots and then was transported to shoots. The Typha angustifolia L. and Ipomoea carnea L. plants show promise for the removal of Pb from contaminated wastewater because they can accumulate high concentrations of Pb in roots (1200 and 1500 mg Pb kg^–1 respectively) and shoots (275 and 425 mg Pb kg^–1 respectively). Lead uptake by both the plants increased with the increasing doses of Pb (50 to 800 mg kg^–1 soil). Physiological parameters such as photosynthesis, respiration, chlorophyll content, and different enzyme activities including nitrate reductase (NR), peroxidase (POD), and succinate dehydrogenase (SD) were also studied for the evaluation of these plant species. In Typha plants, at greater doses of Pb, the rate of photosynthesis and chlorophyll content decreased whereas POD and SD activities increased to combat oxidative stress.     

湿地植物香蒲根系抗氧化酶活性和根系分泌物对阿特拉津胁迫的响应

为探明阿特拉津胁迫下水生植物根系的生理响应特征,以典型湿地植物香蒲（Typha angustifolia L.）为研究对象,采用水培实验,研究阿特拉津（0、0.2、0.4 mg·L^-1和2.0 mg·L^-1）胁迫45 d对香蒲根系阿特拉津积累、抗氧化酶活性以及根系分泌物的影响。结果表明：阿特拉津可以在香蒲根系积累且显著降低香蒲生物量。随阿特拉津胁迫的提升,根系丙二醛（MDA）含量持续升高;超氧化物歧化酶（SOD）活性显著降低（P<0.05）,过氧化氢酶（CAT）活性呈先增加再降低趋势（P<0.05）,且在0.4 mg·L^-1时达到最大值,较对照提高123.7%;阿特拉津胁迫对谷胱甘肽（GSH）活性无明显影响。香蒲根系分泌物中检出的化合物种类随着阿特拉津质量浓度的升高而增多,主要包括烷烃、烯烃、酯、胺、醇、酚、酮和有机酸类化合物,其中烷烃类化合物种类最多且相对含量最大;高浓度阿特拉津胁迫（2 mg·L^-1）抑制酯类和醇类化合物的分泌,而提高酚类和有机酸类化合物的分泌量;根系阿特拉津含量、MDA含量分别与酚类和有机酸类的相对含量呈正相关关系。研究发现,阿特拉津胁迫诱导的氧化应激激活了香蒲根系的抗氧化防御系统,植物通过调节分泌物的组成和含量应对胁迫,最终降低了生物量的积累。     

不同生长期和采收间隔期草芽营养价值的比较

[目的]为合理确定采收时间,提高草芽产量及营养价值提供参考依据。[方法]测定分析草芽根状茎在不同生长期和不同采收间隔期下的含水量、淀粉、蛋白质、有机酸、维生素C等的含量。[结果]草芽鲜嫩根状茎中含水量达90%以上,且随生长期的延长而下降;淀粉含量在21~25叶时含量最高,达4.98%;蛋白质和维生素C含量在16~20片叶时最高,分别为0.455%与0.186%;而有机酸的含量较低,低于0.030%,各生长期差异不大。在不同采收间隔期下,间隔10 d的草芽根状茎中蛋白质、有机酸和维生素C含量均最高,分别为0.455%0、.020%与0.185%,而淀粉含量随采收间隔期的延长呈增加趋势。[结论]在生产中以16~20片叶的根状茎间隔10 d采收最为适宜,所采收的草芽根状茎营养价值最高。     

储藏温度对蒲儿菜采后生理和品质的影响

 在蒲儿菜贮藏过程中,通过评价其外观品质及测定其失重率、腐烂指数、维生素C含量、纤维素含量和多酚氧化酶活性等指标,筛选出蒲儿菜最佳贮藏温度。结果表明：蒲儿菜在采后前20 d维生素C含量迅速下降,失重率和纤维素含量上升较快,10 d后腐烂迅速增加,而多酚氧化酶活性呈低→高→低变化。低温能抑制蒲儿菜储藏期间的蒸腾失水和多酚氧化酶活性,保持较低的纤维素含量和较高的维生素C含量,从而延缓蒲儿菜的衰老与品质下降,延长储藏寿命。     

不同温度与时间条件下狭叶香蒲吸收Cd^2＋的动力学特征

研究了狭叶香蒲对Cd^2＋的吸收动力学特征。结果表明,狭叶香蒲对Cd^2＋的吸收基本符合M ichaelis-Menten动力学模型;高温下狭叶香蒲对Cd^2＋吸收的内在潜力大,但根系吸收位点对Cd^2＋的亲和力较小;高温下短时间内对Cd^2＋的吸收速率较快,但随时间延长则变慢,低温下的表现正好与高温下的相反;用V-C图解法和LB图解两种方法求解的Vmax均以24h＋30℃处理的最大,而24h＋10℃处理的最小;时间和温度同时影响离子吸收;用两种方法求动力学参数,虽然分析结果有差异,但相关性均较好。     

蒲菜汁饮料生产工艺研究

[目的]研究蒲菜鲜汁加工成新型绿色保健饮料的最佳工艺。[方法]通过单因素和正交试验,研究蒲菜汁饮料的最佳配方和工艺条件。[结果]最佳配方为：料液比15％,蔗糖4％、柠檬酸0．09％、明胶0．10％。混合物料经20MPa均质,90～100℃杀菌10min,最终获得乳白色、无沉淀、口感佳、具有浓郁蒲菜香气的饮料。通过感官指标、理化指标、微生物指标进行检测得到合格的蒲菜汁饮料,保存期可达6个月以上。[结论]该工艺条件下生产的蒲莱汁饮料口感好、营养丰富、稳定性强。     

蒲菜真空软包装贮藏技术研究

为延长蒲菜的保鲜期,以新鲜蒲菜为原料,采用保鲜液真空包装的方法,探讨不同保鲜液对蒲菜外观品质及营养指标的影响。试验结果表明：氯化钠、柠檬酸、维生素C保鲜液都对蒲菜具有一定的保鲜作用;复合保鲜液（0.8%氯化钠、0.15%柠檬酸、0.07%维生素C）真空软包装的贮藏效果最佳。     

外源NO对铜、镉胁迫下狭叶香蒲生理反应的影响

为研究外源一氧化氮(NO)对狭叶香蒲耐Cu、Cd胁迫的影响,进而揭示其缓解Cu、Cd胁迫的生理机制,以狭叶香蒲幼苗为试材,在Cu或Cd的胁迫下,分别添加0μmol/L、50μmol/L、75μmol/L和100μmol/L SNP(硝普钠,为NO供体),检测叶片和根系中抗氧化酶活性以及丙二醛(MDA)、抗坏血酸、蛋白质和叶绿素含量。结果表明:在25 mg/L Cu2+或1.5 mg/L Cd2+处理下施加不同浓度的SNP引起反应的生理指标有所不同,总体表现为叶片和根中超氧化物歧化酶(SOD)、过氧化物酶(POD)活性和蛋白质、抗坏血酸含量升高,MDA含量下降,叶绿素含量不受影响。说明外源NO能在一定程度上缓解Cu及Cd胁迫对狭叶香蒲幼苗造成的伤害。     

Effects of herbicide-induced habitat alterations on blackbird damage to sunflower

In August 1992, we treated cattail-dominated wetlands in four 23-km² blocks with aerially-applied glyphosate herbicide (5.3 1 ha⁻¹). Four other blocks of wetlands were left untreated (reference). We assessed the effects of cattail (Typha spp.) reduction on roosting blackbird (Icterinae) numbers and sunflower damage within the blocks. Blackbird numbers did not differ between posttreatment years (P = 0.453) or between treated and reference wetlands (P = 0.469), averaging 6227 ± 4185 (SE) birds per block. Sunflower damage within blocks was similar between posttreatment years (P = 0.250) and did not vary (P = 0.460) between treatments ( ). However, positive linear relationships were detected between blackbird numbers (y) and hectares of live cattails (x) [(y = 442.2 x)] (P = 0.006) and between blackbird numbers (x) and kilograms of sunflower lost per hectare per year (y) [(y = 0.003 x)] (P = 0.0001). Cattail reduction appears to discourage roosting blackbirds and, thus, may reduce sunflower damage in adjacent fields.     

Effect of Phosphorus Concentration on the Growth of Cattail Callus Cells

Abstract

This investigation examined the growth of Typha latifolia (cattail) callus cells grown in five (0, 11, 22, 33, 44 mg L^?1) different phosphorus concentrations. The cells were grown for two successive subcultures on semi‐solid media, and subsequently in suspension culture with the same phosphorus levels. On semi‐solid media, the fresh weight of the cells varied by a maximum of 36% through both subcultures. The 33 mg L^?1 phosphorus supplied in the original Gamborgs B5 media promoted the greatest fresh weight of the cells in suspension culture over all other concentrations tested. When grown in suspension culture with 0 and 11 mg L^?1 phosphorus, the cells showed a 42 and 29% reduction in fresh weight, respectively. Incubating the cells with 22 and 44 mg L^?1 phosphorus caused a 20 and 13% reduction in fresh weight, respectively. In addition, this study compared the phosphorus concentration of callus cells against literature‐reported values of whole cattail plants incubated at similar phosphorus concentrations. Data from this study demonstrate that when the cattail callus cells and whole plants are exposed to similar phosphorus concentrations, the phosphorus concentration in the plant leaves is within the confidence interval ( p ≤ 0.05) of the phosphorus concentration in the cattail callus cells. This suggests that cattail callus cells can be used to predict the concentration of phosphorus in cattail leaves when they are supplied with similar phosphorus levels. If this relationship between callus cells and whole plants is found to be applicable to other marsh plant species, stormwater wetland managers can use callus cells as a rapid method to screen plants for their capacity to absorb phosphorus before the plant is established in a wetland. This can increase the effectiveness of the wetland to absorb unwanted pollutants from the stormwater entering the site.