土壤中的铅对三种蔬菜的影响

通过温室栽培萝卜、青菜和莴苣,研究土壤中的铅对蔬菜生长的影响及其在器官中的残留。在低浓度下,铅对蔬菜生长有不同程度的刺激作用。土壤有效态铅浓度与蔬菜各器官含铅浓度存在显著性正相关(P<0.05)。不同蔬菜对铅的敏感性、耐受力不同。     

Effect of airborne SO_2 on performance of the turnip moth,Agrotis segetum Schiff

SO2 Pollution; rape plant (Brassica chinensis); turnip moth (Agrotis segetum); growth and developmental parameters.     

大树杜鹃Rhododendron protistum var.giganteum和蓝果杜鹃Rhododendron cyanocarpum的濒危原因研究

大树杜鹃ＲｐｒｏｔｉｓｔｕｍｖａｒｇｉｇａｎｔｅｕｍＦｏｒｒｅｓｔｅｔＴａｇｇＣｈａｍｂｅｎｉａｉｎ和蓝果杜鹃ＲｃｙａｎｏｃａｒｐｕｍＦ．Ｗ．Ｓｍｉｔｈ被定为国家三级保护植物［１］。本文对这两种保护植物从资源调查、原产地的土壤分析、种子繁殖和贮存方式、异地保护和异地栽培条件下幼苗生长等４个方面作了濒危原因研究。研究结果表明：大树杜鹃应就地和异地保护并用，蓝果杜鹃则应采取就地保护为宜。     

天山云杉天然林分土壤呼吸速率的时空变化规律分析

天山云杉(Picea schrenkiana var.tianschanica(Rupr.)Chen et Fu)是构成天山山地森林生态系统的主体。在天山中部,从天山云杉在此区域分布的底线开始,结合天山云杉自然分布特征,沿每隔约100m的海拔梯度选择典型地段设置样地。根据远红外气体分析原理,采用LI-6400-09土壤呼吸室和LI-6400便携式光合作用测量系统,于2006年6-9月,测定了天山云杉天然林分在生长季内土壤呼吸速率随海拔高度和时间的变化规律。在空间上,林分的土壤呼吸速率并非随海拔高度呈线性增加或减少的关系,而是有规律的波动,在海拔1950～2110m之间,土壤呼吸速率是随着海拔高度的增加而降低,在2110～2428m之间是随着海拔高度的增加而升高,在海拔2428m处达到最大的呼吸速率值后又降低。不同海拔高度林分的土壤呼吸速率主要受土壤表面空气相对湿度及土壤温度的影响。在时间上,林分的土壤呼吸速率在生长季内随不同月份的变化为单峰曲线,其最大值出现在7月份;生长季内土壤呼吸速率与土壤温度呈显著负相关,与土壤表面空气相对湿度呈极显著正相关。而林分土壤呼吸速率的日变化在各时间点上的大小排序为7月>6月>8月>9月。它的变化与土壤温度具有极显著的正相关性,与土壤表面空气相对湿度具有显著的负相关性。     

3种镉超富集植物毛状根体系对镉胁迫响应的比较

近年来,转基因毛状根组织被越来越多地应用于重金属和有机污染物的植物修复技术研究中,已成为进行污染物毒性响应机制研究的便捷的实验室工具。为了探究龙葵、油菜、芥菜3种镉(cadmium,Cd)超富集植物对Cd毒性胁迫响应的差异,以诱导出的3种植物毛状根为研究材料,从毛状根的生长状态、富集Cd的能力、根组织细胞的凋亡程度和抗氧化酶活性等方面进行了探讨。结果表明:Cd浓度为0~50μmol·L-1时,龙葵、油菜、芥菜毛状根受Cd毒害的影响都不明显;Cd浓度为75~100μmol·L-1时,龙葵、油菜、芥菜毛状根均表现出对Cd胁迫的防御响应。在较高的Cd浓度(100μmol·L-1)下,龙葵毛状根的生物量受Cd毒害的影响最小,芥菜次之,油菜受影响最大;同时龙葵毛状根富集的Cd含量最高(745.0μg·g-1),芥菜次之(681.4μg·g-1),油菜最差(505.2μg·g-1)。龙葵、油菜、芥菜毛状根在Cd胁迫下的细胞凋亡水平均随Cd浓度的升高而升高,当Cd浓度为100μmol·L-1时,龙葵毛状根比油菜和芥菜毛状根的细胞凋亡程度均低。同时3种植物毛状根在不同浓度Cd处理下抗氧化酶活性的变化有一定差异。从上述结果综合来看,龙葵毛状根受Cd毒害的影响最小、富集Cd的能力最好,是进一步开展Cd超富集植物转基因改造研究的较好的实验室载体。     

闽江河口潮汐沼泽湿地CO_2排放通量特征

以闽江河口区面积最大的鳝鱼滩湿地分布的3种植物沼泽湿地：土著种咸草（Cyperus malaccensis Lam.var.brevifolius Bocklr.）沼泽湿地、芦苇（Phragmites australis）沼泽湿地及外来入侵种互花米草（Spartina alterniflora Loisel.）沼泽湿地...     

花叶芦竹水平潜流人工湿地脱氮性能研究

采用花叶芦竹水平潜流人工湿地处理生活污水，对其脱氮性能进行研究。结果表明：在HRT＝5 d，对TOC，NH⁺₄-N，NO^-₂-N，NO^-₃-N和TN的去除效果分别达到92％、93％、84％、51％和88％，相应空白湿地的去除率分别为91％、85％、-232％、-203％和66％。大部分TOC在湿地的前端被去除。花叶芦竹可以直接吸收氮素，向湿地输送氧气，通过根系分泌物提供碳源。因此，花叶芦竹人工湿地具有很好的硝化反硝化能力，实现了良好的脱氮性能。     

Chicken manure enhanced yield and quality of field-grown kale and collard greens

Organic matter and nutrients in municipal sewage sludge (SS) and chicken manure (CM) could be recycled and used for land farming to enhance fertility and physical properties of soils. Three soil management practices were used at Kentucky State University Research Farm, Franklin County, to study the impact of soil amendments on kale (Brassica oleracea cv. Winterbar) and collard (Brassica oleracea cv. Top Bunch) yields and quality. The three soil management practices were: (i) SS mixed with native soil at 15 t acre^?1, (ii) CM mixed with native soil at 15 t acre^?1, and (iii) no-mulch (NM) native soil for comparison purposes. At harvest, collard and kale green plants were graded according to USDA standards. Plants grown in CM and SS amended soil produced the greatest number of U.S. No. 1 grade of collard and kale greens compared to NM native soil. Across all treatments, concentrations of ascorbic acid and phenols were generally greater in kale than in collards. Overall, CM and SS enhanced total phenols and ascorbic acid contents of kale and collard compared to NM native soil. We investigated the chemical and physical properties of each of the three soil treatments that might explain variability among treatments and the impact of soil amendments on yield, phenols, and ascorbic acid contents of kale and collard green grown under this practice.     

Jasmonic acid treatment and mammalian herbivory differentially affect chemical defenses and growth of wild mustard (Brassica kaber)

Summary. Jasmonic acid (JA) is a wound-related hormone found in most plants that, when applied exogenously, can induce increases in levels of chemical defenses in patterns similar to those induced by mechanical damage or insect feeding. Relative to responses to insect and pathogen attack, chemical responses of herbaceous plants to mammalian herbivore attack have been little studied. In a field experiment, we compared the effects of JA treatment and naturally occurring mammalian herbivory on the expression of trypsin inhibitors, glucosinolates, peroxidase activity and growth of wild mustard (Brassica kaber). Exogenous JA significantly increased trypsin inhibitor activity and glucosinolate concentration, and moderately increased peroxidase activity in the eighth true leaves of five-week-old plants, relative to untreated controls. In contrast, levels of these chemical defenses in the eighth true leaves or in regrowth foliage of plants that had ∼80% of their leaf area removed by groundhogs (Marmota monax) did not differ from that in undamaged and untreated controls. Although exogenous JA significantly elevated levels of chemical defenses, it did not affect height of plants through the season and only slightly reduced time to first flower. Groundhog herbivory significantly reduced height and delayed or abolished flowering, but these effects were not substantial unless coupled with apical meristem removal. We hypothesize that the lack of effect of groundhog herbivory on chemical defenses may be due in part to the speed and pattern of leaf area removal by groundhogs, or physiological constraints caused by leaf area loss. Despite having no effect on chemical defense production, leaf area loss by groundhogs was more costly to growth and fitness than the effects of JA application in this study, but only substantially so if coupled with apical meristem removal. We suggest that in general, costs of defense production in plants are likely to be minimal when compared to the risk of losing large amounts of leaf area or primary meristematic tissue. Thus, if they are effective at deterring herbivory, the benefits of inducible defense production likely outweigh the costs in most cases. Received 20 December 2000; accepted 3 May 2001     

Persistence of Bacillus thuringiensis deposits in a hardwood forest,after aerial application of a commercial formulation at two dosage rates

Abstract

A commercial formulation of Bacillus thuringiensis Berliner var. kurstaki (BTK), Foray® 48B, was sprayed aerially over four blocks B13, B14, B15A and B15B in an oak forest in Wayne County, Pennsylvania during May 1990. B13 and B14 were sprayed at 75 billion international units (BIU) in 5.91 litres/ha and the other two at 50 BIU in 3.94 litres/ha. Oak foliage was collected at different intervals of time after treatment. Three types of bioassays were conducted against fourth instar gypsy moth larvae, viz., direct feeding of sprayed foliage, feeding on diet containing homogenized foliage, and force‐feeding of foliar extracts. Larval mortalities were converted into international units of BTK activity per unit area (IU/cm²) of foliage. Foliar extracts were also subjected to enzyme‐linked immunosorbent assay (ELISA) to determine the concentration of delta‐endotoxin protein. Regardless of the type of bioassay used, bioactivity of BTK persisted in foliage for about a week in all the blocks. The half‐life of inactivation, DT₅₀, ranged from ca 12 to 22 h. The immunoassay data indicated a shorter duration of persistence (i.e., about 2 d) of the delta‐endotoxin protein, with DT₅₀ values ranging from 10 to 15 h. Formulation ingredients present in Foray 48B played a role in the toxicity of BTK to gypsy moth larvae.