磷酸缓冲液预处理对高温胁迫下油菜叶片膜脂过氧化及体内保护系统的影响

高温胁迫下，油菜叶片细胞膜相对透性、丙二醛（MDA）含量和过氧化物酶（POD）活性增加；抗坏血酸（ASA）、谷胱甘肽（GSH）、可溶性蛋白质总量及热稳定性蛋白质所占比例与超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性下降;酸缓冲液预处理可维持较高的保护酶活性、抗氧化物质含量和较低的膜脂过氧化水平．     

Identification of Chinese cabbage genotypes with low cadmium accumulation for food safety

The pot-culture experiment and field studies were conducted to screen out and identify cadmium (Cd) excluders from 40 Chinese cabbage genotypes for food safety. The results of the pot-culture experiment indicated that the shoot Cd concentrations under three treatments (1.0, 2.5 and 5.0 mg Cd kg⁻¹ Soil) varied significantly (p < 0.05), with average values of 0.70, 3.07 and 5.83 mg kg⁻¹, respectively. The Cd concentrations in 12 cabbage genotypes were lower than 0.50 mg kg⁻¹. The enrichment factors (EFs) and translocation factors (TFs) in 8 cabbage genotypes were lower than 1.0. The field studies further identified Lvxing 70 as a Cd-excluder genotype (CEG), which is suitable to be planted in low Cd-contaminated soils (Cd concentration should be lower than 1.25 mg kg⁻¹) for food safety.     

TS—303对未成熟油菜种子的子叶细胞中BL分布的影响

用胶体金免疫定位技术对未成熟油菜种子的子叶细胞中BL的定位研究结果表明，金颗粒除主要分布在细胞核外，细胞质中也有少量金颗粒标记，但液泡和细胞壁中没有观察到金颗粒存在外施TS-303可明显导致未成熟种子的子叶细胞核中金颗粒标记密度的大量增加，说明TS-303很可能只影响幼嫩组织的细胞核．     

Leaf surface chemicals stimulating oviposition byPieris rapae (Lepidoptera: Pieridae) on cabbage

Summary The chemical stimulation of oviposition byPieris rapae on cabbage was investigated by leaf washing and extraction. Isolation of the stimulant by various chromatographic techniques was monitored by a bioassay using Sieva bean as a surrogate host plant. Cold water, chloroform, or chloroform followed by cold water washes failed to release the stimulant from leaf surfaces. Boiling water or chloroform followed by methanol was required. The most active stimulatory compound was identified as 3-indolylmethyl glucosinolate (glucobrassicin). Other glucosinolates were identified as sinigrin, which was only slightly active, and glucoiberin, which was completely inactive as a stimulant. The significance of the selective response ofP. rapae andP. brassicae to different glucosinolates and the implications of the binding of polar allelochemicals to leaf surfaces is discussed with respect to host utilization and perception mechanisms of pierids.     

Uptake and localisation of lead in the root system of Brassica juncea

The uptake and distribution of Pb sequestered by hydroponically grown (14days growth) Brassica juncea (3days exposure; Pb activities 3.2, 32 and 217microM) was investigated. Lead uptake was restricted largely to root tissue. Examination using scanning transmission electron microscopy-energy dispersive spectroscopy revealed substantial and predominantly intracellular uptake at the root tip. Endocytosis of Pb at the plasma membrane was not observed. A membrane transport protein may therefore be involved. In contrast, endocytosis of Pb into a subset of vacuoles was observed, resulting in the formation of dense Pb aggregates. Sparse and predominantly extracellular uptake occurred at some distance from the root tip. X-ray photoelectron spectroscopy confirmed that the Pb concentration was greater in root tips. Heavy metal rhizofiltration using B. juncea might therefore be improved by breeding plants with profusely branching roots. Uptake enhancement using genetic engineering techniques would benefit from investigation of plasma membrane transport mechanisms.     

青海湖流域农田生态系统氢氧同位素特征及其水分利用变化研究

水分条件是直接影响农作物产量高低的主要限制因子之一,但对青海湖流域油菜和燕麦植物水分利用方式的认识尚不清楚。论文收集油菜和燕麦整个生育期内降水、植物和土壤水氢氧稳定同位素组成,并通过直接对比法和多源混合模型定量地计算出油菜和燕麦对不同深度土壤水分利用比例。结果表明：降水中同位素组成表征出较大的波动性变化,浅层土壤水同位素组成受蒸发作用影响明显富集于深层土壤水分,且土壤水中同位素在垂直方向上呈浅层土壤水较富集于深层土壤水。油菜在生育期内根系吸水方式在浅层和深层土壤间发生明显的转换,如在蕾薹期、开花期、灌浆期及成熟期主要依赖于0~10 cm（95.1%）、0~10 cm（68%和44.8%）、30~60 cm（69.9%）及0~10 cm（38.8%）的土壤水分。而燕麦根系吸水范围却没有表征出明显的改变,在整个生育期内土壤水分利用深度在0~30 cm间变化。这将为高寒地区耕作方式调整及发展节水高效的现代农业提供理论依据。     

Secondary metabolites of the leaf surface affected by sulphur fertilisation and perceived by the cabbage root fly

Summary. Surrogate leaves treated with methanolic leaf surface extracts of Brassica napus L. (cv Express) plants that received three different sulphur fertilisation treatments showed even more marked differences by the oviposition choice of Delia radicum L. than the potted plants. This confirms that the oviposition preference of D. radicum is mediated by chemical compounds on the leaf surface and that the quality of host-plants in terms of their nutrition status can be perceived by the female insect.The oviposition data were positively correlated with the content of fractionated surface extracts containing either CIF (cabbage identification factor; 1,2-dehydro-3-thia- 4,10,10b-triaza-cyclopenta[.a.]fluorine-1-carboxylic acid) or glucosinolates. Electrophysiological recordings from the tarsal chemoreceptor sensilla C₅ and D_3,4 showed that receptor neurons react to glucosinolate- and CIF-fractions. We found that the chemosensory activity of specific glucosinolate- and CIF-receptor neurons corresponded with the respective behavioural activity in the oviposition choice assays. The responses of D. radicum to glucosinolates in the electrophysiological recordings studies corresponded to the observed oviposition preference on plants or artificial leaves characterised with an higher amount of glucosinolates on leave surfaces. The presented data suggested that CIF and glucosinolates are involved in host-plant preference of D. radicum and are perceived by tarsal chemoreceptors.     

Cd对小白菜生长及氮素代谢的影响研究

采用水培的方法,研究了不同Cd2 水平(0、1、2.5、5、10 mg·L-1)对小白菜叶片中铵态氮、硝态氮、可溶性蛋白质、游离脯氨酸、叶绿素、部分营养元素含量以及蛋白水解酶、硝酸还原酶、谷氨酰胺转化酶与合成酶活性的影响.结果表明,低浓度的Cd处理(1 mg·L-1)刺激了小白菜的生长,提高了小白菜的生物量、叶绿素含量以及硝酸还原酶、谷氨酰胺合成酶与转化酶活性.Cd处理降低了小白菜对Cu、Ca、Fe、Mg的吸收,但促进了P的吸收.10 mg·L-1的Cd处理显著降低了可溶性蛋白质含量、硝酸还原酶、谷氨酰胺合成酶和转化酶活性(p＜0.05),提高了蛋白水解酶活性,不利于叶片中铵态氮与硝态氮的同化,造成叶片中铵态氮和硝态氮的累积.小白菜叶片中游离脯氨酸含量与铵态氮含量成极显著正相关(p＜0.01),说明小白菜叶片中游离脯氨酸的累积在一定程度上缓解了铵的毒害.     

施肥对小白菜产量和品质的影响

为研究安全的蔬菜施肥技术，通过不同质地土壤的田间试验，研究不同氮、钾质量配比对小白菜产量和品质的影响。结果表明，在固定施磷水平的基础上，在不同质地的土壤上，小白菜对氮、钾质量配比有不同的效应，氮、钾合理配施可使蔬菜高产优质；所施氮的形态，对小白菜硝酸盐含量有显著的影响。     

6种矿质元素对青菜中硝酸盐含量的影响

通过盆栽试验 ,研究了B、K、Mn、Mg、Zn、Co对青菜中硝酸盐含量的影响。结果表明 :增施硼酸钠后第 2 0天 ,青菜硝酸盐含量比对照降低 1 4 84%～ 1 9 56 % ;增施K、Mn、Mg、Zn、Co也能降低青菜硝酸盐含量。每盆增施0 1gZnSO4 后第 1 0天 ,青菜中硝酸盐含量比对照减少 1 8 96 % ,每盆增施 0 1gK2 SO4 后第 2 0天 ,青菜中硝酸盐含量比对照减少 2 1 42 % ;矿质元素的施用量对青菜硝酸盐含量影响较大。