Effects of Exogenous Silicon on the Activities of Antioxidant Enzymes and Lipid Peroxidation in Chilling-Stressed Cucumber Leaves

In order to increase vegetable productivity by improving environmental conditions, this article investigates the effects of exogenous silicon on the activities of major antioxidant enzymes and on lipid peroxidation under chilling stress, and it examines whether silicon-induced chilling tolerance is mediated by an increase in antioxidant activity. Cucumis sativus cv. Jinchun 4 was hydroponically cultivated to the two-leaf stage, at which point seedlings were watered with different concentrations of silicon （0, 0.1 and 1 mmol L^-1） and separately exposed to normal （25/18℃） or chilling （15/8℃） temperatures for six days under low light （100μmol m^-2 s^-9. Data were collected from the second leaves on the percentage of withering and the levels of endogenous silicon, malondialdehyde （MDA）, hydrogen peroxide （H202）, superoxide radical （O2^.-）, superoxide dismutase （SOD, EC 1.15.1.1）, glutathione peroxidase （GSH-Px, EC 1.11.1.9）, ascorbate peroxidase （APX, EC 1.11.1.11）, monodehydroascorbate reductase （MDHAR, EC 1.6.5.4）, glutathione reductase （GR, EC 1.6.4.2）, reduced glutathione （GSH） and ascorbate （AsA）. Compared to normal temperatures, chilling resulted in partially withered leaves and increased MDA content. When 0.1 or 1 mmol L^-1 exogenous silicon was combined with chilling, the withering of the cucumber leaves was reduced relative to the original chilling treatment, while the endogenous silicon content was increased, antioxidants such as SOD, GSH-Px, APX, MDHAR, GR, GSH, and AsA were more active, and the levels of H2O2, O2^.-, and MDA were lower. We propose that exogenous silicon leads to greater deposition of endogenous silicon and thereby increases antioxidant activities and reduces lipid peroxidation induced by chilling.     

不同砧木嫁接对黄瓜生长、产量和品质的影响

研究了黑籽南瓜、超级拳王、超丰8848和孝感瓠子4个砧木对嫁接黄瓜生长、产量和品质的影响。与自根苗相比,采用4个砧木嫁接处理显著提高植株第1雌花节位和黄瓜果实可溶性蛋白含量,采用黑籽南瓜、超丰8848和孝感瓠子嫁接显著提高果实维生素C含量;采用4个砧木嫁接对黄瓜的生长速率、单株产量、小区产量、果实长度、果实粗度、瓜把长、瓜刺、果实颜色、果实含水量、果形指数、风味、口感、可溶性糖及游离氨基酸含量均无显著影响。     

低温弱光对黄瓜幼苗地上部和根系生长与呼吸作用的影响

以冷敏感作物黄瓜(Cucumis sativus)为材料,研究低温弱光(100μmol/m2.s-1、8℃)对黄瓜幼苗地上部及根系生长与呼吸作用的影响。结果表明:低温弱光抑制了黄瓜幼苗地上部与根系的生长,并导致根冠比由0.17增加为0.26。叶片总呼吸(Vt)、细胞色素呼吸(ρ’Vcyt)和抗氰呼吸(ρValt)在胁迫初期瞬间急剧增强,后随处理时间延长又迅速下降,其中Vt和ρ’Vcyt低于对照水平,但ρValt仍与对照水平相当;低温弱光虽然降低了根系ρ’Vcyt,但诱导ρValt显著增强,最终导致Vt增加;低温弱光下根系ρValt/Vt的增加程度明显高于叶片。低温弱光下叶片线粒体呼吸控制率下降程度大于根系,说明低温弱光对叶片线粒体的伤害大于根系。     

烟叶下角料有机肥对番茄和黄瓜生长发育的影响

[目的]研究烟叶下脚料有机肥对番茄和黄瓜产量和品质的影响,为合理利用烟叶下角料提供依据。[方法]利用鸡粪和烟叶下角料有机肥在番茄和黄瓜上进行了田间肥效试验。[结果]结果表明,烟叶下角料有机肥对番茄和黄瓜的生长有明显的促进作用,其增产效果好于目前常用的鸡粪有机肥,在番茄上可增产20.0%~22.8%,黄瓜上可增产23.9%~29.6%;在番茄上,施肥净收入增加29 010~33 030元/hm2,黄瓜上净收入增加51 030~63 045元/hm2。[结论]可利用烟叶下角料有机肥代替农家肥,达到节肥增效的目的。     

耐氨固氮菌浸种对低温胁迫下黄瓜幼苗保护酶活性的影响

用耐氨固氮菌浸种处理黄瓜种子,研究了低温胁迫下黄瓜幼苗保护酶活性的变化。结果表明:5℃低温胁迫2 d,清水组黄瓜幼苗叶片相对电导度、MDA含量及CAT活性显著升高,SOD及POD活性、叶绿素含量显著降低,恢复1 d,这种差异更显著,活性变化不明显;经耐氨固氮菌浸种处理后,菌液组黄瓜叶片叶绿素含量及保护酶活性显著增强,5℃低温胁迫2 d,也表现出清水组的变化规律,但CAT活性显著降低,恢复1 d,菌液组黄瓜叶片相对电导度、MDA含量则显著低于清水组(P<0.05),叶绿素含量则显著高于清水组(P<0.05), SOD及CAT活性显著升高(P<0.05),POD和AsA-POD活性则降低。结果显示,经耐氨固氮菌浸种处理后, 黄瓜幼苗提高了机体的抗氧化酶活性而增强耐寒能力,避免低温的伤害。     

草酸对高温胁迫下黄瓜幼苗叶片光合机构和叶黄素循环的影响

 在40℃高温胁迫条件下，研究了外源草酸对黄瓜叶片光合作用、叶绿素荧光参数和叶黄素循环的影响。结果表明，在高温胁迫前3 d用5 mmol·L-1草酸处理叶片减小了高温胁迫下净光合速率（Pn）、蒸腾速率（Tr）、原初光能转换效率（Fv/Fm）、光合电子传递量子效率（φPSⅡ）、光化学猝灭系数（qP）和非光化学猝灭系数（NPQ）的下降幅度，而对气孔导度（Gs）没有影响。草酸处理可提高叶黄素循环库的大小和（A+Z）/（V+A+Z），并使高温胁迫下叶黄素循环库、叶绿素、类胡萝卜素含量的下降幅度和（A+Z）/（V+A+Z）在胁迫后期的下降幅度减小。这些结果说明，草酸对高温胁迫下黄瓜叶片光合机构的破坏具有保护作用。     

黄瓜RAPD分析的影响因素

从样本取样、保存、DNA提取方法,模板DNA、TaqDNA聚合酶、Mg2 、dNTP、随机引物的浓度和适合的RAPD反应体系及操作过程中应注意的事项、产物处理等方面综述了黄瓜RAPD分析的影响因素,为RAPD技术在黄瓜育种研究中的应用提供帮助。     

Effects of Different Irrigation Regimes and Mulches on Yield and Macronutrition Levels of Drip-Irrigated Cucumber Under Open Field Conditions

ABSTRACT

The effectiveness of different mulch types on fruit yield, leaf-nutrient composition, and normal plant growth parameters was investigated in order to maximize water use efficiency (WUE) in cucumber grown under water stress. Treatments were (1) bare soil + water stress (WS), (2) bare soil + unstressed (control, C), (3) black polyethylene mulch + water stress (BPM + WS), (4) wheat straw mulch + water stress (WSM + WS), and (5) wheat straw mulch plus black polyethylene mulch + water stress (WSM + BPM + WS). Seasonal crop evapotranspiration was between 492 and 960 mm. Seasonal irrigation water amounts were 965 and 485 mm for the C and WS treatments, respectively. The WUE ranged from 3.40 to 5.78 kg m^?3, while irrigation water-use efficiency (IWUE) was between 3.39 and 6.08 kg m^?3. IWUE and WUE were increased under WS treatments with mulching compared with the control treatment, as mulching significantly reduced the amount of irrigation water required. Both BPM and WSM improved the fruit yield, fruit size, plant dry matter, total leaf area, and chlorophyll and nutrient concentrations in leaves under the stressed treatments, while these two mulches in combination (BPM + WSM) caused further increases in these parameters. This study confirms that limiting soil evaporation with mulches is a key action to take to save irrigation water and to improve WUE and IWUE. Because use of drip irrigation with mulching can increase WUE, this strategy might be used for vegetable production in semi-arid regions where irrigation water is limited.     

黄瓜酪氨酸硫化转移酶基因CsTPST克隆及其表达分析

【目的】克隆黄瓜酪氨酸硫化转移酶基因(CsTPST),并分析植物多肽在发育过程中的调控作用,为研究CsTPST的功能及多肽与乙烯在黄瓜发育过程中的相互作用打下基础。【方法】以拟南芥TPST蛋白序列信息为基础进行同源比对,经PCR扩增和生物信息学分析获得CsTPST基因序列信息、结构和亲缘关系,并利用qRT-PCR对其表达模式进行分析。【结果】CsTPST基因cDNA全长789 bp,编码262个氨基酸。进化分析结果表明,CsTPST蛋白与甜瓜的TPST蛋白亲缘关系最近,其氨基酸序列相似性为93%。 qRT-PCR分析结果表明,CsTPST基因在黄瓜雌花、根和叶片中表达量较高,在雄花和茎中表达量较低。此外,CsTPST基因在乙烯合成促进剂ACC处理的黄瓜叶片中上调表达,而在乙烯合成抑制剂AVG处理下呈下调表达。 CsTPST基因启动子能激活GFP基因的表达。【结论】CsTSPT基因是一个受乙烯诱导表达的基因,可供开展CsTPST基因的生物学功能及性别决定的分子机理研究参考。     

恩施州高山萝卜适宜氮肥用量研究

选择湖北省恩施州作为鄂西山区高山萝卜(Raphanus sativus Linn.)的代表性种植区域,探讨了高山萝卜的合理施氮量。结果表明,萝卜的生物量随着施氮量的增加呈抛物线增加趋势,当施氮量达到270 kg/hm2时萝卜的生物量最高;氮素表观利用率随着施氮量的增加而降低,而磷素和钾素表观利用率则随着施氮量的增加呈先升高后降低的趋势;施用适量氮肥可提高萝卜的VC含量,但当施氮量达到270 kg/hm2以上时VC含量明显降低;施用氮肥明显降低了萝卜的可溶性糖含量。综合考虑萝卜的生物量、品质和肥料利用率,在该研究条件下恩施市萝卜的适宜施氮量为210~270 kg/hm2。