Silicon-induced basal resistance in tomato against Ralstonia solanacearum is related to modification of pectic cell wall polysaccharide structure

Bacterial wilt incidence was reduced by 38.1% and 100% in silicon-treated plants of the moderately resistant tomato genotype King Kong 2 and the resistant genotype Hawaii 7998 grown in peat substrate. At 5 days post inoculation the bacterial population was significantly reduced in stems and roots of genotype Hawaii 7998, and in stems of King Kong 2 in silicon-treated plants compared to non-treated plants, indicating a silicon-induced resistance, since silicon accumulated in roots, but not in stems, while a tolerance effect was observed in the susceptible genotype L390. Characterization of possible molecular mechanisms involved in silicon-mediated resistance by immuno-histochemical analysis of stem cell walls indicated silicon-induced changes in the pectic polysaccharide structure. After infection homogalacturonan with non-blockwise degradation of methyl-esters was increased in vessel walls in non-silicon-treated plants, but not in silicon-treated plants, possibly indicating the action of pathogen pectinmethylesterase. Also the staining of vessel walls for arabinogalactan-protein in infected, non-silicon-treated plants was not observed in silicon-treated plants. In inoculated, silicon-treated plants, staining for arabinan side chains of rhamnogalacturonan I (RG I) was increased in some vessel walls, and fluorescence of antibodies for galactan side chains of RG I overall increased in the xylem parenchyma compared to non-silicon-amended plants. These observations suggest an induced basal resistance on cell wall level after silicon treatment, while the yellow or brown autofluorescence occurring in inoculated, non-silicon-treated plants disappeared.     

Silicon mediates changes to some physiological and enzymatic parameters symptomatic for oxidative stress in spinach (Spinacia oleracea L.) grown under B toxicity

The effect of exogenous silicon (Si) on the growth, boron (B) uptake, stomatal conductance, lipid peroxidation (MDA), membrane permeability, lipoxygenase activity (LOX), proline and H₂O₂ accumulation, non-enzymatic antioxidant activity (AA) and the activities of major antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT and ascorbate peroxidase, APX) of spinach were investigated under greenhouse conditions. Spinach plants were grown with 0 or 30 mg kg⁻¹ B combined with 0 and 150 mg kg⁻¹ Si. The severity of leaf symptoms of B toxicity was lower when the plants were grown with 150 mg kg⁻¹ Si. Silicon supplied to the soil with high B counteracted the deleterious effects of B on root and shoot growth. Application of B significantly increased B concentration in shoot and in root tissues. However, Si decreased B concentration in the shoots but increased it in the roots. Shoot tissues of spinach contained higher B than the roots in all treatments. Applied Si increased the Si concentration of the root and shoot. Stomatal conductance of the plants was decreased by B, but was increased by Si. The concentrations of H₂O₂ and proline were increased by B toxicity but were decreased by Si applied to plants. Boron toxicity increased the membrane permeability, MDA content and LOX activity of excised leaves of spinach. Applied Si ameliorated the membrane deterioration significantly. Compared with control plants, the activities of AA, SOD, CAT and APX in B-stressed plants without Si applied increased, and application of Si decreased their activities under toxic B conditions. Based on the present work, it can be concluded that Si alleviates B toxicity by preventing oxidative membrane damage and also translocation of B from root to shoots. To our knowledge, this is the first report on the effect of Si in improving B tolerance in spinach.     

硅对玉米种子萌发和幼苗生长作用机制初探

研究硅对玉米种子萌发和幼苗生长代谢的影响, 结果表明: 在Si浓度从1.0 mmol/L到2.5 mmol/L范围内, Si能提高玉米种子萌发过程中淀粉酶、蛋白酶、脂肪酶活性, 促进呼吸代谢, 提高种子发芽率和增加单株鲜重. 在幼苗生长阶段, Si能增加叶绿素含量, 提高光合强度, 增强根系活力和硝酸还原酶活力, 降低蒸腾强度, 提高蒸腾比率、叶     

硫硅配施对水培青蒜苗生长、光合特性及品质的影响

采用深液流水培方式研究硫硅配施对大蒜青蒜苗生长、光合特性及品质的影响。结果表明,硫硅配施可以明显提高青蒜苗株高、假茎长、假茎粗、光合色素含量和光合参数,其中2 mmol·L~(-1)硫配施1.50 mmol·L~(-1)硅效果最佳。适宜浓度的硫硅配施有利于提高青蒜苗中大蒜素、可溶性蛋白、可溶性糖、VC含量,其中硫浓度2～3 mmol·L~(-1)配施硅浓度0.75～1.50mmol·L~(-1)效果最好。综上,硫浓度2 mmol·L~(-1)配施硅浓度0.75～1.50 mmol·L~(-1)最有利于水培青蒜苗的生长和品质。     

硅肥施用方式对小麦白粉病防治效果及籽粒淀粉含量与粉质特性的影响

以西农979和周麦18为材料,在大田条件下研究了硅肥不同施用方式对小麦白粉病防控效果及籽粒淀粉含量和粉质特性的影响。结果表明,增施硅肥能显著降低白粉病感病植株的病情指数,提高抗病能力,尤其是底施硅肥+挑旗期喷施硅肥处理的防控效果为最佳,灌浆中后期效果最为明显。硅肥不同施用方式均能提高籽粒总淀粉和支链淀粉的含量,其中底施硅肥+挑旗期喷施硅肥处理增幅分别达到10.4%和24.7%,降低直链淀粉的含量;同时可延长面团形成时间和稳定时间,提高面粉吸水率,降低弱化度。     

近红外漫反射光谱法(NIRS)分析稻草纤维及硅化物组成

 水稻稻草硅质化是影响稻谷生产与稻草营养品质的主要因素之一 ,对水稻稻草硅化特点的化学分析费时、耗资、准确度较低。利用近红外漫反射光谱法 (NIRS)具有分析速度快、精度高、结果稳定的优点。对同年采自福建省不同种植地、不同季节、不同品种的稻草及稻叶、叶鞘、茎秆共 92份样品进行半纤维素、纤维素、木质素、可溶及不可溶性硅化物成分的近红外光谱分析。研究利用改进最小偏差 (改进最小二乘法回归技术 )回归法 (ModifiedPLS)进行定标建模 ,并进行交叉验证 (cross validation) ,探讨了用近红外漫反射光谱技术建立稻草纤维及硅化物组成快速预测模型的可行性 ,以及影响NIRS技术在建模应用中的主要因素。     

高等植物硅研究进展

从硅在土壤和植物中的存在形式及含量、在植物体中的作用及特点、吸收及短距离运输机制等方面综述了高等植物硅研究进展,并展望了其研究方向。     

喷施不同形态硅对水稻生长与抗逆性的影响

本文研究了喷施纳米硅胶、无机硅和有机硅3种不同形态硅对水稻生长和抗逆性的影响。结果表明,在水分胁迫条件下,喷施3种形态的硅均能降低水稻叶片电解质的渗漏率,维持其较高的叶片水势和相对含水量,增加叶绿素的含量,提高植物的光合能力,促进水稻的生长。与喷清水的对照相比,喷施纳米硅胶、无机硅和有机硅的处理,水稻的生物量分别增加44.92%、29.08%和46.89%。喷施3种形态硅均促进了水稻对氮的吸收和累积。在不同形态硅的处理之间,有机硅在提高水稻叶绿素含量上优于其它两种形态硅。     

应用等温吸附曲线判断水稻土供硅能力 Ⅰ等温曲线方程参数与水稻相对产量的关系

选取低浓度系列平衡液进行等温吸附解吸试验,并结合田间试验的效果,研究了不同水稻土对硅的吸附解吸特征及其与土壤理化性质水稻土供硅能力之间的关系。结果表明:在低浓度梯度条件下,直线方程y=bx-a可以很好地描述土壤对硅的吸附过程。水稻相对产量与a之间存在着极显著的幂指数函数正相关关系,所以,a可以作为评价水稻土供硅能力的指标。     

利用硫化碱废渣制备新型多功能悬浮型种衣剂的研究与应用(Ⅰ)--新型多功能悬浮型种衣剂的研究

本文研究了以工业硫化碱废渣与一类丰富的废弃矿物质等为原料,合成新型阴离子表面活性剂--矽力康复合肥在悬浮型种衣剂中的应用,探讨了矽力康复合肥、不同种类的阴离子、非离子表面活性剂对20%的悬浮型种衣剂稳定性的作用及相互作用,确定了最佳复配条件.结果表明:在使用单一组分中,使用矽力康复合肥比其他9种表面活性剂的稳定性高20.2%～141.2%(15 d);在复配体系中,50g/L矽力康复合肥与15g/L乳化剂A复配体系在90 d后的悬浮率仍达到90.4%,比50g/L十二烷基苯磺酸钠与40g/L乳化剂A的复配体系高29%;产品粘度为500～600mpa·s、对种子的包衣均匀度为95.3%,成膜时间为19min,包衣脱落率为7.42%,热贮稳定性均符合标准,并且产品本身还含有大量促进种子生长的必要元素.