pH值对海藻酸丙二醇酯溶液流变特性的影响

作为一种增稠剂,海藻酸丙二醇酯广泛应用于乳制品或乳饮料中。采用AR-G2流变仪,通过稳态流动、应变扫描、频率扫描、动态黏弹性温度扫描及动态黏度温度扫描等实验研究pH值对海藻酸丙二醇酯溶液流变特性的影响。结果表明:pH值的增加使海藻酸丙二醇酯溶液的黏度降低,同时使其黏弹性与复合黏度降低,损耗正切增加。另外,pH值低于7时,海藻酸丙二醇酯溶液的剪切稀化程度减弱,pH值高于7时,溶液的剪切稀化程度增强。同时,pH值影响海藻酸丙二醇酯溶液的黏度及黏弹性的温度效应。     

Changes in soil hydraulic conductivity, runoff, and soil loss due to irrigation with different types of saline–sodic water

Irrigation with saline–sodic water causes sodic conditions in the soil which reduces soil productivity. We evaluated the changes in a number of important indices related to soil structural stability when treated wastewater (TWW), albeit with higher loads of organic matter and suspended solids, was used instead of more saline–sodic irrigation water, under different degrees of aggregate slaking. We studied soil saturated hydraulic conductivity (HC) using disturbed samples packed in columns, and soil infiltration rate, runoff and erosion under simulated rainfall. Aggregate slaking was manipulated by wetting the samples prior to all tests at either a slow (1–2 mm h^− 1) or a fast (50 mm h^− 1) rate. Samples of a calcareous silty clay (Typic Calciorthids) from the Bet She'an Valley, Israel, were taken from plots irrigated for three years with either TWW, saline–sodic Jordan River water (JRW), or moderately saline–sodic spring water (SPW), and also from a non-cultivated area (control). With little or no aggregate slaking (use of slow wetting), higher HC values and lower amounts of total runoff and soil loss were measured compared to when more severe aggregate slaking was induced (use of fast wetting). The HC values for the TWW treatment were similar to, or lower than, those for the control and significantly higher than those for the JRW treatment. For the runoff and soil loss data, differences among the water quality treatments were, generally, more pronounced when aggregate slaking was substantially reduced, and were related to soil sodicity. Under the latter condition, runoff and soil loss from the TWW treatment were comparable with those from the control and significantly lower than those from the JRW treatment. Our results suggested that replacing saline–sodic irrigation water with TWW could have favorable effects on soil structural stability, especially under conditions where aggregate slaking can be reduced (e.g., in regions with low to moderate rain intensities; and/or use of low intensity irrigation systems).     

三角梅扦插枝化学诱变育种

三角梅是一种重要的热带和亚热带观赏植物。由于三角梅有性繁殖困难,诱变育种是目前比较可行的育种方式。本研究采用甲基磺酸乙酯（EMS）、叠氮化钠（NaN₃）和平阳霉素（PYM）3种不同类型诱变剂对‘伊娃夫人’和‘马尼拉小姐’2个三角梅品种扦插枝进行了化学诱变。研究发现‘伊娃夫人’和‘马尼拉小姐’20 h EMS半致死剂量分别为0.22%和0.62%。随EMS浓度增加,2个品种扦插枝发芽数和最长分枝长呈下降趋势,叶绿素和类胡萝卜素含量逐渐增加;‘伊娃夫人’叶片逐渐向暗色调变化,‘马尼拉小姐’叶片向红色色调变化。20 h酸性NaN₃处理下,‘伊娃夫人’无法存活,‘马尼拉小姐’成活率为82%~92%;随NaN₃浓度升高,‘马尼拉小姐’发芽数呈显著下降趋势。相比对照,20 h PYM显著提高了2个三角梅品种扦插枝最大分枝长度,但对扦插枝存活率无显著影响。中高浓度EMS和PYM处理‘马尼拉小姐’三角梅出现了叶缘缺刻、叶表褶皱和双叶尖等变异株。     

海藻酸钠/壳聚糖基橡胶树死皮康复营养剂微胶囊的制备工艺优化

橡胶树死皮已成为制约天然橡胶生产发展的重要因子之一,研发轻简、高效的死皮防治技术是目前生产中亟需解决的问题。本文以海藻酸钠/壳聚糖为壁材,橡胶树死皮康复营养剂主要有效成分为芯材,通过复凝聚反应将橡胶树死皮康复营养剂制备成微胶囊。以微胶囊的包封率、载药量为制备工艺优化指标,通过L₁₆(4 ⁵)正交实验得出微胶囊的最佳制备工艺条件。研究结果表明,当壳聚糖浓度为2.0 mg/mL、营养剂用量为1 g,体系反应温度为40 ℃,pH为5,10%戊二醛用量为30 mL时,该工艺条件下制备的微胶囊相对圆整、粒度分布相对均匀（10~40 μm）,其包封率达69.31%、载药量达14.35%。所得的最佳工艺制备条件为后期实现木质部埋植橡胶树死皮康复营养剂缓释微胶囊打下良好基础;为最终实现新型高效的橡胶树死皮康复技术应用提供依据。     

Na2SeO3对药食用真菌蛹虫草子实体生长及功能成分腺苷、虫草素的影响

【目的】研究分析Na₂SeO₃对药食用真菌蛹虫草子实体生长及功能成分腺苷、虫草素的影响,大面积人工栽培富硒蛹虫草提供理论依据和技术支持。【方法】以新疆本地蛹虫草菌种作为富硒载体,采用瓶栽法,系统分析不同浓度亚硒酸钠处理对蛹虫草菌丝、子座、子实体生长,产量、生物转化率、总硒及其功能成分腺苷、虫草素含量的影响。【结果】处理1(硒浓度20 mg/L)和处理2(硒浓度40 mg/L)与对照相比其蛹虫草的菌丝体生长、子座生长、子实体出草长度、鲜重、干重、生物转化率等无影响,其子实体中总硒含量最高,功能成分腺苷、虫草素含量明显增加;从处理3(硒浓度60 mg/L)至处理7(硒浓度200 mg/L)与对照相比,其蛹虫草的菌丝体生长、子座生长受到抑制,其子实体出草长度、鲜重、干重、生物转化率等呈显著性差异(P<0.05),呈降低趋势,并随着硒浓度增加,抑制越明显;其子实体中总硒含量逐渐降低,功能成分腺苷、虫草素含量逐渐下降。【结论】以亚硒酸钠作为外源硒,硒浓度20~40 mg/L效果最好,可作为进行蛹虫草富硒栽培较为理想的浓度。     

叶面喷施海藻磷钾肥对金斗香番石榴产量和品质的影响

【目的】金斗香番石榴是广东省农业科学院果树研究所等单位选育的番石榴新品种,通过叶面喷施海藻磷钾肥对其果实品质、产量的影响,为提高金斗香番石榴正造果的产量和品质提供理论依据。【方法】以金斗香番石榴为试验材料,对其叶面喷施不同浓度的海藻磷钾肥,以喷施清水为对照,喷施处理后,统计产量,测定果实质量、横径、纵径、可溶性固形物、可滴定酸、Vc、总糖和蔗糖含量。【结果】海藻磷钾肥可明显促进金斗香番石榴果实生长,提高产量和品质。海藻磷钾肥浓度为1 500倍液时,单果重、果实横径、纵径分别为126.35 g、5.49 cm、5.83 cm,较对照分别增加39.81%、14.85%和14.99%;产量较对照增加35.75%;同时也明显提高了果实品质,Vc、可溶性固形物、总糖和蔗糖含量比对照分别提高20.1%、39.4%、64.3%和72.7%;可滴定酸含量降低14.2%。【结论】叶面喷施海藻磷钾肥提高了金斗香番石榴正造果的单果重、横径和纵径,同时也提高了果实的Vc、可溶性固形物、糖含量,降低了可滴定酸含量。选用海藻磷钾肥1 500倍液效果较佳。     

海藻酸钠/纤维素复合微球的制备及性能表征

以短绒棉浆为原料,在NaOH/尿素溶剂体系中将纤维素与海藻酸钠按比例混合,采用溶胶凝胶转相法制备系列海藻酸钠/纤维素复合微球(SACCM),并探讨了SACCM对水相中磷酸根离子的吸附能力。采用扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)和激光粒度分析仪等对复合微球的结构和性能进行了分析。研究结果表明:系列复合微球均成球形,平均粒径约为360μm,微球均表现为具孔的三维网状结构,孔径2～5μm;通过FT-IR谱图可以看出,纤维素未与海藻酸钠发生化学反应,而是通过物理复合成球。吸附实验结果表明:复合微球对水相中磷酸根均具有较强的吸附性能,且吸附能力随着海藻酸钠质量分数的增加而变强,当海藻酸钠质量分数20%(SACCM20)时,对磷酸根的吸附性能最强,吸附效率可达到85.58%。     

Silicon modulates the activity of antioxidant enzymes and nitrogen compounds in sunflower plants under salt stress

Sunflower (Helianthus annuus L.) is an important oilseed crop with clear sensibility to salt stress. In this study, we evaluated silicon (Si) effect on the nitrogen metabolism and antioxidant enzyme activity in sunflower plants subjected to salinity. A 4 × 4 factorial arrangement of treatments in a completely randomized design with four replicates was used, consisting of four concentrations of Si (0.0; 1.0; 1.5; and 2.0 mM) and four concentrations of NaCl (0; 50; 100; and 150 mM) in the nutrient solution. The salinity reduced the nitrate content, but the increasing Si concentration in the medium improved the nitrate uptake, leading this ion to accumulate in salt-stressed plants, particularly in the roots. The nitrate reductase activity and the proline and soluble N-amino contents were also significantly increased by Si in salt conditions. The salinity increased electrolyte leakage and reduced the activity of enzymes superoxide dismutase, ascorbate peroxidase and catalase in sunflower plants, but these decreases were reversed by Si at 2 mM, thus alleviating the effects of salinity on these variables. We conclude that Si is able to positively modulate nitrogen metabolism and antioxidant enzyme activities in sunflower plants in order to alleviate the harmful effects of salinity.