离子色谱法对食品中丙酸钙的测定

[目的]研究食品中丙酸钙含量的检测方法。[方法]分别采用水蒸气蒸馏法和直接提取法从样品中提取丙酸钙,用离子色谱法分别测定提取液中丙酸钙的含量。[结果]配制乙酸、丙酸和甲酸根离子混合标准溶液,做出乙酸、丙酸和甲酸根离子线性曲线,得到乙酸根离子线性相关性为99.91%,丙酸根离子线性相关性为99.92%,甲酸根离子线性相关性为99.95%,该方法中丙酸根离子的最低检出限为5 mg/L。样品溶液中加入400 mg/L丙酸根离子标准溶液做加标回收率试验,平均加标回收率为98.98%。在相同试验条件下,对400 mg/L丙酸根离子标准溶液进样6次,其相对标准偏差小于0.8%。[结论]样品处理的最佳方法为水蒸气蒸馏法。     

The combined effects of salinity and excess boron on mineral ion relations in broccoli

Two plant stress factors, salinity and high levels of boron, often co-occur in natural and agricultural environments. Many investigations have been conducted to document the influence of the combined stresses on crop growth and yield. Only limited information, however, is available concerning the combined effects of the two stresses on mineral ion uptake and partitioning to shoot organs and tissues. Data for this study were obtained from an experiment conducted in greenhouse sand cultures with two water types: (1) a chloride-dominated system, and (2) sulfate-dominated waters characteristic of those present in the San Joaquin Valley of California. Each saline composition treatment was tested at three salinity levels (2, 12, 18 dS m⁻¹) and three B concentrations (0.046, 1.11, 2.22 mM; 0.5, 12, 24 mg L⁻¹). The gradient in B distribution in individual leaves sampled midseason was steep, with less boron accumulating in petioles than in the blades. The highest B concentrations (>100 mmol B kg⁻¹ dry weight) were found in leaf margins of plants grown in the low salinity-high boron treatments. These leaves were cupped upward, an unusual visual symptom characteristic of B toxicity. At final harvest, concentrations of B, Ca, Mg, Na, K, and Cl were highest in the oldest leaves on the broccoli shoots, decreasing acropetally to the heads. Total-P, however, was highest in broccoli heads, decreasing in the older tissues. Leaf-B accumulation was more closely related to salinity rather than to the concentration of Cl in the irrigation waters. Analysis of variance indicated that substrate B had little effect on Cl accumulation in salt-stressed broccoli leaves regardless of water type. No clear cut relationships were evident that would explain the reciprocal effects of B and Cl on crop yields.     

三种扇贝种间血液生理指标比较及热胁迫对栉孔扇贝血液生理指标的影响

为了比较3种扇贝血液中的K⁺、Na⁺、Ca²⁺和Cl^-浓度，血氧(pO₂)和血二氧化碳(pCO₂)气体分压及血液酸碱度(pH)的差异情况，实验利用血气分析仪对栉孔扇贝、虾夷扇贝和海湾扇贝的血液生理指标进行测定。结果显示，扇贝的血液生理指标呈现显著的物种差异，其中栉孔扇贝血液的K+浓度[(15.74±1.47) mmol/L]、Na+浓度[(388.07±11.38)mmol/L]、Cl-浓度[(462.43±6.88) mmol/L]和p O2[(140.13±15.35) mmHg]最高。此外，栉孔扇贝和虾夷扇贝的Ca²⁺浓度和pCO₂含量较高，而海湾扇贝的pH最高。对相同月龄不同大小栉孔扇贝血液指标进行比较，发现栉孔扇贝的血液pH值与其壳高呈正相关(r=0.611)，而生理指标与壳高呈负相关。随着温度的升高，栉孔扇贝血液的Ca²⁺浓度显著增加，而pO₂显著下降，K<...     

盐胁迫对两个高羊茅品种幼苗生长及生理特性的影响

本研究以两个高羊茅(Festuca arundinacea Schreb.)品种'钛极-2LS’(Festuca arundinacea'Titanium 2LS’)和'易凯’(Festuca arundinacea'Easycare’)幼苗为研究对象，通过盐浓度递增的方式对其进行14 d高盐处理(500 mmol·L^-1 NaCl)，测定两个高羊茅品种幼苗的形态、离子含量、光合参数以及抗氧化酶活性等指标，比较其耐盐性差异。结果表明：在盐胁迫下，两个高羊茅品种幼苗地下生物量，K⁺/Na⁺，光合、荧光参数，超氧化物歧化酶活性均显著降低(P＜0.05)，但'钛极-2LS’的降低幅度低于'易凯’；两个高羊茅品种幼苗内可溶性糖和脯氨酸含量增加，但'钛极-2LS’的增加幅度高于'易凯’；此外，盐胁迫下过氧化物酶活性在'钛极-2LS’中呈上升趋势而在'易凯’中呈下降趋势。综上，盐胁迫下'钛极-2LS’可以维持相对较高的K⁺/Na⁺和较好的光合能力，积累更多渗透调节物质来缓解盐胁迫引起的渗透胁迫、离子毒害和氧化胁迫的伤害，从而更有利于植株生长，因此'钛极-2LS’耐盐性更好。     

离子注入对水稻呼吸作用及酶活性的影响

研究离子注入处理水稻干种子对萌发过程中的呼吸强度、细胞色素氧化酶活性以及酯酶、过氧化物同工酶酶谱的影响。结果表明：在一定剂量范围内,随着剂量的增加,呼吸强度有增强趋势。细胞色素氧化酶对离子注入较为敏感,剂量越大酶的钝化效应越明显;在萌发５２小时和７２小时脂酶同工酶、过氧化物酶同工酶酶谱均发生改变。