Flooding effects on soil phenol oxidase activity and phenol release during rice straw decomposition

Phenol oxidase (Pox) plays a key role in soil C cycle and its presence may affect soil C mineralization during crop residue decomposition. To examine soil dynamics and relationships between Pox, phenols, Fe²⁺, and C mineralization, we designed a 53‐d laboratory experiment conducted with and without rice straw addition and under non‐flooded and flooded conditions. The results demonstrate that rice straw can indeed decompose faster under flooded conditions. The addition of rice straw significantly increased soil Pox activity (up to 15‐fold), but only under flooded conditions. Rice straw application increased alkali extractable phenol (AEP) concentration by 129% at day 4. However, flooded conditions reduced soil AEP by 61% and 49% at day 53 with and without rice straw application, respectively. Phenol oxidase activity was positively correlated with dissolved organic C and Fe²⁺, while negatively related to AEP, which itself was positively correlated with C mineralization (i.e., CO₂ emission rates). Also, all relationships between soil Pox, AEP, Fe²⁺, and C were stronger under flooded conditions. We therefore conclude that flooded conditions in paddy soil may promote straw decomposition as a result of the stimulation of Pox activity and phenol decomposition.     

Paddy management on different soil types does not promote lignin accumulation

Paddy soil management is generally thought to promote the accumulation of soil organic matter (SOM) and specifically lignin. Lignin is considered particularly susceptible to accumulation under these circumstances because of the recalcitrance of its aromatic structure to biodegradation under anaerobic conditions (i.e ., during inundation of paddy fields). The present study investigates the effect of paddy soil management on SOM composition in comparison to nearby agricultural soils that are not used for rice production (non‐paddy soils). Soil types typically used for rice cultivation were selected, including Alisol, Andosol and Vertisol sites in Indonesia (humid tropical climate of Java) and an Alisol site in China (humid subtropical climate, Jiangxi province). These soil types represent a range of soil properties to be expected in Asian paddy fields. All upper‐most A horizons were analysed for their SOM composition by solid‐state ¹³C nuclear magnetic resonance (NMR) spectroscopy and for lignin‐derived phenols by the CuO oxidation method. The SOM composition was similar for all of the above named parent soil types (non‐paddy soils) and was also not affected by paddy soil management. A substantial proportion (up to 23%) of the total aryl‐carbon in some paddy and non‐paddy soils was found to originate from condensed aromatic‐carbon (e.g ., charcoal). This may be attributed to the burning of crop residues. On average, the proportion of lignin was low and made up 20% of the total SOM, and showed no differences between straw, particulate organic matter (POM), and the bulk soil material. The results from CuO oxidation are consistent with the data obtained from solid‐state ¹³C NMR spectroscopy. The extraction of lignin‐derived phenols revealed low VSC (vanillyl, syringyl, cinnamyl) values for all investigated soils in a range (4 to 12 g kg⁻¹ OC) that was typical for agricultural soils. In comparison to adjacent non‐paddy soils, the data do not provide evidence for a substantial accumulation of phenolic lignin‐derived structures in the paddy soils, even for those characterized by higher organic carbon (OC) contents (e.g ., Andosol‐ and Alisol (China)‐derived paddy soils). We conclude that the properties of the parent soil types are more important for the lignin content of the soils than the effect of paddy management itself.     

Effect of vacuum treatment on smoke penetration into boiled skipjack loins for production of smoke-dried skipjack

ABSTRACT: The present work evaluates the effect of vacuum treatment on smoke penetration into boiled skipjack loins for the production of smoke-dried skipjack. Using a vacuum freeze-dryer, the boiled skipjack loins were vacuumed immediately after being boiled at a pressure of 400 Pa for 30 min in order to reduce the lipid and water contents. The vacuumed boiled meats were then smoked and dried at 90 ± 10°C for 3 h a day for 6 days in a metal kiln (internal diameter 24 cm × 24 cm × 70 cm height), using an electric heater (1.2 kW) to heat and generate smoke from cherry tree wood chips. Also, non-vacuumed boiled meats were smoked in the same manner as a control. The vacuum treatment reduced the lipid and water contents by as much as 0.6% and 2.7% on the wet weight basis, respectively. Histological observations showed many clearances among the muscle fibers of the vacuumed boiled meats. The content of phenols that had penetrated the vacuumed boiled meats during the smoke drying procedure was significantly larger ( P < 0.05) than that of the non-vacuumed boiled meats. Accordingly, the vacuum treatment accelerated the penetration of phenols into the boiled meats and enhanced the function of antioxidant substances, which improved the quality of the smoke-dried skipjack.     

AgNO3对刺梨愈伤组织酚类物质含量及酶活性的影响

【目的】抑制刺梨愈伤组织的褐化是刺梨再生体系成功建立的前提。【方法】以‘贵农1号’、‘贵农2号’、‘贵农5号’、‘贵农7号’刺梨叶片愈伤组织为试材,研究不同AgNO3浓度对愈伤组织褐化的影响,比较不同基因型的褐化程度,并对愈伤组织总酚含量、过氧化物酶及多酚氧化酶活性进行动态分析。【结果】结果表明：AgNO3浓度为0.4g/L时,4个基因型叶片愈伤组织褐化率均最低,其中对‘贵农5号’抑制褐化效果最佳,褐化率仅为1.29%。培养10、20、30天,叶片愈伤组织总酚含量及多酚氧化酶活性均随AgNO3浓度的增加先降低后升高;过氧化物酶活性则先升高后降低。以培养20天、0.4g/L处理时褐化程度最轻,总酚含量、多酚氧化酶活性最低;过氧化物酶活性最高,分别为139.32mg/L、17.76U/g、49.00U/g。刺梨叶片愈伤组织总酚含量、多酚氧化酶活性与褐化率呈极显著正相关;过氧化物酶活性与褐化率呈极显著负相关。【结论】该试验确定了AgNO3抑制刺梨叶片愈伤组织褐化的最佳浓度,并通过相关指标进行了验证,为刺梨离体再生体系的建立奠定了基础。     

Effects of long term irrigation with treated wastewater on leaf mineral element contents and oil quality in Olive cv. Chemlali

Water is one of the most limiting factors in agriculture, particularly in arid areas such as Tunisia. Olives are the most important tree fruit in the country and are cultivated over 1.6 million hectares. An olive grove of cv. Chemlali was irrigated either by using treated wastewater (TWW) or fresh water (FW) from 2002 to 2012. The aim of this 10-year study was to investigate the effects of irrigation with TWW on both quality parameters (i.e. K₂₃₂, total phenols, free fatty acids, etc.) and content of mineral elements in the leaves. Data obtained indicated no effects of the irrigation on parameters such as oil content and K₂₇₀, either by using TWW or FW, and significant effects only after 10 years on free acidity and K₂₃₂. Instead, palmitoleic and stearic acid contents significantly decreased after 10 years of irrigation with TWW with respect to FW irrigation. TWW irrigation also increased the content of total phenols, chlorophyll, and minor and major nutrients in the leaves.     

Pinewood nematode population growth in relation to pine phloem chemical composition

The pinewood nematode, Bursaphelenchus xylophilus, native to North America (NA), is now a major invasive pine pest in Eurasia. Pine species differ greatly in their susceptibility to B. xylophilus, and differences in susceptibility might be related to differences in phytochemistry. This study addressed two major questions: (i) which plant chemical profiles (including compounds that act as plant defences and those important for nutrition) favour pinewood nematode development; and (ii) are NA and Portuguese pinewood nematodes different in their capacity to subsist on plant tissues? For this, B. xylophilus isolates from NA and Portugal were tested on pine phloem and xylem of different pine species. It was found that unaltered pine phloem can sustain the population growth of B. xylophilus, but only in a few cases, and this was clearly related to distinct chemical profiles in some pine species. No evidence was found of evolutionary divergence between B. xylophilus populations in Portugal and NA. The pine species with phloem on which pinewood nematodes could grow tended to have low levels of total phenols, condensed tannins, flavonoids and lignin. Evidence was also found that nutrients such as N may be important.     

Folin-Ciocaileu比色法测定红枣总酚

采用Folin-Ciocaileu比色法对红枣中的总酚进行检测,结果表明,该方法简便、快速、准确,是检测红枣总酚的可靠方法。     

冲泡条件对明日叶发酵茶活性物质及抗氧化能力的影响

以纤维素酶辅助发酵的明日叶发酵茶为材料,研究冲泡温度、时间对茶汤中主要活性物质(多酚、黄酮、查尔酮)浸出量及抗氧化能力的影响。结果表明,随着冲泡温度从80 ℃升高至95 ℃,茶汤中多酚、黄酮、查尔酮的浸出量呈先增后减的趋势,90 ℃下茶汤中总酚、总黄酮和总查尔酮浸出量达最大值。随着冲泡时间延长,茶汤中多酚、黄酮和查尔酮溶出量在15 min内迅速增加,之后进入饱和状态。相关性分析结果表明,DPPH法测定的抗氧化性与多酚、黄酮和查尔酮含量呈显著(P<0.05)正相关。     

河南省柿种质资源叶片总酚、黄酮和单宁含量的差异分析

【目的】分析河南省柿种质资源叶片中总酚、总黄酮和单宁含量的差异性,并根据成分含量对资源进行评价及分类,初步筛选出高含量优良柿种质。【方法】对来自河南省不同地区的122份柿种质资源进行叶片总酚、总黄酮和单宁含量测定,分析各成分含量的差异性、分布规律和相关性及其在不同地区间的差异性,并根据各成分含量高低进行资源分类与筛选。【结果】河南省柿资源叶片中总酚、总黄酮和单宁含量平均值分别为122.75,81.09和52.15mg/g,变异系数分别为30.56%,46.85%和27.58%。总酚含量集中分布在103.87~144.25mg/g,黄酮含量集中分布在54.39~96.93mg/g,单宁含量集中分布在44.91~60.55mg/g。不同地区间3种成分含量均存在极显著差异(P0.01),且3种成分含量在不同地区间的变异程度大小基本一致,即洛阳最高,南阳、豫北地区次之,三门峡、平顶山相对较小。3种成分含量彼此间呈极显著正相关关系(P0.01),且一元线性回归拟合效果较好。综合评价3种成分含量的高低,可将所有资源分为4大类,从中初步筛选出了14份高含量优良叶用种质。【结论】河南省柿种质资源叶片中总酚、总黄酮和单宁含量变异程度高,具有丰富的多样性,可根据任何1种成分的含量预测另外2种成分含量的高低。     

增施不同的有机质对烤烟多酚和石油醚提取物含量的影响*

 田间试验以烤烟(Nicotiana tobacum L.)品种云烟87为试材,于2005~2006年在河南南阳研究了常规措施（CK）下增施不同的有机物质对烤烟多酚类和石油醚提取物含量的影响。结果表明:增施有机质可以使烟叶中总酚、绿原酸、芸香苷、石油醚提取物含量明显增加,其中以增施发酵后的豆浆的两个处理最好,其次是增施豆参,增施芝麻和香油的两个处理效果相对稍差。