快速滤过型净化法结合高效液相色谱-串联质谱同时检测人参中的5种农药残留

基于人参样品基质特点,采用快速滤过型净化法 (m-PFC) 结合高效液相色谱-串联质谱 (HPLC-MS/MS),建立了人参中嘧菌酯、苯醚甲环唑、吡虫啉、茚虫威和噻嗪酮5种农药残留同时检测的分析方法。该方法具有较低的检出限 (0.03~0.18 μg/kg) 和定量限 (0.11~0.59 μg/kg),其定量限较中国国家标准GB 2763—2016中规定的对人参中苯醚甲环唑和嘧菌酯的最大残留限量 (MRL) (0.5~1 mg/kg) 低3个数量级,5种农药的线性范围在1~500 μg/L之间。在2、10、50、100和300 μg/kg的添加水平下,方法的平均回收率均在76%~115%之间,相对标准偏差 (RSD) 均小于11%,回收率较好且方法稳定。与传统样品前处理方法相比,该方法具有操作简单、省时省力和灵敏度高等优点。将该方法应用于市售6份人参样品中5种农药残留的检测,结果未检出相应的农药残留。该方法为研发建立更快速、准确地检测人参中农药残留的方法提供了思路,也为后续中国国家标准修订人参中农药最大残留限量提供了参考。     

贵州柑橘园土壤与果实的重金属含量特征及其评价

为探明贵州山地柑橘园土壤与柑橘果实重金属含量特征,为柑橘安全生产提供依据。对贵州省南北盘江、红水河、都柳江和清水江等沿岸的柑橘园进行实地调查取样,分析土壤重金属含量与柑橘果实重金属的含量及其相关性。结果表明:柑橘园土壤重金属含量依次为ZnCrPbCuNiAsCdHg;柑橘果实重金属富集量依次为ZnCuNiCrPbAsCdHg。柑橘果肉中Zn、Cu、Ni和Pb富集量与土壤中含量呈正相关;柑橘果肉中Cr、Cd、As、Hg富集量与土壤中的含量呈负相关。不同果园和不同土壤质地其重金属含量差异较大,不同品种或同一品种柑橘果肉对重金属的富集量差异较大,且来源不同。采用单项污染指数法和综合污染指数法对样品进行评价,样品均为清洁,试验区适宜发展无公害柑橘果品生产。     

Effect of 1-methylcyclopropene on postharvest quality of Chinese chive scapes

The effect of 1-methylcyclopropene (1-MCP) on postharvest quality and lignification of Chinese chive scapes (Allium tuberosum Rottler ex Sprengel) was examined during storage at 20 °C. The results showed that the treatment with 0.5 μL L^?1 1-MCP significantly delayed weight loss and opening rate of flowers, maintained higher chlorophyll and ascorbic acid contents, inhibited respiration, reduced the activities of the enzymes phenylalanine ammonia lyase, cinnamyl alcohol dehydrogenase and peroxidase, and retarded lignin and cellulose accumulation. The results suggest that 1-MCP treatment may be a promising technique to maintain postharvest quality of Chinese chive scapes.     

黑土区基准坡长和LS算法对地形因子的影响

该文结合小区实测坡长资料及Mc Cool数据,对地形因子算法中涉及的基准坡长影响和不同算法计算值的特征进行了讨论。研究表明,在坡长较小的情况下,20和22.13 m基准坡长计算得到的坡长因子相差不大,但随着坡度增加,在坡长指数的复合影响下,两者的差异渐趋增大。理论分析表明,坡长指数采用与坡度相关的变值更为合理。通过与实测数据对比发现,修正版通用土壤侵蚀模型(RUSLE)算法中的坡长因子与其更为接近,结合与Mc Cool数据的对比分析表明,研究区坡长指数更适合细沟和细沟间侵蚀比率中等的情形,或者采用RUSLE模型算法计算得到。同时研究发现,张宪奎算法、Moore算法、Desmet算法和B?hner算法计算得到的LS因子值都要比参照值小,而且4种算法与参照值的接近程度依次降低。空间分布特征而言,栅格累计算法总体较为破碎,并在平直坡面出现较多平行分布条带,而含有面积指标的其他3种算法则总体呈现光滑连续特性,但有无数据区域的存在。该结果对于研究区土壤侵蚀模型地形因子算法选择具有一定的现实意义。     

棚室越夏番茄栽培技术

本文主要介绍了在棚室夏季利用中,接日光温室的黄瓜茬口,利用现有棚膜遮阴防雨,在2茬黄瓜之间抢种1茬番茄技术。主要是通过选择适宜的番茄品种及配套栽培管理,于9月、10月形成番茄产量高峰,抢占这一市场空档期,从而达到增产、增效、增收之目的。     

添加己酸和盐酸对玉米秸秆青贮饲料质量的影响

通过测定盐酸、己酸处理的玉米秸秆青贮饲料的pH值、含水率、有机酸含量及组成、干物质消失率、NDF瘤胃降解率、干物质回收率和青贮饲料化学成分，研究了盐酸、己酸的处理对玉米秸秆青贮饲料质量的影响。试验结果表明：在玉米秸秆青贮饲料中添加盐酸，降低了青贮饲料中乳酸占总酸的比例和干物质回收率，并使青贮饲料的细胞壁物质含量显著增加，明显降低了玉米秸秆青贮饲料的质量；己酸的添加对青贮饲料质量无显著影响(P＞0．05)；盐酸和己酸的共同处理除了明显改善青贮饲料的色泽、气味和质地外，还可明显降低青贮饲料中OB，ADF和ADL的含量(P＞0．05)，显著提高了青贮饲料的营养价值。     

Hybridization among Epimedium (Berberidaceae) species native to China

The hybridization of fourteen plant populations belonging to seven Epimedium species native to China was studied by self-cross, infra-population cross, inter-population cross within species, and interspecific cross. Self-pollination studies on nine populations indicated high incompatibility; capsule-set rates were higher than zero in only three (4.61–6.76%). Interspecific cross-pollinations demonstrated high crossabilities in most cross combination (15.38–92.44% capsule-set rate), and the F₁ seeds possessed high germination rates (>20%). The F₁ hybrids of three interspecific cross combinations were raised to maturity. The morphology, karyomorphology of somatic cells, and pollen mother cell (PMC) meiosis of these F₁ plants revealed that they were all highly fertile (>76.10% in pollen viability), that there were few structural differences in chromosomes among species, and that most PMCs had 6 bivalents at MI. Abnormal chromosomal behaviors occurred in a minority, including chromosome bridges, unequal segregation of chromosome number, lagging chromosomes, and micronuclei. A series of experimental crosses provided strong evidence for an outbreeding system and a weak internal barrier to hybridizations in the taxa studied.     

水曲柳落叶松林土壤养分特性的研究

通过对试验地不同林分土壤性质及营养元素的测定,发现水曲柳叶松混交林土壤ｐＨ值,有机质含量与水曲柳纯林无显著差异,土壤有效性Ｃａ,Ｍｇ,Ｚｎ,Ｆｅ均高于土壤养分的生物有效性临界值,不会对树木生产产生限制作用,而土壤有效Ｍｎ含量较低,在不曲柳纯林林地尤为不足,在水朵柳落叶松混交林中这种状况有较大改善,表现出与林木生长相一致的规律,说明土壤有效Ｍｎ的改善是水曲柳落叶松混交林较水曲柳纯林生产力高的主要原因     

根瘤菌接种方式对复播大豆生长及结瘤的影响

[目的]研究不同根瘤菌接种方式对复播大豆生长及结瘤效果.[方法]以前期分离、鉴定、纯化的3株根瘤菌菌株为材料,对新疆南疆地区复播大豆新大豆8号进行种肥、随水滴施、拌种等接种方式试验,测定其根瘤数、根瘤干重、植株性状、产量及其构成因素的变化.[结果]接种根瘤菌均能促进大豆根系结瘤和生长发育,根瘤菌SN7-2促进效果最明显...     

The effect of temperature on decomposition of leaf litter from two tropical forests by a microcosm experiment

A 120 days’ incubation experiment was conducted to analyze the effect of temperature on the decomposition of leaf litter (Altingia obovata) in two tropical primary montane rainforests with different precipitation conditions. The results showed no difference in mass loss of leaf litter between the two forests at 20 °C, in spite that Jianfengling forest had less precipitation than Diaoluoshan forest. But higher mass loss of leaf litter was found from Jianfengling forest site (30.1%) than that from Diaoluoshan forest site (25.9%) at 30 °C at the end of incubation. Lignin exhibited higher mass loss from Jianfengling forest (29.9%) than from Diaoluoshan forest (23.3%) at 20 °C, but no difference between two forest sites at 30 °C. Total carbohydrates were decomposed faster by the decomposers from Diaoluoshan forest site (42.7%) than that from Jianfengling forest site (36.3%) at 20 °C, but 46.6% and 38.5% for Jianfengling and Diaoluoshan montane rainforests, respectively, at 30 °C. Temperature increase did not significantly lead to the difference in mass loss of leaf litter for the two forest sites. Temperature increase did not affect lignin loss for Diaoluoshan forest, but reduced lignin loss for Jianfengling forest. Temperature increase accelerated the decomposition of carbohydrate for Jianfengling forest, but opposite for Diaoluoshan forest. The response of decomposition of leaf litter to forest type and temperature was positively related to the difference in microbial activities between both montane rainforests.