控制性分根交替灌溉下氮形态对番茄生长、果实产量及品质的影响

以高产大果型西红柿品种中研988为材料,采用分根培养的方法,研究了控制性分根交替灌溉(APRI)条件下,不同氮素形态(硝态氮、铵态氮)对番茄生长、产量及果实品质的影响.结果表明: 同一灌溉方式或下限处理下,铵态氮对番茄植株前期生长有利,而硝态氮促进番茄植株后期生长,并促进果实产量增加.在APRI同一灌水下限下,硝态氮处理可提高果实维生素C含量及糖酸比,提高营养品质.同一氮素形态供应下,APRI番茄的株高和叶面积均小于正常灌溉(CK),但灌水下限为60%田间持水量(θ_f)的APRI处理番茄茎粗在生长后期有所增加.在同一氮素形态下,与CK相比,APRI各处理的产量均下降,其中灌水下限在40%θ_f的APRI处理产量下降了22.4%～26.3%;而灌水下限在60% θ_f的APRI处理仅下降了5.3%～5.4%,下降幅度相对较小,而品质显著提高,并具有明显的节水效果.因此,控制灌水下限在60%θ_f、供应硝态氮的APRI处理为番茄高产、优质、节水的最佳处理.
     

黑果枸杞提取物泡腾片的制备及其质量评价

为了解决黑果枸杞中花青素稳定性问题,本文采用Box-Behnken设计对黑果枸杞提取物泡腾片配方进行优化,并对其进行质量评价。采用酸碱混合制粒压片法,通过单因素实验,筛选出片剂所需的辅料:崩解剂、填充剂、润滑剂以及甜味剂。采用响应面试验,结合感官评价进行处方优化,从而确定最优配方:柠檬酸32%、黑果枸杞提取物25%、碳酸氢钠24%、乳糖15%、甜蜜素3%、聚乙二醇6000 1%;对最优配方进行质量评价,各项指标均符合规定,其中花青素含量为8.06 mg/g。该泡腾片表面光滑,泡腾效果好,具有黑果枸杞香气,为实际生产提供理论依据。     

Thirty-five years of synchrony in the organic matter concentrations of Swedish rivers explained by variation in flow and sulphate

Increasing concentrations of organic matter (OM) in surface waters have been noted over large parts of the boreal/nemoral zone in Europe and North America. This has raised questions about the causes and the likelihood of further increases. A number of drivers have been proposed, including temperature, hydrology, as well as ‐ and Cl^? deposition. The data reported so far, however, have been insufficient to define the relative importance of different drivers in landscapes where they interact. Thirty‐five years of monthly measurements of absorbance and chemical oxygen demand (COD), two common proxies for OM, from 28 large Scandinavian catchments provide an unprecedented opportunity to resolve the importance of hypothesized drivers. For 21 of the catchments, there are 18 years of total organic carbon (TOC) measurements as well. Despite the heterogeneity of the catchments with regards to climate, size and land use, there is a high degree of synchronicity in OM across the entire region. Rivers go from widespread trends of decreasing OM to increasing trends and back again three times in the 35‐year record. This synchronicity in decadal scale oscillations and long‐term trends suggest a common set of dominant OM drivers in these landscapes. Here, we use regression models to test the importance of different potential drivers. We show that flow and together can predict most of the interannual variability in OM proxies, up to 88% for absorbance, up to 78% for COD. Two other candidate drivers, air temperature and Cl^?, add little explanatory value. Declines in anthropogenic since the mid‐1970s are thus related to the observed OM increases in Scandinavia, but, in contrast to many recent studies, flow emerges as an even more important driver of OM variability. Stabilizing levels also mean that hydrology is likely to be the major driver of future variability and trends in OM.     

Ecological indicators of nutrient enrichment, freshwater wetlands, Midwestern United States (U.S.)

Vegetation and soil indicators of nutrient condition were evaluated in 30 wetlands, 10 each in 3 Nutrient Ecoregions (NE) (VI-Corn Belt and Northern Great Plains, VII-Mostly Glaciated Dairy Region, IX-Temperate Forested Plains and Hills) of the Midwestern United States (U.S.) to identify robust indicators for assessment of wetland nutrient enrichment and eutrophication. Nutrient condition was characterized by surface water inorganic N (NH₄-N, NO₃-N) and P (PO₄-P) concentrations measured seasonally for 1 year, plant available and total soil N and P, and aboveground biomass, leaf N and P and species composition of emergent vegetation measured at the end of the growing season. Aboveground biomass, nutrient uptake and species composition were positively related to surface water NH₄-N (N) but not to PO₄-P or NO₃-N. Aboveground biomass and biomass of aggressive species, Typha spp. plus Phalaris arundinacea, increased asymptotically with surface water N whereas leaf P, senesced leaf N and senesced leaf P increased linearly with N. And, species richness declined with surface water N. Soil total P was positively related to surface water PO₄-P but it was the only soil indicator related to wetland nutrient condition. Individual regressions for each NE generally were superior to a single regression for all NEs. In NE VI (Corn Belt), few indicators were related to surface water N because of the high degree of anthropogenic disturbance (85% of the landscape is cleared) as compared to NEs VII and IX (24–53% cleared). Of the indicators evaluated, stem height (r² = 0.42 for all NEs, r² = 0.56 for NE VII + IX) and percent biomass of aggressive species, Typha spp. plus Phalaris, (r² = 0.46 for all NEs, r² = 0.54 for NE VII + IX), were the best predictors of wetland nutrient enrichment. Vegetation-based indicators are a promising tool for assessment of wetland nutrient condition but they may not be effective in NEs where landscape disturbance is intense and widespread.     

麻竹山地笋用林凋落物发生、分解及养分归还动态

对福建省漳洲市南靖国有林场山地麻竹笋用林凋落物的养分动态进行了研究.结果表明,凋落物的发生、养分浓度及养分归还量具有明显的季节性,且都呈双峰型;分解失重呈现出先快后慢的规律,分解剩余率与分解时间呈明显的负指数相关;凋落物分解剩余物N和P浓度呈升-降-升的变化规律,K则在前期流失强烈,中期平缓,后期略有回升.     

水稻物质生产与氮、磷、钾、硅素积累特点及其相互关系

大田条件下研究了30个水稻基因型的干物质与N、P、K、Si积累特性及其相互关系.结果表明,水稻干物质积累总量随N、P、K和Si积累总量的增加呈直线增加,其相关系数早季和晚季均达极显著水平.同时,N、P、K、Si积累的平衡有利于干物质积累,干物质积累量随NBI(养分平衡指数)直线增加,随NDI(养分偏离指数)直线下降.30个水稻品种平均N、P、K、Si积累总量比值早季为3.76:1:4.55:7.10,晚季为2.88:1:4.54:8.09.干物质积累能力以中期最强,前期最弱,而N积累能力却以前期最强,后期最弱.水稻抽穗前积累的干物质主要分配在茎鞘中,当抽穗期茎鞘比率达到最大时,茎鞘重约为叶片重的2倍,而抽穗前积累的N主要分配在叶片中,叶片中N的分配比率全生育期均比干物质分配比率高.成熟期积累的干物质、N和P主要分配在穗部,早、晚季稻的平均分配比率分别为58.01%、66.42%和70.06%,而K主要分配在茎鞘中,早、晚季稻的平均分配比率为62.08%.早季Si在茎中的分配比率(43.11%)最大,而晚季却以穗中的分配比率(46.99%)最大.     

麦麸替代玉米对蛋鸡生产性能和蛋品质的影响

本试验旨在研究用部分麦麸替代基础日粮中的玉米对蛋鸡生产性能的影响。选取24周龄的海兰褐蛋鸡600只,随机分为5组,每组6个重复,每个重复20只。对照组饲喂基础日粮,试验组分别饲喂麦麸替代基础日粮中玉米的5%,10%,15%,20%的试验日粮,预饲期7 d,正式试验期35 d。结果表明:麦麸替代玉米提高了平均日采食量、平均蛋重、产蛋率、料蛋比、蛋比重和哈夫单位(P<0.05)。试验表明,麦麸替代玉米,可以提高蛋鸡生产性能,改善蛋品质,且替代10%的玉米效果最佳。     

Macroinvertebrate community traits and nitrate removal in stream sediments

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True potato seed quality

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Is local distribution of the epiphytic lichen <Emphasis Type="Italic">Lobaria pulmonaria</Emphasis> limited by dispersal capacity or habitat quality?

By surveying and re-surveying 12 forest sites in southern Sweden for the epiphytic lichen Lobaria pulmonaria with a 9-year interval, and measuring tree-related habitat quality variables, we have investigated whether the local distribution of the lichen is limited by poor dispersal capacity or by habitat quality. Dispersal distances were measured indirectly as the distances between colonised trees and the nearest trees occupied by L. pulmonaria in both 1992 and 2001. To compare habitat quality between trees occupied by L. pulmonaria and neighbouring control trees, we recorded tree species and measured age and growth rate of trees, light conditions, bark structure and bryophyte cover. The estimated mean dispersal distance was 35 m, with a recorded maximum of 75 m. Occupied trees were larger and had a larger cover of bryophytes than unoccupied trees of similar size. The results indicate that dispersal capacity probably is the most important factor in limiting the local distribution of L. pulmonaria, but habitat-quality factors may be important on a smaller spatial scale.