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31.
在江西省鹰潭市余江县孙家红壤小流域的典型红壤区随机选取了具有代表性的林地(F)、花生旱地(PU)、新稻田(NP,<30 a)和老稻田(OP,> 200 a),在0~40 cm深度每隔5 cm采集分层土样,分析了土壤全磷(TP)、有效磷(Bray P)、磷素活化系数(PAC)及有机磷(Po)、无机磷(Pi)与各组分磷的深度变化,探讨了土壤pH与土壤有机质(SOM)对红壤磷素有效性的影响。研究结果表明:孙家小流域不同利用方式红壤TP含量大小依次为:老稻田>新稻田>林地>花生旱地;除林地外,花生旱地与稻田土壤TP、Bray P、Pi和Po含量随着土壤深度的增加呈显著降低趋势,且稻田土壤Po含量及其占全磷的比例显著高于林地和花生旱地。花生旱地与稻田0~20 cm土壤中极有效磷(EAP)、中等有效磷(MAP)及EAP、MAP中的无机磷与有机磷的比值均显著高于林地土壤。林地转为旱地和稻田,尤其是长期植稻可以促进土壤非有效磷(NAP)向利于作物吸收的EAP与MAP转化,因而提高土壤磷素有效性。相关分析表明,随着SOM累积量的增加,四种利用方式红壤中EAP、MAP含量均显著提高。 相似文献
32.
长期施肥对水稻根系有机酸分泌和土壤有机碳组分的影响 总被引:3,自引:2,他引:3
本研究以江西省红壤研究所水稻土长期定位试验田(始于1981年)为对象,分析了不施肥(CK)、单施化肥(NPK)、有机无机配施(NPKM)3种施肥措施对水稻根系有机酸分泌速率及土壤有机碳组分的影响。结果表明:NPK和NPKM处理水稻根系分泌有机酸总量均显著高于CK处理(P0.05,下同),其中NPKM处理最高,提高了54.78%;相对于CK处理,NPK处理水稻根系酒石酸分泌速率显著增加,提高了82.63%,NPKM处理的草酸与苹果酸分泌速率显著增加,分别增加了69.93%、110.98%,而NPK和NPKM处理的柠檬酸分泌速率分别降低了36.57%与40.57%。与CK处理相比,NPKM处理土壤有机碳、颗粒有机碳、微生物生物量碳与可溶性有机碳均显著增加,而NPK处理却无显著变化;可溶性有机碳结构的进一步分析表明,NPKM处理促进了可溶性有机碳中类胡敏酸和类富里酸物质的累积,在可溶性有机碳中所占比例分别为31%、44%,NPK处理可溶性有机碳结构无明显变化;CK和NPK处理中可溶性有机碳的有机物来源主要是植物与微生物的混合源,而NPKM处理主要是微生物代谢所分泌的产物。 相似文献
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34.
测试了棉花2个品种4水平种植密度的4个关键生育时期冠层反射光谱,应用微分技术处理棉花冠层反射光谱,提取了红边(680~750nm)波段范围的最大一阶微分值(Dr)和红边面积(SDr)参数。分析了棉花冠层红边参数在不同生育期的变化特征和棉花吐絮期的两种生长类型的冠层红边状况,表明红边位置可以指示它们的氮素状况。以新陆早8号的SDr为自变量与对应的LNA为因变量进行相关分析,SDr与冠层LNA达1%极显著相关(R=0.9186**,n=32),利用其构建的模型方程估算新陆早6号的LNA,实测LNA和估测LNA的估计标准差为0.8909g/m2,估算精度为88.1%(R=0.9277**,n=32),说明采用高光谱提取的红边参数信息是无损实时、快捷评价棉花氮素状况的有效方法。 相似文献
35.
长期施肥对红壤磷组分及活性酸的影响 总被引:3,自引:0,他引:3
以12年的红壤长期肥力监测定位试验不同处理土壤为材料,研究了连续施肥对土壤磷组分、土壤对磷吸附解吸、土壤活性酸铝的影响。连续施用化学磷肥和化肥加有机肥,均可提高土壤全磷、无机磷数量。施用有机肥料,土壤中的磷以Ca-P和Al-P积累为主要表现形式,化学磷肥的施用能够提高土壤的全磷,并以Al-P增幅为最大,在所有处理中均表现为土壤O-P相对稳定。有机肥料处理土壤对外源磷的吸附强度明显少于施用化学磷肥和不施用磷肥的处理,有机肥料能够显著提高吸附磷的再利用,在NPKM处理中解吸磷占吸附磷的47.72%,M处理中占42.89%,其它处理中解吸磷占吸附磷数量一般少于8%。MNPK、M处理的PFI为2.51、2.69比N、NP处理4.53、4.37明显降低。在红壤旱地长期施用化学肥料,土壤交换性酸铝成倍增加,土壤酸化严重;施用有机肥料、有机肥料与化学肥料配合施用,土壤交换酸铝表现稳定。 相似文献
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37.
In this study, phytochemical and antioxidant properties of anthocyanin-rich mulberry species of Morus nigra L. (black mulberry) and Morus rubra L. (red mulberry) fruits harvested from across Turkey were investigated. Fruit color, total phenolics (TP), total monomeric anthocyanin (TMA), titratable acidity (TA), and individual sugar and organic acid compositions were determined. Total antioxidant capacity (TAC) of fruits was assessed by both the trolox-equivalent antioxidant capacity (TEAC) and the ferric reducing antioxidant power (FRAP) assays. Black mulberry exhibited higher TP, TMA, TAC and TA when compared to red mulberry. The average TP contents of M. nigra and M. rubra were 2737 and 1603 μg gallic acid equivalent in g fresh weight basis (GAE/g fw), respectively. M. nigra had the richest amount of anthocyanin with an average of 571 μg cy-3-glu/g fw. Overall, TAC averaged 10.5 and 12.0 mmol TE/L by the TEAC and FRAP methods, respectively. We found that FRAP, TEAC, TP and TMA were significantly correlated (r = 0.64–0.99) with each other. Fructose (5.27 g/100 mL) and glucose (5.81 g/100 mL) were determined to be the major sugars in both mulberries. M. nigra displayed a higher TA (2.05 g/100 mL) than M. rubra (0.78 g/100 mL), with citric acid as the major acid. 相似文献
38.
Tradable biodiversity credit systems provide flexible means to resolve conflicts between development and conservation land-use
options for habitats occupied by threatened or endangered species. We describe an approach to incorporate the influence of
habitat fragmentation into the conservation value of tradable credits. Habitat fragmentation decreases gene flow, increases
rates of genetic drift and inbreeding, and increases probabilities of patch extinction. Importantly, tradable credit systems
will change the level of fragmentation over time for small and/or declining populations. We apply landscape equivalency analysis
(LEA), a generalizable, landscape-scale accounting system that assigns conservation value to habitat patches based on patch
contributions to abundance and genetic variance at landscape scales. By evaluating habitat trades using two models that vary
the relationship between dispersal behaviors and landscape patterns, we show that LEA provides a novel method for limiting
access to habitat at the landscape-scale, recognizing that the appropriate amount of migration needed to supplement patch
recruitment and to offset drift and inbreeding will vary as landscape pattern changes over time. We also found that decisions
based on probabilities of persistence alone would ignore changes in migration, genetic drift, and patch extinction that result
from habitat trades. The general principle of LEA is that habitat patches traded should make at least equivalent contributions
to rates of recruitment and migration estimated at a landscape scale. Traditional approaches for assessing the “take” and
“jeopardy” standards under the Endangered Species Act based on changes in abundance and probability of persistence may be
inadequate to prevent trades that increase fragmentation. 相似文献
39.
40.
The extensigraph is particularly useful in characterizing dough viscoelastic properties; however, testing throughput for standard method is low due to the prerequisite for farinograph water absorption, long dough resting and milling to prepare large amounts of flour. Therefore, a rapid extensigraph method was developed that reduced sample size (165 g wheat) for milling and more than tripled throughput. Wheat is milled in Quadrumat Junior mill with a modified sieving system. The resulting flour (100 g) was mixed with a pin mixer at constant water absorption to allow the evaluation of wheat genotypes at the absorption level they are expected to perform. Dough was subsequently stretched by an extensigraph after 15 min of floor time and 30 min resting. Strong correlations for extensigram Rmax (r > 0.93), extensibility (r > 0.64) and area (r > 0.88) were found for the proposed method compared to the standard method. Mixing parameters (time and energy) obtained during dough preparation provided further information about dough strength and mixing requirement. By significantly reducing sample size requirement and increasing testing throughput, this rapid extensigraph method can be widely adopted in milling and baking industry and meets the need for a fast evaluation of dough strength in breeding trials. 相似文献