Effects of nitrogen feeding for extraradical mycelium of Rhizophagus irregularis maize symbiosis incorporated with phosphorus availability

In terrestrial ecosystems, plants are frequently in symbiosis with arbuscular mycorrhizal fungi (AMF) with mineral nutrients and photosynthesis carbon exchanges in between. This research sought to identify the effects of phosphorus (P) levels on the nitrogen (N) uptake via extraradical mycelium (ERM) and the mycorrhizal growth response (MGR) of maize plants within the AMF symbiosis. Pots were separated into root compartments and hyphae compartments (HCs) with two layers of a 30‐μm mesh membrane and an air gap in between, where only hyphae could pass through, to avoid both N diffusion and root growth effects. Maize plants were inoculated with Rhizophagus irregularis with different N fertilization in HCs under two different P fertilization levels. Our results indicated that a strong increase in MGR with low‐P fertilization. The same tendency was not observed with high‐P fertilization, although both had a large increase in P concentration as a potential source of growth in shoot tissue of mycorrhizal plants. Substantial effects (10.5% more N) were observed in the case of high‐P availability for the host plants from ERM fed with N, whereas under low‐P conditions ERM may prioritize P uptake rather than N uptake. The AM fungi increase the uptake of N and P, which are most limiting in the soil with fewer forces from soil resources. In addition, there was still more P accumulated than N due to the high N for ERM with high‐P supply. Low N in HCs corresponded with a lower colonization rate in roots but with high hyphae density in HCs; this result suggest that N and P availability might change the ratio of extraradical to intraradical hyphae length.     

冬油菜与杂草对长期不同施肥的差异性适应

研究长期水旱轮作条件下,施肥模式对田间冬油菜、杂草、土壤养分及冬油菜–杂草空间分布的影响,为长江流域冬油菜轻简化生产提供依据。2011年在湖北省粮油主产区——江汉平原布置水稻–冬油菜轮作肥效定位试验。2016年冬油菜收获期,调查农田杂草群落多样性和分析油菜–杂草–土壤养分三者状况。结果表明,长期土壤养分亏缺会显著影响油菜–杂草的生长和空间分布、形成不同的杂草优势群落。平衡施肥(NPK处理)有助于增加冬油菜根茎粗、有效分枝数、角果数和最终产量,降低杂草总生物量,提高杂草群落多样性Shannon-Wiener指数。与NPK处理相比,–N、–P和–K均会不同程度地降低籽粒、茎秆、角壳和杂草的养分吸收量,尤以–P处理降幅最为明显。与土壤养分含量的初始值相比,长期不施用化肥会引起土壤氮磷钾有效含量下降,尤其对于土壤钾,现有平衡施肥措施不足以弥补农田钾素亏缺,应重视秸秆还田的补钾效果。总之,长期科学的农田养分管理与调控措施,不仅可以降低杂草对冬油菜的危害、增强生物多样性和形成良性的油菜-杂草竞争环境,也有利于减少化学药剂使用、推动冬油菜的轻简化生产。     

不同种植密度对高粱生长、产量及养分吸收的影响

为了明确密度与高粱[Sorghum bicolor (L.) Moench]农艺和经济性状以及养分吸收的关系,以‘晋杂23号’高粱为试验作物,采用大田试验方法,试验设4.5万株/hm2、7.5万株/hm2、10.5万株/hm2和13.5万株/hm2 4个种植密度,研究了不同种植密度对高粱生长、产量、产量构成因素以及养分吸收的影响。结果表明,随着密度增加,高粱株高显著增高,茎粗显著变细,单株叶面积和单株干重显著下降。在4.5万株/hm2~7.5万株/hm2范围内,籽粒产量随着密度增加呈显著性增加。密度在4.5万株/hm2~10.5万株/hm2时,单位面积穗数随密度增加呈显著性增加。随着密度增加,穗粒数显著性增加,而千粒重影响不显著。除磷以外,密度对高粱氮和钾吸收总量均无显著影响。密度对籽粒氮吸收量没有显著影响;在10.5万株/hm2~13.5万株/hm2范围内,磷和钾吸收量明显下降。与氮和磷不同,钾主要分配在秸秆中,只有少量钾转运到籽粒中。相关分析表明,种植密度与株高、生物产量、籽粒产量和单位面积穗数呈显著性正相关,而与茎粗、单株叶面积、单株干重、经济系数、穗粒数和千粒重呈显著性负相关。本研究表明,种植密度与高粱主要农艺和经济性状以及养分吸收息息相关,在高粱高产高效栽培中起着非常重要的作用。     

滴灌水肥一体化下施氮量对小麦氮素吸收及土壤硝态氮含量的影响

为探明华北地区山前平原水肥一体化条件下小麦合理的氮肥运筹。于2013-2015年2个小麦生长季,设置4个滴灌施氮量(N0-不施氮、N1-120 kg/hm~2、N2-240 kg/hm~2、N3-360 kg/hm~2)处理,研究滴灌水肥一体化下施氮量对小麦氮素吸收积累和土壤硝态氮含量的影响。结果表明:施氮量N1、N2和N3处理的小麦干质量及产量较处理N0显著增加,N1、N2和N3处理间无显著差异;施氮量对小麦茎秆的氮含量影响较大,但对籽粒氮含量的影响差异不显著;处理N3的小麦总吸氮量分别显著高于处理N0、N1和N2,但处理N1和N2之间无显著差异;氮肥收获指数以N2处理最高,氮肥当季回收利用率、氮肥农学效率、氮肥生产效率和氮肥利用效率均表现出随施氮量增加而降低的趋势;施氮量超过240 kg/hm~2,土壤硝态氮含量增加,且随种植年限的延长更加明显。采用一元二次方程拟合,获得小麦最高产量的施氮量为238.46~250.78 kg/hm~2,经济施氮量为174.28~207.18 kg/hm~2。综合考虑经济效益和生态效益,该条件下小麦滴灌经济施氮量以174~207 kg/hm~2为宜。     

施氮和间作对蚕豆根瘤形成及氮素吸收累积的影响

为探究不同施氮水平下小麦蚕豆间作对蚕豆根瘤形成及氮素吸收累积的影响,明确氮肥施用与豆科作物结瘤固氮、氮素吸收累积和产量的关系,通过2年田间试验,分析了N0、N1、N2和N3 4个施氮水平（蚕豆：0、45、90、135kg/hm²;小麦：0、90、180、270kg/hm²）下,单作、间作蚕豆各关键生育期根瘤鲜重、氮素吸收关键参数、地上部氮素累积量和产量的特征。结果表明,N0、N1和N2水平下,间作蚕豆根瘤鲜重比单作分别提高40.9%、27.2%和34.1%;高氮（N3）水平下,单作、间作蚕豆根瘤鲜重无显著差异。与单作相比,4个施氮水平下间作蚕豆的最大氮素累积量（A）和最大氮素吸收速率（R_max）降幅分别为8.01%~13.93%和10.27%~12.98%,表明氮素吸收累积特点与根瘤鲜重相反。在蚕豆营养生长阶段（出苗后90d内）,单作、间作蚕豆氮素累积量无差异;进入结荚期后（出苗90d后）,间作显著降低了蚕豆的氮素累积量。同时,蚕豆产量也受施氮量和种植模式的调控,与单作相比,4个施氮水平下,间作降低蚕豆产量平均达20.66%。整体而言,在N1水平下,蚕豆根瘤鲜重和产量达最大值,随着施氮量增加,蚕豆根瘤鲜重、氮素累积量和产量均随之降低,间作促进根瘤形成的优势减弱甚至消失。因此,间作体系中蚕豆氮肥的运筹与间作优势的形成密切相关。     

高剂量丙酸锌对蛋鸡换羽和换羽后产蛋性能及鸡蛋品质的影响

将240只66周龄罗曼蛋鸡（平均2.46 kg）随机分成4组,每组3个重复,每重复20只。对照组饲喂基础日粮,试验组日粮在基础日粮基础上分别添加0.5%,1.0%和1.5%丙酸锌,以研究丙酸锌对蛋鸡换羽和产蛋性能及鸡蛋品质的影响。结果表明：0.5%,1.0%和1.5%丙酸锌组,蛋鸡的采食量、体重、腹脂重、卵巢重和黄色卵胞数量显著降低（P〈0.05）;1.0%和1.5%丙酸锌组输卵管重量显著降低（P〈0.05）。丙酸锌的3个处理组蛋鸡血清LH、FSH和E2含量均显著降低（P〈0.05）;1.0%和1.5%的丙酸锌处理组蛋鸡产蛋率显著升高（P〈0.05）,蛋壳相对重、蛋壳厚度均比对照组显著增加（P〈0.05）;蛋重、蛋比重、蛋黄指数、蛋形指数、哈夫单位和蛋白高度差差异均不显著（P〉0.05）。结论：丙酸锌能够引起蛋鸡换羽,提高蛋壳质量。     

苏丹草-黑麦草轮作制中施肥对饲料产量、养分吸收与土壤性质的影响

大田试验条件下采用苏丹草(Sorghum sudanense)与黑麦草(Lolium L.)轮作,分别设CK(不施肥)、NP(施氮磷肥)、NK(施氮钾肥)、PK(施磷钾肥)、NPK(施氮磷钾肥) 5个处理研究施肥对饲草产量、养分吸收及土壤养分的影响。结果表明,氮磷钾肥配施显著提高苏丹草与黑麦草鲜草产量,2005—2006年与2006—2007年两季饲草分别为162.7 t hm^-2、114.9 t hm^-2,分别比同期PK、NK、NP处理增产312.9%、26.9%、17.9%和338.5%、20.3%、17.2%。施肥影响饲草的氮、磷、钾含量,且氮磷钾配施可以改善饲草养分吸收,2005—2006年NPK处理的饲草N、P、K吸收量分别为500 kg hm^-2、91 kg hm^-2和997 kg hm^-2,2006—2007年NPK处理的饲草N、P、K吸收量分别为312 kg hm^-2、56 kg hm^-2和402 kg hm^-2。轮作系统中,氮磷钾肥配施条件下氮、磷盈余最少,而钾亏缺。在苏丹草-黑麦草轮作制中,随着种植次数的增多,各施肥处理土壤有机质、全氮均有不同程度上升,施磷(NPK、NP、PK)处理的速效磷、施钾(NPK、NK、PK)处理的速效钾均有上升,而NK处理的速效磷、NP处理的速效钾略有下降。     

氮肥水平对不同育种时代粳稻产量、氮素吸收利用差异的影响

以选育时期不同(两个选育时代)的12个水稻品种为材料,于施氮量为0,225,300 kg/hm~2纯氮大田条件下,研究了不同氮肥水平下两选育时代的水稻品种产量、物质生产积累量及氮素吸收、利用效率的差异.结果表明,水稻产量随着选育时代的更替有所提高,并随施氮量的增加两时代产量表现不同,早期品种中有83.3%的水稻基因型的产量随施氮量增加呈增加趋势,当代品种产量则有一半基因型在225 kg/hm~2氮肥水平下产量达最大,说明早期品种对氮肥反应较当代品种敏感.农艺性状中的株高和穗长随着育种时代的更替有矮化和减小的趋势,着粒密度有所增加.干物质和氮素平均积累量在生育时期各阶段均表现为当代品种大于早期品种,氮素利用效率亦表现相同的规律.相关分析表明,水稻产量与抽穗、成熟期物质积累量和氮素吸收量均呈显著或极显著正相关关系,与拔节期关系不密切.氮素利用效率与产量呈显著正相关,与株高和穗长呈显著负相关.说明随着选育时代的更替,水稻产量、吸氮量及氮素利用效率有所提高,株型趋于矮化,穗型由散穗向密穗型演变.     

The effect of various nitrogen fertilization and foliar nutrition regimes on the concentrations of nitrates,ammonium ions,dry matter and N-total in carrot (Daucus carota L.) roots

Two field experiments (Experiment I in 2003–2005 and Experiment II in 2004–2005) with carrot c.v. ‘Kazan F₁’ were conducted at Trzciana village (50°06′N, 21°85′E). The experiments were arranged in a split-plot design with four replications. Two sub-blocks were identified in both experiments: I, without foliar nutrition; II, receiving plant foliar nutrition. The plants were sprayed three times alternately with: 2% urea solution, 1% solution of multi-component ‘Supervit R’ fertilizer (produced by Intermag, Poland) and again with 2% urea solution. Combinations with diversified nitrogen fertilization were distinguished within both sub-blocks. Experiment I comprised of: (1) Control, (2) Ca(NO₃)₂ 70, (3) Ca(NO₃)₂ 70 + 70, (4) (NH₄)₂SO₄ 70 and (5) (NH₄)₂SO₄ 70 + 70. Experiment II included: (1) Control, (2) ENTEC-26 35 + 35, (3) ENTEC-26 70 + 70, (4) ENTEC 26 105 + 105, (5) NH₄NO₃ 35 + 35, (6) NH₄NO₃ 70 + 70, (7) NH₄NO₃ 105 + 105. Where 70 kg N ha⁻¹ was used before sowing, whereas 35 + 35, 70 + 70 and 105 + 105 kg N ha⁻¹ were applied before sowing and as top dressing. Solid nitrogen fertilizer was added to the soil (produced by): Ca(NO₃)₂, Yara International ASA (Hydro); (NH₄)₂SO₄, Zak?ady Azotowe in Tarnów, Poland; NH₄NO₃, Zak?ady Azotowe in Pu?awy, Poland; and ENTEC-26, COMPO GmbH & Co. KG, Germany. The research aimed at determining the effect of diversified nitrogen fertilization and foliar nutrition on NO₃⁻, NH₄⁺, N-total and dry matter (d.m.) concentrations in carrot, and N uptake by storage roots. In Experiment I, nitrogen fertilization did not affect NO₃⁻ concentration, whereas in Experiment II, the applied N treatment increased NO₃⁻ concentration in carrot in relation to the control, except for the storage roots of plants fertilized with ENTEC-26 35 + 35. Nitrogen fertilization applied in both experiments caused a significant increase in N-total concentration in carrot and N uptake by storage roots in comparison with the control plants. In both experiments, nitrogen fertilization had a different effect on the concentrations of NH₄⁺ and d.m. in carrot. What is more, foliar nutrition treatments in both experiments had a different effect on the concentrations on NO₃⁻, N-total, d.m. in carrot and N uptake by carrot storage roots.     

Contamination of shallow groundwater system and soil-plant transfer of trace metals under amended irrigated fields

This study focuses on experimental pilot assessment of contamination of shallow groundwater systems and soil-plant transfer of trace metals under amended irrigated fields. The study approach involved a pilot experimental (greenhouse) set-up of organo-mineral amended test plots/troughs (40 cm × 47 cm × 46 cm) planted with two common vegetable crops (Amaranthus hybridus and Abelmoschus esculentus) and irrigated with wastewater. In addition to the geochemical analyses of the primary un-amended and amended soils before planting as well as residual soils after harvesting, measurements of the physico-chemical parameters and chemical analyses of trace metals concentrations in irrigation leachates and harvested vegetable tissues were also undertaken following appropriate standard sample preparation and analytical methods.The results of the geochemical analyses carried out on irrigation leachate samples collected during the sprouting stage revealed that most of the analyzed trace metals in the collected leachates exhibited 2-10 folds depletion (except for Cu and Co with enrichment of about 1.5-3 folds) compared to the initial wastewater used for irrigation. A situation attributed to uptake/bioaccumulation of these metals and selective enrichment in the residual soils as well as to leaching by infiltrating irrigation water. Nonetheless, the observed higher trace elements concentrations in the second sets of leachates collected during harvesting stage compared to the first sets of leachates collected during the sprouting/vegetative stage is an indication of higher plant uptake during sprouting/vegetative stage or initial sorption/complexation of biosolids amendment before later vertical re-mobilization by infiltrating irrigation water.Although, virtually all of the analyzed metals exhibited elevated concentrations (2-173 ppm) in both A. hybridus and A. esculentus, a closer evaluation revealed 1.2-8.2 folds enrichment of Cr, Co, Ni, Cd, Cu, and Pb in A. esculentus compared to that of A. hybridus, an indication of the fact that phyto-accumulation of trace metal is plant-specific and dependent on physiological set-up. The overall evaluation had clearly demonstrated the potential danger of bioaccumulation of toxic trace metals under biosolid amended soils as well as impacts of irrigation-induced leaching on the shallow groundwater quality, while the need to evolve a sustainable agricultural practices is also highlighted.

Capsule

Organo-mineral amendment can lead to trace metal bioaccumulation (in plants) and irrigation-induced leaching to shallow groundwater system.