行距配置方式对夏玉米氮素吸收利用及产量的影响

为确定黄淮南部夏玉米产区机械化生产适宜的行距配置方式,2012—2013年同时在河南省方城县和辉县两个试验点设置大田试验,以高、中、低3种株高类型的玉米杂交种‘先玉335’、‘郑单958’和‘512-4’为材料,设置2个种植密度(低:60 000株·hm~(-2);高:75 000株·hm~(-2))、5个行距配置方式(50 cm、60 cm、70 cm、80cm等行距和80 cm+40 cm宽窄行距),研究了不同株型玉米品种在不同密度和行距配置条件下对氮素吸收利用效率和产量的影响。结果显示,低密度种植条件下,高秆的‘XY335’和矮秆的‘512-4’均以60 cm等行距处理产量优势明显;中秆的‘ZD958’在辉县和方城分别以60 cm和70 cm等行距产量最高。在高密度种植条件下,高秆的‘XY335’和中秆的‘ZD958’均以60 cm等行距处理产量最高;而矮秆的‘512-4’则以50 cm等行距种植产量优势明显,但与60 cm等行距处理差异不显著。植株氮积累量随行距的扩大呈先升高后降低的趋势,以60 cm等行距的氮积累量较大,低密度时显著高于80 cm等行距和80 cm+40 cm宽窄行距处理,而高密度下与各行距处理差异不显著;不同品种植株氮积累量对行距反应不同,高秆品种在行距间差异不显著,中秆品种80 cm等行距最低且与其余行距处理差异显著,矮秆品种50 cm和60 cm等行距氮积累量最高且与其余行距差异显著。两个密度种植条件下,籽粒氮积累量和氮素收获指数均随行距的扩大先升高后降低,在60 cm等行距处理达到最大值,并且均显著高于其他行距处理;氮肥偏生产力随行距的扩大呈现先升高后降低的趋势,60 cm等行距处理较高,但在低密度下与其他行距处理差异不显著,高密度时与80 cm等行距处理差异显著。与其他行距处理相比,60 cm等行距处理具有相对较高的氮素吸收利用效率和产量,能够较好地协调玉米土壤与植株的氮素吸收利用关系,兼顾不同株高类型玉米品种在一定密度范围内获得高产,可作为目前黄淮南部地区夏玉米统一的行距配置方式进行推广。     

生物降解膜促进冬油菜养分吸收减少土壤硝态氮累积

针对普通地膜覆盖导致的农田环境污染和土地退化问题,通过2 a田间试验,从土壤有机质含量、硝态氮累积与分布、作物养分吸收和籽粒产量等层面出发,进行了普通地膜覆盖(PM)、生物降解地膜覆盖(JM)和露地(CK)栽培冬油菜的对比研究。结果表明,播种后60和150 d,JM处理的土壤有机质含量、土壤硝态氮的累积和分布与PM处理无显著差异;播种后240 d,JM处理的土壤有机质含量显著大于PM处理,土壤硝态氮的累积量显著小于PM处理,且PM处理土壤硝态氮的淋洗下移峰值更大。PM和JM处理冬油菜的产量及地上部各器官的氮、磷、钾吸收量均显著大于CK,且PM和JM无显著差异。与PM处理相比,JM处理在播种后240 d时土壤有机质质量分数提高7.0%,土壤硝态氮累积量减少34.1%。可见,PM处理在冬油菜生育后期过分消耗地力,且残留在土壤中的硝态氮含量较高。该研究从土壤营养和作物养分吸收利用方面为生物降解地膜应用于农业生产的可行性提供了理论依据。     

氮肥品种和用量对水稻产量和镉吸收的影响研究

采用盆栽试验,研究了Cd污染土壤上,不同氮肥品种和用量对水稻产量和Cd吸收的影响。结果表明,与磷钾配施的4个氮肥处理中,施用尿素处理水稻产量最高,其次为施(NH4)2SO4和NH4Cl处理,施NH4NO3处理水稻产量最低。与施(NH4)2SO4、NH4NO3和尿素处理相比,施NH4Cl处理可显著增加水稻对Cd的吸收,并促进Cd由秸秆向籽粒的转移;而其他3种氮肥对水稻秸秆和籽粒中Cd含量的影响效应相当。适量尿素[0.2g(N)·kg-1]处理能显著降低水稻籽粒Cd含量,而不施尿素和高量尿素处理都显著提高了水稻籽粒中的Cd含量。研究表明,在Cd污染的水稻土上,采用抗Cd污染的水稻品种和优化肥、水管理措施,可使稻米中Cd含量低于国家无公害大米的限量指标。     

不同施氮量对水稻氮素吸收与分配的影响

运用15N示踪法研究了不同施氮量对两个品种水稻（4007和武运粳15）干物质积累量与其对15N吸收及分配的影响。结果表明,当施氮量超过N 150 kg/hm2时, 两个品种水稻子粒产量均不再显著增加。4007在4个施氮量下(N 100,150,200和 250 kg/hm2)分别比无氮区增产22.3%,36.9%,43.2%和38.1%;武运粳15分别增产10.6%,18.8%,27.1%和21.5%。同一施氮量下,4007子粒中15N累积量显著高于武运粳15,但茎叶和根中没有差异。增加施氮量降低了15N在水稻子粒中的分配比例,但提高了茎叶中15N的分配比例。15N在根中的分配比例不受施氮量和品种的影响。研究结果还表明,同一施氮量下,4007对肥料氮的总体利用率要比武运粳15高3～6个百分点。     

Acidulated activation of phosphate rock enhances release,lateral transport and uptake of phosphorus and trace metals upon direct-soil application

Phosphate rock (PR) was activated via acidulation with HCl, EDTA, and oxalic acid to enhance its reactivity. The release, lateral transport, and uptake of phosphorus (P) along with trace metals from pristine and activated PRs were investigated in a soil micro-block system over a period of 27 days, using wheat (Triticum aestivum L.) plants. Significantly (p < 0.05) higher amounts of available soil P, Fe, Mn, and Zn were released from all the PRs after application to soil within first 9 days of seedling transplantation, while the release of other trace metals (Cd, Co, Cr, Cu, Ni, and Pb) was minimal (<1.2 mg kg^?1). On cumulative basis, APR-O (oxalic acid activated PR) was the most efficient amendment releasing 164% more available P, followed by APR-E (EDTA activated PR) releasing 130% more available P, compared to the pristine PR. Similar results were also observed in the release of available Fe, Mn, Zn, and other trace metals. The highest diffusive mass fluxes for available P, Mn, Fe, and Zn in soil were observed after 3 days of seedling transplantation, which reduced subsequently. The uptake of P, Fe, Mn, and Zn by wheat plants was increased by 394%, 715%, 92%, and 91%, respectively, in APR-O application compared to the pristine PR, while it was increased by 280%, 188%, 16%, and 27%, respectively, in APR-E application compared to the pristine PR. Subsequently, APR-O and APR-E amendments resulted in enhanced shoot lengths, root lengths, shoot dry matter, and root dry matter contents of wheat plants. Hence, it was concluded that activation of PR with oxalic acid and EDTA prior to direct soil application may enhance the reactivity of PR and could serve as a cost-effect fertilization strategy for higher wheat crop production.     

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。     

外源调节物质对盐胁迫下植物生长调控研究进展

为了探究外源物质对植物耐盐性的调控机理及进一步利用外源调节物质提高作物耐盐性,归纳了五大类传统植物激素（生长素、赤霉素、乙烯、脱落酸、细胞分裂素）以及褪黑素、水杨酸、多胺、油菜素类固醇、茉莉酸类等外源生长调节物质对盐胁迫下植物生长的调控情况。同时总结了硅、钙等离子类外源调节物对盐胁迫下植物生长的调节作用,多种外源调节物质可通过增强光合作用、提高渗透势、增加抗氧化酶活性及减少离子毒害等方式来减轻盐害。本文为进一步利用单一或复合外源调节物质来缓解作物盐害盐提供理论依据。     

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。     

生物柴油Fe_2(SO_4)_3—Al_2O_3固体酸催化剂的制备

为了解决硫酸铁催化制备生物柴油过程中存在的回收难和部分溶于水等问题,制备了Fe2(SO4)3—Al2O3负载型固体酸催化剂。考察了负载量、焙烤温度、焙烤时间对催化剂活性的影响。结果表明,负载量20%的催化剂在300℃下,焙烤超过4h,活性最高,延长焙烤时间对催化剂活性没有显著影响。对不同焙烤温度下的催化剂进行了扫描电镜、能谱和X射线衍射分析,结果显示300℃下,焙烤的催化剂具有最小的晶粒;超过300℃,催化剂上的Fe2(SO4)3组分开始分解。