几种蔬菜对硝态氮、铵态氮的相对吸收能力

采用溶液培养方法探讨了莴笋、菠菜、小白菜和大青菜 4种蔬菜作物对硝、铵态氮的相对吸收能力以及这两种氮源对它们生长发育的影响。结果表明 ,单独供给NO3-N ,4种作物均生长发育良好 ;供给NO3--N +NH4+-N(NO3-∶NH4+=1∶1) ,生长量均有所下降 ,而单独供给NH4+-N时 ,生长量则大幅度下降。莴笋单独供给NO3--N时 ,其吸氮量显著高于供给NO3--N +NH4+-N的处理 ,大青菜、菠菜供给NO3--N +NH4+-N与单独供给NO3--N相比吸氮量大体相当 ;小白菜同时供应NO3--N +NH4+N时吸氮量最高 ,供给NO3--N时次之 ,供给NH4+-N时显著降低。供给NH4+-N时 4种作物吸氮量均比其它氮源显著降低。 4种作物对NO3--N与NH4+-N的吸收具有明显的偏向性。供给等氮量铵、硝态氮 (NO3--N +NH4+-N处理 )时 ,菠菜、小白菜吸收的NO3-N显著多于NH4+-N ,表现出喜硝性 ,莴笋则与此相反 ,表现出喜铵性 ;而大青菜对两种形态氮素的吸收量相差不多 ,表现出兼性吸收的特点。但上述偏向性具有阶段特点 ,即喜硝作物可能在某一阶段表现出喜铵性状     

铵态氮/硝态氮对水稻铝吸收的影响及其机制研究

选用两个水稻品种武运粳7号（耐铝品种）和扬稻6号（铝敏感品种）作为实验材料,利用水培试验,通过长期和短期处理相结合的方式研究了NH4+-N和NO3--N对水稻Al吸收的影响及其作用机制。结果表明,与NH4+-N相比,NO3--N促进了水稻对Al的吸收。而且随着NO3--N浓度的提高,水稻根中Al含量显著增加,随着NH4+-N浓度的提高,水稻根中Al含量显著降低。这些结果表明NH4+-N和NO3--N对水稻Al吸收的影响具有浓度效应。当向Al溶液添加pH缓冲剂后,NH4+-N和NO3--N对根尖Al累积的影响变小,表明NH4+-N和NO3--N处理下溶液pH的变化可能是NH4+-N和NO3--N对水稻Al吸收影响不同的一个原因。     

铵、硝营养对水稻叶细胞膜H+-ATPase和质子泵活性的影响

用两相法分离铵态氮(NH4+-N)和硝态氮(NO3--N)培养的水稻苗期叶细胞膜,并测定了细胞膜H+-ATPase水解活性和质子泵活性,以期阐明铵、硝营养对水稻叶细胞膜H+-ATPase的影响。结果表明,叶细胞膜H+-ATPase活性最佳pH值均为6.2。 NO3--N培养的水稻叶细胞膜H+-ATPase的水解活性、Vmax和Km均显著高于NH4+-N培养的水稻叶;Western Blot分析结果看出,NO3--N培养的水稻叶细胞膜H+-ATPase酶浓度也高于NH4+-N培养的水稻叶,说明NO3--N培养的水稻叶中单位细胞膜上的H+-ATPase酶分子数量大于NH4+- N培养的水稻叶,这与细胞膜上H+-ATPase蛋白的表达量升高有关。此外,NO3--N培养的水稻叶质子泵初速度和膜囊体内外H+浓度梯度均高于NH4+- N培养。由于NO3-的跨膜运输是与细胞膜上H+-ATPase紧密联系的主动运输过程,NO3--N培养的水稻叶片细胞膜H+-ATPase活性和质子泵活性高可能与水稻叶细胞吸收大量NO3-有关。     

尿素涂层对土壤渗出液NO_3~--N和NH_4~+-N的影响

采用盆栽试验方法,研究尿素涂层后施用于水田土壤其渗出液NO3--N和NH4+-N含量的变化情况。研究结果表明:与未涂层尿素相比,施用尿素涂层可使氮素释放变得平缓,土壤渗出液中NH4+-N和NO3--N浓度明显降低,有利于水稻生长对氮素的吸收利用;在等氮量条件下,施用涂层尿素处理的土壤渗出液中的NH4+-N浓度明显低于未涂层尿素处理,且尿素用量越低这一差异越明显,而土壤渗出液中的NO3--N浓度施入土壤后前10天涂层尿素低于未涂层尿素处理,而至第18天则表现出高于未涂层尿素处理的趋势;涂层处理土壤渗出液NO3--N和NH4+-N之和大都小于未涂层处理。     

潜流人工湿地中3种基质对氮磷净化的影响

通过潜流人工湿地装置,采用间歇运行方式考察不同停留时间下土壤、砾石、炉渣基质在以NO3--N、NH4+-N和PO4--P为主要氮组分的模拟污水对污水中氮的净化效能,并研究湿地系统基质与pH变化、NO3--N和NH4+-N净化效率的关系。结果表明,当水力停留时间为10d时,土壤-炉渣湿地的N,P净化效能高于以其他基质构建的湿地。在试验周期内,各基质的人工湿地系统NH4+-N的净化效率均高于NO3--N的净化效率,氮素的净化效能上层大于下层,湿地系统中pH值先降低后升高的拐点可作为NH4+-N氧化反应结束的指示参数。     

水分及铵、硝营养对水稻幼苗氮素吸收的影响

采用5% PEG模拟水分胁迫,研究武育粳3号水稻幼苗生长状况以及在水分胁迫下对不同NH4+-N / NO3--N质量比例（100/0、75/25、50/50、25/75、0/100）处理的响应。结果表明,模拟水分胁迫后水稻幼苗生长对不同的NH4+-N/NO3--N处理反应不同,水稻对NH4+-N和NO3--N的吸收发生显著改变,水稻幼苗更偏向于吸收NO3--N营养,与正常水分处理相比其对总氮和NO3--N的吸收量显著增加。     

不同外源氮对石灰性土壤硝化作用的影响及其动力学分析

为了揭示外源氮源对石灰性土壤硝化作用的影响机理,以钙积半干润均腐土（Cal-Ustic Isohumasols）为材料,采用室内培养方法研究了不同添加量和不同氮源对土壤硝化作用的影响,并建立了对应的硝化模型。结果表明,NH4+-N消耗速率和NO3--N增加速率呈S曲线变化,NH4+-N消耗速率高于NO3--N增加速率。氮素添加量与NH4+-N消耗速率和NO3--N增加速率呈正相关,硝化菌外的因子对NH4+-N和NO3--N的吸收与NH4+-N添加量呈正相关;不同氮素添加量对硝化作用影响程度不同,当氮素添加量为N 75 mg /kg,干土时,硝化作用较彻底。SO42-可加快硝化作用速率,同时也可改变其他因子对NH4+-N和NO3--N的利用。     

不同水、氮条件对水稻苗生长及伤流液的影响

为探明不同水分供应和氮素形态对水稻根苗及伤流液的影响,设正常水分及50 g/L PEG模拟水分胁迫和3种不同质量比例的NH4+-N/NO3--N（9/1,5/5,1/9）氮素营养处理,测定了水稻幼苗生物量,根系形态指标,根系活力及根基伤流量。结果表明,正常水分条件下,NH4+-N促进水稻根系平均直径增大,有利于水稻地上部物质累积;NO3--N则使水稻根系总吸收面积增大,促进根系物质累积;NH4+-N/NO3--N为5/5处理的水稻活跃吸收面积最大,活跃吸收面积比亦最高。水分胁迫条件下,NH4+-N/NO3--N为5/5的处理更有利于水稻地上部分的生长,NO3--N有利于水稻鲜重和干重增加,促进根系平均直径增大,水稻的根系总吸收面积、活跃吸收面积均随NO3--N供应比例的增加呈上升趋势。正常水分条件下,水稻幼苗白天的耗水量随NH4+-N/ NO3--N比例降低呈下降趋势,水分胁迫条件降低了水稻对水分的吸收。水分胁迫显著降低各处理水稻伤流量,正常水分条件下,NH4+-N/NO3--N为5/5处理的水稻伤流量最大;水分胁迫后,9/1处理的水稻伤流量相对较多。     

局部根系干旱条件下分蘖期水稻对供氮形态的生物学响应

采用室内分根营养液培养及PEG模拟水分胁迫的方法,研究不同氮素形态(NH4 -N、NO3--N、NH4 -N/NO3--N比为50/50)对水稻局部根系遭遇水分胁迫后的生物学响应状况。结果表明,在非水分胁迫的条件下,供应NO3--N营养相对促进分蘖期水稻的根系发育,而供应NH4 -N营养相对促进分蘖期水稻的地上部发育;在局部根系受到水分胁迫的条件下,NH4 -N和NO3--N混合营养水稻生物量增量分别比全NO3--N和全NH4 -N营养水稻高31.7%和37.7%,其中地上部生物量增量也分别比全NO3--N和全NH4 -N营养水稻高33.5%和33.2%。全NO3--N营养水稻未受水分胁迫一侧根系生物量的增量明显高于另一侧受水分胁迫的根系生物量的增量,且明显高于两侧根系均未受水分胁迫的相同供氮形态营养的水稻单侧根系生物量的增量;而全NH4 -N以及NH4 -N和NO3--N混合营养水稻未受水分胁迫一侧根系和受水分胁迫的根系生物量增量之间没有明显差异,但均高于两侧根系均未受水分胁迫的相同供氮形态营养的水稻,为NH4 -N营养提高水稻抗旱能力提供了证据。     

钼对冬小麦硝态氮代谢的影响

采用全硝态氮霍格兰营养液为培养基质,在供应0(缺钼)、0.78(适钼)、2.74mol/L(高钼)3种钼浓度下培养小麦.,分期测定其体内ＮＯ3--Ｎ、NH4+-N、全Ｎ、吸氮量及硝酸还原酶活性.(ＮＲＡ).,研究钼对小麦ＮＯ3--Ｎ代谢的影响。结果表明.,ＮＲＡ受硝酸盐代谢库和贮存库之间的调节而不断变化.,但任何情况下钼对ＮＲＡ都有明显影响。培养初期适钼处理ＮＲＡ最高.,高钼次之.,缺钼最低.;培养后期由于缺钼处理的NO3--N浓度高于施钼处理.,ＮＲＡ随之增至最高。植株内NH4+-N、ＮＯ3--Ｎ浓度之和在不同测定时间大致稳定.,ＮＯ3--Ｎ浓度高时则NH4+-N浓度低.,反之亦然.,两者之间存在一定的负相关关系。稳定情况与钼供应有关.,适钼条件下培养开始时高的NH4+-N与低的ＮＯ3--Ｎ浓度明显对应.,之后两者浓度接近.;缺钼条件下与此类似.,但NO3--N浓度变化不大.,NH4+-N、ＮＯ3--Ｎ浓度之和最高.;高钼条件下NH4+-N浓度一直高于NO3--N。作物由溶液吸收的NO3--N与作物的吸氮量一致.,适钼时最多.,高钼次之.,缺钼最少。从适钼时作物体内NH4+-N、ＮＯ3--Ｎ浓度之和最低.,而吸氮量又最高可以看出.,合适的钼供应不但有利于NO3--N的吸收和向NH4+-N转化.,也有利NH4+-N向有机氮转     

作物产量差研究与展望

作物实际产量与潜在产量间存在较大差距,地区间甚至同一地区不同田块间作物产量也存在显著差异,这种现象在世界范围内的农业生产中广泛存在.缩小该差距对于提高粮食产量,确保粮食安全具有重要意义.本文在阐述开展作物产量差研究重要性和必要性的基础上,从产量差的内涵、研究尺度的扩展及分析方法等方面介绍了目前国内外有关作物产量差的研究进展,并综述了作物生长模拟模型在产量差研究中的应用,最后分析了目前作物产量差研究中存在的问题和不足之处,并探讨了未来作物产量差研究的发展方向.     

UV-B辐射的增强对作物形态及生理功能的影响

通过综述UV-B辐射增强对作物产生的影响,为进一步揭示作物对UV-B辐射增强的响应机制、适应变化和寻找相应的解决方法提供参考.分析发现UV-B辐射增强能对作物的形态在根、茎、叶营养器官和生殖器官方面产生负面影响,从而进一步影响作物的生物量和产量;UV-B辐射增强对植物生理的影响主要通过影响作物的叶绿体、光合作用及矿质代谢而起作用,并且这些影响具有品种间和生育期的差异.因此研究紫外辐射对作物的影响具有重要的生态学意义.     

作物水分生产函数研究进展

作物水分生产函数(cropwaterproductionfunctions,CWPF)一般指作物产量(cropyield,Y)与蒸散发(evapotranspiration, ET)之间的函数关系,是作物模型中联系水分和生产力的关键。本文系统地梳理了近半个世纪以来CWPF的相关研究,发现CWPF受多种因素影响,不同地区获得的田间试验结果往往差异较大;常用的CWPF模型多是基于统计信息,缺少坚实的物理基础和可靠的理论支撑,在跨地区、跨物种应用时存在一定缺点。同时基于碳同化过程的机制模型和更为复杂的作物模型也因为参数过多而不易在实际中应用。在以往研究的基础上,从公开发表的41篇文献中筛选出592组田间试验数据,发现小麦产量与ET基本呈线性关系,但数据分布相对离散,而玉米、棉花、水稻因数据量较少其产量与ET关系不明显。利用生长季降水量和累计蒸发皿蒸发数据对不同地区获得的小麦水分生产函数进行了修正,发现改进后的小麦水分生产函数表现出较好的跨地区应用潜力(r2从0.36提高到0.75),并提出了进一步的CWPF修正思路。指出通过改进函数关系虽然能提高统计模型的可移植性,但发展机制模型仍是未来CWPF研究的根本出路。     

全球变暖影响下农作物气候适宜性研究进展

简介了近年来国内外有关全球气候变暖对农作物气候适宜性影响的研究方法和基本观点 ,对动态模拟和控制试验所得结论给予评述 ,并针对目前气候影响评价与预测存在的主要问题提出今后研究重点。     

农业生物质热裂解实验研究

研究了温度和加热速率等因素对玉米秆、棉柴、麦秸和稻草等农业生物质热裂解过程中产品得率的影响。实验结果表明,适宜的热解温度为500～600℃,原料滞留时间以6～8min为宜,可燃气、生物炭和木焦油等三种热解产品的得率(wt％)分别为40.2％、34.7％和25.1％;产品成份和有关指标的测试结果表明,燃气的热值为12.88MJ/m³,生物炭的热值为25MJ/kg,冷凝木焦油中的有机组份主要包括甲醇、糠醛、苯酚、邻甲酚、甲苯和醋酸等。     

云南玉米需水规律及灌溉效应的试验研究

基于玉米苗期控水试验和玉米需水量田间试验，分析研究了土壤含水量和灌溉对出苗率、成活率、有效株数和玉米产量经济性状的影响，得到了云南玉米生长季内各月平均日需水量和玉米作物系数。研究认为，苗期灌溉或降水条件好能确保基本的有效株数，促进营养生长；在光照条件好但干旱缺水年份，灌溉的增产效益十分突出；但在干旱缺水影响较小的条件下，玉米灌溉的增产效益并不显著。     

Effects of tillage systems and rotations on crop production for a thin Black Chernozem in the Canadian Prairies

Soil degradation is the single most important threat to global food production and security. Wind and water erosion are the main forms of this degradation, and conservation tillage represents an effective method for controlling this problem. The objective of this study was to quantify the effects of three tillage methods [zero (ZT), minimum (MT) and conventional (CT)] and three four-year crop sequences [spring wheat (Triticum aestivum L.)–spring wheat–winter wheat–fallow; spring wheat–spring wheat–flax (Linum usitatissimum L.)–winter wheat; spring wheat–flax–winter wheat–field pea (Pisum sativum L.] on crop establishment, plant height, seed weight, soil water storage, crop water use, crop water use efficiency and grain yield over a 12-year period under Canadian growing conditions. Plant establishment was not adversely affected by tillage systems or crop sequences except for flax, where a small reduction was observed with ZT and MT. Conservation tillage showed a yield benefit over CT of 7%, 12.5% and 7.4% for field pea, flax and spring wheat grown on cereal stubble, respectively over the 12 years of the study. Much of the yield increase was due to an increase in soil water in the 0–30 cm soil layer with ZT and MT. However, tillage systems had no effect on grain yield for spring wheat grown on fallow and field pea stubble due to a lack of differences in spring soil water content. Flax grown in sequence with cereals only yielded higher than when it was grown in the sequence which included field pea, even though flax was seeded on spring wheat stubble in both cases. Winter wheat yielded higher when grown on flax stubble than on spring wheat stubble. The results indicate that a one-year non-cereal break crop was enough to alleviate the negative effects of consecutive cereal crops on winter wheat. Spring wheat grown on field pea stubble always yielded more than when grown on cereal stubble. A 10% increase in water use efficiency was observed with flax grown with ZT and MT management. Crop sequence improved water use efficiency in flax and spring wheat. Growing spring wheat on field pea stubble as opposed to growing it on cereal stubble resulted in a 10% increase in water use efficiency. Overall, rainfall accounted for 73%, 72%, 67% and 65% of total water used by field pea, flax, winter wheat and spring wheat, respectively. This explains the large year effect as a result of variation in growing (May–August) season precipitation. The non-significant tillage system by year interaction implies that the positive benefits of ZT and MT occur over a wide range of growing conditions, while the absence of a tillage system by crop sequence interaction suggests that knowledge developed under CT management also applies to ZT and MT. The results of this study support the large shifts towards in conservation tillage being observed in the Canadian prairies.     

鲁北地区地膜覆盖对棉花需水量、作物系数及水分利用效率的影响

作物系数和需水量是制定作物灌溉制度和计算区域水资源平衡的重要参数,不同气候和不同栽培条件下作物系数和需水量会发生变化。本文通过大田试验,以水量平衡法计算作物需水量、以Penman-Monteith公式计算参照作物蒸散量和作物系数。结果表明,鲁北地区棉花地膜覆盖栽培比露地栽培生育期内作物需水量减少101.5mm,作物系数降低17.6%,水分利用效率增加29.3%。     

A comparison of operational remote sensing-based models for estimating crop evapotranspiration

The integration of remotely sensed data into models of evapotranspiration (ET) facilitates the estimation of water consumption across agricultural regions. To estimate regional ET, two basic types of remote sensing approaches have been successfully applied. The first approach computes a surface energy balance using the radiometric surface temperature for estimating the sensible heat flux (H), and obtaining ET as a residual of the energy balance. This paper compares the performance of three different surface energy balance algorithms: an empirical one-source energy balance model; a one-source model calibrated using inverse modeling of ET extremes (namely ET = 0 and ET at potential) which are assumed to exist within the satellite scene; and a two-source (soil + vegetation) energy balance model. The second approach uses vegetation indices derived from canopy reflectance data to estimate basal crop coefficients that can be used to convert reference ET to actual crop ET. This approach requires local meteorological and soil data to maintain a water balance in the root zone of the crop. Output from these models was compared to sensible and latent heat fluxes measured during the soil moisture–atmosphere coupling experiment (SMACEX) conducted over rain-fed corn and soybean crops in central Iowa. The root mean square differences (RMSD) of the estimation of instantaneous latent and heat fluxes were less than 50 W m⁻² for the three energy balance models. The two-source energy balance model gave the lowest RMSD (30 W m⁻²) and highest r² values in comparison with measured fluxes. In addition, three schemes were applied for upscaling instantaneous flux estimates from the energy balance models (at the time of satellite overpass) to daily integrated ET, including conservation of evaporative fraction and fraction of reference ET. For all energy balance models, an adjusted evaporative fraction approach produced the lowest RMSDs in daily ET of 0.4–0.6 mm d⁻¹. The reflectance-based crop coefficient model yielded RMSD values of 0.4 mm d⁻¹, but tended to significantly overestimate ET from corn during a prolonged drydown period. Crop stress can be directly detected using radiometric surface temperature, but ET modeling approaches-based solely on vegetation indices will not be sensitive to stress until there is actual reduction in biomass or changes in canopy geometry.     

Whole Forage Barley Crop Quality as Affected by Different Deficit Irrigation and Fertilizing Systems

Effects of organic, biological, and chemical fertilizers along with water-deficit regimes were investigated on forage barley in a field experiment during 2007–2008. Irrigation regimes were nonstressed (NS), moderately stressed (MS), and severely stressed (SS) and fertilizer treatments were no fertilizer (NF), phosphorus and nitrogen biofertilizers (BF), chemical fertilizer (CF), vermicompost (VC), chemical fertilizer + vermicompost (CV), and chemical fertilizer + biofertilizer (CB). Water stress reduced leaf/stem ratio and dry-matter digestibility (DMD), but increased crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF). However, the effect of water deficit on DMD, ash, and NDF depended on the fertilizer treatment. In BF and CV, the barley forage had the greatest DMD and least ash and NDF under water-deficit conditions. The integrated fertilizing systems are more reliable than conventional systems to produce high-quality forage barley in arid environments with late water stress or water deficit irrigation system.