大气CO2浓度升高对矿质元素在水稻中分配及其根际有效性的影响

在开放式空气CO_2浓度升高(free-air CO_2 enrichment, FACE)条件下,研究了籼稻IIY084与粳稻WYJ23根际土壤矿质元素(Fe、Mn、Cu、Zn、Ca和Mg)有效态含量及其在水稻各组织中的吸收与分配,结合前期稻米矿质元素含量下降的研究结果,探讨了其下降的机制。结果表明:大气CO_2浓度升高,显著增加水稻穗、茎、根和整株生物量,两个品种平均增加19.4%、9.3%、23.4%、16.0%;根际土壤中矿质元素的有效态含量大体呈增加趋势;除Ca吸收量增加外,水稻其他矿质元素总吸收量未发生显著变化;显著促进大部分矿质元素在穗中的吸收与分配,而降低其在茎中的分配比;在穗内有增加大部分矿质元素在壳梗中滞留的趋势,相应地减少其在糙米中的分配比。品种效应分析显示,IIY084的茎和整株生物量,以及穗中Fe、Mn、Cu,叶中Zn、Mg,茎中Cu的吸收量与分配百分数均显著高于WYJ23,而叶中Mn、茎中Fe和根中Cu、Zn则呈相反趋势。可见,大气CO_2浓度升高条件下,碳水化合物与矿质元素从植株营养器官到籽粒的不平衡转运以及在壳梗中的滞留可能是导致两水稻品种糙米中矿质元素含量降低的重要原因。     

大气CO2浓度升高与氮肥互作对玉米光合特性及产量的影响

为阐明大气CO_2浓度升高和氮肥交互作用对C4作物玉米光合生理和产量的影响,本研究利用自由大气CO_2富集(FACE)平台,以玉米品种‘郑单958’为试验材料,在不同施氮量[常氮180kg(N)×hm~(-2)、低氮72kg(N)×hm-2]下比较大气CO_2浓度[(400±15)μmol×mol-1]和高CO_2浓度[(550±15)μmol×mol-1]对玉米生长的影响。结果表明:1)大气CO_2浓度升高使玉米苗期叶片叶绿素浓度显著(P=0.025)增加9.5%,抽雄期净光合速率显著(P=0.009)增加9.0%;低氮和常氮下,高CO_2浓度使玉米各主要生育期胞间CO_2浓度分别显著增加34.8%～48.5%和40.0%～49.4%,气孔导度在大口期和抽雄期分别显著下降21.6%(P=0.015)和22.1%(P=0.010),玉米叶片水分利用效率在大口期、抽雄期和灌浆期分别显著增加12.9%(P=0.002)、 9.8%(P=0.019)和18.8%(P=0.001);高CO_2浓度使玉米非光化学淬灭呈降低趋势、PSII有效光化学量子产量有增加趋势;相同氮水平下,高CO_2浓度对玉米产量没有显著影响。2)高CO_2浓度和合理施氮交互作用对玉米功能叶叶绿素含量、净光合速率、PSⅡ有效光化学量子产量增加有一定的促进作用,如在大口期和抽雄期,常氮+高CO_2浓度处理叶绿素含量比低氮+大气CO_2浓度处理增加17.3%和10.7%,高CO_2浓度和合理施氮量交互作用有增加玉米产量的潜力,合理增加施氮量促进了CO_2肥效的发挥。在未来大气CO_2浓度升高条件下合理施氮对C4作物玉米生长发育有促进作用。     

CO2浓度升高和氮素供应对黄瓜叶片光合色素的影响

本文通过N供应浓度[2(低N),7(中N)和14(高N)mmol/L]和CO_2浓度[400(C1),625(C2),1 200(C4)μmol/mol]处理的水培试验一,以及硝铵比[14/0(N1),13/1(N2),11/3(N3)和8/6(N4)]和CO_2浓度[400(C1),800(C3),1 200(C4)μmol/mol]处理的水培试验二,共同研究黄瓜叶片光合色素对CO_2升高、N供应浓度和形态的响应。研究结果表明:苗期时,低、中和高N下,C4处理使得植物干物质都明显增加;而初果期干物质提高程度下降,植株生长速率降低。中等CO_2浓度(C3)显著增加植物在各硝铵比处理的干物质量,但最高CO_2浓度(C4)有提高N3处理的干物质量的趋势。苗期时,在低N和中N供应时C4处理显著降低叶片叶绿素a、叶绿素b和胡萝卜素含量;但高N时,C3处理提高总色素含量,C4处理提高叶绿素b含量;初果期时CO_2浓度处理对色素含量无显著影响;N2硝铵比处理,中等CO_2浓度(C3)下叶片的3种色素含量最高。因此当苗期N素供应浓度较低时,CO_2浓度升高会显著降低叶片3种色素的含量,这主要可能与苗期植物生长速率显著提高产生的稀释作用有关。当N浓度为14 mmol/L时,CO_2浓度适当提高显著促进色素合成,其合成速率大于植物生长速率,导致色素含量提高,提高光合能力;初果期时,CO_2浓度升高的促进作用降低缓和了色素浓度的下降。适当提高NH4+-N供应比例也能达到提高色素含量的效果,但CO_2浓度不宜过高。故而植物光合色素含量可能受到CO_2浓度升高导致的植物干物质增加速率和光合色素合成速率改变的双重调节。中N和高N供应时,叶绿素a/b在苗期随着CO_2浓度的升高而降低,在初果期仅在高N时有显著降低。而在硝铵比试验中,植株种植稀疏时,C4处理提高叶绿素a/b。因此,CO_2浓度升高下的植物捕光能力的提高,可通过适当降低叶片光照强度和提高N供应浓度来实现。从实际生产角度出发,使用中等浓度CO_2施肥,提高N肥供应浓度和NH4+-N比例,结合植株的适当密植更有利于光合色素含量提高,优化其组成,从而有利于黄瓜生物量的提高。     

大气CO2浓度升高对谷子生长发育及玉米螟发生的影响

人类活动导致全球大气CO_2浓度持续升高,研究大气CO_2浓度升高对C4作物谷子(Setaria italica)生长发育及虫害发生的影响,可以为谷子等C4作物制订应对气候变化栽培措施提供理论依据。本研究利用OTC(Open Top Chamber)系统,设两个CO_2浓度梯度(正常大气CO_2浓度、正常CO_2浓度+200μmol·mol-1)模拟CO_2浓度升高对谷子生长发育的影响。结果表明:大气CO_2浓度升高后,谷子净光合速率(Pn)、气孔导度(gs)、叶片蒸腾速率(Tr)和水分利用率(WUE)分别增加38.73%、27.53%、6.93%和40.56%;谷子叶片光系统Ⅱ最大光化学量子产量(Fv/Fm)和非光化学淬灭系数(NPQ)显著下降,光系统Ⅱ实际光化学量子产量(ΦPSII)和表观电子传递效率(ETR)显著增加,而对光化学淬灭系数(q P)无显著影响;此外,谷子株高、茎粗和小穗数分别增加3.41%、13.28%和13.11%;而叶重、茎重、千粒重、单株粒数和产量无显著变化,穗重和地上部分生物量分别显著下降12.8%和7.44%;大气CO_2浓度升高后,谷子灌浆期和收获期玉米螟(Ostrinia furnacalis)发生数量显著增加。大气CO_2浓度升高将有利于谷子的生长发育,但会增加玉米螟危害。     

高温、高CO2对农作物影响的试验研究

在人工气候室试验研究高温和高CO2浓度对农作物的影响结果表明，高温、高CO2浓度使农作物生育进程加快，作物生育期缩短，作物的光合作用速率升高，蒸腾速率下降和气孔阻力增加；在相同的发育期使作物叶面积、根、茎、叶生长量不足，生物量下降；对不同作物产量结构的影响有差异，对小麦的影响主要是小穗数和穗粒数下降，而对玉米的影响主要是籽粒百粒重下降。高温、高CO2浓度可使农作物叶片中微量元素含量发生显著变化。     

不同浓度CO2施肥对温室番茄果实积硒效应的影响

试验以"兴海12号"番茄为研究对象,在施用4种不同浓度的CO_2的基础上,又对每个CO_2浓度处理下的番茄做了4个不同浓度的硒处理。研究了不同浓度CO_2施肥对番茄积硒效应的影响。设各独立隔间CO_2浓度依次为大气浓度(CK)、(600±25)μmol·mol~(-1)(T1)、(800±25)μmol·mol~(-1)(T2)、(1 000±25)μmol·mol~(-1)(T3)。在此基础上每个隔间的番茄材料实施包括空白在内的4个硒水平的处理L0(空白)、L1(2 mg·L~(-1))、L2(4 mg·L~(-1))、 L3(6 mg·L~(-1))。在相同的CO_2条件下叶面喷硒,随着施硒浓度的升高,使番茄果实内总硒和有机硒含量均有所升高,并且当施硒浓度相同时,随着CO_2浓度升高,番茄果实内总硒及有机硒都有显著的提升,且800μmol·mol~(-1)处理下效果最佳。本次试验在研究了CO_2施肥对番茄硒积累及转化的同时也比较了不同CO_2与亚硒酸钠的不同组合配施下成熟果实主要营养物质含量,结果为单独施硒与CO_2以及硒与CO_2的配施均使番茄营养品质得到提升。果实内维生素C、番茄红素及可溶性总糖在组合T2L3(CO_2浓度为800μmol·mol~(-1),硒浓度为6 mg·kg~(-1))时含量最高,提升显著。在T3L2(CO_2浓度为1 000μmol·mol~(-1),硒浓度为4 mg·kg~(-1))时有较高的糖酸比。     

大气CO2浓度升高对旱作玉米不同生育期土壤碳氮及组分的影响

为探明大气CO_2浓度升高对旱作玉米不同生育期土壤碳氮及其组分的影响,以旱作春玉米为研究对象,基于田间定位试验,利用改进的开顶式气室(OTC)模拟大气CO_2浓度升高的环境,设置当前自然大气CO_2浓度(CK)、CO_2浓度升高(700μmol/mol,OTC+CO_2)与OTC气室对照(OTC)3种处理,研究大气CO_2浓度升高对玉米各生育期土壤有机碳、全氮、水溶性有机碳、水溶性氮、易氧化有机碳的影响。结果表明:与OTC相比,大气CO_2浓度升高(OTC+CO_2)对土壤有机碳及组分、土壤全氮均无显著影响,使水溶性氮在12叶期(V12)降低18.17%,灌浆期(R3)升高108.56%(P0.05)。与CK相比,OTC+CO_2处理显著降低了各生育期土壤有机碳(收获期R6除外)和全氮(V12除外)含量,降幅分别为4.47%～14.42%和6.78%～12.48%(P0.05),降低了苗期(V6)水溶性有机碳、V12期水溶性氮、抽雄吐丝期(R1)与R6期易氧化有机碳含量,升高了R3期水溶性有机碳含量(P0.05)。因此,试验设置条件下,大气CO_2浓度升高对土壤有机碳及组分、土壤全氮均无显著影响,对水溶性氮的影响因生育期而异。在利用OTC系统模拟大气CO_2浓度升高进行相关研究时,OTC对试验结果的影响不可忽视。     

大气CO2浓度增高对不同水稻品种稻米品质的影响

大气CO_2浓度升高导致全球变暖,同时亦对作物生长发育产生深刻影响。作为光合作用的底物,大气CO_2的浓度升高增加水稻产量,但对稻米品质的影响及其品种间差异的研究相对较少且存在分歧。本研究利用稻田FACE (free air CO_2 enrichment)技术平台,以8个水稻品种为材料,设背景CO_2浓度(Ambient)和高CO_2浓度(增200μmol·mol~(-1), FACE)两个水平,研究大气CO_2浓度升高对稻米加工品质、外观品质、食味品质以及部分营养品质的影响及其种间差异。本研究所有测定的品质性状供试品种间均存在显著或极显著差异。与Ambient相比,FACE处理下水稻糙米率、精米率和整精米率略降,但单位面积糙米、精米和整精米产量平均分别极显著增加23.7%、23.5%和20.9%。FACE处理对整精米长度、宽度和长宽比影响较小,但使整精米垩白率和垩白度平均分别增加18.6%和31.8%,均达极显著水平。FACE处理使所有品种稻米直链淀粉含量和胶稠度平均分别下降6.5%和3.1%,但均未达显著水平。从淀粉RVA谱看,FACE处理使所有品种峰值黏度、崩解值平均增加1.3%、6.9%,使热浆黏度、冷胶黏度、消减值分别下降2.2%、5.1%和65.6%,其中消减值达显著水平。FACE处理使所有品种整精米植酸含量平均增加5.3%,而蛋白质含量平均减少9.9%,均达显著水平。不同品种稻米品质性状对高CO_2浓度的响应方向和程度存在一定差异,其中FACE处理与品种对整精米长度、垩白率、垩白度、峰值黏度、热浆黏度和最终黏度存在显著的互作效应。以上数据表明,大气CO_2浓度升高使水稻产量大幅增加,稻米加工、外观和营养品质呈变劣趋势,但适口性可能变优,稻米品质对大气CO_2浓度增高的响应存在不同程度的品种差异。     

高浓度CO2下氮素对小麦叶片干物质积累及碳氮关系的影响

高大气CO₂浓度下植物叶片干物质积累、碳氮关系和糖含量的变化对光合作用的适应性下调有重要的反馈作用,通过研究不同施氮量对高大气CO₂浓度下植物叶片干物质积累、叶氮浓度和糖含量的影响,可进一步明确氮素对植物光合作用适应性下调的调控机制。以不同大气CO₂浓度和氮素水平为处理条件,测定盆栽小麦拔节期叶片鲜重、干重、含水量、还原糖、可溶性糖、全氮含量,研究了氮素对长期高大气CO₂浓度(760μmol·mol-1)下小麦叶片的干物质积累、糖含量及碳氮含量的影响。结果表明,大气CO₂浓度升高使小麦叶片的鲜重和干重增加,含水量下降。大气CO₂浓度升高使N0处理的小麦叶片还原糖含量下降,而可溶性糖含量显著升高;施氮后小麦叶片还原糖含量无显著变化,但可溶性糖含量降低。高大气CO₂浓度条件下小麦叶片全氮含量下降,C/N比增加,而增施氮素后C/N比显著下降。可溶性糖含量和C/N比的下降有利于减轻同化物质对光合作用的反馈抑制,提高大气CO₂浓度增高条件下小麦叶片的P_n。     

CO2浓度升高对三江平原湿地土壤碳氮含量的影响

利用开顶箱薰气室(open-top chamber,OTC),设置正常大气CO2浓度(ambient CO2)和高CO2浓度(elevated CO2,700μmol/mol)2个水平和不施氮(NN,0g/m2),常氮(MN,5g/m2)和高氮(HN,15g/m2)3个氮素水平,研究了CO2浓度升高对三江平原草甸小叶章湿地(Calamagrostis angustifolia)土壤碳氮含量的影响。结果表明,CO2浓度升高连续运行两个生长季后,湿地土壤总有机碳含量没有显著变化,不同N处理增加了0.5%～1.8%。CO2浓度升高,土壤总氮含量总体呈下降趋势。就各生长期平均值而言,CO2浓度升高使土壤NH4+—N的含量分别降低了8.2%(NN),8.9%(MN)和9.7%(HN)。CO2浓度升高使不同N处理的土壤NO3-—N含量也呈降低趋势,其中高氮水平(HN)降低最多,降幅为9.6%。土壤有效态氮是控制植物对高CO2浓度响应的关键因素。     

硫酸根自由基高级氧化技术对污染场地多环芳烃的修复效果研究

硫酸根自由基高级氧化技术(sulfate radical(SO_4~(·–))based advanced oxidation processes,SR-AOPs)是一种被广泛应用于降解土壤有机污染物的原位氧化修复技术。然而,关于SR-AOPs降解土壤多环芳烃(polycyclic aromatic hydrocarbons,PAHs)的报道相对较少。本研究以南京某炼钢厂附近土壤作为试验样本,通过设置不同比例混合体系的过硫酸钠(Na_2S_2O_8)和亚铁离子(Fe~(2+))以及反应不同时间,探究SR-AOPs对土壤中16种PAHs的修复效果以及最佳技术方案。结果表明:Na_2S_2O_8和Fe~(2+)的配比会显著影响土壤PAHs的降解效果,当两者比例达到10︰1时,即Na_2S_2O_8用量为5 mmol/g,Fe~(2+)用量为0.5 mmol/g,反应时间为24 h时,PAHs总降解率最高,可达到29.32%;不同环数的PAHs决定了SR-AOPs的降解效果,其中SR-AOPs对四环PAHs降解效率最高,总降解率达到37.32%;此外,降解效率随反应时间增加而增加,在24 h达到效果最佳。因此,本研究结果可为SR-AOPs修复土壤PAHs提供理论依据。     

Elevated CO2 and O3t concentrations differentially affect selected groups of the fauna in temperate forest soils

Rising atmospheric CO₂ concentrations may change soil fauna abundance. How increase of tropospheric ozone (O_3t) concentration will modify these responses is still unknown. We have assessed independent and interactive effects of elevated [CO₂] and [O_3t] on selected groups of soil fauna. The experimental design is a factorial arrangement of elevated [CO₂] and [O_3t] treatments, applied using Free-Air CO₂ Enrichment technology to 30 m diameter rings, with all treatments replicated three times. Within each ring, three communities were established consisting of: (1) trembling aspen (Populus tremuloides) and paper birch (Betula papyrifera) (2) trembling aspen and sugar maple (Acer saccharum) and (3) trembling aspen. After 4 yr of stand development, soil fauna were extracted in each ring. Compared to the control, abundance of total soil fauna, Collembola and Acari decreased significantly under elevated [CO₂] (−69, −79 and −70%, respectively). Abundance of Acari decreased significantly under elevated [O_3t] (−47%). Soil fauna abundance was similar to the control under the combination of elevated [CO₂+O_3t]. The individual negative effects of elevated [CO₂] and elevated [O_3t] are negated upon exposure to both gases. We conclude that soil fauna communities will change under elevated [CO₂] and elevated [O_3t] in ways that cannot be predicted or explained from the exposure of ecosystems to each gas individually.     

A survey of yield differences between transgenic and non-transgenic crops

In the current survey, there was no clear evidence that GM (genetically modified) crops are higher yielding than those conventionally bred<fnoteref rid="fn1">1</fnoteref>. Furthermore, there were no trials to support valid comparisons of yield per se. This article investigates GM crop yields, introducing the importance of hybrid vigour and a non-stress environment for higher percentage heritability selection and therefore more productive conventional plant breeding and improved crops. GM technology and crops are compared with proven plant breeding methods, with respect to hybrid vigour and the economic viability of both systems. These proven methods of plant breeding are (1) traditional landrace cropping, (2) conventional Mendelian breeding and (3) Isolection Mendelian breeding, and are also considered historically.     

Agronomic biofortification of chickpea with zinc and iron through application of zinc and urea

ABSTRACT

Zinc (Zn) and iron (Fe) deficiency-related health problems in humans may be solved by improving their concentration in edible grains. The study, conducted in 2015–16 and 2016–17, investigated the effects of soil and foliar application of Zn and foliar application of urea on grain Zn and Fe accumulation of chickpea grains. Soil application of ZnSO₄ @ 25 kg ha^?1 + foliar spray of ZnSO₄ @ 0.5% at flowering and pod formation stages resulted in the highest Zn (45.06 & 44.69 mg Zn kg^?1 grain in the first and second year of study) and Fe (59.74 & 62.88 mg Fe kg^?1 grain) content. Urea application @ 2% at flowering and pod formation stages also resulted in the highest grain Zn (41.12 & 40.26 mg Zn kg^?1 grain) and Fe (58.95 & 61.95 mg Fe kg^?1 grain) content. Grain yield and protein content were significantly increased over control with these treatments. As compared to the sole application of Zn, the combined use of Zn and urea improved the grain Zn and Fe contents. Zinc and urea can be applied to improve Zn and Fe content in chickpea grains and, therefore, can help in ameliorating malnutrition in burgeoning human population.     

Monthly variation of forage and soil minerals in central Florida II. trace minerals

Abstract

A two‐year study was conducted to determine the trace mineral status of cattle grazing forages (bahiagrass) and soils on a ranch in central Florida. Forage and soil samples were collected every month for two years. Month effect (P < 0.05) on soil trace mineral concentrations were observed in manganese (Mn) and zinc (Zn) in years 1 and 2, and in copper (Cu) and iron (Fe) only in year 2. All soil trace minerals studied showed higher (P < 0.05) concentrations in year 2. Month differences (P < 0.05) in forage trace mineral concentrations were found in cobalt (Co), Cu, Fe, Mn, molybdenum (Mo), selenium (Se), and Zn. The majority of forage trace minerals were higher in spring‐summer months. Year means were similar (P > 0.05) in forage trace mineral concentrations. Few and low correlation coefficients were observed between and within soil and forage trace minerals concentrations. Percentages of total forage collected with trace minerals below critical values (in parentheses) and suggestive of deficiency were as follows: in forage, Co (0.1 ppm), 93%; Cu (8 ppm), 98%; Fe (50 ppm), 75%; Mn (40 ppm), 41%; Mo (> 6 ppm), 0%; Se (0.2 ppm), 98%; and Zn (25 ppm), 84%; in soil, Cu (0.3 ppm), 77%; Fe (2.5 ppm), 7%; Mn (5 ppm), 91%; and Zn (1.5 ppm), 53%.     

Assessment of Fe,Zn, Cd,Hg, and Pb in the Jordan and Yarmouk River Sediments in Relation to Their Physicochemical Properties and Sequential Extraction Characterization

Forty-six surface sediment samples taken along the beds of boththe Jordan and Yarmouk Rivers were analysed for Pb, Cd, Zn, Fe andHg by atomic absorption spectrophotometer. Extraction techniqueswere used to establish the association of the total concentrations of Pb, Cd, Zn and Fe in the sediment samples withtheir contents in the exchangeable, carbonate, Fe/Mn oxides, organic and residual fractions.In the sediments of the Jordan River the recorded heavy metalsconcentrations were as follow: 8.1 ppm for Pb, 0.63 ppm for Cd, 20.3 ppm for Zn, 6 ppm for Hg and 1265.6 ppm for Fe; whereas in the sediment of Yarmouk River were 8.4 ppm for Pb, 0.67 ppm for Cd, 26.4 ppm for Zn, 6.2 ppm for Hg and 1370 ppmfor Fe. Pb, Cd, Zn, and Fe concentrations in the sediments ofboth rivers reflect the natural background value in shale, whereas Hg is moderately enriched. I-geo (geo-accumulation index) of metals in the sediments under study indicates thatthey are uncontaminated with Pb, Zn and Fe; contaminated tomoderately contaminated with Cd; and strongly contaminated with Hg. Heavy metal content in the sediments were found to be significantly influenced by different physico-chemical parameters. The effect of these physico-chemical parameters canbe arranged in the following order: clay fraction > organicmatter fractions > carbonate fraction > silt fraction. As sequential extraction procedure shows that the total concentration of the heavy metals are largely bound to the residual phase (retained 79.5% of Pb, 38% of Cd, 54.4% of Zn and 51.6% of Fe in Jordan River Sediments; and 88.6% of Pb, 48.2% of Cd, 37.6% of Zn and 59.5% of Fe in the YarmoukRiver sediments). The following sequence of mobility are suggested: Fe > Cd > Zn > Pb in Jordan River sediments, and Fe > Zn > Cd > Pb. in Yarmouk River sediments.     

氮肥及黄腐酸对盐渍土有机碳和团聚体特征的调控作用

为了探明不同氮肥水平下黄腐酸对盐碱障碍土壤的改良及培肥效应,本研究以滨海滩涂新垦轻中度盐碱障碍土壤为研究对象开展田间试验,采用水稻-小麦轮作种植模式,通过测定土壤电导率、pH、有机碳和土壤团聚体含量及其稳定性,研究黄腐酸与不同氮肥水平对土壤盐分消减调控和土壤地力提升效应。结果表明:黄腐酸能有效降低耕层土壤盐分,在氮水平300 kg/hm~2条件下黄腐酸处理对耕层0～20 cm土壤电导率与p H降低效果最好;黄腐酸可以有效改善土壤结构及稳定性,小麦季与水稻季,在氮水平300kg/hm~2条件下黄腐酸处理土壤2mm水稳性大团聚体含量相较于不施肥对照分别增加18.6%和13.8%,土壤团聚体平均重量直径与当地常规施肥相比增加38%;围垦初期,氮水平处理相较于黄腐酸处理对耕层土壤有机碳含量的影响更大,氮水平300kg/hm~2处理相较于低氮(225kg/hm~2)与高氮(325kg/hm~2)处理,两季土壤总有机碳积累量分别增加31.0%和120.0%。综合考虑土壤改良效应,黄腐酸处理土壤表层盐分降低、水稳性大团聚体含量增加且稳定性增强、有机碳含量提升,因此黄腐酸结合适宜用量氮肥是一条轻中度盐碱障碍土壤的优化施肥措施。     

Zinc bioavailability response curvature in wheat grains under incremental zinc applications

Zinc application is generally recommended to enrich wheat grains with Zn; however, its influence on Zn bioavailability to humans has not received appreciable attention from scientists. In this pot experiment, seven Zn rates (from 0 to 18 mg kg^?1 soil) were applied to two wheat cultivars (Shafaq-2006 and Auqab-2000). Application of Zn significantly increased grain yield, grain Zn concentration and estimated Zn bioavailability, and significantly decreased grain phytate concentration and [phytate]:[Zn] ratio in wheat grains. The response of grain yield to Zn application was quadratic, whereas maximum grain yield was estimated to be achieved at 10.8 mg Zn kg^?1 soil for Shafaq-2006 and 7.4 mg Zn kg^?1 soil for Auqab-2000. These estimated Zn rates were suitable for increasing grain Zn concentration and Zn bioavailability (>2.9 mg Zn in 300 g grains) to optimum levels required for better human nutrition. Conclusively, Zn fertilization for Zn biofortification may be practiced on the bases of response curve studies aimed at maximizing grain yield and optimum Zn bioavailability. Moreover, additive Zn application progressively reduced the grain Fe concentration and increased the grain [phytate]:[Fe] ratio. However, a medium Zn application rate increased grain Ca concentration and decreased the grain [phytate]:[Ca] ratio. Hence, rate of Zn application for mineral biofortification needs to be carefully selected.     

Considering sink strength to model crop production under elevated atmospheric CO2

Climatic changes and elevated atmospheric CO₂ concentrations will affect crop growth and production in the near future. Rising CO₂ concentration is a novel environmental aspect that should be considered when projections for future agricultural productivity are made. In addition to a reducing effect on stomatal conductance and crop transpiration, elevated CO₂ concentration can stimulate crop production. The magnitude of this stimulatory effect (‘CO₂ fertilization’) is subject of discussion. In this study, different calculation procedures of the generic crop model AquaCrop based on a foregoing theoretical framework and a meta-analysis of field responses, respectively, were evaluated against experimental data of free air CO₂ enrichment (FACE) environments. A flexible response of the water productivity parameter of the model to CO₂ concentration was introduced as the best option to consider crop sink strength and responsiveness to CO₂. By varying the response factor, differences in crop sink capacity and trends in breeding and management, which alter crop responsiveness, can be addressed. Projections of maize (Zea mays L.) and potato (Solanum tuberosum L.) production reflecting the differences in responsiveness were simulated for future time horizons when elevated CO₂ concentrations and climatic changes are expected. Variation in future yield potential associated with sink strength could be as high as 27% of the total production. Thus, taking into account crop sink strength and variation in responsiveness is equally relevant to considering climatic changes and elevated CO₂ concentration when assessing future crop production. Indicative values representing the crop responsiveness to elevated CO₂ concentration were proposed for all crops currently available in the database of AquaCrop as a first step in reducing part of the uncertainty involved in modeling future agricultural production.     

REVIEW: Biofortification of Durum Wheat with Zinc and Iron

Micronutrient malnutrition affects over 2 billion people in the developing world. Iron (Fe) deficiency alone affects >47% of all preschool aged children globally, often leading to impaired physical growth, mental development, and learning capacity. Zinc (Zn) deficiency, like iron, is thought to affect billions of people, hampering growth and development, and destroying immune systems. In many micronutrient‐deficient regions, wheat is the dominant staple food making up >50% of the diet. Biofortification, or harnessing the powers of plant breeding to improve the nutritional quality of foods, is a new approach being used to improve the nutrient content of a variety of staple crops. Durum wheat in particular has been quite responsive to breeding for nutritional quality by making full use of the genetic diversity of Fe and Zn concentrations in wild and synthetic parents. Micronutrient concentration and genetic diversity has been well explored under the HarvestPlus biofortification research program, and very positive associations have been confirmed between grain concentrations of protein, Zn, and Fe. Yet some work remains to adequately explain genetic control and molecular mechanisms affecting the accumulation of Zn and Fe in grain. Further, evidence suggests that nitrogen (N) nutritional status of plants can have a positive impact on root uptake and the deposition of micronutrients in seed. Extensive research has been completed on the role of Zn fertilizers in increasing the Zn density of grain, suggesting that where fertilizers are available, making full use of Zn fertilizers can provide an immediate and effective option to increase grain Zn concentration, and productivity in particular, under soil conditions with severe Zn deficiency.