盐渍条件下不同施锌量对玉米幼苗生长和锌形态转化的影响

为揭示外源锌在绿洲盐化潮土中的转化特征,通过盆栽模拟试验,探究了盐渍条件下不同施锌量对玉米幼苗生长和锌形态转化的影响。结果表明,无论非盐渍条件还是盐渍条件下,随着施锌量的增加玉米的株高和干重均呈先增加后减小的趋势,施锌量为5～10 mg/kg时达到最大。玉米含锌量随施锌量的增加而增大,吸锌量随施锌量的增加先增大后减小,施锌量为10 mg/kg时达到最大。施锌0.5、1.0、2.0、5.0、10.0、20.0 mg/kg处理的株高与不施锌比较,在非盐渍条件下分别增加13.60%、13.89%、15.58%、20.84%、21.57%、19.58%,在盐渍条件下分别增加3.31%、8.00%、9.74%、11.51%、8.41%、6.87%。由此认为,绿洲盐化潮土的适宜施锌量为5～10 mg/kg,有害或过量施锌量为≥20 mg/kg。随施锌量的升高,盐渍条件下的土壤有效锌(DTPA-Zn)、碳酸盐结合态锌(CAB-Zn)、松结有机结合态锌(WBO-Zn)、氧化锰结合态锌(OxMn-Zn)、无定形氧化铁结合态锌(AOFe-Zn)、晶形氧化铁结合态锌(COFe-Zn)和残留矿物态锌(RES-Zn)均呈上升趋势,分别增加了15.63%～767.19%、7.69%～296.92%、5.68%～270.45%、0.72%～19.42%、1.82%～65.25%、1.01%～37.61%、0.18%～6.92%。与非盐渍条件下相比,盐渍条件下的玉米株高、干重、含锌量、吸锌量、土壤有效锌(DTPA-Zn)、植物可利用态锌(碳酸盐结合态锌、松结有机结合态锌、氧化锰结合态锌)均降低,其他态锌(无定形氧化铁结合态锌、晶形氧化铁结合态锌和残留矿物态锌)均升高。综合分析认为,施用适量锌肥能显著提高玉米的耐盐性,缓解长期盐分胁迫带来的毒害,在短期内能有效改善土壤-作物系统的锌营养水平。     

锌源和施锌方法对石灰性土壤锌组分及锌肥利用率的影响

【目的】选用合适的锌肥以及合理的施肥方式不仅可以提高小麦籽粒锌营养品质,还可以提高石灰性土壤的锌肥利用率。因此,研究不同锌源和施肥方式对石灰性土壤中锌组分含量以及锌肥利用率的影响具有重要意义。【方法】采用盆栽试验,设置两种锌源(水溶态锌肥Zn SO4·7H2O和螯合态锌肥Zn-EDTA)全层混匀均施和表面条施两种方式,调查了土壤中交换态Zn(Ex-Zn)、松结有机态Zn(LOM-Zn)、碳酸盐结合态Zn(Carb-Zn)、氧化锰结合态Zn(Ox Mn-Zn)、紧结有机态Zn(TOM-Zn)5种形态锌的含量,分析了小麦对锌肥的利用率。【结果】全层混匀均施与表面条施,两种锌肥均增加了小麦籽粒和秸秆Zn含量,全层均施Zn SO4·7H2O处理的籽粒Zn含量比对照提高43%,均施和表面条施Zn-EDTA的籽粒Zn含量分别比对照提高57%和75%;Zn-EDTA均施和条施的锌肥利用率分别为6.5%和5.3%,Zn SO4·7H2O均施和条施的锌肥利用率分别为3.6%和1.3%。小麦收获后,条施Zn SO4·7H2O和Zn-EDTA的施锌区有效锌含量分别为9.25和1.97 mg/kg,分别为均施处理的2倍和1.8倍;与对照相比,Zn SO4·7H2O和Zn-EDTA条施及均施的4个处理均增加了土壤中各形态锌的含量,并且4个处理与对照土壤中各形态Zn含量的规律一致,即:松结有机态碳酸盐结合态紧结有机态氧化锰结合态交换态。均施Zn SO4·7H2O和Zn-EDTA 2个处理的交换态Zn含量分别为0.12和0.13 mg/kg,条施分别为0.38和0.54 mg/kg;均施处理松结有机态Zn含量分别为5.26和1.56 mg/kg;不同处理碳酸盐结合态Zn含量变化趋势与松结有机态Zn含量基本一致;条施Zn SO4·7H2O施肥区氧化锰结合态Zn含量为对照的4倍,不同处理的土壤中紧结有机态Zn含量变化规律与氧化锰结合态Zn含量变化规律相似。相关分析表明,土壤交换态Zn、松结有机态Zn和碳酸盐结合态Zn含量均与有效锌含量呈显著正相关关系,与不施锌肥相比,Zn-EDTA施入土壤后,小麦收获后松结有机态Zn和碳酸盐结合态Zn含量明显增加,而紧结有机态Zn则相对减少。【结论】潜在缺锌石灰性土壤上施用螯合态锌肥Zn-EDTA能显著增加土壤中潜在有效的锌组分以及锌肥利用率,而且施用螯合态锌肥后,较高的有效锌含量可以维持至小麦收获后,有效提高了锌肥利用率。与均施处理相比,条施这种集中施用的施肥方法可以增加近根系土壤中有效性较高的锌形态含量。     

绿洲盐化潮土施锌对玉米生长和锌形态转化的影响

为了揭示施锌对绿洲盐化潮土区玉米生长和锌形态变化的影响,通过盆栽模拟的方法,探讨了不同盐分浓度条件下(轻度、中度、重度)外源锌施入对玉米株高、干重、含锌量、吸锌量和各形态锌含量的影响。结果表明:相同盐分浓度条件下,施锌10 mg/kg使得玉米株高、干重、含锌量、吸锌量和土壤有效锌含量分别增加了8.5%～21.6%、21.7%～333.3%、107.3%～154.7%、166.7%～965.9%和451.3%～547.2%,碳酸盐结合态、松结有机态、氧化锰结合态、无定形氧化铁结合态、晶型氧化铁结合态、残留矿物态锌含量分别增加了147.4%～173.3%、122.4%～152.1%、11.6%～12.6%、32.6%～33.4%、17.6%～18.0%、3.1%～3.2%;相同施锌条件下,随着土壤盐分浓度的增加,玉米株高、干重、含锌量、吸锌量和土壤有效锌含量分别降低了6.5%～36.4%、12.8%～89.9%、5.5%～22.0%、17.4%～92.2%和4.8%～18.1%,碳酸盐结合态、松结有机态、氧化锰结合态锌含量分别降低了4.7%～15.0%、3.6%～13.7%、10.4%～25.6%,无定形氧化铁结合态、晶型氧化铁结合态、残留矿物态锌含量分别升高了1.9%～5.8%、0.4%～3.5%、0.6%～2.2%。综合分析认为,在盐渍化环境中,施锌能够改善玉米生长状况的主要原因是大幅度提高了碳酸盐结合态、松结有机态2种有效态锌含量,在短期内改善了土壤-作物系统锌营养水平,提高了玉米的耐盐性。     

磷与富啡酸配施对潮土中磷锌有效性及锌形态转化的影响

采用室内培养方法,研究了磷与富啡酸(fulvic acid,FA)配施对石灰性潮土中磷锌有效性及锌形态转化的影响。结果表明:潮土中速效磷含量随外加磷量的增加而显著增加,且随着培养时间的延长发生了明显的固定,而且外加磷越高,土壤对其的固定越明显。土壤速效磷含量随添加FA量的增加而增加,即FA提高了磷有效性,但在低磷处理下,FA对磷的活化作用很小,而在高磷处理下作用明显;土壤速效磷含量随添加锌量的增加而降低,即高锌降低了速效磷的含量。土壤DTPA-Zn含量随锌添加量的增加显著增加,且随培养时间的延长而显著降低;低量磷可提高DTPA-Zn含量,但当土壤磷添加量太高时(高于120 mg kg-1或160 mg kg-1)则降低DTPA-Zn含量。土壤DTPA-Zn含量随FA添加量的增加而增加,但FA对长时间培养土壤锌的活化作用不明显。对土壤锌分级表明,土壤锌主要以残渣态(RES)形式存在,而交换态和有机质结合态锌在石灰性土壤中含量极低。同时,外源可溶性锌明显提高了土壤中RES-Zn、CAB-Zn、OFe-Mn-Zn和EX-Zn含量,但OM-Zn增加趋势不明显,且随着培养时间的延长,土壤中有效性较高的EX-Zn和OM-Zn逐渐向无效态RES转化,FA对土壤锌形态转化作用不明显。     

不同退耕年限下菜子湖湿地土壤Cu和Zn形态特征

以安庆市菜子湖不同退耕还湖年限(3 a,5 a,7 a,9 a,11 a,21 a)的湿地、仍耕油菜地和原始湿地土壤为研究对象,研究不同退耕年限下湿地土壤重金属Cu和Zn的各赋存形态变化特征。结果表明:退耕后湿地土壤Tot-Zn和Tot-Cu含量随退耕年限增加而呈增加趋势;土壤Cu和Zn的各赋存形态分布比率不同,但均以残渣态含量为主,残渣态Cu、Zn分别占总含量的42.55%~62.40%和40.75%~71.18%;土壤Cu和Zn各赋存形态含量大小的顺序分别为:残渣态(RES-Cu:10.11~19.86 mg kg-1)>有机结合态(OM-Cu:4.40~12.07 mg kg-1)>铁锰氧化态(RED-Cu:2.24~6.94 mg kg-1)>碳酸盐结合态(CARB-Cu:0.65~1.99 mg kg-1)>可交换态(EXC-Cu:0.03~0.41 mg kg-1)和残渣态(RES-Zn:12.79~27.71 mg kg-1)>铁锰氧化态(RED-Zn:5.37~23.27 mg kg-1)>有机结合态(OM-Zn:2.49~8.31 mg kg-1)>可交换态(EXC-Zn:0.02~4.95 mg kg-1)>碳酸盐结合态(CARB-Zn:0.00~2.87 mg kg-1);随着退耕年限增加湿地土壤Cu和Zn各个形态变化趋势存在差异,讨论结果表明退耕还湖后湿地淹水条件和植被恢复状况改变,导致湿地土壤理化性质变化,进而影响了湿地土壤Cu和Zn的形态组分、总量及生物有效性。     

湖南省主要茶园土壤锌的形态及其有效性

采用野外调查采样分析和田间试验方法研究了湖南省主要茶园生态系统中土壤Zn的形态及其有效性.结果显示:①成土母质明显影响土壤中各种形态Zn的含量,与母质本身的特性有关;②生物 秸秆和秸秆覆盖处理能明显提高茶园土中有效态Zn与有机态Zn的含量,而对其他形态Zn的含量影响不太明显;③土壤中对有效态Zn(AZn)含量影响最大的是交换态Zn(ExZn)与无定形氧化铁结合态Zn(AFeZn),其次为氧化锰结合态Zn(MnOZn)、有机态Zn(OMZn)及晶形氧化铁结合态Zn(CFeZn).     

有机质对冻融黑土重金属Zn赋存形态的影响

冻融作用对不同有机质含量的土壤重金属Zn赋存形态转化产生显著影响,以24h为1个冻融周期,对150mg(Zn)·kg-1的黑土冻融8次,结果表明,随着有机质含量的增加,未经冻融土壤的交换态和铁锰氧化物结合态Zn含量逐渐降低,有机结合态Zn含量逐渐增加,残渣态Zn含量变化不显著。冻融作用可促进交换态和铁锰氧化物结合态Zn含量降低,促进有机结合态和残渣态Zn含量增加。随着土壤有机质含量的增加,冻融作用使重金属Zn生物有效态含量降低。通过有机质含量与各形态Zn含量拟合,在未冻融和冻融条件下,各形态Zn含量与有机质含量之间呈二次多项式的函数关系,相关系数r2在0.664和0.995之间。     

硫酸锌和EDTA-Zn不同施用方法对第二季小麦籽粒锌和土壤锌有效性的影响

【目的】在潜在缺锌石灰性土壤上,特别是种植小麦并以此为主粮的地区,缺锌问题日益受到人们的关注。提高小麦籽粒锌含量以满足人体锌需求,对于改善人体锌营养不良的现状具有重要意义。【方法】以ZnSO₄和Zn-EDTA为锌源,布置了2个为期两年的田间定位试验。试验均采用裂区设计,即主因子为喷施锌肥,设喷施与不喷2个主处理;副因子为土施方法,设不施锌、均施、条施3个副处理。在第1季试验基础上,第2季不再土施锌肥,调查了小麦籽粒锌含量、土壤有效锌含量及锌组分含量,分析了第1季锌肥的后效。【结果】第2季单独喷施ZnSO₄小麦籽粒Zn含量提高了11.13 mg/kg,提高幅度为33%,而喷Zn-EDTA无明显效果。不喷Zn时,第1季均施和条施的ZnSO₄在第2季均表现出一定后效,小麦籽粒锌含量比对照分别提高了6.05、3.51 mg/kg,提高幅度为20%和11%;喷Zn时,第2季均施和条施ZnSO₄处理的小麦籽粒锌含量增加了28.59和21.59 mg/kg,增幅100%和76%,表现出显著富锌作用,但增加幅度比单独喷施要小很多。第1季土施的两种锌肥在第2季小麦收获后DTPA-Zn仍维持在1 mg/kg以上,即不喷Zn时,均施和条施ZnSO₄处理的土壤有效锌含量分别为1.99和1.65 mg/kg,均施和条施Zn-EDTA的有效锌含量分别为1.23和1.01 mg/kg;喷Zn时,均施和条施ZnSO₄处理的土壤有效锌含量分别为1.44和2.22 mg/kg,均施和条施Zn-EDTA处理的有效锌含量分别为1.16和1.10 mg/kg。土壤各锌组分含量均表现为:松结有机态Zn > 碳酸盐结合态Zn > 氧化锰结合态Zn > 紧结有机态Zn > 交换态Zn。具体而言,第1季均施和条施ZnSO₄,第2季结束后交换态Zn（Ex-Zn）、松结有机态Zn（Wbo-Zn）、碳酸盐结合态Zn（Car-Zn）含量均显著提高,其提高幅度分别为184%和116%;75%和85%;53%和43%。而均施和条施Zn-EDTA仅Ex-Zn、Wbo-Zn含量显著提高,其提高幅度分别为232%和132%;18%和10%。均施Zn-EDTA处理的锌肥利用率为0.27%,条施为0.70%,后者约为前者的3倍;而条施与均施ZnSO₄无差异。【结论】在潜在缺锌石灰性土壤上,单独喷施ZnSO₄显著提高了小麦籽粒锌含量,而喷施Zn-EDTA效果不显著;土施ZnSO₄和Zn-EDTA,不论条施或均施,虽然会使有效锌（DTPA-Zn）及较高活性锌形态（Ex-Zn、Wbo-Zn）长时间维持较高含量,但对第2季小麦籽粒富锌的后效有限;土施基础上配合喷施ZnSO₄对小麦籽粒锌的含量效果最令人满意。     

苏南经济快速发展区土壤Cu、Ni、Pb、Zn形态及其有效性定量分析——以昆山市为例

研究了江苏省昆山市农田土壤有效态Cu、Ni、Pb、Zn各形态含量及其有效性。结果表明,土壤重金属Cu、Ni、Pb、Zn各形态含量以残渣态有机质结合态铁锰氧化物结合态碳酸盐结合态、可交换态,残渣态含量明显高于其他形态。Cu和Pb有机质结合态所占比例相对也较高,分别达36.09%和28.30%。土壤可交换态含量、碳酸盐结合态含量、Fe-Mn氧化物结合态含量及残渣态含量均以Zn最高;土壤有机质结合态含量以Cu最高;土壤可交换态含量变异系数、土壤碳酸盐结合态含量变异系数及土壤Fe-Mn氧化物结合态含量变异系数以Ni为最大;土壤有机质结合态含量变异系数以Zn最大;土壤残渣态含量变异系数以Pb最大。土壤铁锰氧化物结合态铜和可交换态铜对土壤有效态铜含量影响最大;土壤可交换态镍含量对土壤有效态镍含量最大;土壤铁锰氧化物结合态铅和有机质结合态铅对土壤有效态铅含量影响最大;土壤可交换态锌和碳酸盐结合态锌对土壤有效态锌含量影响最大。     

黑土锌有效度的物理化学研究法

锌是动植物必需微量元素同时亦是污染土壤的重金属元素,研究黑土中锌形态及其有效度对保护黑土农业生态环境具有重要意义。以黑土13年长期定位试验为研究对象,采用物理化学研究法,分析评价黑土Zn形态转化及锌有效度。结果表明,长期不施肥黑土有效锌(DTPA-Zn)含量可达1.96 mg kg-1,长期施肥可显著增加黑土交换态Zn和无定型氧化铁结合态Zn含量,从而显著提高黑土有效Zn含量,可增至3.3 mg kg-1,对土壤全Zn未有明显增加;配施有机肥可显著增加矿物态Zn以外其他各形态Zn含量,土壤有效锌含量随有机肥施用量增加而逐渐增加,最高可达14.5 mg kg-1。长期施肥使土壤酸化从而降低了黑土对Zn2+的吸附强度和容量,且其吸附的Zn2+更易解吸出来,配施一定量有机肥处理虽未能减缓土壤酸化,可在一定程度上增加土壤对Zn2+的吸附强度与容量,但其吸附的Zn2+更难以解吸。总体黑土有效锌含量相对较高,对Zn2+吸附强度和容量均较高,但随着施肥引起土壤酸化而降低其对Zn2+吸附强度和容量。     

Soil zinc and pH effects on leaf zinc and the interaction of leaf calcium and zinc on zinc toxicity of peanuts

Abstract

Zinc toxicity of peanuts (Arachis hypogaea L.), resulting from excessive amounts of Zn applied to previous crops, has been observed for many years in a limited number of peanut fields in Georgia. A tentative critical value of 12 mg/kg of Mehlich No.1 extractable soil Zn has been reported, but soil pH should be considered in establishing a more precise critical value since availability of soil Zn is affected greatly by soil acidity. A 3‐year study was conducted on a Tifton loamy sand (thermic, Plinthic Paleudults) to evaluate the relationship between soil pH and soil Zn on concentration of Zn in peanut leaves. Factorial treatments were 0, residual, medium, and high rates of Zn and soil pH levels near 5.5, 5.9, 6.2, and 6.8. Pod yields were not affected by treatments and Zn toxicity was not observed. Leaf Zn was affected more by soil pH than by soil Zn, but correlation coefficients were highest where both soil pH and soil Zn were included in the determination. A regression equation, based on soil pH and soil Zn, showed that an increase in soil Zn from 1.0 to 10.0 mg/kg increased leaf Zn 202 mg/kg at soil pH 4.6 and only 9 mg/kg at pH 6.6. Data from growers’ fields, in which samples were collected from eight healthy and toxic areas, indicated that a leaf Ca:Zn ratio of 50 or less was required for Zn toxicity of peanuts rather than high concentrations of leaf Zn per se.     

Comparison of soil zinc extractants for detection of applied zinc and prediction of leaf zinc concentration

Abstract

Many soil extractants have been developed for determination of zinc (Zn) availability to plants. The optimum soil Zn extractant should be useful not only for prediction of plant Zn concentration but also for detection of applied Zn levels. The objectives of this study were: i) to compare soil Zn extradants for detecting applied Zn and for predicting peanut leaf Zn over a range of soil pH levels, and ii) to correlate other soil‐extractable Zn levels with Mehlich‐1. Soil and peanut leaf samples were taken from a field study testing pH levels as the main plots and Zn application rates in the sub‐plots. Extractable Zn was determined on soil samples using Mehlich‐1, Mehlich‐3, DTPA, MgNO₃, and many dilute salt extradants of varied strength and pH. Correlation of extractable soil Zn to cumulative applied Zn levels revealed Mehlich‐1, Mehlich‐3, DTPA, and AlCl₃ extradants to be among the best indicators of applied Zn. Leaf Zn concentration was best correlated with soil Zn extracted by dilute salts, such as KCl, CaCl₂, NH₄Cl, CaSO₄, and MgCl₂. Including soil pH as an independent variable in the regression to predict leaf Zn considerably improved R‐square values. The DTPA‐extractable soil Zn levels were very well correlated with Mehlich‐1‐extractable Zn. Mehlich‐3 extracted about 20% more soil Zn than Mehlich‐1, but Mehlich‐3 soil Zn was not as well correlated to Mehlich‐1 soil Zn as DTPA soil Zn. Lower pH solutions extracted more of the applied Zn, but more neutral solutions extracted Zn amounts which were better correlated with Zn uptake. On the other hand, Mehlich‐1, which had a lower pH, had better correlations with both applied Zn and leaf Zn than did Mehlich‐3. Shortening the DTPA extraction time to 30 minutes resulted in better correlations than the standard two hour extraction time. Chloride (Cl) was the best anion tested in relation to soil applied Zn recovery in combination with potassium (K), calcium (Ca), and aluminum (Al), and Cl optimized leaf Zn correlations for ammonium (NH₄), K, Ca, and magnesium (Mg). The larger the valence of the cation, the better the correlation with applied Zn and the poorer the correlation with leaf Zn.     

Effects of zinc complexes on the distribution of zinc in calcareous soil and zinc uptake by maize

The movement and availability of Zn from six organic Zn sources in a Typic Xerorthent (calcareous) soil were compared by incubation, column assay, and in a greenhouse study with maize (Zea mays L.). Zinc soil behavior was studied by sequential, diethylenetriaminepentaacetate, and Mehlich-3 extractions. In the incubation experiment, the differences in Zn concentration observed in the water soluble plus exchangeable fraction strongly correlated with Zn uptake by plants in the greenhouse experiment. Zinc applied to the surface of soil columns scarcely moved into deeper layers except for Zn-ethylenediaminetetraacetate (EDTA) that showed the greatest distribution of labile Zn throughout the soil and the highest proportion of leaching of the applied Zn. In the upper part of the column, changes in the chemical forms of all treatments occurred and an increase in organically complexed and amorphous Fe oxide-bound fractions was detected. However, the water soluble plus exchangeable fraction was not detected. The same results were obtained at the end of the greenhouse experiment. Significant increases were found in plant dry matter yield and Zn concentration as compared with the control treatment without Zn addition. Increasing Zn rate in the soil increased dry matter yield in all cases but Zn concentration in the plant increased only with Zn-EDTA and Zn-ethylenediaminedi-o-hydroxyphenyl-acetate (EDDHA) fertilizers. Higher Zn concentration in plants (50.9 mg kg(-)(1)) occurred when 20 mg Zn kg(-)(1) was added to the soil as Zn-EDTA. The relative effectiveness of the different Zn carriers in increasing Zn uptake was in the order: Zn-EDTA > Zn-EDDHA > Zn-heptagluconate >/= Zn-phenolate approximately Zn-polyflavonoid approximately Zn-lignosulfonate.     

玉米幼苗对短暂供锌的反应及缺锌后再供锌的恢复

用溶液培养的方法研究了玉米幼苗对短暂供锌的反应及缺锌后再供锌的恢复效果.结果表明:10～12小时的正常供锌后再缺锌培养,对玉米幼苗的危害比一直缺锌的还大;缺锌培养使玉米幼苗出现缺锌症状后再正常供锌,可使之恢复,低锌使玉米出现的缺锌症状比缺锌培养的更难以恢复,证明低锌比缺锌对玉米造成的危害更大,缺锌使玉米的有机酸分泌增加,低锌增加的更多.     

不同白菜品种对锌的响应及锌利用效率研究

采用盆栽试验研究了白菜[Brassica campestris L.ssp.Chinensis(L.)Makino]4个品种对不同浓度锌(Zn 0、1、10 mg/kg)的响应.结果表明,白菜的生物量及体内锌含量随锌水平的增加而增加;但白菜品种对锌营养反应的敏感性不同.地上部锌含量、锌积累量和锌吸收效率均以日本华冠(J...     

锌对不同基因型玉米缺锌后的恢复效果及胚乳在缺锌中的作用

用溶液培养法研究不同Zn浓度对玉米缺Zn后恢复效果及胚乳在缺Zn中作用结果表明,不同基因型玉米缺Zn后恢复所需的适宜Zn浓度不同,敏感品种比非敏感品种要求更高的Zn浓度。缺Zn后恢复所需适宜Zn浓度高于正常培养所需适宜Zn浓度,低浓度Zn(0.1μmol/L)无恢复作用(生物量)。带上胚乳使敏感品种在缺Zn、低Zn下受抑程度(缺Zn与供Zn生物量差值)提高,而非敏感品种受抑程度反而减小。缺Zn与低Zn培养时体内P含量提高,胚乳可缓解这种影响。缺Zn后再供Zn可使体内Zn含量提高,而P含量降低,玉米对Zn产生奢侈吸收,使体内Zn含量超过正常供Zn水平,表明缺Zn后植物对Zn的要求提高。0.1μmol/L Zn恢复对“吉单120”玉米Zn含量无明显影响,但“辽单22”玉米Zn含量显著提高,这表明非敏感品种比敏感品种利用低Zn的能力更强。     

Soil zinc and pH effects on zinc concentrations of corn plants

Abstract

Z1nc (Zn) deficiency of corn (Zea mays L.) has been detected in 20 or more states 1n the United States including Georgia. Since soil pH is a major factor in assessing the availability of soil Zn, this measurement has been included with acid extractable soil Zn in developing calibration Zn soil tests in North Carolina and Virginia. The objectives of this study were to develop a reliable soil test for Zn based on soil pH and Mehlich 1 soil Zn for corn gown on coarse‐textured soils and to compare our soil test values with those recently published from North Carolina where Mehlich 3 was the extractant. The study was conducted 1n 1979 to 1981 on a Tifton loamy sand (Plinthic Paleudult) site which had been used to study the influence of lime rates on micronutrient availability since 1970. Treatments consisted of four soil pH levels ranging from 5.3 to 6.6 and soil Zn levels ranging from 0.5 to 4.9 mg/kg. The Zn levels were established from the previous study where 5.6 kg Zn/ha had been applied annually for eight years (residual treatment) and by applying 3.36 or 6.72 kg Zn/ha during 1979, 1980 and 1981.

Soil Zn, corn shoot, and ear leaf Zn values were reflective of the amount of Zn applied except that the residual Zn treatment resulted in Zn concentrations > than the annual application of 3.36 kg Zn/ha. Zinc tended to accumulate in the soil and in corn leaf tissue more from the residual Zn than the recently applied Zn treatments, especially at the highest pH levels. Increasingly more soil Zn was required to increase corn shoot and ear leaf Zn one mg/kg as soil pH increased. In the initial year, each unit (kg/ha) of applied Zn increased corn shoot Zn approximately 4 units (mg/kg) at pH 5.3 and only 0.3 unit at pH 6.6. Zinc deficiency symptoms developed in corn shoots for the two highest soil pH levels in two of three years. Corn yields were increased by Zn only in 1980 and were increased by residual or applied Zn at pH levels of 6.2 and 6.6. Regression equations from these studies were utilized to develop predictive corn shoot and ear leaf Zn values over wide ranges in soil Zn and pH. Our field research data using Mehlich 1 extractant could possibly be used satisfactorily in North Carolina regression equations where Mehlich 3 was the extractant; however, certain limitations would need to be imposed in the North Carolina equations.     

Effects of zinc fungicides and different zinc fertilizer application methods on soluble and total zinc in potato plant shoots

Abstract

The experiment was carried out to evaluate the effects of fungicides [with or without zinc (Zn)] and different Zn fertilizer application methods (no fertilizer; soil application; shoot application; soil plus shoot application) on the soluble and total Zn in the dry matter of potato shoots. Zinc fertilizer was applied to the shoots at 20 and 45 days after plant emergence (DAE), immediately before plant sampling. At 25 DAE, Zn fungicide increased soluble and total Zn in the fourth leaf. The same occurred, at 45 DAE, with the Zn fertilizer applied to the shoots. It were not observed significant increases on both soluble and total Zn contents in the fourth leaf of plants that received soil Zn fertilization. Even in the leaves with 262 mg Zn kg^‐1, there was no phytotoxicity symptoms. The total Zn concentration at 20 DAE was the best index correlated to potato tuber yield reaching 50.9 mg Zn kg^‐1 in the fourth leaf of plants at the highest marketable tuber yield treatment. Plant nutrient element contents [phosphorus (P), calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe), and manganese (Mn)] were not affected by the treatments.     

Effects of chelated zinc,soluble and coated fertilizers,on soil zinc status and zinc nutrition of maize

Abstract

Maize (Zea mays L.) was greenhouse cultivated with doses of 5, 10, and 15 ppm of zinc (Zn) in order to test the effectiveness of laboratory‐prepared coated and uncoated Zn fertilizers with commercial Zn‐EDTA and Zn‐ligno‐sulphonate (LS). Large increases were achieved both in crop yield and in Zn uptake in all cases while a large part of the Zn applied remained in the soil in easily plant‐available forms. Positive significant correlations were obtained between available Zn and the first three sequentially extracted fractions (water soluble plus exchangeable, organically complexed and that associated to amorphous sesquioxides) and also between the variables, yield, Zn concentration, and plant Zn uptake. Zinc uptake by the maize plants can be fairly accurately predicted from its sequential fractioning in the soil using an equation obtained by multiple regression analysis. Consideration of the amounts of Zn remaining as available (DTPA extractable) in the soil and results of a plant analysis let us conclude that under the conditions of our tests, Zn‐EDTA is a better Zn source than Zn‐LS. In addition, coating of Zn‐EDTA products with rosin improves their performance.     

Prediction of residual effects of zinc sulfate on growth and zinc uptake of corn plants using three zinc soil tests

Abstract

A significant portion of chemical zinc (Zn) fertilizers applied to calcareous soils is not absorbed by the first crop and may, therefore, affect the growth and chemical composition of the subsequent crops. This is called the residual effect of Zn. Soil tests may be used to predict such effects. The present experiment was conducted to study the residual effects of zinc sulfate (ZnSO₄) on the second crop of corn (Zea mays L.) grown on selected highly calcareous soils of Iran and to compare the suitability of three soil tests for prediction of the effects. Twenty highly calcareous soils of southern Iran (16–58% calcium carbonate equivalent; pH 7.9–8.5), previously treated with three levels of Zn (0, 10, and 20 mg Zn/kg as ZnSO₄) and under one crop of corn, was used in greenhouse to grow a second crop of corn without additional Zn fertilizer but with uniform application of nitrogen (N), phosphorus (P), and iron (Fe). Soils were sampled before the second crop and extracted with three Zn extradants, DTPA, EDTA‐(NH₄)₂CO₃, and EDTA. Dry weight of plant tops and Zn concentration and uptake after eight weeks under the greenhouse conditions were used as the plant responses to residual Zn. Statistical analyses including F‐test and multiple regression equations showed that the overall effect of previously‐applied Zn on dry matter was nonsignificant, but Zn concentration and uptake were significantly increased. The three soil tests predicted the Zn concentration and uptake equally well. Moreover, DTPA and EDTA soil tests could predict the dry matter of plants at the highest level of previuosly‐applied Zn (20 mg Zn/kg), especially when selected chemical properties of soil, namely, calcium carbonate equivalent or organic matter content, were considered in the regression equations.