Zinc bioavailability in maize grains in response of phosphorous–zinc interaction

Phosphorous (P) and zinc (Zn) are plant nutrients that interact with each other in soil–plant systems. Such interactions may cause deficiency of one of the nutrients interacting with each other if interactions are antagonistic. In the present trial, a field experiment was conducted to investigate the interactive effect of Zn (0 and 16 kg ha^?1) and P (0 and 60 kg ha^?1) on growth, yield and grain Zn concentration of two maize (Zea mays L.) genotypes, i.e., Neelam (local) and DK‐6142 (hybrid). Growth and yield of both maize genotypes were increased by the application of Zn and P treatments compared with control, but Zn+P was more effective than their sole application. When compared to control, combined application of Zn+P increased grain Zn and P concentrations by 52% and 32%, respectively, averaged for the two genotypes. Single application of P decreased grain Zn concentration by 10% over control. Application of P and Zn particularly in combination decreased the grain [phytate] : [Zn] ratio and increased the estimated human Zn bioavailability in grains based on a trivariate model of Zn absorption in both maize genotypes. Conclusively, combined Zn+P application appeared more suitable for enhancing grain yield and agronomic Zn biofortification in maize grains. However, Zn fertilization aiming at increasing grain yield and grain Zn concentration should consider the genotypic variations and P rate.     

Silicon Requirement of Coarse and Fine Varieties of Rice

ABSTRACT

Silicon (Si) provides extra strength to plants against lodging. A hydroponic study was conducted to compare Si requirements of three high yielding, nitrogen (N) responsive, coarse varieties of rice (KSK-133, PK-3717-12, and IRRI-6) with four low yielding, lodging susceptible, fine varieties of rice (BAS-191, BAS-385, BAS-370, and PK-3300). Two-week-old uniform seedlings were grown in half strength Johnson's nutrient solution containing 0, 25, 75, and 150 mg Si kg^{? 1} as sodium silicate. The plants were allowed to grow for 45 days after transplanting. Silicon application significantly (P ≤ 0.01) increased root and shoot dry matter production in all the rice varieties. The maximum shoot dry matter production occurred at 75 mg Si kg^?1 and decreased uniformly in all the rice varieties at 150 mg Si kg^{? 1}. However, growth response to Si application varied significantly (P ≤ 0.01) among various rice varieties. Root: shoot growth ratio, varying from 0.11 to 0.15, did not follow any trend. Different rice varieties and Si addition had a significant (P ≤ 0.01) main and interactive effect on concentration and total uptake of Si in rice root and shoot. Relative increases in Si content, both in shoot and root, were gradual and several fold with increasing rates of Si application. The effect was more pronounced in Basmati varieties (BAS-198, BAS-385, and BAS-370) than other varieties. A 0.91 mg Si g^{? 1} plant tissue was optimum for growth of KSK-133 (coarse), which was significantly higher than the optimum level, 0.62 mg Si g^{? 1} plant tissue, for Bas-370 (fine). However, further verification of the results is warranted under field situation.     

Zinc Nutrition of Onion: Proposed Diagnostic Criteria

ABSTRACT

Zinc (Zn) deficiency is a global nutritional problem in crops grown in calcareous soils. However, plant analysis criteria, a good tool for interpreting crop Zn requirement, is scarcely reported in literature for onion (Allium cepa L.). In a greenhouse experiment, Zn requirement, critical concentrations in diagnostic parts and genotypic variation were assessed using four onion cultivars (‘Swat-1’, ‘Phulkara,’ ‘Sariab Red,’ and ‘Chilton-89’) grown in a Zn-deficient (AB-DTPA extractable, 0.44 Zn mg kg^?1), calcareous soil of Gujranwala series (Typic Hapludalf). Five rates of Zn, ranging from 0 to 16 mg Zn kg^?1 soil, were applied as zinc sulphate (ZnSO₄·7H₂O) along with adequate basal fertilization of nitrogen (N), phosphorus (P), potassium (K), and boron (B). Four onion seedlings were transplanted in each pot. Whole shoots of two plants and recently matured leaves of other two plants were sampled. Zinc application significantly increased dry bulb yield and maximum yield was produced with 8 mg Zn kg^?1. Application of higher rates did not improve yield further. The cultivars differed significantly in Zn efficiency and cv. ‘Swat-1’ was most Zn-efficient. Fertilizer requirement for near-maximum dry bulb yield was 2.5 mg Zn kg^?1. Plant tissue critical Zn concentrations were 30 mg kg^?1 in young whole shoots, 25 mg kg^?1 in matured leaves, 16 mg kg^?1 in tops and 14 mg Zn kg^?1 in bulb. Zinc content in mature bulb also appeared to be a good indicator of soil Zn availability status.     

锌对不同基因型玉米幼苗光合特性及锌积累的影响

为探究不同基因型玉米幼苗对锌敏感性差异,以玉米杂交品种天农九(TN9)和信玉9(XY9)为材料,研究不同Zn浓度(0.00、0.01、0.1、1.0、10.0、100μmol·L-1)对叶片光合色素含量、光合作用参数及叶绿素荧光特性的影响。结果表明,玉米最适生长锌浓度为0.1~1μmol·L-1,低锌(0~0.01μmol·L-1)和高锌(10~100μmol·L-1)条件均对不同基因型玉米幼苗的生长产生抑制作用,其中XY9在低锌及高锌胁迫下光合参数及光合色素含量降幅显著,从而导致其植株长势和干物质积累等对锌浓度的动态响应更为强烈,而TN9则对低锌及高锌环境具有较强的适应性。同时,随着锌处理浓度的不断升高,玉米植株中锌含量和积累量均逐渐升高,锌利用率则逐渐降低,其中XY9植株锌积累量低于TN9,而锌利用率则高于TN9;相比于不敏感型品种(TN9),敏感型品种(XY9)对锌的吸收、积累和利用受锌浓度变化的影响更为明显。本研究为植物锌高效利用研究提供理论基础。     

Maize Yield Response to Zinc Sources and Effectiveness of Diagnostic Indicators

Maize yield is often limited by zinc (Zn) deficiency. The objectives of this study were to (i) evaluate maize yield response to Zn applied at four different rates, (ii) evaluate the yield response and agronomic efficiency of maize to the application of a complex fertilizer, MicroEssentials SZ (12N–40P–0K–10S–1Zn), compared to different rates of monoammonium phosphate (MAP) + ammonium sulfate (AS) + zinc sulfate (ZnSO4), and (iii) evaluate the association between tissue Zn concentration and soil-test Zn with the maize response to Zn fertilizer. Eleven experiments were carried out during the 2010, 2011, and 2012 growing seasons throughout eight states in the USA. Treatments consisted of four Zn rates of a physical blend of MAP + AS + ZnSO₄ (0, 2.24, 4.48, 6.72, and 11.2 kg/ha Zn) and MicroEssentials SZ at a Zn rate of 2.24 kg/ha Zn. Nitrogen, phosphorus (P), and sulfur (S) rates were balanced across treatments (40 kg/ha P, 22 kg/ha S) and fertilizers were broadcast and incorporated immediately prior to planting. Treatment and location main effects were significant (P < 0.001) on corn yields, whereas the interaction treatment × location was not (P = 0.33). Maize responded positively to Zn fertilization; average yields across locations increased from 10,540 kg ha^?1 without Zn to 11,530 kg ha^?1 with 11.21 kg Zn ha^?1 applied as a physical blend. The yield response and Zn agronomic efficiency of maize with the application of the complex fertilizer at a rate of 2.24 kg Zn ha^?1 averaged 1004 kg ha^?1 and 448 kg maize kg Zn^?1, respectively, significantly higher (P < 0.1) than the yield response and Zn agronomic efficiency with the application of a physical blend with the same Zn rate, which averaged 293 kg ha^?1 and 131 kg maize kg Zn^?1, respectively. The Zn concentration in plant tissue of unfertilized plots varied greatly and was not related to the maize response to Zn fertilizer (r = 0.01; P = 0.98). With respect to soil Zn, a negative but nonsignificant relationship was found between maize response to Zn fertilizer and soil-test Zn (r = ?0.51; P = 0.16).     

云南杂交玉米SSR标记核心引物的筛选及多样性分析

为降低合成引物成本,加快杂交玉米品种鉴定进程,筛选适用于云南玉米杂交种SSR标记鉴定的核心引物.本研究用玉米SSR标记鉴定规程中推荐的40对SSR引物对12个杂交玉米品种DNA进行扩增,筛选出多态性高、扩增效果好、稳定性好的20对引物,推荐其作为云南玉米杂交种特异性鉴定的核心 引物.并用筛选的核心引物对云南220个杂交...     

ROOT ZONE TEMPERATURE INFLUENCES ZINC REQUIREMENT OF MAIZE CULTIVARS ON A CALCAREOUS LOAM SOIL

The zinc (Zn) requirement of a maize (Zea mays L.) hybrid (‘FHY-396’) and an indigenous variety (‘EV-7004’) was measured at low (22.4 ± 5°C) and high (28.8 ± 5°C) root-zone temperatures (RZT). Four Zn rates (0, 3, 9 and 27 mg kg^?1 soil) were applied to a calcareous loam soil in pots for the glasshouse study. Shoot and root dry matter yields were significantly more at the higher RZT. Regardless the RZT, maximum relative shoot dry matter yield in hybrid and variety was produced, respectively, at 9 and 3 mg Zn kg^?1 soil. Zinc concentration in roots and shoots of both the cultivars increased with Zn rates and it was significantly more at the higher RZT. Cultivars differed in critical Zn concentration (C_ZnC) required for maximum shoot dry matter yield. The C_ZnC ranged from 25 to 39 μg Zn g^?1 plant tissue for optimum growth of both the cultivars at low and high RZT.     

土壤中施加锌对豌豆(Pisum sativum L.)中锌浓度以及其种子产量的影响

A 2-year field experiment was conducted to assess the effect of applied zinc（Zn） on the seed yield of pea（Pisum sativum L.） and to determine the internal Zn requirement of pea with emphasis on the seed and leaves as index tissues.The experiment was carried out at two different locations（Talagang,Chakwal district and National Agricultural Research Centre（NARC）,Islamabad） in the Potohar Plateau,Pakistan by growing three pea cultivars（Green feast,Climax,and Meteor）.The soils were fertilized with 0,2,4,8,and 16 kg Zn ha^-1 along with recommended basal fertilization of nitrogen（N）,phosphorus（P）,potassium（K）,and boron（B）.Zinc application increased seed yield significantly for all the three cultivars.Maximum increase in the pea seed yield（2-year mean） was21%and 15%for Green feast,28%and 21%for Climax,and 34%and 26%for Meteor at Talagang and NARC,respectively.In all cultivars,Zn concentrations in leaves and seed increased to varying extents as a result of Zn application.Fertiliser Zn requirement for near-maximum seed yield varied from 3.2 to 5.3 kg ha^-1 for different cultivars.Zinc concentrations of leaves and seeds appeared to be a good indicator of soil Zn availability.The critical Zn concentration range sufficient for 95%maximum yield（internal Zn requirement）was 42-53 mg kg^-1 in the pea leaves and 45-60 mg kg^-1 in the seeds of the three pea cultivars studied.     

Effect of Excess Cadmium and Zinc Ions on Roots and Shoots of Maize Seedlings

The effect of 8-day-old exposure maize seedlings with cadmium (Cd) or zinc (Zn), separately, are described with special attention being given to ultrastructural changes as well as changes of the growth. These elements, frequent pollutants found in the soil, were added as 1 mM solutions to nutrient solution used for roots and shoots of maize seedlings, investigated 8 days after germination. The symptoms of heavy metal toxicity were clear showing that Cd inhibits root growth more strongly than the shoots and more effectively than zinc ions. The results of scanning electron microscopy revealed changes in the leaf surface, particularly in the guard cells of the stomata. The ultrastructural analyses of the parenchyma mesophyll cells showed extensive chloroplast disorganization, mainly affecting the thylakoid membranes and grana.     

Critical Ratio of Calcium and Boron in Maize Shoot for Optimum Growth

Boron (B) deficiency is widely reported in alkaline calcareous soils of the world, including Pakistan. High calcium (Ca) content in such soils can affect the availability and utilization of B by plants. Effect of applied B at different levels of Ca addition on maize was studied in hydroponics. Four maize cultivars (‘EV-5089’, ‘SWL-2000’, ‘EV-6089’, and ‘Sultan’) were grown at three levels of Ca (0.25 mM, 1 mM, and 2 mM) and two levels of B (0 and 25 μ M). Application of both the nutrients increased shoot dry matter production. However, application of Ca antagonized the B concentration in shoot of four maize cultivars. A curvilinear relationship existed between Ca/B ratio in shoot and relative shoot dry matter of maize cultivars. Implication of using of Ca/B ratio for managing commonly occurring B deficiency in calcareous soils is suggested.     

Effect of Zinc Application on Cadmium Uptake of Maize Grown in Alkaline Soil

The aim of this research is to investigate the effect of zinc (Zn) application on cadmium (Cd) uptake of maize (Zea mays L.) grown in alkaline soil. Four doses of cadmium (Cd; 0, 2.5, 5, and 10 ppm) in the form of cadmium chloride and four doses of Zn (0, 10, 20, and 40 ppm) in the form of zinc sulfate were applied to the soils. Plants were harvested at the 45th day of their developments. The Cd amounts in shoots and roots were analyzed separately. Significant differences between Cd amounts in shoots and roots are obtained with the application of different Zn doses (P < 0.01). In all Cd levels, Zn application increases Cd in both shoots and roots relative to Cd contents of plants grown in the pots that not applied Zn. It is also found that Cd content of the roots is greater than that of shoots.     

Mitigation Effects of Silicon on Maize Plants Grown at High Zinc

The effects of exogenous silicon (Si) on key growth parameters and mineral nutrients were investigated in maize grown at high zinc (Zn). Four treatments with three replicates were investigated consisting of a control (basal nutrients with 0.05 mM Zn with or without 1.0 mM Si added), 0.5 mM Zn, and 0.5 mM Zn plus 1.0 mM Si. Plants growing with high Zn alone had a lower chlorophyll (Chl.) content, leaf relative water content (RWC) and produced less biomass than the control plants. Proline content and membrane permeability was higher in zinc-treated plants than in untreated controls. Compared with the plants treated with high Zn alone, added Si significantly increased plant growth, chlorophyll content, and RWC and significantly reduced the membrane permeability and proline content. As expected, added high Zn increased leaf and root Zn, but reduced leaf phosphorus (P) and iron (Fe). Added Si reduced Zn concentration and increased Fe in leaves of maize. It can be concluded that improvement in the key growth parameters tested and mineral nutrition status in maize plants grown at high Zn induced by Si addition may protect membrane permeability under high zinc, thus mitigating Zn toxicity and improving the growth of maize plants. The results of the present experiment support the conclusion that Si may be involved in physiological and nutritional changes in plants grown at high Zn.     

DISTRIBUTION AND PHYTOAVAILABILITY PREDICTION OF ZINC IN AGRICULTURAL CALCAREOUS SOILS

The extractability and distributions of zinc (Zn) were evaluated in calcareous agricultural soils from South-West Iran. Both single [diethylenetriaminepentaacetic acid (DTPA)] and sequential extraction procedures (Singh scheme) were applied to 20 representative soils. The DTPA extractable zinc levels were low (on average 3.34%). The sequential extraction procedures were also utilized for the study of zinc phytoavailability in maize plants (Zea mays L.) in a greenhouse experiment. The Singh scheme was significantly better than DTPA plus soil properties in phytoavailability prediction of zinc in soils. Significant correlations were found between the amounts of DTPA extractable zinc and the iron (Fe) oxides-bound (AFe and CFe) and residual fractions extracted by the Singh procedure. Zinc concentrations in plant samples (mean value of 27.49 mg kg^?1) were poorly correlated with the different extracted soil fractions (single and sequential). The Singh procedure provided better predictions of zinc uptake by plants than DTPA extraction method.     

Effects of Forms and Rates of Zinc Fertilizers on Cadmium Concentrations in Two Cultivars of Maize

Abstract

A pot experiment was conducted to investigate the effects of three soluble zinc (Zn) fertilizers on cadmium (Cd) concentrations in two genotypes of maize (Zea mays): Jidan 209 and Changdan 374. Zinc fertilizers were added to soil at four levels: 0, 80, 160, and 240 mg kg^?1 soil as nitrate [Zn(NO₃)₂], chloride (ZnCl₂), and sulfate (ZnSO₄). Cadmium nitrate [Cd(NO₃)₂] was added to all the treatments at a uniform rate equivalent to 10 mg kg^?1 soil. The biomass of maize plants was increased with the application of three zinc fertilizers, of which Zn(NO₃)₂ yielded more than others. Under ZnCl₂ treatment, plant growth was promoted at the lower level and depressed at the higher one. All the three fertilizers decreased Cd concentration in shoots in comparison with treatments without Zn, but there were variations with different forms, especially in plants treated with Zn(NO₃)₂, which had the minimal value. The orders of average Cd concentration in shoots with different zinc fertilizers were ZnSO₄>ZnCl₂>Zn(NO₃)₂ for Jidan 209 and ZnCl₂>ZnSO₄>Zn(NO₃)₂ for Changdan 374, respectively (P<0.001). There was no significant difference between ZnSO₄ and ZnCl₂ treatments. The lowest Cd concentration in shoots was found in the 80‐mg‐kg^?1 soil or 160‐mg‐kg^?1 soil treatment. Cadmium concentration in roots in the presence of ZnCl₂ was the lowest and under ZnSO₄ the highest. The mechanism involved needs to be studied to elucidate the characteristics of complexation of Cl^? and SO₄ ^2? with Cd in plants and their influence on transfer from roots to shoots.     

施用锌肥和硼肥对玉米穗粒性状和品质的影响

为了探究微量元素锌和硼对玉米果穗的影响,以豫单606为材料,采用盆栽试验,设置不施用锌肥和硼肥(对照,CK)、施用锌肥、施用硼肥、同时施用锌肥和硼肥4种处理,调查了玉米穗粒性状和品质的变化。结果表明,施用锌肥和硼肥,秃尖减少,行粒数增加,产量显著提高;施用锌肥籽粒长度增加,粒厚、百粒体积和百粒重降低,由于穗粒数提高,单穗产量增加;施用硼肥籽粒长度、百粒重、百粒体积和单穗产量均增加。与CK相比,单施锌肥、硼肥及锌肥和硼肥配施均能提高籽粒蛋白质含量;施用锌肥籽粒脂肪含量显著提高,施用硼肥籽粒脂肪含量降低;各施肥处理淀粉含量均无显著差异。与CK相比,施用锌肥或硼肥以及锌肥和硼肥配施显著提高了籽粒锌和硼的含量。本研究结果为锌肥和硼肥在玉米生产中的应用提供了参考。     

川中丘区玉米氮高效品种筛选及增产潜力分析

为探究高产氮高效玉米品种在减肥增效措施中的增产潜力,本研究通过对川中丘陵区近十年11个主推玉米品种在2个环境(简阳和中江)和3个氮水平[0(LN)、150(MN)和300 kg·hm^-2(HN)]下的田间产量及产量构成因子等进行方差和相关性分析,依据产量的基因型×氮互作效应对玉米品种进行氮效率分类,研究不同类型玉米的增产潜力以及与增产潜力有关的产量性状。结果表明,基因型、氮、环境及其互作显著影响玉米产量,基因型×氮互作显著影响穗粗和百粒重;11个试验玉米品种存在氮效率的基因型差异,包括双高效型、高氮高效型、耐低氮型和双低效型4种类型,其中双高效型和高氮高效型占总数的45.5%,其在HN和LN的增产潜力分别为6.74%～7.54%和9.88%～13.45%;高产氮高效品种(双高效型和高氮高效型)在2个试验点的节氮潜力差异较大,HN的节氮潜力可达19.18%以上;增产潜力与穗粗、百粒重等产量构成因子显著正相关;正红311、川单189和绵单1256在2个环境下均表现出高产氮高效品种特征。在川中丘陵区不同肥力的土壤上选择种植高产氮高效或耐低氮的玉米品种,通过合理施肥,可以...     

Labile pools of copper and zinc in calcareous soils as measured by DTPA and plant extraction

Abstract

Labile pools of Cu and Zn were measured on two calcareous soils from Saudi Arabia, using successive extraction with DTPA, and successive cropping followed by extraction with DTPA after cropping. The examined soils differed in their ability to supply Cu and Zn. The first DTPA extraction removed a major proportion of the labile pool, particularly in the sandy soil. The two soils showed a general decrease in extractable Cu and Zn with progressive extractions, with DTPA extractable Cu declining more rapidly than Zn. DTPA extractable Cu and Zn determined after cropping were highly correlated with DTPA extractable Cu and Zn values obtained after successive extractions. The results gave evidence on both the contribution of element dissolution from insoluble forms with progressive extraction or cropping, and the usefulness of the DTPA extractant for monitoring the availability of Cu and Zn in these calcareous soils.     

Yield and Zinc,Copper, Manganese and Iron Concentration in Maize (Zea mays L.) Grown on Vertisol as Influenced by Zinc Application from Various Zinc Fertilizers

Zinc (Zn) deficiency in soils and field crops is widespread across the world, including India, resulting in severe reduction in yield. Hence, soil application of Zn fertilizers is recommended for ameliorating Zn deficiency in soil and for obtaining higher crop yield and better crop quality. Zinc sulfate is commonly used Zn fertilizer in India because of its solubility and less cost. However, good quality and adequate quantity of zinc sulfate is not available in the market round the year for farmers' use. Field experiments were therefore conducted during rainy season of 2010 and 2011 at research farm of Indian Institute of Soil Science, Bhopal, India to assess the influence of Zn application through zinc sulfate monohydrate (33% Zn), zinc polyphosphate (21% Zn) and Zn ethylenediaminetetraacetate (EDTA) (12% Zn) on yield and micronutrient concentration and uptake by maize (Zea mays L.). In both the years, grain and vegetative tissue (stover) yield of maize increased significantly with successive application of Zn up to 1 kg ha^?1 added through zinc sulfate monohydrate and zinc polyphosphate. Addition of 2.5 kg Zn ha^?1 did not increase yield further but resulted in highest stover Zn concentration. Zinc, copper (Cu), manganese (Mn), and iron (Fe) concentration in maize grain varied from 22.2 to 27.6, 1.6 to 2.5, 3.5 to 4.7 and 19.9 to 24.5 mg kg^?1 respectively in both the years. Maize stover had 25.9 to 36.2, 7.9 to 9.8, 36.7 to 44.9 and 174 to 212 mg kg^?1 Zn, Cu, Mn, and Fe, respectively. Zinc application did not influence Cu, Mn and Fe concentration in both grain and stover of maize. Transfer coefficients (TCs) of micronutrients varied from 0.72 to 0.95, 0.18 to 0.30, 0.08 to 0.13 and 0.10 to 0.15 for Zn, Cu, Mn, and Fe respectively. Total Zn uptake significantly increased with Zn application from 0.5 to 2.5 kg ha^?1 supplied through zinc sulfate monohydrate and zinc polyphosphate. Recovery efficiency of Zn declined with increased Zn rates.     

新疆石灰性土壤锌有效性及其影响因素

为探讨新疆石灰性土壤锌的组分分布特征及锌有效性的影响因素,对南北疆3种最主要土壤类型农田土壤锌及其组分含量进行研究。结果表明:新疆石灰性土壤有效锌平均含量为潮土(0.69mg/kg)>棕漠土(0.57mg/kg)>灰漠土(0.51mg/kg),变异系数为灰漠土>潮土>棕漠土。在土壤锌组分中,松结有机态锌(WBO)、碳酸盐结合态锌(CARB)、氧化锰结合态锌(OxMn)、紧结有机态锌(SBO)、无定形铁结合态锌(AOFe)平均含量均为潮土>棕壤土>灰漠土。南北疆土壤锌背景值不同,南疆土壤全锌含量高于北疆土壤,而北疆土壤全锌变异较大。土壤碳酸钙含量和物理性粘粒含量与松结有机态、碳酸盐结合态、紧结有机态锌分配率高度相关。松结有机态锌、碳酸盐结合态锌及松结有机态锌分配率与土壤物理性粘粒含量呈(极)显著正相关。交换态锌与松结有机态锌呈显著正相关。松结有机态锌与碳酸盐结合态锌呈显著正相关。石灰性土壤有效锌含量与松结有机态锌、碳酸盐结合态锌含量呈显著正相关,可用方程Y=0.306+0.123WBO+0.116CARB(F=20.095,r2=0.801**)预测。     

AMELIORATION OF ZINC DEFICIENCY OF CORN IN CALCAREOUS SOILS OF THAILAND: ZINC SOURCES AND APPLICATION METHODS

A variety of zinc (Zn) fertilizer sources are applied with varied responses on calcareous soils in Thailand. Seed treatment is an alternative method to deliver Zn to corn and alleviate Zn deficiency. To address this Zn delivery methods we conducted greenhouse studies on corn grown in three calcareous soils of Thailand to three Zn fertilizer sources [zinc sulfate (ZnSO₄), Zn-ethylenediaminetetraacetic acid (EDTA) and Zn citrate]. We also evaluated effectiveness of soaking corn seed in three concentrations of ZnSO₄ (0.4, 0.8 and 1.6%) prior to planting compared to soil applied methods. Applications of zinc increased the growth, dry matter yield and zinc uptake of corn with few differences observed among the types of fertilizers. Seed soaking with ZnSO₄ solution also increased Zn uptake, growth rate and yield comparable to soil-applied Zn. Seed soaking prior to planting is an effective and efficient method to supply Zn to corn grown in Zn deficient calcareous soils of Thailand.