磷锌肥配施对冬小麦籽粒锌生物有效性的影响

为查明磷锌肥配施对小麦籽粒锌生物有效性的影响, 本研究选用锌效率不同的4种冬小麦基因型, 从P-Zn-植酸关系出发, 进行了田间试验。结果表明, 锌肥的施用在不同程度上降低了小麦籽粒的磷含量、磷锌比、植酸含量以及[植酸]/[Zn²⁺]摩尔比, 降低幅度分别为0.5%、1.85%、2.7%及6.2%, 提高了小麦籽粒的锌生物有效性。相对于锌肥, 磷肥对小麦籽粒植酸含量及[植酸]/[Zn²⁺]摩尔比的影响更大: ①总体上提高了小麦籽粒中的植酸含量及[植酸]/[Zn²⁺]摩尔比, 降低了小麦籽粒锌生物有效性, 以施用100 kg·hm^-2磷肥时为例, 植酸含量及[植酸]/[Zn²⁺]摩尔比与不施磷肥相比分别提高13.4%和25.94%; ②植酸含量及[植酸]/[Zn²⁺]摩尔比随着磷肥用量的增加呈单峰曲线变化, 并分别在100 kg·hm^-2和150 kg·hm^-2用量下达到5.02 mg·g^-1和11.56的峰值, 而过量施用磷肥会降低小麦籽粒中植酸的合成和累积; ③[植酸]/[Zn²⁺]摩尔比在适量施磷(100 kg·hm^-2)条件下与少量(50 kg·hm^-2)施磷相比几乎没有变化, 但明显低于高量施磷(150 kg·hm^-2)。总之, 通过合理的磷肥调控, 辅以锌肥的施用, 相对降低小麦籽粒的[植酸]/[Zn²⁺]摩尔比可能是提高小麦籽粒锌生物有效性的关键。     

氮肥用量和喷施锌钾肥对小麦籽粒锌含量及生物有效性的影响

  【目的】  小麦籽粒锌(Zn)含量普遍较低,在没有外源锌施用措施下难以满足以小麦为主食人群健康所需。探索提升小麦籽粒Zn含量,尤其是其加工产品面粉Zn含量和Zn生物有效性的农艺措施,具有实际重要的意义。  【方法】  于2013、2014年分别在陕西杨凌示范区和三原试验站进行小麦田间试验,两地均为潜在缺锌石灰性土壤,DTPA-Zn含量分别为0.67、0.90 mg/kg,种植制度为小麦–玉米轮作。以氮肥用量为主处理,杨凌试验点为N 0 (N₀)、120 (N₁)和240 (N₂) kg/hm2;三原试验点为传统施氮量(N 150 kg/hm2,N_C)、减氮15% (N 127.5 kg/hm2,N_R1)和减氮30% (N 105 kg/hm2,N_R2)。喷施处理为副处理,两地均为灌浆前期喷施清水(CK)、0.5% K₂SO₄ (K)、0.3% ZnSO₄·7H₂O (Zn)和0.3% ZnSO₄·7H₂O+0.5% K₂SO₄ (Zn+K)。测定了小麦籽粒及其加工面粉Zn等矿质养分含量、Zn形态及锌生物有效性。  【结果】  杨凌试验点,中等施氮量N₁ (120 kg/hm2)处理显著增加了小麦籽粒全粒及面粉和麸皮Zn含量,分别较N₀提高了8.78%、13.2%和17.3%,而N₂ (240 kg/hm2)降低了全粒及其各组分Zn含量,N₁处理显著降低了各加工组分植酸含量;与Zn处理相比,Zn+K处理对小麦全粒Zn含量提升幅度两季平均达13.1%;在中等施氮量条件下,Zn+K处理与Zn处理相比显著增加了面粉Zn含量,特别是增加了可溶性Zn含量,还大幅度降低了全粒和面粉的植酸/Zn摩尔比;氮肥用量与喷肥处理对籽粒Zn形态和Zn生物有效性具有显著的交互作用。三原试验点,小麦全粒、面粉和麸皮Zn含量均在N_R1处理下达到最高;与Zn处理相比,Zn+K处理并未显著影响小麦籽粒及其加工组分Zn含量;施氮量与喷施锌钾肥处理的交互作用(N×Zn)对面粉Zn含量两季均有显著影响。  【结论】  在北方潜在缺锌石灰性土壤上,适宜的氮肥用量和叶面喷施锌肥均可显著提升小麦籽粒和面粉Zn含量,降低植酸/Zn摩尔比,提高锌的生物有效性,且氮肥用量与喷施锌肥对提升小麦锌含量有显著的交互作用。喷施效果以锌与钾肥配合总体好于单独喷施硫酸锌。综合两地两年试验结果,获得高锌小麦的适宜氮肥用量为120 kg/hm2左右,喷施效果以硫酸锌和硫酸钾配合喷施为好。     

我国主要麦区小麦籽粒锌含量对叶喷锌肥的响应

【目的】我国小麦籽粒锌含量普遍偏低,叶喷锌肥是提高小麦籽粒锌含量的重要措施,研究我国主要麦区小麦籽粒锌含量对叶喷锌肥的响应,对小麦科学施用锌肥、 调控小麦籽粒锌营养状况有重要意义。【方法】本研究在我国14个省(市)主要麦区布置了30个田间试验,在每个试验点设置不喷锌对照和叶面喷锌两个处理,以当地主栽小麦品种为供试作物,通过测定收获期小麦产量、 各器官锌含量,研究了叶喷锌肥提高小麦籽粒锌含量的效果、 区域差异及其与土壤主要理化性质、 小麦拔节前植株锌含量的关系。【结果】 30个试验点的结果显示,叶面喷锌对小麦籽粒产量、 生物量和收获指数均无明显影响,但籽粒锌含量显著提高,叶面喷锌的籽粒锌含量比对照平均提高5.2 mg/kg(17.5%), pH7.0的区域提高5.3 mg/kg(16.4%), pH 7.0的区域提高5.2 mg/kg(18.4%)。小麦地上部锌吸收与分配在两个区域间没有显著差异,叶面喷锌的小麦籽粒、 颖壳和茎叶平均锌吸收量分别为255.5、 26.0和117.5 g/hm2,比对照增加19.4%、 28.7% 和99.2%; 锌收获指数为64.1%,比对照降低12.2%。籽粒锌利用率和籽粒锌强化指数也不受区域的影响,平均值锌利用率为3.0%,锌强化指数为3.8 mg/kg。无论叶面喷锌与否,籽粒锌含量和土壤有效锌均呈显著正相关,土壤有效锌含量每升高1.0 mg/kg,籽粒锌含量平均提高约4.0 mg/kg; 籽粒锌含量和土壤pH呈显著负相关,土壤pH每升高1个单位,籽粒锌含量平均降低3.8 mg/kg; 籽粒锌含量与土壤有机质没有显著相关性。小麦籽粒锌含量与拔节前植株锌含量极显著正相关,拔节前植株锌含量每升高1.0 mg/kg,籽粒锌含量平均提高0.4 mg/kg。【结论】 除叶面喷施锌肥外,调节土壤酸碱性,提高土壤有效锌含量,促进小麦生长前期植株对锌的吸收对改善我国小麦锌营养均具有重要意义。     

土施和喷施锌肥对冬小麦子粒锌含量及生物有效性的影响

为揭示潜在性缺锌土壤上不同施锌方式对小麦子粒锌含量及其生物有效性的影响,选用5个冬小麦品种进行了土施和喷施锌肥的田间裂区试验。结果表明,供试土壤条件下,不同施锌方式对小麦产量均无明显影响,但是在一定施锌方式下小麦子粒锌含量大幅度提高。与对照相比,土施、喷施及土施+喷施锌肥提高小麦子粒锌含量幅度分别为-6.1%、64%和83%,提高小麦子粒锌携出量幅度分别为-3.6%、69%和83%。3个施锌处理降低子粒中植酸含量的幅度分别为-2.4%、7.2%和1.5%,降低植酸与锌摩尔比的幅度分别为-25%、41%和44%,且不同品种之间也存在一定差异;虽然植酸与锌的摩尔比有所下降,但仍高于20。此外,单独土施锌肥虽可大幅度提高耕层土壤有效锌含量,但对子粒锌含量及生物有效性的影响很小。总之,在小麦生长后期喷施锌肥是提高潜在性缺锌土壤上小麦子粒锌含量和生物有效性较为经济的方式,对改善小麦锌营养品质有较好作用。     

旱地高产小麦品种籽粒锌含量差异与氮磷钾吸收利用的关系

【目的】明确旱地条件下高产小麦品种籽粒锌含量差异与氮磷钾吸收利用的关系，为品种选育和科学施肥提供依据。【方法】于2013—2016年连续三年在黄土高原旱地进行田间试验，试验采用裂区设计，主处理为不施肥 (CK) 和施肥 (NP)，副处理为来自我国主要麦区的123个品种。施肥处理为N 150 kg/hm2 (尿素，含N46%)、P₂O₅100 kg/hm2 (过磷酸钙，含P₂O₅ 16%)。成熟期在每个品种中间2行随机抽取30穗小麦，连根拔起后，从根茎结合处剪断弃去根系，分为茎、叶、颖壳 (含穗轴) 和籽粒，称风干重。分析了样品中氮、磷、钾、锌含量，计算了养分的吸收量及转移量。【结果】施肥条件下高产小麦品种籽粒锌含量存在显著差异，高锌品种比低锌品种显著高54%。高锌品种的籽粒氮、磷含量分别比低锌品种显著高9%、7%，钾含量无显著差异，施肥使两组品种的氮含量显著提高，磷钾含量降低。高产高锌品种具有更高的籽粒和地上部氮、磷吸收能力，钾吸收能力与低锌品种相比无显著差异，施肥可使高锌品种的氮磷钾吸收量增幅高于低锌品种；两组品种间的氮、磷转移能力无显著差异，而高锌品种的钾转移能力较低，且两组品种的氮磷钾转移能力因施肥降低幅度一致。【结论】旱地条件下土壤养分供应充足时，高产高锌小麦品种的氮磷吸收能力强，钾转移能力弱，籽粒氮磷含量高，与低锌品种相比钾含量无显著差异。通过品种选育可同时提高旱地高产小麦籽粒锌和蛋白质含量，并提高磷含量。考虑到磷含量高时会降低籽粒锌的生物有效性，生产中通过施肥措施，适当调控磷肥，增加氮肥，在提高小麦籽粒氮锌含量的同时提高籽粒锌的生物有效性。     

生物强化提高水稻糙米锌含量及其生物有效性

【目的】研究利用有机锌肥生物强化水稻糙米锌含量的可行性及其生物可给性。【方法】锌生物强化试验在江苏溧阳进行，供试锌肥为糖醇螯合态锌(Zn 170 g/L)，供试水稻品种为中熟晚粳稻‘南粳46’。设5个处理：喷施清水(CK)；锌肥喷施一次，用量为2.55 kg/hm² (Zn1)、5.10 kg/hm² (Zn2)；锌肥喷施两次，总施用量为5.10 kg/hm² (Zn3)、10.20 kg/hm² (Zn4)。水稻成熟后，测定糙米中锌、植酸含量，测定糙米中锌赋存形态含量，计算糙米植酸/锌摩尔比、糙米锌赋存形态占比，并利用in vitro人工胃肠模拟法分析糙米锌在胃阶段和胃肠阶段的溶出量，以溶出锌与糙米锌量之比来计算糙米锌生物可给性。【结果】与CK处理相比，锌生物强化对糙米植酸含量无显著影响，但显著提高了糙米锌含量，Zn1、Zn2、Zn3和Zn4处理的增幅分别为23.93%、37.51%、82.38%和87.81%,Zn3和Zn4处理增幅差异不显著。Zn1、Zn2处理对糙米植酸/锌摩尔比无显著影响，Z...     

旱地高产小麦品种籽粒锌含量差异与产量构成和锌吸收利用的关系

【目的】 明确旱地条件下高产小麦品种籽粒锌含量差异与产量构成及锌吸收利用的关系，对通过品种选育和施肥调控提高旱地小麦籽粒产量和锌营养，实现小麦高产优质生产有重要意义。 【方法】 于2013—2016年连续三年在黄土高原典型旱地进行了小麦裂区田间试验。 以我国主要麦区的123个小麦品种为试材，每个品种设置不施肥和施N 150 kg/hm2、P₂O₅ 100 kg/hm2两个处理。分析了高产小麦籽粒锌含量差异及其与干物质累积、产量构成、锌吸收和分配之间的关系。 【结果】 施肥条件下，高产小麦品种籽粒锌含量存在显著差异，小麦籽粒锌含量与籽粒产量间无显著相关性，但与千粒重、锌吸收量、锌收获指数和籽粒锌形成效率呈显著正相关，与穗粒数呈显著负相关。在高产品种中，无论施肥与否高锌品种的籽粒锌含量均显著高于低锌品种；高锌品种的籽粒锌含量因施肥而显著提高，低锌品种却降低。施肥条件下，高锌品种的籽粒产量、生物量和收获指数与低锌品种相比无显著差异，穗数却显著降低；高锌品种的籽粒锌吸收量、地上部锌吸收量、锌收获指数和籽粒锌形成效率均显著高于低锌品种。且高锌品种的产量、生物量、穗数、穗粒数和锌吸收量因施肥引起的提高幅度均亦显著高于低锌品种。 【结论】 在黄土高原旱地低锌土壤上，无论是品种选育还是施肥调控，促进小麦锌的吸收和向籽粒的转移是提高小麦籽粒锌含量的关键。      

锌肥施用方式对小麦、玉米产量和籽粒锌含量的影响

以"郑单958"和"先玉335"玉米品种,"良星99"小麦品种为试验材料,在田间试验条件下研究了土施和叶面喷施锌肥对小麦、玉米产量和籽粒锌含量的影响。结果表明:在华北石灰性土壤上,土施和叶面喷施锌肥并没有显著提高玉米产量,小麦产量有一定程度增加;土施以及叶面喷施锌肥均显著提高小麦、玉米籽粒锌含量,叶面喷施锌肥的效果更好,并且小麦籽粒锌含量增加幅度显著高于玉米。土施和叶面喷施均能显著降低小麦、玉米籽粒磷锌摩尔比,增加籽粒锌的生物有效性,叶面喷施的效果更好。因此,单独叶面喷施锌肥或与土施相结合是提高小麦、玉米籽粒锌含量的有效措施,是保障人体锌营养健康的重要途径之一。     

旱地石灰性土壤上长期施磷对小麦籽粒铁锰铜锌含量的影响

  【目的】  研究石灰性土壤上施用磷肥引起的小麦铁、锰、铜、锌含量的变化及其与作物养分吸收和土壤养分有效性的关系,为旱地小麦磷肥合理施用和丰产优质生产提供科学依据。  【方法】  于2004年在陕西杨凌设置不同磷肥用量的长期定位田间试验,土壤为石灰性土壤,pH 8.3。试验在每个小区施氮(N) 160 kg/hm2的基础上,设置施用P₂O₅ 0、50、100、150、200 kg/hm2 5个水平。于2013—2016年3个收获期取样,测定了小麦地上部各器官生物量和铁、锰、铜、锌含量,及0—20和20—40 cm土层土壤有效铁锰铜锌含量。  【结果】  与不施磷相比,施用磷肥提高了小麦产量和籽粒铁、锰含量,但降低了籽粒铜、锌含量,同时提高了土壤有效铁、锰、锌含量,对有效铜含量影响不显著。进一步回归分析得出,施P₂O₅ 165 kg/hm2时产量最高,为6492 kg/hm2;施P₂O₅ 100 kg/hm2时籽粒铁含量最高,为41.7 mg/kg;施P₂O₅ 94 kg/hm2时籽粒锰含量最高,为37.5 mg/kg;施P₂O₅ 136 kg/hm2时籽粒锌含量最低,为25.4 mg/kg;籽粒铜含量在每增施P₂O₅ 100 kg/hm2时会降低0.4 mg/kg。土壤有效锰、锌在施P₂O₅ 100 kg/hm2时达到最大值,比对照分别提高24%和35%;土壤有效铁在施P₂O₅ 200 kg/hm2时增幅最大,为8%;土壤有效铜在各施磷量下无显著变化。产量为最高产量的95% 时施磷量为 108 kg/hm2,当超过这一施磷量时,产量增幅减小,籽粒铁锰含量不再增加,铜锌含量持续降低。  【结论】  黄土高原石灰性旱地土壤上,长期施磷提高了小麦籽粒铁、锰含量,降低了籽粒铜、锌含量。籽粒铁、锰含量增加与土壤有效铁、锰增加促进了小麦的吸收及向籽粒的转移有关,而籽粒铜、锌含量降低与施磷后土壤有效铜没有显著提高,且高磷抑制铜转运和锌吸收有关。为了兼顾小麦高产与营养平衡,这一地区的施磷量应不超过P₂O₅ 108 kg/hm2,以防止小麦籽粒铜、锌含量进一步降低,并维持合适的籽粒铁、锰含量。     

长期不同氮、 磷用量对冬小麦籽粒锌含量的影响

【目的】小麦是我国西北地区主要的粮食作物,主要种植在低锌的石灰性土壤上,其籽粒锌含量普遍较低,难以满足人们的锌营养需求,因此提高冬小麦籽粒中的锌含量对保证人体健康具有非常重要的意义。氮素、 磷素供应不足或过量会影响冬小麦对锌的吸收与利用,本文基于黄土高原南部9年的长期定位试验,研究了长期不同氮、 磷肥用量对旱地冬小麦籽粒锌含量的影响及籽粒锌含量与氮、 磷吸收与分配的关系,以期为有效调控冬小麦籽粒锌营养品质和优化旱地冬小麦氮、 磷肥管理提供理论依据和切实可行的措施。【方法】田间定位试验开始于2004年10月,位于陕西杨凌西北农林科技大学农作一站。采用单因素完全随机区组设计,重复4次。供试小麦品种为小偃22,整个生育期不灌水。试验一为小麦施氮量试验,在施磷量为P2O5100 kg/hm2的基础上,设置0、 80、 160、 240、 320 kg/hm2 5个氮肥(N)水平;试验二为小麦施磷量试验,在施氮量为N 160 kg/hm2的基础上,设置P2O5 0、 50、 100、 150、 200 kg/hm2 5个磷肥水平。分别于2011～2013年连续两年进行田间取样,测定小麦籽粒产量及其构成因素,籽粒、 茎叶和颖壳中的氮、 磷、 锌含量,计算小麦地上部的氮、 磷、 锌吸收量。【结果】小麦施氮量试验表明,氮肥用量不超过N 320 kg/hm2时,小麦籽粒锌含量和地上部锌吸收量与施氮量呈极显著的正相关关系,施氮量每增加N 100 kg/hm2,籽粒锌含量平均提高4.0 mg/kg,地上部锌吸收量平均提高36.4 g/hm2;籽粒中的锌含量与氮含量之间、 地上部的锌吸收量与氮吸收量之间也均呈极显著的正相关关系,籽粒氮含量每增加1 g/kg,籽粒锌含量平均提高2.0 mg/kg,地上部氮吸收量每增加100 kg/hm2,其锌吸收量平均提高142.9 g/hm2。小麦施磷量的试验结果表明,施磷量不超过200 kg/hm2时,籽粒锌含量与施磷量呈极显著的负相关关系,施磷量每增加P2O5 100 kg/hm2,籽粒锌含量平均下降9.2 mg/kg;籽粒锌含量与磷含量也呈极显著的负相关关系,籽粒磷含量每增加1 g/kg,籽粒锌含量平均降低24.0 mg/kg;地上部锌吸收量与施磷量、 地上部磷吸收量之间均没有显著相关关系。【结论】综合考虑冬小麦籽粒产量和籽粒锌含量,建议这一地区冬小麦的施氮量和施磷量分别控制在N 160～240 kg/hm2和P2O5 50～100 kg/hm2。     

Fortification of Bread Wheat Using Synthesized Zn-Glycine and Zn-Alanine Chelates in Comparison with ZnSO4 in a Calcareous Soil

ABSTRACT

Calcareous soils typically suffer from zinc deficiency and zinc sulfate is incorporated in many cultivated soils. Utilization of ZnSO₄ has some kinds of interaction with soil particles and organic matter. In this study, the efficacy of two znic(Zn)-amino acid chelates (Zn-ACs) i.e., Zn-alanine (Zn-Ala) and Zn-glycine (Zn-Gly) on wheat (Triticum aestivum, cv. N91-8) growth characteristics and zinc concentration in wheat was examined under greenhouse conditions and compared to the a commercial ZnSO₄. Results showed that Zn-Ala and Zn-Gly significantly increased the dry weight and shoot length of wheat in comparison to ZnSO₄ treatment. Soil application of Zn-Amino acid chelates proved to be the most influential source of zinc in increasing wheat growth and yield indices. Number of fertile spikelet and grain yield increased significantly respectively compared to ZnSO₄ treatment. Zn concentration and protein content of wheat grain in Zn-ACs treatment was significantly higher than the ZnSO₄ treatment. Soil application of Zn-ACs caused a significant decrease in the grain phytic acid (PA) concentration and also phytic acid to zinc molar ratio in comparison with ZnSO₄ treatment. According to the results, Zn-ACs could be utilized as a zinc fertilizer source for improving the zinc bioavailability in wheat.     

Phytic acid,iron and zinc content in wheat ploidy levels and amphiploids: the impact of genotype and planting seasons

Micronutrient deficiency is one of the most common and widespread nutritional issues. Among the factors mitigating the bioavailability of Zn (zinc) and Fe (iron), phytic acid plays a key role; therefore, in order to scrutinize genetic alterations ?related to micronutrient and phytate contents, we examined the concentrations of zinc, iron, and phytic acid, as well as its mole ratio to ?zinc in various wheat species grown in two planting seasons. The concentrations of phytic acid and its mole ratio to zinc were 0.61?1.55 g kg^?1 dry weight and 1.88?4.17 for autumn, and 0.97?2.02 g kg^?1 dry weight and 2.10?4.05 for spring planting. There was a significant discrepancy among wheat species; tritipyrum had the highest concentration of iron, phytic acid and its mole ratio to zinc, and T. monococcum and T. aestivum recorded reasonable zinc bioavailability. Correlation studies between grain phytic acid concentrations and other measured traits revealed various relationships, denoting an irrefutable impact of planting season and wheat ploidy levels on modification of wheat genotypes. The characters contributing more positively with principal component (PC) 1 were Zn and Fe under spring planting and Fe under autumn planting. Spike number per square meter, biological yield and grain yield in spring cultivation, and grain zinc concentration in autumn cultivation were positively correlated to principal component (PC) 2. Given that the concentration of Fe and Zn in all the studied genotypes is relatively high and due to the existence of other desirable agronomic traits, this study believes that it could possibly enhance the applicability of some of these genotypes for breeding purposes.     

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.     

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.     

Response of Wheat Plants to Zinc,Iron, and Manganese Applications and Uptake and Concentration of Zinc,Iron, and Manganese in Wheat Grains

This experiment was conducted at Zahak Agricultural Research Station in the Sistan region in southeast Iran. A factorial design with three replications was used to determine the effects of zinc (Zn), iron (Fe), and manganese (Mn) applications on wheat yield, Zn, Fe, and Mn uptakes and concentrations in grains. Four levels of Zn [soil applications of 0, 40, and 80 kg ha^?1 and foliar application of 0.5% zinc sulfate (ZnSO₄) solution], two levels of iron sulfate (FeSO₄; 0 and 1%) as foliar application, and two levels of Mn (0 and 0.5%) also as foliar application were used in this study. Results showed that the interactive effects of Zn and Mn were significant on the number of grains in each spike. The highest number of grains resulted from the application of 80 kg ZnSO₄ ha^?1 and foliar Mn. The interactive effects of Zn and Fe were significant on weight of 1000 grains. The highest weight of 1000 grains resulted from application of 80 kg Zn and foliar Fe. Application of 80 kg ZnSO₄ ha^?1 alone and 80 kg ZnSO₄ ha^?1 with foliar application of Mn significantly increased grain yield in 2003. The 2‐year results showed that foliar application of Zn increased Zn concentration and Fe concentration in grains 99% and 8%, respectively. Foliar application of Fe resulted in a 21% increase in Fe concentration and a 13% increase in Zn concentration in grains. The foliar application of Mn resulted in a 7% increased in Mn concentration in grains.     

Zinc fertilization approaches for agronomic biofortification and estimated human bioavailability of zinc in maize grain

Maize (Zea mays L.) is generally low in bioavailable zinc (Zn); however, agronomic biofortification can cure human Zn deficiency. In the present experiment, Zn was applied in pots as ZnSO₄ · 7H₂O to maize cultivar DK-6142 as foliar spray (0.5% w/v Zn sprayed 25 days after sowing and 0.25% w/v at tasseling), surface broadcasting (16 kg Zn ha^?1), subsurface banding (16 kg Zn ha^?1 at the depth of 15 cm), surface broadcasting + foliar and subsurface banding + foliar in comparison to an unfertilized control. As compared to control, all treatments significantly (P ≤ 0.05) increased growth, yield and nutritional attributes in maize. Grain Zn and protein concentrations were correlated and ranged from 22.3 to 41.9 mg kg^?1 and 9 to 12 %, respectively. Zinc fertilization also significantly reduced grain phytate and increased grain Zn concentration. Zinc fertilization, especially broadcasting and subsurface banding combined with foliar spray decreased grain [phytate]:[Zn] ratio to 28 and 21 and increased Zn bioavailability by trivariate model of Zn absorption to 2.04 to 2.40, respectively. Conclusively, broadcasting and subsurface banding combined with foliar spray is suitable for optimal maize yield and agronomic Zn biofortification of maize grain. This would also be helpful to optimize Zn and protein concentration in maize grain.     

Zinc bioavailability and nitrogen concentration in grains of wheat crop sprayed with zinc sulfate,ammonium sulfate,ammonium chloride,and urea

Abstract

It is still unclear if different sources of nitrogen (N) can variably influence grain accumulation of zinc (Zn), N, and phytate. We tested foliar treatments of 0 or 0.25% Zn as zinc sulfate in combination with 0 or 1% N as ammonium chloride, ammonium sulfate or urea sprayed on field-grown-wheat (Triticum aestivum L.) foliage at anthesis and 10 days later. Leaf burning caused by ammonium chloride significantly decreased grain yield. Grain N concentration was the highest in the urea +0.25% Zn treatment. Foliar N application influenced grain Zn concentration only if Zn was included in the spray. Grain phytate concentration was significantly decreased by both N and Zn sprays. Estimated Zn bioavailability in grains was the highest at 0.25% Zn and was not influenced by the N sources. Based on grain yield, grain N concentration, and Zn bioavailability in grains, foliar application of Zn?+?urea is an optimal strategy.     

Zinc in wheat grain as affected by nitrogen fertilization and available soil zinc

Greenhouse and field experiments were conducted to determine the influence of nitrogen (N) fertilization and DTPA‐extractable soil zinc (Zn) on Zn concentration in wheat (Triticum aestivum L., cv. Pioneer 2375) grain. Application of zinc sulfate (ZnSO₄) in the range of 0 to 8 mg Zn kg^‐1 increased linearly DTPA‐extractable Zn in an incubated calcareous soil from 0.3 to 5.0 mg kg^‐1. Application of these rates of ZnSO₄ to the same soil under greenhouse conditions increased Zn concentration of wheat grain from 26 to 101 mg kg^‐1. The influence of 134 kg urea‐N ha^‐1 on Zn concentration in wheat grain at eight field sites, with DTPA‐extractable soil Zn levels ranging from 0.3 to 4.9 mg kg^‐1, was studied. Nitrogen fertilizer increased wheat‐grain yields in four of the eight experiments but had little effect on grain‐Zn concentration. Grain‐Zn concentration ranged from 31 to 45 mg kg^‐1 in N‐fertilized plots at the various sites and was related (r=0.74*) to DTPA‐extractable soil Zn.     

Zinc biofortification of bread wheat,triticale, and durum wheat cultivars by foliar zinc fertilization

Poor zinc (Zn) nutrition of wheat is one of the main causes of poor human health in developing countries. A field experiment with no zinc and foliar zinc application (0.5% ZnSO₄.7H₂O) on bread wheat (8), durum wheat (3), and triticale (4) cultivars was conducted in a randomized block design with three replications in 2 years. The experimental soil texture was loamy sand with slightly alkalinity. The grain yields of bread wheat, triticale, and durum wheat cultivars increased from 43.6 to 56.4, 46.5 to 51.6, and 49.4 to 53.5 t ha^?1, respectively, with foliar application of 0.5% ZnSO₄.7H₂O. The highest grain yield was recorded by PBW 550 (wheat), TL 2942 (triticale), and PDW 291 (durum), which was 5.22, 4.24, and 4.56% and significantly higher over no zinc. Foliar zinc application increased zinc in bread wheat, triticale, and durum wheat cultivars grains varying from 31.0 to 63.0, 29.3 to 61.8, and 30.2 to 62.4?mg kg^?1, respectively. So, agronomic biofortification is the best way which enriching the wheat grains with zinc for human consumption.