Behavior of zinc from six organic fertilizers applied to a navy bean crop grown in a calcareous soil

The objective of this study was to compare the mobility, leaching, availability, and relative effectiveness of Zn from Zn-polyhydroxyphenylcarboxilate (Zn-PHP), Zn-HEDTA (Zn-N-2-hydroxyethyl-ethylenediaminetriacetate), Zn-EDDHSA [Zn-ethylenediamine-di-(2-hydroxy-5-sulfophenylacetate)], Zn-EDTA (Zn-ethylenediaminetetraacetate), Zn-S,S-EDDS (Zn-ethylenediaminedisuccinate), and Zn-EDTA-HEDTA sources by applying different Zn rates (5 and 10 mg kg(-1)) to a calcareous soil under greenhouse conditions. A lysimeter experiment was carried out for 60 days and using navy bean (Phaseolus vulgaris L.) as an indicator plant. The Zn available to the plant and easily leachable Zn were determined in soil by different single extractions, while the distribution of Zn in the soil was assessed by sequential speciation. The utilization of applied Zn by the navy bean was greatest when the Zn treatments were Zn-EDTA, Zn-EDTA-HEDTA, Zn-HEDTA, and Zn-EDDHSA. Both total Zn in the plants and soluble Zn in the plant dry matter (extracted with 1 mM 2-morpholino-ethanesulfonic acid) were positive and significantly correlated with the following: the amounts of Zn extracted with the three single extractions used to estimate soil available Zn and the amounts of Zn in the water soluble plus exchangeable and organically complexed fractions. The Zn-HEDTA, Zn-EDDHSA, Zn-EDTA-HEDTA, Zn-S,S-EDDS, and Zn-EDTA sources significantly increased the mobility of micronutrients through the soil with respect to the control and Zn-PHP source. The maximum Zn concentration obtained in the leachate fractions was 65 mg L(-1) (13% of Zn applied) for the Zn-S,S-EDDS chelate applied at a rate of 10 mg Zn kg(-1) soil. In the course of the crop, the soil pH + pe parameter increased significantly with experimental time.     

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.     

Zinc transformations in neutral soil and zinc efficiency in maize fertilization

The effect of six Zn sources (Zn-phenolate, Zn-EDDHA, Zn-EDTA, Zn-lignosulfonate, Zn-polyflavonoid, and Zn-glucoheptonate) was studied by applying different Zn levels to a representative Calcic Haploxeralf neutral soil (the predominant clay is montmorillonite) in incubation and greenhouse experiments. Zinc soil behavior was evaluated by sequential DTPA and Mehlich-3 extraction procedures. In the incubation experiment, the highest percentage recovery values of Zn applied to soil occurred in the water-soluble plus exchangeable fraction (29%) in fertilization with 20 mg of Zn kg(-1) of Zn-EDTA fertilizer. In the greenhouse experiment with maize (Zea mays L.), a comparison of different Zn carriers showed that the application of six fertilizers did not significantly increase the plant dry matter yield among fertilizer treatments. The highest yield occurred when 20 mg of Zn kg(-1) was applied as Zn-EDDHA fertilizer (79.4 g per pot). The relative effectiveness of the Zn sources in increasing Zn concentration in plants was in the following order: Zn-EDTA (20 mg kg(-1)) > Zn-EDDHA (20 mg kg(-1)) approximately Zn-EDTA (10 mg kg(-1)) > Zn-EDDHA (10 mg kg(-1)) approximately Zn-phenolate (both rates) approximately Zn-polyflavonoid (both rates) approximately Zn-lignosulfonate (both rates) approximately Zn-glucoheptonate (both rates) > untreated Zn. The highest amounts of Zn taken up by the plants occurred when Zn was applied as Zn-EDTA fertilizer (20 mg kg(-1), 7.44 mg of Zn per pot; 10 mg kg(-1) Zn rate, 3.93 mg of Zn per pot) and when Zn was applied as Zn-EDDHA fertilizer (20 mg kg(-1) Zn rate, 4.66 mg Zn per pot). After the maize crop was harvested, sufficient quantities of available Zn remained in the soil (DTPA- or Mehlich-3-extractable Zn) for another harvest.     

Accumulation of zinc,phosphorus, and magnesium by navy bean seed

Considerable variation is found in zinc (Zn Concentration in navy bean (Phaseolus vulgaris L.) seed, an important food source of Zn and magnesium (Mg). The influence that phosphorus (P) and Zn fertilizers, and source of nitrogen (N) (inoculation with Rhizobium phaseoli versus 150 mg/kg NH₄NO₃‐N) had on growth and nutrient uptake of ‘Upland’ navy bean was studied under greenhouse conditions on a Glyndon loamy fine sand, a Calciaquoll low in available N, P, and Zn. Yields of stems (+ pod walls), blades, and seed were increased by N, P, and Zn fertilizers. Zinc concentration at maturity varied between 13 and 37 mg/kg for seed, 15 and 39 mg/kg for blades, and 5 and 30 mg/kg for stems. Zinc fertilizer was the chief factor responsible for this variability. Phosphorus concentration at maturity varied between 4.0 and 6.2 g/kg for seed, 1.9 and 11.8 g/kg for blades, and 1.0 to 2.7 g/kg for stems. Added P fertilizer increased P concentration in the three tissues, but the effect was most pronounced for blades of plants without added Zn. Magnesium concentration at maturity was mainly affected by N fertilizer.and ranged from 1.6 to 1.9 g/kg for seed, 4.0 and 9.7 g/kg for blades, and 4.0 to 7.1 g/kg for stems. Soil management can greatly affect Zn concentration in navy bean seed.     

Differential responses of soybean and dry bean to zinc deficiency 1

Whether a legume obtains its nitrogen (N) from the air, through dinitrogen fixation, or from the soil, as nitrate (NO₃), may influence its susceptibility to zinc (Zn) deficiency. The influence of N source [potassium nitrate (KNO₃)+ native soil N versus rhizobium‐inoculated seed + native soil N] and phosphorus (P) (0 and 200 mg P/kg), and Zn fertilizers (0, 1, and 8 mg Zn/kg) on growth and nutrient composition of soybean (Glycine max L. cv. McCall) and navy bean (Phaseolus vulgaris L. cv. Seafarer) grown on a calcareous soil were studied under greenhouse conditions. Inoculated plants, but not their KNO₃‐treated counterparts, had root nodules. However, due to N deficiency resulting from suboptimal N fixation, growth of these inoculated plants, especially of navy bean, was poorer than that of similarly treated KNO₃‐fed plants. As a consequence of this restricted growth, responses to P and Zn fertilizers were generally greater in KNO₃‐treated plants. Added P decreased the yield of KNO₃‐treated navy bean in the absence of added Zn, but P‐induced Zn deficiency had little effect on the growth of similarly treated inoculated plants. Plant excess bases (EB)/total plant N ratios [EB = 1/2 Ca + l/2Mg + Na + K ‐ Cl ‐ total S (S = divalent) ‐ total P (P = monovalent)] were less in KNO₃‐treated soybean than in correspondingly treated navy bean. Therefore, rhizosphere pH values around navy bean roots were probably less than those around soybean roots. Despite the hypothesized lower rhizosphere pH values, KNO₃‐treated navy bean was more susceptible to Zn deficiency than soybean. This greater susceptibility of navy bean to Zn deficiency was apparently at least partly due to poor translocation of Zn from the roots to the tops.     

Zinc transformations in acidic soil and zinc efficiency on maize by adding six organic zinc complexes

Experiments under laboratory and greenhouse conditions were conducted to study the response of maize (Zea mays L.) to Zn fertilizer applications (Zn-phenolate, Zn-EDDHA, Zn-EDTA, Zn-lignosulfonate, Zn-polyflavonoid, and Zn-heptagluconate) in an Aquic Haploxeralf soil. The application of Zn complexes significantly increased Zn uptake by the plant compared with that in the control soil. The highest enhancements were obtained in soil treated with Zn-EDTA, Zn-lignosulfonate, and Zn-EDDHA. The highest percentages of Zn taken up by the plants occurred when 20 mg x kg(-1) Zn was applied as Zn-EDTA fertilizer and 10 mg x kg(-1) as Zn-lignosulfonate fertilizer. In the greenhouse experiment, Zn speciation in soil after harvesting showed that almost all Zn was found in the residual fraction followed by metal in the water-soluble plus exchangeable fraction and metal bound to organic matter. The most effective fertilizers maintaining Zn in the most labile fractions were Zn-phenolate, Zn-EDTA, and Zn-lignosulfonate. Conversely, in the incubation experiment, only a small percentage of Zn was found in the water-soluble plus exchangeable fraction and no differences in the Zn distribution were observed between the different fertilizer treatments. The micronutrient content in maize was positively correlated with the water-soluble plus exchangeable Zn as well as with the available Zn determined by the diethylenetriaminepentaacetic acid and Mehlich-3 methods, in the greenhouse experiment. Results of this study showed that the incubation experiment in acidic soil is not a suitable tool to establish the different effectiveness of Zn chelates in plants.     

Enhancing nutrient translocation,yields and water productivity of wheat under rice–wheat cropping system through zinc nutrition and residual effect of green manuring

Abstract

Efficient nutrient and water use are two important considerations to obtain good harvests of wheat. This necessitates the development of an effective nutrient management technique that not only increases yield, but simultaneously can save nutrient and water use. In this context, a field experiment was conducted at Indian Agricultural Research Institute, New Delhi, India to evaluate the residual effect of sesbania and rice bean (in-situ), subabul (ex-situ) green manuring and Zinc (Zn) fertilization, using chelated Zn-ethylenediaminetetraacetic acid (Zn-EDTA) on nutrient use, yields and water productivity of wheat under rice–wheat cropping system. Among residual effects of green manure crops and Zn fertilization, sesbania and foliar spray of 0.5% chelated Zn-EDTA at 20, 40, 60 and 80 days after sowing (DAS) recorded significantly higher nutrient content and uptake and yields than other green manure crops and Zn treatments. Residual effect of sesbania saved about 46.5?×?10³ and 30.5?×?10³ L irrigation water per tonne of wheat over subabul and rice bean, respectively. Foliar spray of 0.5% chelated Zn-EDTA at 20, 40, 60 and 80 DAS saved about 55.5?×?10³, 47?×?10³ and 13?×?10³ L irrigation water per tonne wheat over residual effect of 5?kg Zn ha^?1 through chelated Zn-EDTA as soil application, 2.5?kg Zn ha^?1 through chelated Zn-EDTA as soil application + 1 foliar spray of 0.5% chelated Zn-EDTA at flowering and foliar spray of 0.5% chelated Zn-EDTA at active tillering?+?flowering?+?grain filling, respectively. Correlation analysis showed positive correlation between Zn uptake and grain yield.     

Zinc concentration of navy bean seed as affected by rate and placement of three zinc sources

Increased zinc (Zn) concentration in seed may sometimes improve human health. The influence of rate and placement of three Zn sources (ZnEDTA, ZnSO₄, and Rayplex‐Zn) on Zn concentration in navy bean (Phaseolus vulgaris L.) seed grown on a Calciaquoll was studied in the greenhouse. Application of 4 and 8 mg Zn/kg mixed throughout the soil increased seed Zn concentration by approximately 60 and 68%, respectively, and the responses were similar with the three Zn sources. The mixed‐throughout‐the‐soil ZnEDTA, ZnSO₄, and Rayplex‐Zn treatments applied at 8 mg Zn/kg reduced seed phosphorus (P) concentration by 10,13, and 15%, respectively. The corresponding reductions with 4 mg Zn/kg were 10, 8, and 13%, respectively. Banding ZnEDTA, ZnSO₄, and Rayplex‐Zn at 4 mg Zn/kg in 17‐cm‐long, 3‐cm‐deep bands reduced seed Zn concentration by 8, 34, and 31 % compared to their mixed‐throughout‐the‐soil counterparts. A significant Zn source x placement interaction resulted from marked reduction in Zn uptake as a result of banding ZnSO₄ and Rayplex‐Zn. Banding of ZnSO₄ and Rayplex‐Zn in calcareous soils is less likely to increase the Zn concentration of navy bean seed than is banding of ZnEDTA.     

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。     

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。     

Mobility and leachability of zinc in two soils treated with six organic zinc complexes

A study of soil columns was conducted to evaluate Zn movement potential in two reconstructed soil profiles. Zn-phenolate, Zn-EDDHA, Zn-EDTA, Zn-lignosulfonate, Zn-polyflavonoid, and Zn-heptagluconate were applied in the upper zone of the column. The different physicochemical properties of the two soils and the micronutrient source may influence Zn leaching, the distribution of Zn among soil fractions, and the Zn available to the plant in the depth of the layers. In Aquic Haploxeralf soil, the application of six fertilizers produced little migration and very small leaching of Zn in the soil profiles. In Calcic Haploxeralf soil, Zn-EDTA migrated and was distributed throughout the soil columns. This Zn chelate produces a loss of Zn by leaching, which was 36% of the added Zn. In the latter soil, Zn leached very little with the other five fertilizer treatments. The same as for these organic Zn complexes, the retention of added Zn indicated the potential of metal accumulation in the A(p) horizons of the two soil profiles. A large portion of applied Zn was available to plants [diethylenetriaminepentaacetic acid (DTPA) and Mehlich-3 extractable Zn] in the depths reached by the different commercial formulations. The relationship between the two methods was highly significant (Mehlich-3-Zn = 1.25 + 1.13 DTPA-Zn, R(2) = 99.19%). When Zn was added as Zn-EDTA, the amounts of the most labile fractions (water-soluble plus exchangeable and organically complexed Zn) increased throughout the entire profile column in comparison with the control columns, although in the B(t) horizon of the Aquic Haploxeralf soil they increased only slightly.     

Factors in iron‐stress response mechanism enhanced by Zn‐deficiency stress in Sanilac,but not Saginaw navy bean

Zinc‐inefficient Sanilac and Zn‐efficient Saginaw navy bean (Phaseolus vulgaris L.) differ in their susceptibility to Zn‐deficiency stress. Sanilac accumulates Fe under Zn‐deficiency stress and Saginaw does not. These two navy bean cultivars were grown at 0, 0.006 and 0.12 mg/L Zn in modified Hoagland nutrient solution. Various Fe‐stress response mechanisms were quantified periodically over a 12‐day experimental period to determine if known factors in the Fe‐stress response mechanism were enhanced by Zn‐deficiency stress. Visual Zn‐deficiency symptoms were more severe in Sanilac than Saginaw navy bean under equivalent Zn treatments. Sanilac contained lower leaf Zn than Saginaw when Zn was present in solution (0.006 and 0.12 mg/L Zn), but the two cultivars were similar in leaf Zn in the absence of Zn (0 mg/L Zn). Sanilac accumulated more leaf Fe than Saginaw when under Zn stress (0 and 0.006 mg/L Zn). The higher levels of leaf Fe in Sanilac than Saginaw were closely associated with enhanced release of reductants and increased reduction of Fe³⁺ to Fe²⁺ by roots of Sanilac. Saginaw navy bean roots reduced Fe³⁺ to Fe²⁺ similarly to Sanilac with adequate Zn present in solution (0.12 mg/L), but experienced minuscule levels of Fe³⁺ reduction under Zn deficiency. Zinc deficiency stimulated the initiation of the Fe‐stress response mechanism in Sanilac, but not Saginaw, which may have enhanced the development of Zn‐deficiency symptoms in Sanilac due to the increased uptake of Fe by this cultivar. The common Fe‐deficiency stress response associated primarily with grasses (release of phytosiderophore) was not found in either navy bean cultivar.     

Effect of zinc application methods on apparent utilization efficiency of zinc and potassium fertilizers under rice-wheat rotation

Apparent utilization of zinc (Zn) and potassium (K) fertilizers was examined in rice (Oryza sativa L.)-wheat (Triticum aestivum L.) using combinations of no K; soil applied K levels and no Zn; soil and foliar applied Zn. Application of 33.2 kg K ha^?1 in rice and 24.9 kg K ha^?1 in wheat along with foliar spray of 2 kg Zn ha^?1 at 30 and 60 days gave the highest mean grain yields. Foliar application of zinc increased Zn concentration in flag leaves, grain, and straw of rice and wheat and K concentration in flag leaves of rice and straw of wheat significantly. Potassium application increased Zn concentration in rice grain and straw and K concentration in wheat straw significantly. Zinc and K increased the uptake of each other in grain; straw and total uptake by both crops significantly. Zinc fertilizer enhanced the utilization of soil K. Potassium fertilizer enhanced the utilization of applied Zn.     

Comparative efficacy of ZnSO4 and Zn-EDTA application for fertilization of rice ( Oryza sativa L.)

Widespread Zn deficiency for rice crop has been reported from different parts of the world, including India. To correct such deficiency, Zn is often applied to the soil as fertilizer. Its concentration in soil solution and its availability to crops is controlled by sorption?–?desorption reactions at the surfaces of soil colloidal materials. The objective of this study was to compare the availability and relative effectiveness of Zn from Zn-EDTA and ZnSO₄ sources by applying different Zn levels to a calcareous soil in field experiments through soil application. The uses of Zn-EDTA also increase the yield of rice dry matter yield and grain yield. Regarding maintenance of Zn in soil, it has been observed that the amount of Zn content was recorded higher with the split application of Zn-EDTA as compared to ZnSO₄ with the simultaneous 26.1% increase in the yield of rice.     

Effect of split application of zinc on yield of rice (Oryza sativa L.) in an inceptisol

Abstract

Rice is mostly transplanted under puddled low land soil conditions in India, where Zinc (Zn) deficiency is a common problem. The objective of this study was to find out the efficacy of split application of Zn on growth and yield of rice in an inceptisol. The split application of Zn as ZnSO₄ · 7H₂O performed better than its single basal application, while the split application of Zn-EDTA did not show any significant difference on yield and yield components of rice over its single basal application. Zn-EDTA was found to be better for growth and yield of rice among the two sources of Zn. The soil application of Zn at 1.0 kg ha^?1 as Zn-EDTA (T₇) recorded highest grain yield of 5.42 t ha^?1, filled grain percentage of 90.2%, 1000-grain weight of 25.41 g and number of panicles m^?2 of 452. The Zn content of grain and straw were found to be maximum in the treatment T₇ i.e. 38.19 and 18.27 mg kg^?1, respectively. Linear regression studies indicated that grain yield of rice is significantly influenced by Zn content of grain, Zn content of straw and DTPA extractable Zn content of soil at the level of 95.96, 96.74 and 95.57%, respectively.     

Effect of Nitrogen Fertilizers on Zinc Accumulation in Fescue

Abstract

This research evaluated effects of nitrogen fertilizers on availability of zinc (Zn) in soils. Two slit loams of the Hadley series (Typic Udifluvents) were used. Zinc sulfate was mixed with the soils to give Zn at 125, 250, 500, or 1,000 mg/kg and incubated for 14 days. Fertilizers (compost, cow manure, urea) were mixed with the soils to supply N at 200 mg/kg. Fourteen days after the fertilizers were mixed with the Zn‐treated soils, soil samples were taken for analysis of plant‐available Zn by extraction with Morgan's solution or water. After the soil samples were taken, fescue (Festuca arundinacea Schreb.) seeds were placed into pots to assess germination, growth, and Zn accumulation. Higher concentrations of Morgan's extractable Zn were detected in soils treated with compost (201 mg/kg) than with calcium nitrate (179 mg/kg), manure (153 mg/kg), or urea (152 mg/kg). However, with water extraction, higher Zn concentrations were detected in soils treated with calcium nitrate (36 mg/kg) with the lowest concentrations being extracted from soils treated with urea (8 mg/kg). Extraction of Zn by Morgan's solution or water increased as the soil‐Zn levels increased. Fescue germinated and grew at all of the soil‐Zn levels. The highest concentration of Zn occurred in plants grown in soils amended with calcium nitrate or urea, and the lowest concentration was in plants grown in soils amended with compost or manure. Fescue grown in soils amended with urea had the largest dry mass, and plants grown with compost or manure had the smallest. Zinc concentration and accumulation for fescue shoots increased as the soil‐Zn levels increased. These results suggest that accumulation of Zn in fescue can be enhanced by selection of nitrogen‐containing fertilizers that affect the solubility of Zn in soils.     

国内外主要粮食作物对施用锌肥响应的研究进展

【目的】 锌 (Zn) 对于人体健康至关重要，缺Zn会影响人体正常发育，并易受致病菌的入侵，降低人体耐受氧化胁迫的能力。人体主要通过摄食的方式补Zn，占全球50%的用于种植粮食作物的耕地缺Zn，主要粮食作物中可食部分的Zn含量普遍偏低，世界上50%的人口健康受到了影响。本文通过探讨国内外主要粮食作物对Zn肥施用的响应，旨在为以后相关的作物富Zn研究提供理论依据。 主要进展 施用Zn肥可以有效改善主要粮食作物籽粒部分的缺Zn状况，土施与叶面喷施均可提高主要粮食作物小麦、水稻和玉米可食部分的Zn含量，并能够增加产量。但由于受到土壤pH、有机质含量等的影响，土施Zn肥有效性偏低，施用的量较大，Zn肥的表观利用率低于叶喷Zn肥，叶喷Zn肥的增产效果显著低于土施Zn肥；锌肥的效果还受营养元素之间交互作用的影响，Zn与P和Fe存在拮抗作用，与Cu存在协同作用；Zn元素在籽粒的不同组份中为不均匀分配，在麦麸、小麦籽粒、白面粉中的含量依次递减，在水稻籽粒、糙米、精米中的含量也依次下降，Zn元素在主要食用的白面和精米中的分配较低；小麦籽粒部分的Zn来自于根的吸收以及茎和叶的再分配，水稻籽粒部分的Zn主要来自于根的吸收。 问题与展望 目前有关Zn在肥–土–作物系统中的迁移分配规律尚不清楚，施用Zn肥的成本较高，肥料中各营养元素的最佳投入量与最佳配比还不确定。因此，Zn肥施用可在以下六个方面进行深入研究:1) Zn元素在肥–土–作物系统中的吸收分配机制，清楚掌握Zn元素在肥–土–作物系统中的富集与分配规律，建立全国主要农田土壤的Zn数据库，构建产量、富Zn量与Zn肥之间的响应模型；2) 研发肥料施用技术及新型廉价肥料，降低补施Zn肥的成本；3) 继续研究Zn与其它营养元素之间的协同和拮抗作用，找到最佳投入量与最佳配比，整体提升粮食作物的营养价值；4) 改善土壤理化性质，提高Zn肥对于农作物的有效性及其肥效的持久性；5) 加强高富Zn品种的筛选，获得对Zn肥高产量与高富Zn量响应的品种类型；6) 研究主要粮食作物富Zn的分子生物学机制，进行品种的改良。      

QUANTIFYING THE RESIDUAL VALUE OF ZINC FOR CANOLA PRODUCTION DUE TO REMOVAL OF ZINC IN SHOOTS AND GRAIN AND CONTINUED REACTION OF ZINC WITH SOIL

About half of the almost 18 million ha used for agriculture in southwestern Australia were initially acutely zinc (Zn) deficient. Canola (oilseed rape, Brassica napus L.) is a recent crop species grown in the region and there is only limited information on its Zn requirements. In the glasshouse pot study reported here five levels of Zn (0, 0.8, 1.6, 3.2, and 6.4 mg Zn pot^?1) were applied before sowing the first canola crop on an acid sandy loam, and shoot and grain yield responses to applied Zn, and removal of Zn in the shoots and grain, were measured for five successive crops grown to maturity. Before sowing each crop, canola seed was treated with fluquinconazole to successfully control blackleg disease [Leptosphaeria maculans (Desm.) Ces. et de Not.]. Soil samples were collected from each pot before sowing each crop, and after harvesting the last crop, to measure the Zn extracted from soil by diethylenetriaminepentaacetic acid (DTPA) (soil test Zn). Removal of Zn in shoots and grain, and continued reaction of applied Zn by soil, both decreased the effectiveness of applied Zn for successive crops. For all five crops about 71% of the low levels of Zn applied (0.8, 1.6 mg Zn pot^?1) were removed in shoots and grain of the five crops, compared with about 46% for the larger levels of Zn applied (3.2 and 6.4 mg Zn pot^?1). Corresponding values for Zn removed in the grain was about 56 and 30%. Soil test Zn decreased with time since Zn application. The decrease could not all be explained by Zn removed in shoots and grain and was attributed to continued reaction of Zn with soil. For the soil type used, the relationship between either grain yield or total yield (shoots plus grain at maturity), and soil test Zn, was similar for each crop. Therefore, the soil test Zn that was related to 90% of the maximum grain or total yield (critical soil test Zn) was about 0.35 mg Zn kg^?1 soil for each crop.     

Determination of 67Zn distribution in navy bean (Phaseolus vulgaris L.) after foliar application of 67Zn-lignosulfonates using isotope pattern deconvolution

The improvement of Zn fertilizers requires new techniques to evaluate their efficacy. In this paper, the (67)Zn stable isotope was used as tracer of several Zn-lignosulfonate complexes to study the foliar-applied Zn uptake and distribution behavior in the plant, compared with ZnEDTA. Navy bean plants ( Phaseolus vulgaris L.) were grown hydroponically in a Zn-free nutrient solution, and six modified lignosulfonates and EDTA complexed with (67)Zn were used in foliar application in the young leaves as Zn sources. Zinc isotopes in roots, stems, and sprayed and unsprayed leaves were determined by ICP-MS, and signal interferences caused by the compounds of the digested vegetal samples were corrected. The mathematical procedure of isotope pattern deconvolution allowed the minimization of the uncertainty in the measured molar fractions of Zn from fertilizer or from natural sources. Significant differences in Zn use and distribution were observed among the fertilizers when the calculated concentrations of Zn from the fertilizer were compared, whereas they were unnoticeable attending to the total Zn in plant tissues, usually determined at the conventional studies. By foliar spray, higher Zn uptake and mobilization to leaves and stems were achieved with (67)ZnEDTA than with (67)Zn-LS complexes. The ultrafiltered LS and phenolated LS showed slightly better ability to provide Zn to the bean plants than the other LS. The foliar-applied Zn use and distribution in the plant were related with the stability of the Zn-lignosulfonates complexes. Those presenting the lower stability versus pH, but the highest complexing capacity, were slightly more suitable to supply foliar-applied Zn to navy beans.     

Evaluation of different zinc sources for lowland rice production

 ZnSO₄, Zn-enriched farmyard manure (Zn-FYM), Zn-tetraammonia complex sorbed on FYM [Zn(NH₃)₄-FYM] and Zn-ethylenediaminetetraacetate (Zn-EDTA) were compared as Zn sources for rice production under lowland conditions. The amount of Zn supplied by Zn-EDTA was one-tenth of that supplied by the other Zn sources. Zn application to a Zn-deficient soil corrected the visual symptoms of Zn deficiency and significantly increased the total biomass, grain yields and the harvest index of rice, as well as the Zn concentration in the grain and the uptake of Zn by the straw and the grains. Even with lower rates of application (0.25 and 0.5 mg Zn kg^–1 soil), Zn-EDTA treatments gave comparable values for these parameters, and the highest "Zn-mobilization efficiency" compared to the other Zn sources. The content of diethylenetriaminepentaacetate (DTPA)-extractable Zn in the soil of the different treatments after the harvest of rice was in the order; ZnSO₄=Zn-FYM>Zn(NH₃)₄-FYM=Zn-EDTA. The application of Zn also significantly increased the number of panicles that emerged between 80 to 93 days after transplanting, though the total number of panicles at harvest remained unaffected. The calculated panicle-emergence index had a positive correlation with the grain yield of rice. The Z_n-EDTA treatment, inspite of supplying the lowest amount of Zn, as well as leading to the lowest rate of Zn uptake, produced the highest yields. Therefore, we concluded Zn-EDTA to be the most efficient source of Zn for lowland rice production. Received: 20 October 1998