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.     

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.     

Effect of Zinc × Boron Interaction on Plant Growth and Tissue Nutrient Concentration of Corn

ABSTRACT

A pot experiment was conducted in a greenhouse on a calcareous soil (fine, mixed, mesic, Fluventic Haploxerepts) to study the interaction of zinc (Zn) and boron (B) on the growth and nutrient concentration of corn (Zea mays L.). Treatments consisted of a factorial arrangement of seven levels of B (0, 2.5, 5, 10, 20, 40, and 80 mg kg^{? 1}as boric acid), two sources of Zn [zinc sulfate (ZnSO₄ · 7H₂O) and zinc oxide (ZnO)], and three levels of Zn (0, 5, and 10 mg kg^{? 1}) in a completely randomized design with three replications. Plants were grown for 70 d in 1.6 L plastic containers. Applied Zn significantly increased plant height and dry matter yield (DMY) of corn. Source of Zn did not significantly affect growth or nutrient concentration. High levels of B decreased plant height and DMY. There was a significant B × Zn interaction on plant growth and tissue nutrient concentration which were rate dependent. In general, the effect of B × Zn interaction was antagonistic on nutrient concentration and synergistic on growth. It is recommended that the plants be supplied with adequate Zn when corn is grown in high B soils, especially when availability of Zn is low.     

EFFECT OF ZINC NUTRITION ON GROWTH,YIELD, AND QUALITY OF FORAGE SORGHUM IN RESPECT WITH INCREASING POTASSIUM APPLICATION RATES

A two-year field study was conducted to determine the effect of two zinc (Zn) levels [0 and 10 kg zinc sulfate (ZnSO₄) ha^?1] in respect with four potassium (K) levels (0, 20, 40 and 60 kg K₂O ha^?1) on growth, yield and quality of forage sorghum. The soil of the experimental field was loamy sand (Inceptisol), carrying 70, 08, 77, and 0.51 mg nitrogen (N), phosphorus (P), K, and Zn kg^?1 soil, respectively. Increasing K levels significantly improved most of the growth, yield, and quality attributes gradually irrespective of the Zn levels. Zinc applied at 10 kg ZnSO₄ ha^?1 proved significantly better than no zinc application at various K application rates. The benefit of zinc application increased progressively with increasing K rates for most of the parameters studied, indicating significant response of the crop to positive K × Zn interaction in plants in respect with K and Zn application to the soil. Accordingly, 60 kg K₂O ha^?1 applied with10 kg ZnSO₄ ha^?1 boosted most of the attributes maximally. It resulted in about 20–40% increase in growth attributes, 25% increase in fresh matter yield, 36–38% increase in dry matter yield, and 38% increase in protein yield compared to the comparable K level applied without zinc. It also enhanced N uptake by 38%, P uptake by 5–19%, K uptake by 40–42%, and Zn uptake by 114–144%. Across the K rates, application of 10 kg ZnSO₄ surpassed no zinc application by 30–35% in N uptake, by 8–15% in P uptake, by 33–36% in K uptake, by 120–140% in Zn uptake, by 19–21% in fresh matter yield, by 29–31% in dry matter yield, and by 30–34% in protein yield.     

Distribution of zinc forms in highly calcareous soils as influenced by soil physical and chemical properties and application of zinc sulfate

Abstract

Water‐soluble zinc (Zn) fertilizers are rapidly converted to insoluble forms in calcareous soils resulting in lower efficiency of such fertilizers. A knowledge of distribution of native and applied Zn in such soils is necessary for understanding the fate of applied Zn fertilizers and finding ways to increase their efficiency. This experiment was conducted to obtain such information in selected highly calcareous soils of Iran. A sequential extraction method was used to fractionate the Zn forms of surface horizons (0–20 cm) of 20 highly calcareous soils [16 to 58% calcium carbonate (CaCO₃) equivalent; pH 7.9 to 8.5] which had previously received 0, 10, or 20 mg Zn/kg as zinc sulfate (ZnSO₄) and had been under one corn (Zea mays L.) crop in the greenhouse. The forms determined were exchangeable (EXZN), sorbed (SRZN), organic (ORZN), carbonate (CRZN), residual (RSZN), and sum of forms (SMZN). The native SMZN ranged from 32.4 to 66.7 mg/kg with a mean of 49.9 mg/kg. Application of 10 and 20 mg Zn/kg as ZnSO₄ increased the mean to 57.7 and 62.7 mg/kg, respectively. Concentration of different forms of Zn in the soils was determined to be in the following order: RSZN >>> CRZN > SRZN > EXZN > ORZN. The concentration of native EXZN+SRZN+ORZN forms constituted less than 5% of SMZN, while concentration of CRZN alone ranged from 4.37 to 16.05% with a mean of 8.36%. Application of ZnSO₄, while significantly increased the concentration of all forms of Zn, had a pronounced effect on CRZN. Averaged over all soils, 58 and 60% of the applied ZnSO₄ was converted to CRZN for the 10 and 20 mg Zn/kg, respectively. Regression equations relating different Zn forms to soil physical and chemical properties indicated that the Zn forms are significantly influenced by soil properties.

It was concluded that conversion of applied ZnSO₄ to CRZN was mainly responsible for retention of this fertilizer in highly calcareous soils, making it temporarily unavailable to plants, and therefore decreasing its apparent recovery by the first crop.     

Effect of Zn binding to phytate and humic substances on its uptake by wheat (Triticum durum L.) as affected by carbonates and Fe oxides

Although complexation with soil organic matter may improve zinc (Zn) bioavailability to plants, the effect of Zn sorbent surface on the use of complexed Zn by plants remains unknown. The objective of this research was to elucidate how Zn complexation with humic substances (HS) and phytate affects the uptake of Zn by wheat plants depending on the main sorbent surface in growth media, i.e., carbonates and Fe oxides. To this end, two pot experiments were performed, one using Fe oxide-coated siliceous as the siliceous growth medium sand and the other using a mixture of calcareous sand and siliceous sand as the calcareous growth medium. Each experiment involved three Zn sources, Zn-HS complex, Zn phytate, and ZnSO₄. All sources were applied with surface irrigation at two Zn rates (0.25 and 2 mg kg^-1 growth medium). The Zn-HS complex significantly increased Zn uptake by plants in both media, relative to the other two Zn sources, but no significant difference was observed between Zn phytate and ZnSO₄. In the calcareous medium, Zn-HS complex and Zn phytate resulted in significantly higher dry biomass yields of wheat than ZnSO₄. In the siliceous medium, spike and shoot dry biomass yields with Zn-HS complex at the low rate and Zn phytate at both rates were not significantly different from those with ZnSO₄ at the high rate. After harvest, approximately 50% of the Zn applied as Zn-HS complex remained extractable by diethylenetriaminepentaacetic acid (DTPA), while this proportion was less than 20% for the other Zn sources. Thus, Zn-HS complex and Zn phytate are sources of available Zn for plants, and they are more effective than ZnSO₄ in increasing plant growth, particularly when carbonates are the main Zn sorbent surface.     

CUMULATIVE AND RESIDUAL EFFECTS OF ZINC SULFATE ON GRAIN YIELD,ZINC, IRON,AND COPPER CONCENTRATION IN CORN AND WHEAT

Re-application of zinc (Zn) sulfate for corn (Zea mays L.) production in rotation of wheat-corn has varied effects on yield of crops grown in Zn deficient soils. Therefore, this study was done as split plots in a complete randomized block design (CRBD) where the main plots were control with and without Zn application in wheat (Triticum aestivum L.) production. Sub-plots were of control, without Zn fertilizer, base application of 75 kg per hectare (kg Zn ha^?1), 25% and 50% less than base application and as foliar spray in combination with the 4 soil Zn treatments for corn production. Effect of previous Zn application on grain Zn concentration of corn was significant (P < 0.01). Zinc concentrations in treatments of without previous Zn (nil Zn) application and with Zn application were 28.1 and 31.8 mg kg^?1, respectively. Soil application of 75 kg ha^?1 and foliar application of Zn sulfate gave the highest yield (8853 kg ha^?1) showed an increase of 25 percent in compared with nil-Zn. Although re-application of Zn has small effect on yield, but resulted in was the highest grain concentration.     

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.     

CRITICAL DEFICIENCY LEVEL OF ZINC FOR CORN ON CALCAREOUS SALT-AFFECTED SOILS IN CENTRAL IRAN

A greenhouse experiment with 11 soil series and two zinc (Zn) rates (0 and 15 mg Zn kg^?1 as zinc sulfate) was performed to determine critical deficiency level of Zn for corn (Zea mays L.) on calcareous salt-affected soils in central Iran. In addition, the most important soil properties affecting Zn phytoavailability were determined. Critical Zn deficiency levels were determined using the Cate-Nelson and Mitscherlich procedures. In most soils, application of Zn increased the dry matter yield, and Zn concentration and content in the shoot and root of corn. A positive correlation was observed between the soil electrical conductivity (EC) with Zn concentration in shoots, roots and whole plant while shoot Zn content was negatively correlated with buffer capacity of Zn in soil. Critical deficiency levels of Zn in soil for corn based on the Cate-Nelson and Mitscherlich method were 1.35 and 1.23 mg kg^?1 for diethylenetriaminepentaacetic acid (DTPA)-extracted soil Zn, respectively.     

Efficiency of soil-applied 67Zn-enriched fertiliser across three consecutive crops

A very small amount of applied zinc (Zn) is taken up by crops, resulting in low recovery by plants. Adding elemental sulphur to zinc oxide (ZnO) fertiliser could improve Zn solubilisation and exert a higher residual effect on crops than soluble Zn sources. We produced an isotopically labelled Zn-elemental sulphur fertiliser and evaluated its performance in comparison to traditional Zn sources during sequential crop cultivation. Three ⁶⁷Zn-labelled fertilisers, ZnO, zinc sulphate (ZnSO₄), and ZnO co-granulated with elemental sulphur (ZnOS⁰), were soil applied, and their contributions to the uptake of Zn by three consecutive crops, wheat, ryegrass, and corn, were assessed in a 294-d pot experiment. The contributions of Zn fertilisers followed the order:ZnSO₄ > ZnO=ZnOS⁰. The relative contributions of Zn fertilisers were lower in the first crop than in the subsequent crops. The overall recovery of applied Zn by the three crops was higher for ZnSO₄ than for ZnO and ZnOS⁰, reaching 1.56%, 0.45%, and 0.33% of the applied Zn, respectively. Zinc recovery by plants was very low, regardless of the source of Zn. Adding elemental sulphur to ZnO did not increase its effectiveness up to 294 d after application. Fertiliser contribution was higher for the subsequent crops than for the initial crop, indicating the importance of assessing the residual effects of Zn fertilisers.     

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.     

Extractability of previously‐applied zinc as influenced by properties of calcareous soils

Abstract

The recovery of applied zinc (Zn) by plants is relatively small. Coupled with lack of leaching, this leads to accumulation of Zn in topsoil which may result in unfavorable growth conditions for the subsequent plants. Different extractants may be used for assessing the Zn status of soils previously treated with Zn sources. The extractability of retained Zn is influenced by soil properties. This experiment was conducted to study the influence of selected properties of calcareous soils on extractability of Zn by three popular Zn soil tests. Twenty samples from surface horizons (0–20 cm) of highly calcareous soils of southern Iran (pH 7.9 to 8.5; calcium carbonate equivalent 16 to 58%) previously treated with three levels of Zn (0, 10, and 20 mg Zn kg^‐1 soil as ZnSO₄#lb7H₂O) in triplicate and under one crop of corn (Zea mays L.) were extracted with DTPA, EDTA‐(NH₄)₂CO₃ and Na₂‐EDTA. Extractability (EXT) in a particular extractant was defined as the slope of the regression line, relating extractable Zn of each soil to the rate of applied Zn, multiplied by 100. The EXT values of soils ranged from 24.9 to 73.0% for DTPA, 47.2 to 84.4% for EDTA‐(NH₄)₂CO₃, and 28.2 to 56.7% for Na₂‐EDTA. Stepwise regression equations showed that cation exchange capacity (CEC) and calcium carbonate equivalent (CCE) followed by clay content were the most influential soil properties in EXT of retained Zn of highly calcareous soils. The EXT values decreased with increase in CEC, and CCE but increased with increase in clay.     

Zinc requirement of corn grown on two calcareous soils of Pakistan

In greenhouse studies, corn (Zea mays L.) growth increased with Zn fertilization of two alkaline calcareous soils. Zinc concentration and total uptake increased with Zn application. Very high correlations were recorded between plant tissue Zn concentration, total Zn uptake and soil Zn levels determined by DTPA and AB-DTPA soil tests. Correlation between Zn concentration in plants and relative yield was poor. However, close relationships were revealed between extractable soil Zn and relative yield. Near maximum dry matter yield of corn was associated with a fertilizer rate of 2 mg Zn/kg soil. Plant tissue Zn-requirement was 27 mg/kg in 15 days old plants and 32 mg/kg in corn shoots of 40 day age. Critical soil test Zn level was 1.2 mg/kg by DTPA and 1.7 mg/kg by AB-DTPA method. Use of AB-DTPA soil test is suggested for evaluating Zn status of calcareous soils.     

IMPROVING SEED YIELD OF BLACK GRAM (VIGNA MUNGO L. VAR. DPU-88-31) THROUGH FOLIAR FERTILIZATION OF ZINC DURING THE REPRODUCTIVE PHASE

The response of zinc (Zn) deficiency on reproductive yield and recovery through foliar application of Zn was determined in black gram, an important edible legume in India. Results revealed that foliar spray of Zn [0.01 and 0.5% zinc sulfate (ZnSO₄)] improved not only the flowering, pollen producing capacity, pollen viability, stigma-receptivity and pollen-stigma interaction but also the yield parameters like number, size and weight of pods and seeds. Zinc deficiency induced changes in pollen grain structure, activity of esterase and poor stigmatic exudation leading to improper pollen-stigma interaction, which seem to be the main cause of poor fertility and decreased seed yield. Foliar application of 0.5% ZnSO₄ after bud formation was most beneficial not only for reproductive yield but also seed Zn content.     

The effectiveness of seed priming and foliar application of zinc- amino acid chelates in comparison with zinc sulfate on yield and grain nutritional quality of common bean

Abstract

The efficacy of seed priming and foliar application of zinc-amino acid chelates including zinc-histidine [Zn(His)₂] and zinc-methionine [Zn(Met)₂] in comparison with zinc sulfate (ZnSO₄) on yield and grain nutritional quality of two common bean cultivars (Phaseolus vulgaris L., cvs Talash and Sadri) was investigated in a severely Zn-deficient calcareous soil (DTPA-Zn: 0.38?mg kg^?1 soil) in a pot experiment. Bean response to Zn application varied depending on the Zn fertilizer, application method and cultivar. In ‘Talash’, seed priming with [Zn(His)₂] and [Zn(Met)₂] led to 24.1 and 11.6% increase in the grain yield of bean in comparison with ZnSO₄ treatment, respectively. In both cultivars, foliar application of [Zn(His)₂] led to significant increase in the grain yield in comparison with ZnSO₄. The highest grain Zn concentration was obtained by seed priming with [Zn(Met)₂] in ‘Sadri’ and [Zn(His)₂] in ‘Talash’, respectively. For Zn-amino acid chelates, seed priming was more effective than foliar application in increasing grain yield and Zn concentration. Foliar application of [Zn(His)₂] and [Zn(Met)₂] in ‘Sadri’ and [Zn(Met)₂] in ‘Talash’ resulted in higher protein content in bean grain as compared with ZnSO₄. In both cultivars, foliar application of [Zn(Met)₂] was the more effective than seed priming to increase grain protein content. The highest water-soluble carbohydrates concentration of grain was obtained by seed priming with [Zn(Met)₂] and [Zn(His)₂] in ‘Sadri’ and ‘Talash’ cultivars, respectively. Therefore, seed priming with [Zn(His)₂] and ZnSO₄ in ‘Sadri’ and [Zn(Met)₂] in ‘Talash’ can effectively be used for improving yield of common bean in Zn-deficient calcareous soils.     

Mobility of Organic and Inorganic Zinc Fertilizers in Soils

Abstract

Zinc sulfate (ZnSO₄ · H₂O) has traditionally been the “reliable” source of zinc (Zn) fertilizer, but other sources of Zn are also available. Some are derived from industrial by‐products, varying from flue dust reacted with sulfuric acid to organic compounds derived from the paper industry. The degree of Zn mobility in Zn sources derived from these various by‐products is related to the manufacturing process, the source of complexing or chelating agents (organic sources), and the original product used as the Zn source. Many claims are made regarding the relative efficiency of traditional inorganic Zn fertilizers and complexed Zn sources. The objective of this column study was to compare the mobility of several commercial Zn fertilizer materials (organic and inorganic) that are commonly used to correct Zn deficiencies in soils. The sources included three granular inorganic Zn sources, two granular organically complexed Zn sources, and liquid ZnEDTA. Soil columns were leached five times with deionized water. Leaching events were separated by approximately 48 h. At the conclusion of the leaching phase, columns were analyzed for plant‐available Zn. Water solubility was the primary factor affecting Zn movement, not total Zn content or organic complexation of the fertilizers. The Zn sources evaluated can be separated into three groups: ZnEDTA, ZnLigno, and ZnSO₄ were the most mobile Zn sources; the ZnOx55 was less mobile, but seemed mobile enough to meet crop needs; ZnOx26 and ZnSuc were relatively immobile Zn sources.     

Effect of Zinc Humate on Growth of Soybean and Wheat in Zinc‐Deficient Calcareous Soil

Abstract

Humic acids have many benefits for plant growth and development, and these effects may be maximized if these materials are combined with micronutrient applications. In the present study, pot experiments were conducted to evaluate the effects of zinc (Zn) humate and ZnSO₄ on growth of wheat and soybean in a severely Zn‐deficient calcareous soil (DTPA‐Zn: 0.10 mg kg^?1 soil). Plants were grown for 24 (wheat) and 28 days (soybean) with 0 or 5 mg kg^?1 of Zn as either ZnSO₄ or Zn humate. Zinc humate used in the experiments was obtained from Humintech GmbH, Germany, and contained 5% of Zn. When Zn was not supplied, plants rapidly developed visible symptoms of Zn deficiency (e.g., chlorosis and brown patches on young leaves in soybean and necrotic patches on middle‐aged leaves in wheat). Adding Zn humate eliminated Zn‐deficiency symptoms and enhanced dry matter production by 50% in soybean and 120% in wheat. Zinc‐humate and ZnSO₄ were similarly effective in increasing dry matter production in wheat; but Zn humate increased soybean dry matter more than ZnSO₄. When Zn was not supplied, Zn concentrations were 6 mg kg^?1 for wheat and 8 mg kg^?1 for soybean. Application of Zn humate and ZnSO₄ increased shoot Zn concentration of plants to 36 and 34 mg kg^?1 in wheat and to 13 and 18 mg kg^?1 in soybean, respectively. The results indicate that soybean and wheat plants can efficiently utilize Zn chelated to humic acid in calcareous soils, and this utilization is comparable to the utilization of Zn from ZnSO₄. Under Zn‐deficient soil conditions, plant growth and yield can be maximized by the combined positive effects of Zn and humic acids.     

A comparison of the availability of three zinc sources to maize (Zea mays L.) under greenhouse conditions

 The objective of this study was to compare the availability of Zn from granular ZnSO₄, a granular Zn humate-lignosulfonate (ZnHL), and liquid Zn ethylenediaminetetraacetate (ZnEDTA). The two granular sources were applied directly (“as is”) and also powdered and mixed with the soil. A calcareous sandy loam soil with low available Zn was used. Zn rates were 0, 4, 8, 16, and 32 mg pot^–1, and two crops of maize (Zea mays L.) were grown. For the first crop, all Zn sources provided an excellent dry matter response when powdered and mixed with the soil. The ZnEDTA was superior with regard to Zn uptake. The availability of ZnSO₄ granules was almost zero for the first crop. The availability of the ZnHL complex was better than ZnSO₄ when applied in granular form, but not when the two materials were powdered and mixed with the entire soil mass, suggesting that availability differences between these sources were due to physical, not chemical, factors. After mixing with the soil, only small differences existed between the Zn sources for the second crop. All sources provided for a good dry matter and Zn uptake response, and all Zn sources were about the same in increasing diethylenetriaminepentaacetate (DTPA)-extractable Zn levels at the end of the experiment. This research suggests that the three Zn materials were equal long-term Zn sources, but that the short-term response varied dramatically, depending on how the materials were applied. Received: 8 March 1999     

氮锌互作对水稻产量及籽粒氮、锌含量的影响

为探明氮锌互作对水稻产量及氮、锌含量的影响,以镇稻11号为供试材料,在大田条件下研究了2个氮肥用量（N 200、300 kg/hm2）下6个施锌水平（ZnSO47H2O 0、10、25、50、100、150 kg/hm2） 对水稻产量及成熟期植株氮、锌浓度及累积量的影响。试验结果表明: 在本试验条件下,锌肥的施用对水稻产量的增加不显著,但施锌能显著提高水稻各部位的锌浓度和籽粒锌累积量,并能提高水稻籽粒的氮浓度和粗蛋白含量,且表现出随施锌量的增加籽粒的氮浓度和粗蛋白含量增加的趋势; 高施氮量有利于水稻的增产及对锌的吸收与累积。因此,氮锌配施具有增加籽粒锌富集和提高蛋白质含量的双重效益。     

ZINC-COATED UREA IMPROVES PRODUCTIVITY AND QUALITY OF BASMATI RICE (ORYZA SATIVA L.) UNDER ZINC STRESS CONDITION

A field study conducted for two years (2006 and 2007) at the Research Farm of the Indian Agricultural Research Institute, New Delhi, India showed that zinc (Zn) fertilization increased yield attributes, grain and straw yield, enhanced Zn concentrations and its uptake and improved kernel quality before and after cooking in basmati rice ‘Pusa Sugandh 5’. A 2% Zn-coating with zinc sulfate (ZnSO₄·7H₂O) was found to be the best but a 2% Zn-coating with zinc oxide (ZnO) was very close to it in terms of grain and straw yield and Zn concentrations in basmati rice grain and straw under Zn stress conditions. Partial factor productivity (PFP) of applied Zn varied from 984–3,387 kg grain kg Zn^?1, agronomic efficiency (AE) varied from 212–311 kg grain kg^?1 Zn (applied) and physiological efficiency (PE) of Zn varied from 6,384–17,077 kg grain kg^?1 Zn (absorbed). Thus, adequate Zn fertilization of basmati rice can lead to higher grain yield and Zn-denser grains with improved cooking quality in basmati rices under Zn stress soil conditions.