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Critical Soil Zinc Deficiency Concentration and Tissue Iron: Zinc Ratio as a Diagnostic Tool for Prediction of Zinc Deficiency in Corn M. Zare a; A. H. Khoshgoftarmanesh a; M. Norouzi b; R. Schulin c a Department of Soil Sciences, Isfahan University of Technology, Isfahan, Iran b Soilless Culture Research Centre, Isfahan University, Isfahan, Iran c Institutes of Terrestrial Ecology, ETH Zurich, Zurich, Switzerland Online Publication Date: 01 December 2009

To cite this Article Zare, M., Khoshgoftarmanesh, A. H., Norouzi, M. and Schulin, R.(2009)'Critical Soil Zinc Deficiency Concentration

and Tissue Iron: Zinc Ratio as a Diagnostic Tool for Prediction of Zinc Deficiency in Corn',Journal of Plant Nutrition,32:12,1983 — 1993 To link to this Article: DOI: 10.1080/01904160903308101 URL: http://dx.doi.org/10.1080/01904160903308101

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Journal of Plant Nutrition, 32: 1983–1993, 2009 Copyright © Taylor & Francis Group, LLC ISSN: 0190-4167 print / 1532-4087 online DOI: 10.1080/01904160903308101

Critical Soil Zinc Deficiency Concentration and Tissue Iron: Zinc Ratio as a Diagnostic Tool for Prediction of Zinc Deficiency in Corn

Downloaded By: [Isfahan University of Technology] At: 01:26 3 November 2009

M. Zare,1 A. H. Khoshgoftarmanesh,1 M. Norouzi,2 and R. Schulin3 1

Department of Soil Sciences, Isfahan University of Technology, Isfahan, Iran 2 Soilless Culture Research Centre, Isfahan University, Isfahan, Iran 3 Institutes of Terrestrial Ecology, ETH Zurich, Zurich, Switzerland

ABSTRACT Zinc (Zn) fertilizer application is most economic if based on soil test and plant analysis information. The aim of this study was to determine the soil test [diethylenetrinitrilopentaacetate (DTPA) and ethylenetriaminepentaacetic acid (EDTA) extractable] Zn-critical levels and tissue Fe/Zn ratio for corn (Zea mays L.). A greenhouse experiment with 12 soil series and two Zn fertilizer treatments (0 and 15 mg Zn kg−1 as zinc sulfate) was conducted. Critical Zn deficiency levels were determined using the Cate-Nelson procedure. Relative corn yield varied from 0.59 to 1.64. Critical deficiency levels based on the Cate-Nelson method were 1.50 and 1.17 mg kg−1 for DTPA and EDTA-extracted soil Zn, respectively. No accurate critical deficiency level could be established using the shoot Zn concentrations. The critical iron (Fe)/Zn ratio in the corn shoot was 3.9. Values greater than 3.9 indicate hidden Zn deficiency and probable response to applied Zn. Keywords: Cate-Nelson, DTPA, EDTA, relative yield, Zea mays L.

INTRODUCTION Proper fertilizer management is necessary to obtain maximum net return from crop production (Cox and Barnes, 2002). The soil and plant testing has often been used as an effective approach to distinguish nutrient status in field crops (Yin and Vyn, 2004). Analysis of nutrient concentrations in soil and plants is also a useful tool to detect nutrient deficiency in plants (Ulrich and Hills, 1967). Received 19 March 2008; accepted 7 August 2008. Address correspondence to A. H. Khoshgoftarmanesh, Department of Soil Sciences, Isfahan University of Technology, Isfahan 81746-7344, Iran. E-mail: amirhkhosh@ cc.iut.ac.ir 1983


1984

M. Zare et al.

Comparing the soil and plant analysis results with the recommended critical values is necessary to determine whether nutrient concentrations are sufficient to produce maximum plant growth and yield (Black, 1993). In fact, critical soil and plant nutrient deficiency values have to be determined to separate the responsive from the non-responsive soils and to efficient use of the fertilizer (Singh, 1986). Critical nutrient concentration is defined as the concentration of a specific nutrient in soil or plant tissue at which growth or yield begins to be suppressed (Ulrich and Hills, 1967). Critical deficiency level of nutrients varies for different soils, crops, and environments (Genc et al., 2002; Yin and Vyn, 2004). Corn is an important crop in Iran and is affected severely by zinc (Zn) deficiency (Alloway 2005). Application of Zn fertilizers is a common practice to correct Zn deficiency (Broadley et al., 2007; Marschner, 1995). One of the problems in Zn fertilizer management is to predict crop response to Zn fertilization and define the soil and plant Zn concentrations below which Zn fertilizer recommendations will be made. The critical deficiency level of Zn in soil has been reported to be 0.6 mg kg−1 to 2.0 mg kg−1 depending on the extraction method (Bhupinder et al., 2005). In a greenhouse study with two calcareous soils, the Zn critical deficiency level for corn was determined 1.2 and 1.7 mg kg−1 using the diethylenetrinitrilopentaacetate (DTPA) and ammonium bicarbonate (AB)-DTPA methods, respectively (Rashid and Rafique, 1989). The critical deficiency level of Zn in corn shoot was determined to be 27 mg kg−1 and 32 mg kg−1 in 15-day-old and 40-day-old seedlings, respectively (Rashid and Rafique, 1989). Pal et al. (1989) and Srivastava and Gupta (1996) reported that the critical level of Zn in some Indian soils for corn was 0.6 mg kg−1 . Singh (1986) reported the DTPA-extractable soil Zn and plant tissue Zn critical level for corn as 0.54 and 15.4 mg kg−1 , respectively. Takkar et al. (1989) reported that critical concentrations of soil Zn for maize ranged from 0.38 mg kg−1 to 1.40 mg kg−1 for different soils of India. Alley et al. (1972) used the graphical approach developed by Brown et al. (1962) to calibrate the ethylenediaminetetraacetic (EDTA)- ammonium carbonate [(NH 4 ) 2 CO 3 ] extractable procedure with yield response of corn to Zn application and reported the critical level 0.8 mg kg−1 for growth of corn in field condition. Triewieler and Lindsay (1969) reported the EDTA-(NH 4 ) 2 CO 3 extractable Zn critical value 1.4 mg kg−1 for 42 Colorado soils in greenhouse condition. No information is available regarding the critical level of Zn in soils of central Iran in respect to corn. Therefore, this investigation was carried out to determine the soil and plant tissue critical levels of Zn for corn.

MATERIALS AND METHODS The experiment was carried out in the research greenhouse of Isfahan University of Technology, Isfahan, Iran, in 2007 under natural daylight conditions. During


Critical Zinc Deficiency Level in Corn

1985

the experiment, the day temperature was maintained at 24 to 30◦ C, and the night temperature was never lower than 15◦ C. Other growth conditions were: 32/66% relative humidity (RH), 14 h of light at 150–500 µmol m−2 s−1 . Twelve surface (0–30 cm) soil samples with variable Zn concentration were collected from major soil series in Isfahan province. Selected properties of the soils are shown in Table 1. Soil texture was measured with a hydrometer method (Gee and Bauder, 1986). Soil pH was measured with a digital pH meter in water (Model 691, Metrohm AG, Herisau, Switzerland) (Thomas, 1996), and electrical conductivity (ECe) was measured with an EC meter (Model Ohm-644, Metrohm AG, Herisau, Switzerland) (Rhoades, 1996). The calcium carbonate (CaCO 3 ) equivalent was determined by neutralizing with hydrochloric acid (HCl) and back titration with sodium hydroxide (NaOH) (Black et al., 1965). Organic matter content was determined by the Walkley and Black method (Nelson and Sommers, 1982). Available- potassium (K) was extracted with ammonium acetate (NH 4 OAc) and determined on a flame-photometer (Chapman and Pratt, 1961). Available-phosphorus (P) content in the soil was extracted from the soil with 0.5 M sodium bicarbonate (NaHCO 3 ) (Olsen and Sommers 1982) and determined by a colorimetric method (Black et al., 1965). Chelate-extractable Zn was extracted using DTPA and EDTA buffered with ammonium carbonate [(NH 4 ) 2 CO 3 ] (Lindsay and Norvell, 1978) and then determined on atomic absorption spectrometry (AAS) (Black et al., 1965). The bulk soil samples were air-dried, crushed to pass a 5-mm sieve and brought to the greenhouse. Homogenized soil samples weighing 2 kg were put in pots. Polyethylene pots (25 cm height, 12 cm diameter) were first filled with a 5-cm layer of well-washed sand to improve drainage. On the top of the sand, 2 kg soil were added. Two Zn fertilizer rates [0 and 15 mg Zn kg−1 in the form of zinc sulfate (ZnSO 4 )] were applied to soils. At planting, nitrogen, phosphorus, potassium, iron, manganese and copper fertilizers were applied as ammonium sulfate [(NH 4 ) 2 SO 4 ], potassium phosphate (K 2 HPO 4 ), potassium sulfate (K 2 SO 4 ), iron sulfate (FeSO 4 7H 2 O), manganese sulfate (MnSO 4 4H 2 O), and copper sulfate (CuSO 4 5H 2 O), respectively, to each pot as recommended by the Iranian Soil and Water Research Institute (SWRI) fertilizer recommendation method (Milani et al., 1998). All fertilizers were sprayed thoroughly on the soils before planting. Corn (Zea mays L.) was seeded in pots, thinned to three plants per pot after 10 d, and grown for 60 d. Soil moisture was maintained near 75% of water-holding capacity using deionized water with frequent watering to weight. At harvest, roots and shoots were separated, washed, dried at 70◦ C, ground, and ashed at 550◦ C for 8 h, and the ash was dissolved in HCl (Chapman and Pratt, 1961). Concentrations of Zn and Fe in the digest solutions were determined by AAS. The accuracies of Zn analyses were controlled by analyzing certified standard materials and including blanks in digestion batches. Analysis of NIST soil

1986

Shah Karam Ziar Isfahan Zarandid Roudasht Barkhoar Taljerd Rangideh Ghomsheh Fouladshar Zayandehroud Homayounshahr

Soil Series

Silty clay Sandy clay Silty loam Sandy loam Sandy clay loam Sandy loam Silty clay Sandy clay Silty clay Sandy clay loam Sandy clay loam Sandy clay loam

Texture

8.4 8.2 8.2 8.2 8.2 8.0 8.2 8.4 8.1 8.2 7.9 7.8

49 35 41 40 33 30 48 47 32 50 32 51

4.5 1.5 7.1 1.7 3.1 8.2 3.2 4.9 1.8 1.1 1.3 1.5

CaCO 3 ECe pH (%) (dS m−1 ) 0.49 0.42 0.99 0.42 0.45 0.06 0.60 0.62 0.66 0.18 0.45 0.63

OC (%) 82 80 130 120 60 106 160 96 274 93 82 45

109 165 323 105 95 285 104 195 573 79 79 99

1.72 1.52 1.77 0.55 0.90 1.02 1.00 1.57 1.30 2.10 1.35 1.20

1.02 1.36 0.85 0.75 0.82 0.50 0.65 0.97 1.25 1.20 1.12 1.225

(mg kg−1) 1.85 5.87 0.80 2.45 2.25 0.80 5.07 2.75 12.82 15.47 8.32 11.60

1.45 1.78 0.76 0.77 1.01 0.63 1.30 1.02 5.03 4.85 5.71 4.95

NaHCO 3 -P NH 4 AC-K DTPA-Zn EDTA-Zn DTPA-Fe ETDA-Fe

Table 1 Selected physical and chemical properties of the studied soils


Critical Zinc Deficiency Level in Corn

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standard (San Joaquin #2709; Zn 106 ± 3 µg g−1 ) gave Zn concentrations of 98 ± 5 µg g1 . Recovery of Zn was 90% for apple leaf standard (#1573A). The experiment was set up in a completely randomized factorial design with triplicates. Results were analyzed using ANOVA procedures and means were separated using protected LSD at the 0.05 probability level (SAS Institute, 2000).

RESULTS AND DISCUSSION The studied soils varied in different physical and chemical properties (Table 1). All soils were calcareous with alkaline reaction and low organic matter content. The ECe of the soils varied from 1.0 to 8.2 dS m−1 with a mean value of 3.2 dS m−1 . The pH ranged from 7.8 to 8.4 with a mean value of 8.1 and organic carbon content varied from 0.18 to 0.99%. The calcium carbonate content of the soils was higher than 30%. High pH and calcium carbonate content are the main reasons for the low availability of Zn for plants (Karimian and Moafpouryan, 1999). The Olsen’s P in soils ranged from 22 to 80 mg kg−1 with a mean value of 55 mg kg−1 . It has been reported that high applications of phosphate fertilizers reduce Zn availability (Khoshgoftarmanesh et al., 2006). The DTPA and EDTA-extractable Zn in soils ranged from 0.55 to 2.10 mg kg−1 and 0.50 to 1.36 mg kg−1 , respectively. There was a significant difference in the soil Zn extracted by the DTPA or EDTA extractants (Table 1). Higher Zn was extracted by the DTPA than with the EDTA solution. This result is in contrast to the findings of Stanhope et al. (2000) and Gray et al. (2003). The EDTA is a strong chelator of metals and is considered to act by chelating surface-bound and solubilizing moderately soluble metal ions from the soil solid phase (Stanhope et al., 2000; Gray et al., 2003). The lower Zn extracted by the EDTA extractant in the present study is probably due to the higher pH (8.6) of its solution and as a result, lower Zn dissolved from the soil than with the DTPA solution with a pH of 7.2. Visual Zn deficiency symptoms, such as inhibition of shoot elongation and development of light colored whitish brown necrotic patches on the leaf blades, were noted in the no-added-Zn treatment in soils with the DTPA-Zn being