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This article in SSSAJ

  1. Vol. 65 No. 2, p. 385-390
     
    Received: Jan 21, 2000
    Published: Mar, 2001


    * Corresponding author(s): c-trostle@tamu.edu
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doi:10.2136/sssaj2001.652385x

HEDTA–Nitrilotriacetic Acid Chelator-Buffered Nutrient Solution for Zinc Deficiency Evaluation in Rice

  1. Calvin L. Trostle *a,
  2. P.R. Bloomb and
  3. D.L. Allanb
  1. a Texas A&M Univ. Research & Extension Center, Route 3, Box 213AA, Lubbock, TX 79403
    b Dep. of Soil, Water, & Climate, Univ. of Minnesota, 439 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108-6028

Abstract

Chelator-buffering methods with N-(2-hydroxyethyl)ethylenedinitrilotriacetic acid (HEDTA) are used to elucidate Poaceae growth response to micronutrient metal activities including (Zn2+), but reliable hydroponic methods that maintain stable (Zn2+) for evaluating Zn deficiency in rice (Oryza sativa L.) have not been reported. The objective was to develop a chelator-buffered method that gauges rice growth response to (Zn2+) in an otherwise chemically stable environment. Using GEOCHEM-PC to estimate solution activities, an aerobic HEDTA–nitrilotriacetic acid (NTA) dual-chelator method was developed that imposed five (Zn2+) levels on cv. IR-36 seedlings for 21 d after transplanting (DAT) in a growth chamber. Control of pH 5.50 ± 0.05 using 3.0 mM 2-(4-morpholino)-ethanesulfonic acid (MES) combined with periodic adjustment was critical to preserving target (Zn2+). Solution treatments ranged from Zn deficient, where (Zn2+) = 10−10.0 M (0.25 μM total chelated Zn), to fully Zn sufficient where (Zn2+) = 10−8.8 M (4.00 μM total chelated Zn). Using 200.0 μM total chelated Fe(III), adequate Fe was maintained at (Fe3+) = 10−14.3 M Phosphorous supply was controlled to prevent toxic P accumulation at low (Zn2+). With increasing (Zn2+), total biomass at 21 d ranged from 0.94 to 1.90 g plant−1 Shoot Zn responded to (Zn2+), not total chelated Zn2+, and roots responded similarly. Critical (Zn2+) for normal growth was 10−9.1 M, and leaf Zn-deficiency symptoms were observed at (Zn2+) ≤10−9.4 M (≤28 mg Zn kg−1 shoot). The HEDTA-NTA method provides a rapid and reliable means for evaluating Zn deficiency tolerance in IR-36 via diagnostic visual and physical symptoms in response to a range of (Zn2+) levels.

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Copyright © 2001. Soil Science SocietyPublished in Soil Sci. Soc. Am. J.65:385–390.