15 Zinc J. Benton Storey Texas A&M University, College Station, Texas CONTENTS 15.1 Introduction 411 15.1.1 Early Research on Zinc Nutrition of Crops 411 15.2 Absorption and Function of Zinc in Plants 412 15.3 Zinc Deficiency 412 15.4 Zinc Tolerance 415 15.5 Trunk Injection 422 15.6 Zinc in Soils 422 15.7 Phosphorus–Zinc Interactions 423 15.8 Tryptophan and Indole Acetic and Synthesis 423 15.9 Root Uptake 423 15.10 Foliar Absorption 424 15.10.1 Influence of Humidity on Foliar Absorption 427 15.11 Role of Zinc in DNA and RNA Metabolism and Protein Synthesis 428 15.12 Zinc Transporters and Zinc Efficiency 428 15.13 Summary 429 References 430 15.1 INTRODUCTION 15.1.1 E ARLY RESEARCH ON ZINC NUTRITION OF CROPS Discovery of zinc as an essential element for higher plants was made by Sommer and Lipman (1) while working with barley (Hordeum vulgare L.) and sunflower (Helianthus annuus L.). However, Chandler et al. (2) stated that Raulin, as early as 1869, reported zinc to be essential in the culture media for some fungi, and speculated that zinc was probably essential in higher plants. Skinner and Demaree (3) reported on a typical Dougherty county pecan (Carya illinoinensis K. Koch) orchard in Georgia. Pecan trees that were placed in a study that started in 1918 increased in trunk diameter, but their tops had dieback each year, and their condition ‘appeared hopeless’in 1922. Fertilizers (N, P, K), cover crops, and all known means were of no avail. Rosette, or related dieback, had been rec- ognized since around 1900, but it was in 1932 before zinc was found to be the corrective element (4,5). The common assumption among pecan growers was that a deficiency of iron was responsible for rosette as pecans were brought into cultivation in the early 1900s. Alben used 0.8 to 1.0% solu- tions of FeCl 2 and FeSO 4 in his rosette treatments in 1931 and obtained conflicting results. The 1932 treatments included injections into dormant trees, soil applications while the trees were dor- mant and after the foliage was well developed, and foliar spraying and dipping. The only favorable results were obtained when Alben mixed the iron solutions in zinc-galvanized containers. Analysis proved that the solutions contained considerable quantities of zinc. These experiments led to the use 411 CRC_DK2972_Ch015.qxd 7/1/2006 7:36 AM Page 411 412 Handbook of Plant Nutrition of ZnSO 4 and ZnCl 2 solutions, which permitted normal development of new leaves. Satisfactory results were obtained with trees located on alkaline or acid soils. The most satisfactory results were obtained with a foliar spray of 0.18% ZnSO 4 and a 0.012% ZnCl 2 solution. Roberts and Dunegan (6) also observed a bactericidal effect when using a ZnSO 4 -hydrated lime mixture that controlled bacterial leaf spot (Xanthomonas pruni), which later became a serious pest for susceptible peach (Prunus persica Batsch.) cultivars like ‘Burbank July Elberta’ in the 1940s, ‘Sam Houston’ in the 1960s, and ‘O-Henry’ in the 1990s (personal experience). Hydrated lime was necessary to prevent defoliation of peach trees by ZnSO 4 toxicity. 15.2 ABSORPTION AND FUNCTION OF ZINC IN PLANTS Zinc is taken up predominantly as a divalent cation (Zn 2ϩ ), but at high pH it is probably absorbed as a monovalent cation (ZnOH ϩ ) (7). Zinc is either bound to organic acids during long distance trans- port in the xylem or may move as free divalent cations. Zinc concentrations are fairly high in phloem sap where it is probably complexed to low-molecular-weight organic solutes (8). The metabolic func- tions of zinc are based on its strong tendency to form tetrahedral complexes with N-, O-, and partic- ularly S-ligands, and thus it plays a catalytic and structural role in enzyme reactions (9). Zinc is an integral component of enzyme structures and has the following three functions: cat- alytic, coactive, or structural (9,10). The zinc atom is coordinated to four ligands in enzymes with catalytic functions. Three of them are amino acids, with histidine being the most frequent, fol- lowed by glutamine and asparagine. A water molecule is the fourth ligand at all catalytical sites. The structural zinc atoms are coordinated to the S-groups of four cysteine residues forming a ter- tiary structure of high stability. These structural enzymes include alcohol dehydrogenase, and the proteins involved in DNA replication and gene expression (11). Alcohol dehyrogenase contains two zinc atoms per molecule, one with catalytic reduction of acetaldehyde to ethanol and the other with structural functions. Ethanol formation primarily occurs in meristematic tissues under aero- bic conditions in higher plants. Alcohol dehyrdrogenase activity decreases in zinc-deficient plants, but the consequences are not known (7). Flooding stimulates the alcohol dehydrogenase twice as much in zinc-sufficient compared with zinc-deficient plants, which could reduce functions in sub- merged rice (12). Carbonic anhydrase (CA) contains one zinc atom, which catalyzes the hydration of carbon dioxide (CO 2 ). The enzyme is located in the chloroplasts and the cytoplasm. Carbon dioxide is the substrate for photosynthesis in C 3 plants, but no direct relationship was reported between CA activity and photosynthetic CO 2 assimilation in C 3 plants (13). The CA activity is absent when zinc is extremely low, but when even a small amount of zinc is present, maximum net photosynthesis can occur. Photosynthesis by C 4 metabolism is considerably different (14,15) than that occurring in C 3 plants. For C 4 metabolism, a high CA activity is necessary to shift the equilibrium in favor of HCO 3 Ϫ for phosphoenolpyruvate carboxylase, which forms malate for the shuttle into the bun- dle sheath chloroplasts, where CO 2 is released and serves as substrate of ribulosebisphosphate car- boxylase. 15.3 ZINC DEFICIENCY Zinc deficiency is common in plants growing in highly weathered acid or calcareous soils (16). Roots of zinc-deficient trees often exude a gummy material. Major zinc-deficient sites are old barn- yards or corral sites, where an extra heavy manure application accumulated over the years. Zinc ions become tied to organic matter to the extent that zinc is not available to the roots of peach trees (17,18). Zinc deficiency initially appears in all plants as intervenial chlorosis (mottling) in which lighter green to pale yellow color appears between the midrib and secondary veins (Figure 15.1 and Figure 15.2) Developing leaves are smaller than normal, and the internodes are short. Popular names describe these conditions as ‘little leaf’ and ‘rosette’ (19,20). Pecan trees in particular suffer CRC_DK2972_Ch015.qxd 7/1/2006 7:36 AM Page 412 Zinc 413 FIGURE 15.1 Zinc deficiency of peaches (Prunus persica Batsch) is expressed as developing leaves that are smaller than normal and the internodes are shorter causing leaves to be closer to each other and thence the pop- ular names which describes the terminal branches as ‘little leaf’. (Photograph by J.B. Storey.) (For a color pres- entation of this figure, see the accompanying compact disc.) FIGURE 15.2 Zinc-deficient pecan (Carya illinoinensis K. Koch) leaves (left) can contain less than 30 mg Zn per kg compared to over 80 mg Zn per kg Zn in healthy leaves (right). The zinc-deficient leaves have small crinkled leaves that are mottled with yellow. Healthy zinc-sufficient leaves are dark green. Actual zinc con- centration of each leaf is shown in the photograph. (Photograph by J.B. Storey.) (For a color presentation of this figure, see the accompanying compact disc.) CRC_DK2972_Ch015.qxd 7/1/2006 7:36 AM Page 413 from shortened internodes (rosette) (Figure 15.3). Shoot apices die (shoot die-back) under severe zinc deficiency, as in a tree in Comanche county, Texas (Figure 15.4). Forest plantations in Australia have shown similar symptoms (21). Citrus often show diffusive symptoms (mottle leaf) (Figure 15.5). The ideal time to demonstrate citrus trace element deficiency symptoms is in winter months when the 414 Handbook of Plant Nutrition FIGURE 15.3 Zinc-deficient pecan (Carya illinoinensis K. Koch) trees have shorter internodes so that the leaves are closer together forming a rosette of poorly formed crinkled, chlorotic leaves. (Photograph by J.B. Storey.) (For a color presentation of this figure, see the accompanying compact disc.) FIGURE 15.4 If the rosetted pecan (Carya illinoinensis K. Koch) trees are not treated, the terminals die fol- lowed by death of the entire tree. Dieback can occur on young or old trees. (Photograph by J.B. Storey.) (For a color presentation of this figure, see the accompanying compact disc.) CRC_DK2972_Ch015.qxd 7/1/2006 7:36 AM Page 414 soil is relatively cold. Treatment with zinc fertilizers is not necessary if the symptoms disappear when the soil temperature rises in the spring. Sorghum (Sorghum bicolor Moench) that is deficient in zinc forms chlorotic bands along the midrib and red spots on the leaves (22). Shoots are more inhibited by zinc deficiency than roots (23). For most plants, the critical leaf zinc deficiency levels range from 10 to 100 mg kg Ϫ1 depending on species (Table 15.1). 15.4 ZINC TOLERANCE Zinc is the heavy metal most often in the highest concentrations in wastes arising in industrialized communities (21). Zinc exclusion from uptake, or binding in the cell walls, does not seem to con- tribute to zinc tolerance (24,25). Zinc exclusion might exist in Scots pine (Pinus sylvestris L.), where certain ectomycorrhizal fungi retain most of the zinc in their mycelia, resulting in the ability of the plant to tolerate zinc (26). Infections with ectomycorrhizal fungi are beneficial for the growth and development of pecan (27). These fungi are highly specialized parasites that do not cause root disease. They are symbiotic, thus gaining substance from the root and contributing to the health of the root. Tolerance is achieved through sequestering zinc in the vacuoles, and zinc remains low in the cytoplasm of tolerant plants, whereas zinc is stored in the cytoplasm of non-tolerant clones (28). Positive correlation between organic acids such as citrate and malate with zinc in tolerant plants indicates a mechanism of zinc tolerance (29,30). Zinc tolerance in tufted hair grass (Deschampsia caespitosa Beauvois) was increased in plants supplied with ammonium as compared to nitrate nutri- tion. This effect apparently is caused by greater accumulation of asparagine in the cytoplasm of ammonium-fed plants, which form stable complexes with asparagines and zinc (31). Foliar application of chelates is inefficient because of poor absorption of the large organic mol- ecules through cuticles (32,33). Foliar ZnSO 4 treatments are toxic to peach leaves (34) and to many other species, probably because sulfur accumulates on leaves and results in salt burn. A zinc nitrate- ammonium nitrate-urea fertilizer (NZN TM ; 15% N, 5% Zn; Tessenderlo Kerley Group, Phoenix, AZ, U.S.A.) did not burn peach leaves. Apparently, NZN-treated peach leaves do not suffer from salt burn because the nitrate in NZN is readily absorbed in response to the need of leaves for nitro- gen in protein synthesis thus not accumulating on the surface to cause leaf burn (34). Zinc 415 FIGURE 15.5 Mottled leaf symptoms characterize zinc deficiency symptoms in citrus (Citrus spp. L.). (Photograph by J.B. Storey.) (For a color presentation of this figure, see the accompanying compact disc.) CRC_DK2972_Ch015.qxd 7/1/2006 7:36 AM Page 415 416 Handbook of Plant Nutrition TABLE 15.1 Tissue Analysis Values Useful in Indicating Zinc Status Conditions of Sampling Concentration of Zinc in Dry Matter (mg kg ϪϪ 1 ) Showing Sho wing Type of Tissue Age, Stage, Condition Deficiency Low Intermediate Toxicity Plant Culture Sampled or Date of Sample Symptoms Range Range High Range Symptoms Reference Asparagus (Asparagus Field Spears at harvest time 52 99 officinalis L.) Azalea (Rhododendron Soil Data bank Flowering— Ͻ15 15–60 100 indicum Sweet) youngest mature leaf Barley (Hordeum Soil WS Above ground portion at Ͻ15 15–70 Ͼ70 101 vulgare L.) emergence of head at boot stage Alfalfa (Medicago sativa L.) Field Tops 12 weeks old 13 39–48 102 Almond (Prunus dulcis Field Leaves (t) Midshoots Ͻ15 25–30 103 D.A. Webb) Apple (Malus spp.) Field Leaves Ͻ20 35–50 104 Apricot (Prunus Field Leaves Apical 6 to 8 in 24–30 19–31 105 armeniaca L.) (September–October) Avocado (Persea Field Leaves Mature 4–15 50 106 americana Mill.) Clover, subterranean Solution Tops 12 weeks old 24–25 76–90 102 (Trifolium subterraneum L.) Beans Field Mature Various ages 7–22 18–40 107 (Phaseolus vulgaris L.) leaf blade Beans Field Lea flets Peak harvest 46 108 Beans Field Pods Peak harvest 34 108 Beans Field Seed Seed harvest 37 108 Beet (Beta vulgaris L.) Field Youngest Mature 15–30 109 mature leaf ϩ petiole Blueberry, High bush Field Leaves From 6th node from tip Ͻ8 8–30 31–80 Ͼ80 110 (Vaccinium corymbosum L.) CRC_DK2972_Ch015.qxd 7/1/2006 7:36 AM Page 416 Zinc 417 Boston Fern Soil Early Pinnae from whole fronds 35–50 111 (Nephrolepis exaltata culture sprout or 10–12 cm midsection Schott.) growth Brussels Sprouts Field Upper Heart, 7 cm 26–35 112 (Brassica oleracea var. leaves gemmifera Zenker) Cabbage (Brassica Field Head Peak harvest 34 109 oleracea var. capitata L.) (core sample) Carnation (Dianthus 5th pair of leaves from apex Ͻ15 25–75 100 caryophyllus L.) of lateral before flowering Capsicum (Capsicum Soil and Youngest Early fruit 18–19 20–200 113 annuum L.) Bell Pepper database mature leaf ϩ petiole Carrot (Daucus carota Peat Above Peak harvest 184–490 114 var. sativus Hoffm.) ground portion Cassava (Manihot Leaves 63 days–youngest mature leaf Ͻ35 35–50 40–100 115 esculentum Crantz) Cassava Field Young 43 days Ͻ25 25–30 30–60 60–120 Ͼ120 116 leaf blade Celery (Apium graveolens Field Petioles Midgrowth 30–100 99 var. dulce Pers.) Cherry (Prunus avium L.) Field Midshoot Ͻ15 15–19 20–50 51–70 Ͼ70 117 leaves Chrysanthemum Sand Lower leaf Above ground portion Ͻ6.8 7 7.0–26.0 Ͼ100 118 (Chrysanthemum on flower 70 days after planting morifolium Ramat.) stem Citrus (Citrus spp. L.) Field Midshoot Ͻ16 16–24 25–100 100–300 Ͼ300 119 leaves Coffee (Coffea arabica L.) Field Leaves Four pairs of leaves from tip Ͻ10 10–15 15–30 120 of actively growing shoots Corn (Zea mays L.) Field Lower Tasseling 9–9.3 31.10–36.60 121 leaves Corn Field Leaves 6th node from base At silking 15–24 25–100 101–150 113 Continued CRC_DK2972_Ch015.qxd 7/1/2006 7:36 AM Page 417 TABLE 15.1 ( Continued ) Conditions of Sampling Concentration of Zinc in Dry Matter (mg kg ϪϪ 1 ) Showing Sho wing Type of Tissue Age, Stage, Condition Deficiency Low Intermediate Toxicity Plant Culture Sampled or Date of Sample Symptoms Range Range High Range Symptoms Reference Corn Field 6th leaf Full tasseling 15 122 above base Corn Field Ear leaf Silking Ͻ10 20–70 71–100 Ͼ100 123 blade Cotton (Gossypium Soil Youngest 43 days 13–14 17–48 200 124 hirsutum L.) culture mature leaf blade Cowpea (Vigna Soil Upper leaf 40 days 15–17 20 50–290 125 unguiculata Walp.) culture blades Cucumber (Cucumis Field Youngest Harvest 50–150 126 sativus L.) mature leaf Dieffenbachia Database Portion above ground 25–150 127 (Dieffenbachia exotica) Fig (Ficus carica L.) Field Midsummer. 1st full Ͻ15 Ͼ15 128 size basal leaf Flax (Linum Pots Tops 71 days old 18 32–83 129 usitatissimum L.) Geranium Flowering All above ground portion Ͻ6 8–40 100 (Pelargonium zonale Ait. Grape (Vitis vinifera L.) Vineyard 1 petiole Petiole of basal leaf opposite Ͻ15 15–26 Ͼ26 130, 131 for each bunch cluster 100 vines Hazelnut (Corylus Orchard Midshoot leaves of current Ͻ10 60–80 80–300 Ͼ300 128 avellana L.) season’s growth Kiwi fruit Vineyard Minimum 1st leaf above fruit toward Ͻ12 15–22 23–30 Ͼ30 132 (Actinidia chinensis Planch.) of 10 leaves growing tip Lettuce (Lactuca sativa L.) Peat– Leaf 28 day old 39–71 133 vermiculite 418 Handbook of Plant Nutrition CRC_DK2972_Ch015.qxd 7/1/2006 7:36 AM Page 418 Macadamia (Macadamia Mature 4 pairs of Fruit set half developed Ͻ10 10–15 15–50 Ͼ50 134 integrifolia Maiden and leaves leaves from Betche and M. tetraphylla when 20 trees L.A.S. Johnson) hardened Mango (Mangifera Leaves 60 leaves in 2nd or Ͻ15 20–150 135 indica L.) after 3rd position back of base flowering of bloom Muskmelon (Cucumis Field Youngest Harvest 30–80 109 melo L.) mature leaf Oat (Avena sativa L.) Hydroponic Plant tops Ͻ15 15–70 Ͼ70 136 Olive (Olea europea L.) Orchard Fully Collect 4 leaves/tree 10–30 103 expanded from 25 trees basal to midshoot leaves Onion (Allium cepa L.) Field First mature Midgrowth 30–100 99 leaf Orange (Citrus sinensis Field Leaves 4–7 months old Ͻ15 16–24 25–100 110–200 300 137 Osbeck.) Oil palm (Elaeis Leaflets 6 upper Frond 17 mature or 15–20 138 guineensis Jacq.) and 6 Frond 3 if young planting lower leaflets from frond Ground nuts ( Arachis Field Young Preflower to flower 18–20 25–80 Ͼ80 139 hypogaea L.) midleaf Pea (Pisum sativum L.) Field Above Bud stage 34–36 236–665 140 ground portion Pea Field Pods Early pod fill 24 108 Pea Field Seed Seed harvest 61 108 Peach (Prunus persica Orchard 4 leaves Middle leaves from current Ͻ15 15–19 20–50 51–70 Ͼ70 141 Batsch.) from season shoots 25 trees Pear (Pyrus communis L.) 15 15–30 Ͼ40 104 Pecan (Carya illinoinensis Orchard Leaflets 10 leaflets from mids Ͻ30 30–49 50–100 Ͼ250 142 K. Koch) hoot of 10 trees Continued Zinc 419 CRC_DK2972_Ch015.qxd 7/1/2006 7:36 AM Page 419 TABLE 15.1 ( Continued ) Conditions of Sampling Concentration of Zinc in Dry Matter (mg kg ϪϪ 1 ) Showing Sho wing Type of Tissue Age, Stage, Condition Deficiency Low Intermediate Toxicity Plant Culture Sampled or Date of Sample Symptoms Range Range High Range Symptoms Reference Pecan Orchard 100 leaflets Select leaves from mid shoot Ͻ30 40–50 60–100 100–200 74 from 50 in midseason (July) at half tree midshoot height or 2 m. leaves Pistachio (Pistacia vera L.) Orchard Single 6 subterminal leaflets near 7–14 143 leaflets mid-non-bearing shoots 1 mo before harvest Poinsettia (Euphorbia Upper most mature leaf Ͻ15 25–60 100 pulcherrima Willd.) just before flowering Potato (Solanum Field, Youngest Tubers half grown 20–40 109 tuberosum L.) Sand and mature leaf Database Plum (Prunus spp. L.) Orchard Leaves from Collect 4 leaves/tree Ͻ15 15–19 20–50 51–70 Ͼ70 144 midcurrent in midseason season Raspberry, red Leaves 5th to Leaves taken 2–3 weeks Ͻ13 34–80 145 (Rubus idaeus L.) 12th leaves after final pick Rice (Oryza sativa L.) Soil All top Flowering 16 20–100 190 146 part of plant Rose, hybrid tea 2nd and 1 day before flowering 24 147 (Rosa spp. L.) 3rd 5 leaflet leaves Sorghum (Sorghum Sand All top part Stage 3 Ͻ11 40–50 Ͼ70 148 bicolor Moench) of plant Soybean All top Early flower 20–100 149 (Glycine max Merr.) part of plant Spinach Field Youngest 30–50 days of age 50–75 109 (Spinacia oleracea L.) mature leaf ϩ petiole 420 Handbook of Plant Nutrition CRC_DK2972_Ch015.qxd 7/1/2006 7:36 AM Page 420 [...]... concentrations of the two solutions were applied, the active mass of the ZnSO4 solution was only 75% of that in the Zn(NO3)2 solution Application of a 1 0- L drop of a 200 mg LϪ1 solution of 65ZnSO4 resulted in sorption of 46% of the applied label The portion of the applied label absorbed by a leaf treated with a 1 0- L drop of 200 mg LϪ1 65Zn(NO3)2 was 74% Therefore, sorption from the ZnSO4 solution was 62% of. .. elongation growth upon resupply of zinc (54), which would be expected if growth was a response of increased supply of auxin caused by application of zinc Low levels of IAA in zinc-deficient plants are probably the results of inhibited synthesis of IAA (55) There is an increase in tryptophan content in the dry matter of rice (Oryza sativa L.) grains by zinc fertilization of plants grown in calcareous soil... (Fragaria sp.) CRC_DK2972_Ch 015. qxd Page 421 Zinc 421 CRC_DK2972_Ch 015. qxd 7/1/2006 7:36 AM 422 Page 422 Handbook of Plant Nutrition 15. 5 TRUNK INJECTION Experience with trunk injections of zinc has been disappointing in all cases despite rumors of success It would seem logical that placement of any form of zinc in the secondary xylem of an actively transpiring tree would utilize the xylem vessels to... when other micronutrients are deficient Enhanced phosphorus uptake in zinc-deficient plants can be part of an expression of higher passive permeability of the plasma membranes of root cells or impaired control of xylem loading Zinc-deficient plants also have a high phosphorus content because the retranslocation of phosphorus is impaired 15. 8 TRYPTOPHAN AND INDOLE ACETIC ACID SYNTHESIS The most distinct zinc... revealed variation between seedlings of open pollinated pecans with respect to rate of Zn absorption (37) For example, one set of seedlings absorbed extremes from 0.7 to 91 mg Zn kgϪ1 if roots were exposed to 65Zn in a beaker of water for 96 h CRC_DK2972_Ch 015. qxd 7/1/2006 7:36 AM Page 424 424 Handbook of Plant Nutrition Grauke et al (58) detected the highest concentration of zinc in pecan seedlings originating... Effectiveness of Three Different Zn Fertilizers and Two Methods of Application for the Control of ‘Little-Leaf’ in Peach Trees in South Texas Master of Science Thesis, Texas A&M University, College Station, TX:1991 20 J.P Arce, J.B Storey, C.G Lyons Effectiveness of three different Zn fertilizers and two methods of application for the control of ‘Little-Leaf’ in peach trees in south Texas Commun Soil Sci Plant. .. sampling of Boston fern J Am Soc Hortic Sci 108:90–93, 1983 112 J.A Cutcliffe Effects of lime and gypsum on yields and nutrition of two cultivars of Brussels sprouts Can J Soil Sci 68:611– 615, 1988 113 H.A Mills, J.B Jones Plant Analysis Handbook II Athens, GA: MicroMacro Publishing, 1996 114 U.C Gupta, E.W Chapman Influence of iron and pH on the yield and iron, manganese, zinc and sulphur concentrations of. .. concentrations of spray solutions can be reduced by one eighth to one fourth of the current recommended rate as ZnSO4 at 86 g per 100 L of water Use of the lowest rate of Zn(NO3)2, 10.8 g per 100 L of water ϩ UAN, increased yield and income over the recommended rate of ZnSO4 (66) This paper plus earlier work that led to the formulation of Zn(NO3)2 ϩ UAN was patented under the CRC_DK2972_Ch 015. qxd 7/1/2006... All top part of plant All plant parts above ground Oldest mature leaf ϩ petiole Leaves All top part of plant All top part of plant Sheaths 3–6 3rd and 4th Leaves below flower bud Ear leaf Midgrowth Fleeks scale 10.1 Midgrowth Mature fruit Flowering At plucking Postsilking Florets about to emerge Rapid growth Select 30 or 40 leaves of 1 cultivar during growing season 83 days old 9 20 17 Ͻ3 15 17 30 Ͻ10... 20–200 15 70 20–60 24–60 20–80 20–40 190 10–100 10–80 30–50 Ͼ70 240 Ͼ240 104 136 108 156 155 154 109 153 152 151 150 104 7:36 AM Sweet corn (Zea mays rugosa Bonaf.) Tea (Camellia sinensis O Kuntze) Tobacco (Nicotiana tabacum L.) Solution culture Sugar beet (Beta vulgaris L.) Blade ϩ petiole 58–73 7/1/2006 Soil and databank Field Field Strawberry (Fragaria spp L.) Strawberry (Fragaria sp.) CRC_DK2972_Ch 015. qxd . uptake in zinc-deficient plants can be part of an expression of higher passive permeability of the plasma membranes of root cells or impaired control of xylem loading. Zinc-deficient plants also. Storey.) (For a color presentation of this figure, see the accompanying compact disc.) CRC_DK2972_Ch 015. qxd 7/1/2006 7:36 AM Page 415 416 Handbook of Plant Nutrition TABLE 15. 1 Tissue Analysis Values. flower 20–100 149 (Glycine max Merr.) part of plant Spinach Field Youngest 30–50 days of age 50–75 109 (Spinacia oleracea L.) mature leaf ϩ petiole 420 Handbook of Plant Nutrition CRC_DK2972_Ch 015. qxd 7/1/2006 7:36