1. Micronutrient elements Chapter 14 General Characteristics

2. NutrientSoil Content (kg/ha)Corn Removal (kg/ha) Boron (B) 22-2250.07 Copper (Cu) 2-4500.06 Iron (Fe) 11,200 – 224,0000.12 Manganese (Mn) 112-11,2000.09 Molybdenum (Mo) 1-80.03 Zinc (Zn) 22-6750.17 Micronutrients in Soils and Crops

3. A. Micronutrients are required by all plants but in smaller amounts compared to the macronutrients. Deficiencies of micronutrients can reduce growth just as much as deficiencies of macronutrients. Remember the “Law of the Minimum”. General Characteristics

4. B The amount of micronutrient that is needed by the plant can have a narrow range. If the amount of micronutrient is too high, it is possible for toxicity to occur. Available forms 1. Cations: Fe 2+, Fe 3+, Mn 2+, Zn 2+, Cu 2+ 2. Anions: MoO 4 2-, Cl - 3. Neutral: H 3 BO 3 General Characteristics

5. Micronutrient function in plants 1. Enzymes and coenzymes a) Structural component of enzymes b) Involved in the activation and regulation of enzymes 2. Oxidation and reduction reactions Micronutrients are involved in electron transport

6. Micronutrient transformations in the soil 1. The transformations that micronutrients undergo in the soil vary depending on the nutrient, but overall, the reactions are similar to what has already been discussed for macronutrients. a) Mineralization and immobilization b) Adsorption and desorption to clay or organic matter surfaces c) Precipitation and dissolution of secondary minerals

7. Micronutrient transformations in the soil 2. Micronutrients undergo one transformation that is quite different from the transformations that we discussed for the macronutrients. That transformation is called chelation.

8. a) The word chelate means “claw”. Chelation refers to the process in which organic molecules in the soil form a complex with micronutrient ions. b) The chelated micronutrients are carried by mass flow and diffusion to the root surface. The chelation process in the soil

9. c) The chelate is broken down in rhizosphere. The micronutrient is taken up by the root and the organic molecule diffuses away. d) The organic molecule can complex with more micronutrients and the process is repeated. The chelation process in the soil

10. e) There is still a lot about the chelation of micronutrients that is unknown. The organic molecule that forms the chelate may be derived from: Natural chelates (1) Organic compounds released by the roots or soil microorganism, such as Siderophores 高铁载体 and phytosiderophores 植物高铁载体 (2) Compounds released during the decomposition of soil organic matter,such as fulvic acids (3) Man-made chelates: EDTA, DTPA EDDHA etc The chelation process in the soil

11. Soluble chelates increase the availability of micronutrient cations: Fe, Zn, Mn, and Cu. The chelates help protect the ions from precipitation or adsorption reactions. The chelation process in the soil

12. a) Solubility of the micronutrient (affected by factors such as pH) b) Percent of exchange sites that are occupied by the micronutrient c) Soil organic matter (1) Affects the balance between adsorption and desorption (2) Organic matter is also involved in the chelation process Factors that affect micronutrient availability

13. Iron Fe in the soil Fe is one of the most abundant elements in the surface of the earth. It makes up about 5% weight of the earth’s crust and is invariably present in all soils.

14. Iron forms in soil Mineral bearing iron Primary mineral: olivine, augite( 辉石 ), hornblende and biotite( 黑云母 ). Minerals Fe oxides Geothite (α-FeOOH 针铁矿 ), haematite （赤铁矿 ) and ferrihydrate （ HFe 5 O 8 · 4H 2 O 水化铁） etc

15. Iron in the soil solution 1. Soil solution concentrations are very low. The concentration of Fe 3+ in the soil is ~10 -15 to 10 -20 M. Soluble inorganic forms include Fe 3+, Fe(OH) 2+, Fe(OH) 2+ and Fe 2+ Iron solubility is largely controlled by the pH and Eh. Fe 3+ +3OH - = Fe(OH) 3 At higher pH levels Fe 3+ activity in solution decrease 1000 fold for each pH unit rise

16. In aerobic soils, Fe 2+ is oxide to Fe 3+, and formation of Fe(OH) 3 precipitation. In water-saturated soils (anaerobic), Fe 3+ is converted into Fe 2+, which increase Fe solubility. Fe(OH) 3 +e - +3H + Fe 2+ +3H 2 O Iron in the soil solution

17. Siderophores and phytosiderophores Siderophores are a kinds of organic substance (such as nicotinamine ( 烟酰胺 ), mugineic acid 麦 根酸 and avenic acid etc) produced by the bacteria, fungi and plant), which can form organic complexes or chelates with Fe 3+, and increase the movement of iron in soil.

18. Characteristics of siderophores they are molecules with a high affinity for Fe 3+, and removes the Fe from minerals and contributes their dissolution. these Fe-chelates are highly soluble and are stable over a wide pH range. they are of crucial importance for the Fe transport in soils and the Fe supply of plants.

19. Plant uptake of Fe 1. Plants can take up both Fe 2+ and Fe 3+. In general, Fe 2+ pass through a species channel of PM. Fe 3+ is reduced to Fe 2+ before absorption occurs. Fe 3+ uptake is important for grasses Phytosiderophores molecular is take up by specific transporters located in PM of graminaceous 禾本科 monocots root, and Fe is reduced in cells.

20. Factors that affect Fe uptake 1. Plants have different abilities to take up Fe from the soil solution Not only different species (wheat vs. bean) but even different genotypes. 2. pH Fe 3+ reduction requires a pH of about 5 at the apoplastic site of the reductase. The Fe uptake of general plant is affected by the pH, but Fe uptake of graminaceous monocots is little affected by pH. 3. Ability of Fe 3+ reduction in the root

21. Effect of pH in the nutrients solution and N sources on the Fe concentrations in leaves and roots and chlorophyll concentration in the youngest leaves of helimanthus annuus (Kosegarten et al 1998)

22. Translocation of iron The Fe 2+ in the cytosol is presumably oxidized in transport into the xylem. Long- distance transport in the xylem is Fe 3+ complex when an excess of citrate in the xylem. In the phloem and in the symplasm Fe is transported as an nicotianamin.

23. Fe concentration in the plant Fe concentration in the plant Fe concentrations in dry plant tissue are commonly around 50-100 μg/g (compared to N which is typically 10,000- 50,000 μg/g Most of Fe is in the vegetative parts, grains and tubes are often considerably low. The content of iron in the plant is effected by the soil iron availability.

24. 1. Fe is important in the process of chlorophyll and haem formation in plants text book p392 2. Fe is required for electron transport in photosynthesis. It is an important part of several molecules that are involved in photosynthesis. Iron sulphur proteins or ferredoxin and ferritin( 铁 蛋白 ) Roles of iron in plant

25. Roles of iron in the plant 3. Chelate complex Fe is an important electron acceptor in redox reactions Haem is prosthetic groups 辅基 of several enzymes (catalase, peroxides, cytochrome oxidase etc.). 4. Nitrogenase comprises an Fe protein and FeMo protein; 5.Ribonucleotide reductase. It is required of synthesis of DNA and RNA, which is required for the synthesis of proteins.

26. Fe deficiency symptoms 1. Interveinal yellowing and chlorosis of whole leaves and emerging leaves. Symptoms appear on youngest upper leaves The leaves are yellow, with the veins remaining green. 2. Whole leaves become chlorotic and pale and reduction of leave. 3. Not all species are equally susceptible to Fe deficiency Calcifuge species ( 避钙植物） is susceptible to Fe chlorosis; The most important commercial crops affected are citrus, deciduous fruit trees 落叶果树 and vine; Field beans, soybeans, legumes, and tomato etc.

27. Iron deficiency in soybeans

28. Iron deficiency in rice Wheat Plants Iron deficiency Severe chlorosis of leaves, most severe on younger growths; die-back of chlorotic leaves Oat Plants Iron deficiency Young leaves severe chlorosis; chlorosis begins as interveinal stripes.

29. 越橘

31. Fe deficiency of grape leaves (up) Fe deficiency of pear (left and middle of bottom), and apple tree (right of bottom) Tip leaves chlorotic; small veins show as fine network in early stages; margins develop brown patches

32. Potato Foliage Iron deficiency Young leaver strongly chlorotic; veins may remain green; margins and tips brown patches. Potato Foliage Iron deficiency Young leaver strongly chlorotic; veins may remain green; margins and tips brown patches.

33. TOMATO FOLIAGE Iron deficiency Tip leaves, especially basal areas of leaflets, intense chlorotic mottling; stem near tip also yellow. Cabbage Plant (Savoy 皱叶 甘兰 ) Iron deficiency Severe chlorosis of leaves beginning as a chlorotic mottling 色斑.

34. 水稻铁中 毒：青铜 色叶片 bronzing leave or bronzed disease

35. Lime induced chlorosis Iron chlorosis may result from an absolute Fe deficiency in soil, such as organic soils and degraded sandy soils. But such cases are rare. However, iron chlorosis occurs frequently on the calcareous or saline and sodic soils. The chlorosis is not caused by absolute Fe deficiency. The Fe concentration in the chlorotic leaves can be higher than in the green leaves. Why?

36. Lime induced chlorosis Calcareous soils, high pH and high HCO 3 - concentrations in soil solution may depress or even block F 3+ reduction in the root apoplast. The nitrate nutrition is predominately in Calcareous soils, which induce high apoplastic leaf pH,so Fe 3+ reduction in the leaf apoplast is restricted and hence the uptake of Fe from the apolast into the cytosol impaired. Spraying chlorotic leaves with dilute acids results in regreening. So does fusicoccin ( 壳梭孢素 )as well as IAA

37. Effect of spraying Fe-EDDHA or dilute H 2 SO 4 for curing Fe chlorosis on chlorophyll concentration and pod yield of Pisum sativum (Shau 1987)

38. Common Fe Fertilizers Common Fe Fertilizers 1. Ferrous sulfate, FeSO 4 ·7H 2 O, (20% Fe) a) applied to foliage as a solution b) injected into the tree trunk 2. Iron oxalate, Fe 2 (C 2 O 4 ) 3, (30% Fe) 3. Iron citrate, FeC 6 H 5 O 7 ·X H 2 O,(16%- 18% Fe)

39. Common Fe Fertilizers Common Fe Fertilizers 3. Chelated iron Chelated iron compounds consist of an organic molecule that binds iron and makes it solubility in soil solution and more available to plants. FeEDDHA, Fe 6% FeDTPA, Fe10% FeEDTA, Fe 9-12% HEDTA, Fe 5-9%

40. b) Chelated compounds must be placed into the root zone to be most effective. Or foliage application. Applications should be made in the spring to coincide with the beginning of growth. In most cases, it is necessary to treat the soil every year. Common Fe Fertilizers

41. Management strategies Management strategies A. Soil application can be helpful when the pH is low, but not at high pH. B. Alternative methods of Fe-fertilization include: 1. Foliar application 2. Seed coating 3. Injecting Fe into the tree trunk

42. Other management strategies 1. Lower the pH of the soil (increases soluble Fe 2. Combined the organic matter content and FeSO 4 together. 3. Choose varieties that are not so sensitive to iron deficiencies.

43. Zinc

44. Soil Zinc The total amount of Zn in the soil is relatively small. The average Zn content of the soil is 17 to160μg Zn/g soil. The level of Zn in soils is very much related to the parent materials. Basic igneous rocks > siliceous parent materials sometimes, pollution soil have high Zn levels zinc content in soil

45. Soil Zinc primary and secondary soil minerals: augite ( 辉石）， hornblende, and biotite ( 黑云母） salts : ZnS, Sphalerite (ZnFe)S 闪锌矿， smithsonite (ZnCO 3 ) 菱锌矿 willemite (Zn 2 SiO 4 ) 硅锌矿 Zinc fraction in soil

46. Soil Zinc Soil solution Zn 1. the Zn concentration is very low and in the 3 ╳ 10 -5 to 5 ╳ 10 -3 mol/l. 2. forms of Zn in soil solution Zn 2+, ZnOH + or ZnCI + Most of the Zn in the soil solution is usually in the chelated form

47. Soil Zinc Exchange Zn Clay minerals and organic matter have exchange site of Zn ions. Specific adsorption of Zn 2+ by carbonate: Magnesite ( 菱镁矿） >dolomite （白云石） >calcite （方解石） Adsorption and occlusion of Zn by carbonate are major cause of poor Zn availability and the appearance of Zn deficiency on calcareous soils.

48. Soil Zinc Organic Zn Zn can interact with organic matter in soil Soluble Zn organic complexes is about 60% of total Zn in soil solution. Amino acids, organic acids and fulvic acids 富哩酸 complexes with Zn are soluble; but insoluble organic complexes are derive from humic acid 胡敏酸.

49. Soil Zinc pH: Soluble Zn +2 is ~100 times lower with a pH increase of 1 unit organic matter Zn complexes can either increase or decrease the availability of Zn to the plant. carbonate content History of arable soil Excess application P fertilizers or iron Mn etc Factors affecting soil Zn availability

50. Zinc in plants Zn Content in plant For most plant species Zn concentrations in leaves below 10-15 μg Zn/g dry matter are indicated of Zn deficiency and concentration in the range of 20 to 100 μg Zn/g dry matter are sufficiency.

51. Zinc in plants Uptake and translocation The uptake may be as facilitated diffusion through membrane channels or mediated by specific transporters. The uptake is strongly inhibited by the Cu, the Fe, Mn and alkaline earths cations 碱土金属离子 etc. And is reduced by low temperature.

52. Zinc in plants Translocation Zn is not bound to stable ligand. It is translocated as zinc citrate complexes Zn is phloem-mobile, but its translocation is varies among different plants. In the high Zn level, excess Zn is deposited to a large extent in the older leaves

53. Zinc in plants Function of Zn in plants 1. Activates 300 enzymes Carbonic anhydrase( 碳酸酐酶） is particularly important for C4-species. Alcohol dehydrogenase is important in root under anaerobic conditions. Cu-Zn superoxide dismutase (SOD) is required for the detoxification of the superoxide radical 超氧自由基. It is important to resist the sunscald ( 日灼病） Enzymes involved in the carbohydrate metabolism.

54. Zinc in plants Function of Zn in plants 2. Necessary for the plant hormone (for example IAA) In Zn deficient plant it is low rates of stem elongation, low auxin activities and low trytophan ( 色氨酸） 3. Zinc is very closely in the N metabolism of plant. RNA polymerase contains Zn Zinc deficiency affected the structural integrity of the cytoplasmic ribosomes.

55. Deficiency symptoms 1. Stunted (reduced) growth Unevenly distributed clusters or rosettes of small stiff leaves (Small, narrow, thick leaves) are formed at the ends of the young shoots. Frequently the shoots die off and leaves fall prematurely. Apple tree: rosette and little leaf. 小叶病 与簇叶病． Fewer bud, bark is rough and brittle

56. Deficiency symptoms 2. Chlorosis in the interveinal areas of the leaf In the monocots chlorotic bands form on either side of midrib of the leaf which later become necrotic. The symptoms appears on young leaves. In most case, the deficiency symptoms of vegetable crops is characterized by short internodes and chlorotic areas in older leaves. Sometimes chlorosis also appears in younger leaves.

57. Zinc deficiency in corn

58. Zinc deficiency in canola ( Zinc deficiency in canola (chlorotic mottling and than necrosis)

59. Zinc deficiency of citrus spring summer

60. Zinc deficiency of rice

61. Center: healthy shoot from zinc deficient apple tree; Left and Right: shoots showing zinc deficiency symptoms; buds along shoots fail to develop, leaves small and narrow ("Little Leaf" condition) and tend to form rosettes at tips of shoots.

62. Zinc toxicity and tolerance Excess Zn supply results in reduction of root and leaf expansion which is followed by chlorosis. Red-brown pigment was formed under conditions of excess Zn in soya beans. Some plants species are Zn tolerant. They can accumulated 600 to 7800 μg Zn/g dry matter.

63. Sugar Beet Plants Zinc toxicity Growth severely stunted; young leaves show chlorotic iron deficiency symptoms followed by severe intervenal necrosis

64. Excessive Zn of cucumber: dark green of older leave (left). Younger leave shows slight green with interveinal brown spot like pinhole

65. Conditions that may have Zn deficiencies Conditions that may have Zn deficiencies A. Soils with a high pH (low Zn solubility) B. Fine-textured soils (Zn adsorption) C. Cool, wet conditions

66. D. High levels of Cu, Fe, Mn or P can cause a Zn deficiency E. Some crops are more sensitive than others 1. Corn and beans are sensitive 2. Sensitive crops following sugar beets may have a Zn deficiency. Conditions that may have Zn deficiencies

67. Zinc fertilizer A. Kinds of Zn fertilizer 1. Manure supplies Zn and organic molecules for chelation 2. ZnSO 4 (35% Zn) is most common fertilizer 3. Chelated zinc

68. Application of Zn fertilizer 1. Zn may be applied to the soil or to the foliage 2. Banding is usually more efficient than broadcasting – but don’t band P and Zn together. Zinc fertilizer

69. Copper Copper

70. Copper in the soil The total amount of Cu in the soil is relatively small. The average Cu content of the soil is 5-50 μg/g. It is contained in a number of primary and secondary soil minerals.

71. Copper fractions in soil Minerals Largest fraction of Cu is usually present in the crystal lattices of primary and secondary minerals, such as olivine, hornblende, picrites 辉石, biotite, feldspar, chalcopyrite 黄铜矿 etc.

72. Copper fractions in soil Absorbed Cu or occluded Cu Cu ion is adsorbed to inorganic and organic negatively charged groups. Copper is specifically adsorbed to carbonates, soil organic matter, phyllosilicate ( 层状硅酸盐 ), and hydrous oxides of Fe, AI and Mn. The divalent Cu ion has a strong affinity to soil organic matter compared with other divalent cations Cu>Nickel>Pb (lead) ＞ (Lead)>Cobalt>Ca>Zn>Mn>Mg

73. Copper fractions in soil Copper fractions in soil Cu in soil solution The Cu concentration of the soil solution is usually very low being in the range of 0.01 to 0.6mmol/m 3. The majority of the Cu in the soil solution is in the chelated form (complexed with organic molecules)

74. The factors controlling Cu availability in soils 1.Soil pH The amount of soluble Cu is about 100 times lower with a pH increase of 1 unit. 2. Soil organic matter Organic matter complexes (molecular weight 5000. 3.Carbonate or oxides 4.History of arable soil and applications of agrochemicals such as Bordeaux mixture ( 波 尔多液）.

75. The factors controlling Cu availability in soils So Cu deficiency often occurs on the Cu inherently low soils such as sandy podzolic soils 灰化土 and soils developed on parent materials poor in Cu; organic soil and peaty soil calcareous soils high in clay content. Reclamation disease 开垦病

76. Copper in plants Cu content in plant In most plant species, the Cu concentration in plant is low and in the range of 5 to 20 μg Cu/g and is normally less than 10 μg Cu/g dry matter. Anthers ( 花） are normally very high in Cu. Crops species differ in their sensitivity to Cu deficiency. The most responsive crops: oats, spinach, wheat, and lucerne ( 紫花苜蓿 ) Medium range: cabbage, cauliflower, sugar beet and maize Low response crops: beans, grass, potatoes and soya beans

77. Copper in plants Uptake and transport The mechanism of Cu uptake is not yet clear, But Cu 2+ must be reduced before is transport across the PM Cu uptake appears to be metabolically mediated process Zn strong inhibit the Copper uptake and vice versa

78. Copper in plants Uptake and transport Cu is very strongly bound to the root apoplast. Copper is not readily mobile in the plant. when supplied with copper, Cu can move from leaves to the grains; but in deficiency plants Cu is relatively immobile. Cu is transported in the form of anionic Cu complex.

79. Function of Cu in plants 1. Important component of many enzymes The most common of the three types of superoxide dismutase iosenzymes contains Cu and Zn (Cu-ZnSOD) Cytochrome c oxidase is one of the most well studied of Cu containing enzymes in the mitochondrial transport chain. The enzymes phenolase (tyrosinase 酪氨酸氧化酶 and polyphenol oxidase 多酚氧化酶 ) Ascorbic acid oxidase Amine oxidase which catalyze oxidative deamination.

80. Function of Cu in plants 2. Necessary for photosynthesis Blue protein or plastocyanin 质体蓝素 (2Cu/molecular) is essential redoxsystem of the photosynthesis e - transport chain. 3. Involved in the lignification of cell walls Phenolase ( 酚酶 ) and laccase ( 漆酶 ) are involved in lignin synthesis.

81. Function of Cu in plants 4. Copper influences both carbohydrate and nitrogen metabolism In the vegetative stage Cu deficiency can induce lower concentration of soluble carbohydrate and an accumulation of soluble carbohydrate in the leaves and roots after anthesis ( 开花期） owing to failure of flower set and consequent lack of grain filling process. 5. Important for the formation of pollen sterility of pollen in Cu deficient plant.

82. Copper deficiency symptoms In cereals crops deficiency shows first in the leaf tips at tillering ( 分蘖 期 ) ． The tips becomes white and leaves are narrow and twisted. The growth of internodes is depressed; excessive tiller occurs; ear （小穗） and panicle( 圆 锥花序） formation is absent in severe conditions. Or ear are not fully developed and may be partially blind in less deficiency.

83. Copper deficiency symptoms In Cu deficient trees the development of “ pendula”( 摇摆） forms may occurs. In N application soil plant is easily to lodging if Cu deficient.

84. Copper deficiency in barley Pigtail whip tail of barley shows copper deficiency Left normal wheat. Right wheat with severe copper deficiency symptoms

85. upright empty headed Park wheat at right is grown on 0.6 ppm DTPA Cu soil. At left, same crop grown on soil amended with 12 lb Cu per ac as CuSO4. Yields were 19 bu per ac vs 51 bu per acre

86. Left normal barley. Right severe copper deficiency Heads of wheat grown in copper deficient soil become bleached and then turn grey; stems of some cultivars darken significantly due to melanosis 黑变病.

87. Toxic of Cu For most plants species high concentrations of available Cu in nutrient medium are toxic to growth. Chlorosis is commonly observed symptom of Cu toxicity, superficially resembling Fe deficiency. Inhibit of root growth is one of most rapid response to toxic Cu levels

88. Conditions that may have copper deficiencies Conditions that may have copper deficiencies 1.Cu deficiency is most common in soils with very high levels of organic matter or sandy soils with a high pH. 2. High levels of Fe, Zn, and P can also cause Cu deficiency 3. Small grains, carrots, and onions are sensitive to low levels of Cu

89. Copper fertilizer Copper sulfate (CuSO 4 ·5H 2 0) – 25% Cu is the most common fertilizer Cu Oxides 75% -89% Cu, insoluble in water Chelated Cu: EDTA, Cu amino acids and Cu fulvic complex Manure and other organic sources can supply chelates as well as Cu

91. Cu concentrations of organic manures and wastes (Dam Kofoed 1980)

92. Soil application Cu can be applied to the soil with rate of 1-10 kg Cu/ha, more for organic soil If added to the soil, Cu should generally be broadcast and incorporated. There is some concern that putting Cu in bands could cause root damage. Foliar applications CuSO 4, CuO or Cu chelates Application

93. Manganese

94. Manganese in the soil Total Mn content in the soil The average Mn content in the soil is20 ~3000 μg Mg/g. It is found in primary minerals (pyrolusite or MnO 2 软锰矿,manganite or MnO(OH) 水 锰矿 ),clays, oxides, and hydroxides.

95. Manganese in the soil Mn fractions in soil Crystalline Mn oxides: MnO 2, MnO · nH 2 O Easily reduced Mn (amorphous): Mn 2 O 3, MnO(OH) etc Exchangeable Mn: bounded to the organic or clay Soluble Mn: Mn 2+

96. Oxdation/reduction processes of Manganese in the soil Mn 2+ Mn 2 O 3 MnO 2 ·nH 2 O MnO 2 Aerobic and OH - Aerobic and OH - dehydrate Aerobic and OH - Anaerobic and H +

97. Factors of control of Mn availability in soil Redox conditions as Eh increase, the Mn availability decrease pH pH>5 to 6, the reduction rate decrease by a factor 10 to 100 Forms of Mn oxide amorphous > crystalline Organic matter large organic matter reserves are particularly prone to Mn deficiency Microbial activity pH dependent (pH=7)

98. Effect of liming and a three day period of flooding on dry matter yield and Mn concentrations in lucerne (Graven et al. 1965)

99. Manganese in plants Mn uptake and translocation Mn uptake occurs in the forms of Mn 2+ by facilitated diffusion presumably. Mg 2 + and Ca 2 + depress Mn 2+ uptake Mn 2+ depress the Fe uptake Mn is relatively immobile in the plant and is scarsely translocated in the phloem. Mn is preferentially translocated to meristem. Si enhanced the distribution of Mn in barley plants

100. Manganese in plants Function of Mn in plants 1. Activates a number of enzymes Mn bridge ATP with the enzyme complex, such as phosphokinase and phosphotransferases) It activates PEP carboxylase. It depress the peroxidase and IAA oxidase activity 2. Mn containing enzymes MnSOD detoxifies the superoxide radical in the mitochondria of eukaryote ( 真核细胞）

101. Manganese in plants 3. Photosynthesis Involved in the splitting of H 2 O and O 2 evolution in photosynthesis – Hill reaction

102. Manganese in plants 4. Other reactions associated with the photosynthetic e - transport are affected by the Mn deficiency. Photophosphorylation Reduction of CO 2 Reduction of nitrite Reduction of sulphate etc

103. Deficiency symptoms Chloroplasts are the most sensitive of all organelles to the Mn deficiency and disorganization of lamellar( 片层） system occurs. So interveinal chlorosis of young leaves. It is resembles Mg deficiency (older leaves). In monocots and particularly in oats, Mn deficiency symptoms appear at the basal part of leaves as greenish grey spots and strips during tillering stage.-- “grey speck” 灰斑病

104. Wheat, Oats, Barley Manganese deficiency Field comparison of susceptibility. Oats (center) more susceptible than barley (left) and wheat (right).

105. Oat Leaves and Heads Manganese deficiency (right): Leaves, grayish- brown elongated specks and streaks, most prevalent in basal halves; breaking of leaves with distal areas remaining green empty panicles. Irregular, grayish-brown lesions, which coalesce and bring about collapse of leaf (gray speck symptoms 灰斑病 ) (left).

106. Rye and wheat Mn deficiency ： interveinal chlirotic spot and stripe on the middle and basal halves

107. Manganese deficiency in oranges In dicots, the symptoms are often characterized by small yellow spots on the leaves and interveinal chlorosis. It differs from that of Fe deficiency where the whole young leaf becomes chlorotic.

108. Apple, Variety, Early Victoria. Leaves severe chlorosis over most of tree; young leaves of terminal shoots not as severely affected as older leaves. Apple Foliage Manganese deficiency Leaves intervenal chlorosis progressing from margins towards midrib.

109. Dwarf Bean Plants Manganese deficiency :Leaves severe chlorosis and necrosis ； Haricot Bean Plants Manganese deficiency Leaves strong chlorotic motting Pea Seeds Manganese deficiency :Brown lesions in centers of cotyledons ("Marsh Spot") (left of bottom) Runner Bean Seeds Manganese deficiency brown lesions in cotyledons. (right of bottom)

110. Manganese toxic The critical deficiency level for most plant species is in the range of 10 to 20μg Mn/g dry matter. 200μg Mn/g dry matter for maize and 5300μg Mn/g dry matter for sunflower are toxicity. The toxicity symptoms are generally characterized by brown spots of MnO 2 in older leaves surrounded by chlorotic areas.

111. Mn toxicity of orange and lemon

112. Mn toxicity of vegetable rice

113. Manganese toxic Mn toxicity in spring barley was characterized by dark brown spots at the leaf tips which were enrolled and had extremely high Mn concentrations. Another symptom of Mn toxic is the loss of dominance and the proliferation of auxiliary shoot （分枝，分蘖增加）. Some times Mn excess can induce a deficiency of other mineral nutrients such as Fe, Mg and Ca.

114. Conditions that may have Mn deficiencies 1. High pH soils 2. High organic matter soils 3. High levels of Cu, Fe or Zn 4. Dry weather 5. Soils organic soils, some podzolic soils( 灰化土 ) and sandy soils etc 6. Crops oats and peas are the most sensitive to Mn deficiency; other sensitive crops are: apple, cherry, citrus, raspberry( 悬钩子 ), and sugar beet

115. Manganese Fertilizer Kinds of manganese fertilizer 1 ． Manganese sulfate (MnSO 4 ·4H 2 0) Mn 26-28% MnSO 4 · 4H 2 0 is the most common source of Mn. It can be added to the soil or applied to the foliage. Banding is more effective than broadcasting. 2. Manganese chloride MnCl 2 17 %

116. 3 ． Chelated Mn Mn EDTA Mn 12% Used for foliar applications. Applying chelated Mn to the soil is ineffective, because Fe or Ca will replace the Mn in the chelate. 4 ． Manure supplies Mn and organic matter for the formation of chelates Kinds of manganese fertilizer

117. Boron Boron

118. Soil boron Total boron in the soil The content of B in the soil ranges between 20-200 mg/kg dry weight. Most of which is inaccessible to plants.

119. Boron in the soil solution 1.Between pH 5 and 9, H 3 BO 3 is the dominant form of B in the soil solution. 2. The pH of the soil solution and the amount of clay, oxides, and organic matter are important factors that affect B availability. Soil boron fraction

120. B containing Minerals Tourmaline (30-40 mg B/kg) and hydrated minerals Absorbed B AI and Fe oxides, clay minerals, calcium carbonate, and organic matter Ligand exchange: kaolinite>montmorillonite>illite Soil boron fraction

121. Organic matter bounding B the sorption capacity for B in composed organic matter is about 4 times greater than for soil or clay. It is believed to be ligand exchange. Hot water soluble B (0.5-2.0 mg B/L) S oluble B consists mainly of boric acid which under most soil pH conditions (pH 4-8) B(OH) 3 + H 2 O B(OH) 4 - ; pK4=9.2 Soil boron fraction

122. Factors affecting boron availability 1. pH Absorption of B is closely dependent on soil pH, adsorption increase the pH range 5-9 2. B leaching In acid, sandy soil or podzolic soil, B is easily leached from soil; but in arid and semiarid regions, B may accumulate to toxic concentration. 3. Organic matter Native B and hot water soluble B in soil are significantly correlated with organic C content.

123. Effect of soil pH and carbonate on the proportion of sugar beet infected by crown and heart rot (scheffer and Welte 1955)

124. B deficient Soils Soils developed from sandstones and acid igneous rocks Spodosol 灰土 and podzols 灰壤 Sometimes Andosols, Lithosols 石质土 and Luvisols 淋溶土 Sandy soil Liming acids with marginal B concentrations Hot water soluble B <0.5 mg/L

125. Boron in plant Uptake B uptake is a possible combination of active transport as esters with cis diols ( 顺式 二 醇 ) and passive diffusion as undissociated boric acid. But the exact nature of boric acid transport across cell membrane is still not totally resolved.

126. B in plant Translocation To most of plant species, B is translocated through the xylems, and limited phloem. It is controlled by the transpiration flow. B is not readily transported in the plant. Deficiencies occur first in the growing points and young leaves. But in some species, such as celery, carrot, bean, and cauliflowers, apple, pear, and apricot 杏, B is mobile and is transported as a complex with polyols ( 多元醇）.

127. Function of B in the plant Cell walls B is now believed to play a key role in the structure and integrity of cell walls. The chemical composition and ultrastructure of cell walls are quickly affected by a lack of B. The role of B in cell walls is cross linking of pectic polymers (B-RG ）. It is important to cell wall structure.

128. Function of B in the plant Membrane function 1.The effects of B are thus mediated either directly or indirectly by the plasmamembrane bound H + pumping ATPase. 2.The effects of B are primarily on plasmmembrane itself (Cakmak and R Ö mheld 1997). B stabilizes the structure of plasma membrane by complexing membrane compounds containing cis-diol groups such as glycoproteins and glycolipids to keep channels and enzymes at optimum conforation within the membrane. 3.B exerts its most important influence at the cell/plasma interphase.

129. Function of B in the plant Other functions Pollination B was associated with the higher growth rate of pollen tubes. Root elongation IAA levels is regulated by the B via IAA oxidase activity Meristematic activity synthesis of N-bases such as uracil

130. Deficiency symptoms 1. Abnormal or retarded growth of apical growing points, in advantage stage, death of the terminal growing points 2. Stems have an unusual shape. They may become thick and crack. 3. Youngest leaves are misshapen, wrinkled and are often thicker and of a darkish blue- green color. Irregular chlorosis between the intercostal veins 肋间脉 occur.

131. 4. The roots may grow in a very unusual way. In turnips 芜青 and swedes 甘蓝, B deficiency result in glassy like root which are hollow and cracked 5.Flower and fruit formation is restricted or inhibited. The tissue of the fruit may have some soft, brown spots. Sometimes it results parthenogenesis ( 单性生殖 ). Drop of buds, flowers and fruits Fruits developed remain very small and are of poor quality. Deficiency symptoms

132. Boron deficient potatoes Growth stunted; growing point killed; leaves dull grayish green, changing to yellow before dying off. Boron toxicity shown by narrow brown rims on leaflets; magnesium deficiency by intervenal necrosis and withering

133. 黄瓜缺硼： B deficiency of cucumber. older leave developed yellow ； new leave are distorted and appear mottled ； Aborted fruit (top); twisting and scarring ；

134. B deficiency: Stems stiff; terminal buds die and growths die back （ up is capsicum ； bottom is cucumber and tomato ）

135. 番茄果实缺硼：表面 有凹痕软木区，成熟 不平衡，类似缺钙。 Fruits pitted and corky areas in skin; ripening uneven

136. Cauliflower Head Boron deficiency Browning of curd Longitudinal section. Browning of curd and lesions in pith. (Not specific for boron; may be due to other causes in the field) Secondary infection of Bacillus Carotovorus. Corky condition of epidermis (bottom)

137. Young Sugar Beet Plant Boron deficiency Early stage of boron deficiency. Young leaves distorted and fail to expand. （ left) “Crown Rot“ 茎腐病 and death and distortion of young leaves; older leaves cracking and distortion of laminae, yellow pigment formation and severe marginal scorch. (right)

138. Table Beet Plants Boron deficiency Collapse of foliage, beginning with young leaves; rotting of outer tissues of the roots. ("Canker") ； Transverse section. "Canker" lesions, mainly in outer tissues. Rough skin condition which may accompany "Brown Heart" condition.

139. 蕉青甘蓝缺硼： Swede Plant Boron deficiency Mottling and tinting of foliage and death of growing point. (right) Rough skin condition which may accompany "Brown Heart" condition. (middle and right)

140. Runner Bean Stem and Leaves Boron deficiency Stem thickened and stiff; growing points die; leaves slight chlorotic mottling. Carrot Plants Boron deficiency Growth of young leaves restricted giving a rosette effect, older leaves orange tints; growing point may die.

141. Crops sensitive to B deficiency Crops differ in their sensitivity to B deficiency. Most sensitive crops: Cruciferae （十字花科） such as cabbage, turnips, brussels( 抱子甘蓝）, sprouts, cauliflower and Chenopodiaceae( 藜科） such as sugar beet and swede. Others crops sensitive to B deficiency: celery, groundnut （落花生）, coffee, oil palm （油棕榈）, cotton, sunflower, olive, and pines （松树）. Legumes and fruit trees have a high B requirement Graminaceous monocots have a low B requirement.

142. Boron concentrations of various plant groups (Syworotkin 1958) B in μg/g DM

143. Boron toxicity The symptoms of B toxic often occurs on the older leaves. Begin with chlorosis on the tips and margins and finally spreads between the lateral vein, followed by progressive necrosis in the advantage stage. The leaves take on a scorch ( 焦枯） appearance and drop prematurely.

144. B toxicity of Mellon （ left of up ） and sweet potato (bottom0

145. B toxicity ： rice （ up ）

146. +B Symptoms of B toxicity are first seen in older leaves. They include yellowing between the veins,followed by necrosis. Note small brown necrotic spots,and large areas of dead tissue

147. B toxic of cucumber in the greenhouse

148. Boron toxic soils Arid and semi-arid soils with high B level B concentration in the irrigation water >0.3-1mg/L for sensitive crops; 1-2mg/L for semi tolerant plants and 2.1-4 mg/L for tolerant plants Industrial pollution

149. Sensitivity of crops to B toxicity Sensitive crops: peach, grapes, kidney beans( 菜豆 ) and figs( 无花果 ) Semi-tolerant crops: barley, peas, maize, potato, lucerne( 苜蓿 ), tobacco, and tomato Most tolerant crops: turnips( 芜青 ), sugarbeet and cotton.

150. Boron fertilizer

151. Application of boron fertilizer 1. Soil application 2.Foliage spray early autumn or anthering 3. Application as starter or pop-up

152. Molybdenum

153. Soil molybdenum Content of Mo in soil 0.8-3.3 mg/kg in agriculture soil Soil derived from granitic rocks ( 花岗岩 ), shells （贝壳）, slates （板岩） or argillaceous schist （片岩） are often high in Mo Highly weathered acids soils tends to be deficient Soils formed from igneous rocks （火成岩） and shale( 页岩 ) and poorly drained neutral or alkaline organic soils have high level Mo

154. Soil molybdenum Fraction of soil Mo Dissolved Mo Mo occluded with oxides Mo solids phases ： including molybdenite 辉钼矿 (MoS 2 ), powellite (CaMoO 4 ), ferrimolybdite 水钼铁矿 (Fe 2 (MoO 4 ) 3 and PbMoO 4. Mo associated with organic compounds.

155. Soil molybdenum Mo availability in soil Molybdate is the most prominent form in soil solution above a pH about 4. Molybdate is absorbed by sequioxides and clay minerals via ligand exchange similar to phosphates. The Mo concentration in soil solution is usually determined predominantly by soil pH and total Mo content of the soil. As the pH falls the Mo soil solution concentration decrease.

156. Soil molybdenum Soils derived from quartzic material, sandy pebbly( 多卵石的 ) alluviums( 冲积物 ), and sandy loam and soils with high anion exchange capacity are often Mo deficiet. Peat soils Calcareous soil derived from loess and alluvium

157. Mo in physiology Content of Mo in plant The Mo concentration of plant materials is usually low and plants are adequately supplied with less than 1 mg/kg dry matter. Deficiency is usually under 0.2 mg/kg dry matter.

158. Mo concentration in different plants in μg Mo/g in the dry matter (Johnson 1966)

159. Mo in physiology Mo uptake and translocation Mo is absorbed by plants as molybdate. The uptake is depressed by the SO 4 - and phosphate. Mo may possibly move in xylem as MoO 4 2-, as Mo-S amino acid complex or as a molybdate complex with sugar or polyhydroxy compounds. Mo is moderately mobile in plant.

160. Mo function in plant Mo is an essential component of nitrate reductase and nitrogenase Mo plays another essential role in the N metabolism in legumes such as soybean and cowpea.—xanthine dehydrogenase ( 黄嘌呤脱 氢酶） Other functions Synthesis of vitamins IAA oxidase activity Phosphatase activity Chlorophyll structure stability

162. Symptoms of Mo deficiency Mo deficiency frequently begins in the middle and older leaves. Interveinal mottling, marginal chlorosis of the older leaves and upward curling of the leaf margins are all typical. As the deficiency progress necrotic spots appear at leaf tips and margins.

163. Symptoms of Mo deficiency In the cruciferae the lamella is not properly formed and in the extreme case only the leaf rib is present, like a whip, so the deficiency is called “whiptail” Curd( 胚乳） formation is also distorted In Mo deficiency maize the tasseling stage( 抽 穗期） is delayed; flower fail to open and grain size and viability is greatly reduced; premature sprouting （萌发） of grains.

164. Mo deficiency of cauliflower: interveinal mottling, marginal chlorosis of the older leaves and upward curling of leaf margins and tip necrosis in early stage ； in the serious deficiency, leaf lamella is not properly formed and in extreme case only the leaf rib is present. it is called whiptail ）； curd formation is also distorted.

165. TOMATO PLANTS Molybdenum deficiency Leaflets somewhat chlorotic, strongly incurled and die back from tips. Left: healthy leaf receiving molybdenum. Right: Molybdenum deficient leaf; leaflets, incurled margins, intervenal chlorotic motting and death of tips.

166. Young Cabbage Plants (Savoy) Molybdenum deficiency Leaves cupped and show chlorotic mottling, especially around margins; tips and margins develop dead patches; plants fail to heart. (Similar to manganese toxicity ；

167. Mo toxicity High Mo levels in fodder and a Mo concentration of 5 to 10 mg Mo/kg in the dry matter is dangerous to ruminants such as cattle. Molybdenosis ( 慢性钼中毒 ): diarrhoea （腹泻）, depigmentation ( 褪色 ) of hair or wool, bone formation and reduction in growth. Poorly drained soils derived from granitic ( 花岗岩） alluvium and black shales ash on highly organic soils.

168. Mo fertilizers Molybdenum trioxide MoO 3 Mo 60% Ammonium molybdate(NH 4 ) 6 Mo 7 O 24.4H 2 O Mo 54% Na molybdate Na 2 MoO 4.2H 2 O Mo 38- 46% Molybdenized superphosphate

169. Application of Mo fertilizers Seed treat ７ g/ ha Soil apllication 0.01-0.5kg/ha Foliage spray 85g/ha