Chapter 12 Micronutrients and
Micronutrient Fertilizer
[目的与要求]
学习掌握7种必需
微量营养元素吸收、利用、营养功能、缺乏和中毒的形态鉴定，以及各种微肥种类、特性和施用技术。
[重点]
1必需
微量营养元素吸收、利用、营养功能、缺素症诊断。
2微肥种类、特性和施用技术。
[难点]
必需
微量营养元素缺素症的诊断。
[课堂组织]
讲述、生活实例和多媒体教具结合
[教学内容]
表12－1 微量元素的发现
12.1 Iron
12.1.1 Content and distribution
Fe content in most plants ranges from 100-300 mg/kg (DW），and varies among species and organs.
Vegetable crop,legumes> cereals
Stems in cereals > seed
Fe2+ is main form taken by plans，and chelated Fe could be taken. Most plants are difficult to absorb Fe3+ because of its insolubility at high pH.
In long-distance transport in xylem, Fe3+ complexes is a predominance, which oxidates from Fe2+ to Fe3+ at root cell, and then chelates with citric acid.
12.1.2 Physiological Function
12.1.2.1 Chloroplast and photosynthesis
About 80% of Fe is located in chloroplasts in rapidly growing leaves, regardless of Fe nutritional status.
Fe is not a component of chloroplasts,but Fe is essential element in chloroplast synthesis.Fe is relatively immobile and show firstly Fe-deficient symptom in younger.Fe affects not only redox system, but also photophosphorylation and reduction process of CO2.
12.1.2.2 Electron transfer
Fe as transition element is characterized by the relative ease by which it may change its oxidation state
Fe3+ +e- → Fe2+
ferredoxin, nitrogenase, nitrate & nitrite reductases,
在氧化磷酸化过程中，电子传递是在多种特殊物质的参与下完成的。其中铁氧还蛋白和细胞色素类都是含铁的重要化合物。
12.1.2.3 Respiration
Fe is a component of enzymes involving respiration, such as cytochromes, catalase
12.1.3 Fe deficiency symptom
The distinctive symptom of iron deficiency is chlorosis of the youngest leaves. Initially, a yellow interveinal chlorosis develops, which is characterised by a sharply contrasting green network of veins. However, as the condition becomes more severe, the chlorosis becomes white and the veins may lose their green colour.
While all the leaves of the plant may become affected, youngest leaves generally show the greatest intensity. However, if iron supply has been restored, new leaves become bright green and chlorotic leaves may be found below them.
Fe deficiency is a worldwide problem in crop production on calcareous soils. It is the major factor responsible for so-called lime-induced chlorosis.
图12－1水稻缺铁：新叶脉间失绿，叶脉绿色， 图12－2玉米缺铁：新叶黄化，脉间失绿，呈清呈条纹状，老叶保持绿色。 晰的条纹叶，老叶仍保持绿色。
图12－3大豆缺铁：新叶叶脉黄绿色，脉间黄化，图12－4菜豆缺铁: 黄化，叶脉仍保持绿色
中部叶片两边叶缘由外向内逐渐变黄。
12.1.4亚铁的毒害
在排水不良的土壤和长期渍水的水稻土上经常会发生亚铁（Fe2+)中毒现象。当水稻叶片中亚铁含量>300mg/kg时，可能出现铁的毒害作用。铁中毒的症状表现为老叶上有褐色斑点，根部呈灰黑色，易腐烂。
防治的方法是：适量施用石灰，合理灌溉或适时排水晒田等。也可选用优良品种。
图12－5豌豆(铁毒害): 叶上布满大小不一的棕褐色斑点
小结：
铁缺乏
（1） 顶端或幼叶失绿黄化；
（2） 脉间失绿发展至全叶淡黄白色；
（3） 根系发育差，豆科根瘤少。
铁过量
叶色暗绿，叶尖及边缘焦枯，脉间有褐斑。
12.2 Boron
12.2.1 Content and distribution
B Content varies from 2 to 100 mg/kg.
In general: dicot > monocot plants， shoots> roots, reproductive > vegetative organs
表12－2 B content in plants
Plant species B content Plant species B content |
|||
Barley |
2．3 |
Cotton |
19．6 |
Wheat |
3．3 |
Tobacco |
25．0 |
Maize |
5．0 |
Radish |
64．5 |
Rice |
2．7 |
Lettuce |
70．0 |
Oat |
2．2 |
Sugar beet |
75．6 |
Potato |
13．9 |
Dandelion |
80．0 |
Pea |
21．7 |
Euphorbia |
93．0 |
Rape |
24．9 |
Popper |
94．7 |
Plants take up boron mainly as undissociated boric acid, H3BO3 !
A linear relationship between boron uptake, accumulation and transpiration rate.
Passive!
Different species shows differ significantly in the rate of boron accumulation even when they grown under identical environmental conditions.
active process!!
Both passive diffusion and active process!!
Boron is relatively immobile in plants, it is translocated mainly through the xylem, and it is largely accumulated in old leaves
12.2.2 Physiological Function
12.2.2.1 Role in Cell Wall Structure
More than 90 % of plant B in the cell wall, which exists in the forms of borate esters.
A mechanism for crosslinking cell wall polymers and stabilized the structure of cell wall.
图12－6 Rhamnogalacturonan II(RG-II, 鼠李半乳糖醛酸聚糖）→ B-RG-II
12.2.2.2 Carbohydrate Transport and Metabolism
One of the most distinct symptoms of B deficiency is inhibited in transport of carbohydrate.
The hypothesis of borate-sugar complexes.
Acceptable?
Sucrose forms only weak complexes with boron, and in the mechanisms of phloem loading of sucrose boron is not involved.
May an indirect effect: callose in the sieve tubes or by the lack of sink activity in roots and shoot apices
12.2.2.3 Development of reproductive organs
Boron plays an important role in pollen germination and the growth of pollen tubes due to significant effect of boron on cell wall synthesis and plasma membrane integrity.
12.2.2.4 Auxin (IAA), Phenol and Lignin Metabolism
缺硼时，多酚氧化酶活性提高，将酚氧化成黑色醌类化合物，使作物出现病症。如甜菜“腐心病”和花椰菜的“褐心病”等。
12.2.2.5 other
（1）Cell extension and division
（2）DNA and RNA synthesis
（3）plasma membrane stability
（4）Nitrogen fixation
12.2.3 Symptom of boron deficiency
The first external symptom of boron deficiency is generally the abnormal or retarded growth of the apical growing point of the main stem.
This is followed by growth of lateral buds into side shoots, the apices of which then die. Further symptoms are wrinkled and are slight thickening and of a darish blue-green colour of the leaves, a tendency for there to curl, and sometimes a slight chlorosis.
The typical dying off symptom of the apical growing point as a result of boron deficiency is shown for Brassica. such as “heart rot” in sugar beet, “brown heart” in turnip, “cracked stem: in celery, “top sickness” in tobacco, “corky core” or “brown heart” in apple, “flowering but seeding”, and so on.
图12－7小麦缺硼：花不能受粉，颖壳张开， 图12－8棉花缺硼：叶片卷曲皱缩，
麦穗透亮。 叶柄上出现暗绿色或褐色带。
图12－9油菜缺硼：顶端持续开花，花期延长，荚果少而不结实。出现“翻化”“多头”现象
图12－12柑桔缺硼：果实小，瓤瓣发育不全并干缩。 图12－13 玉米缺硼
小结
硼缺乏
（1） 茎尖、根尖生长停止或萎缩死亡；
（2） 叶片肥厚，粗糙，发皱卷曲，呈失水似的凋萎；
（3） 茎基部肿胀；
（4） 花而不实，蕾花脱落，花期延长；
（5） 根发褐，豆科根瘤少
硼过量
叶尖及边缘发黄焦，叶片上出现棕褐色坏死斑块。
12.2.4 B in Soil
In China, total B content in soil ranges from trace to 50 mg/kg, the average is 64 mg/kg. the available boron in soils ranges from trace to 1.73 mg/kg.
Boron Form in Soil :
（1）Mineral boron
（2）Adsorbed boron
（3）Soil solution boron
Plants take up boron mainly as undissociated boric acid, H3BO3
Soil solution boron includes two forms: undissociated boric acid H3BO3 and borate acid anion B(OH)4-.
表12－3 Available soil boron and grade
12.3 Manganese
12.3.1 Content and distribution
Ma contents in plant tissues are generally in the order of 20 to 100 mg Mn /g dry matter and vary considerably in different crops
表12－4 Mn contents in several crops (μg/g)
Crop species |
Grain |
Leaves and stalks |
Rice |
20-250 |
280-900 |
heat |
16-140 |
30-350 |
Legume crop |
14-80 |
110-130 |
Tuber crop |
110-130 |
120-320 |
Plant absorbs Mn mainly as Mn2+.Manganese is relatively immobile in the plant and it is scarcely translocated in the phloem.
图12－14 Relationship Between Mn in Plant and Soil pH
12.3.2 Physiological Function
12.3.2.1 Role in photosynthesis
Hill reaction: photolysis of water and O2 evolution system associated PSⅡ in photosynthesis.
H2O → 2H++2e-+1/2O2
12.3.2.2 Enzymes Activation
Manganese acts as cofactor, activating about 35 different enzymes
（1）Decarboxylases and dehydrogenases of the TCA cycles
（2）The chloroplast RNA polymerase
（3）Several enzymes of shikimic acid pathway,
（4）Activity of IAA oxidase
（5）Superoxide dismutases (SOD): Mn (MnSOD)
12.3.3 Mn deficiency and toxicity
Mn deficiency symptoms are first visible in younger leaves---interveinal chlorosis.
In cereal, Mn deficiency symptoms appear at the basal part of leaves as greenish grey spots and stripes.Oats in particular are prone to Mn deficiency during the tilling stage, known as ‘grey speck’. In legumes, Mn deficiency symptoms on the cotyledons are known as ‘marsh spot’ in peas or as ‘split seed’ disorder in lupins;
图12－15Manganese deficiency is interveinal 图12－16菜豆
chlorosis of the upper, new leaves of corn.
图12－17蚕豆：子叶中心出现不同程度的棕色病斑 图12－18 胡萝卜
Mn toxicity
Mn toxicity is mainly found on acid to very acid soils.More than 600 mg/kg in plants will show Mn toxicity symptoms.
Symptoms of Mn toxicity are generally characterized by brown spots on mature leaves.
表12－5 不同作物体内锰中毒的一般含量
|
玉 米 200 木 豆 300 大 豆 600 棉 花 750 甘 薯 1380 向日葵 530 |
图12－19菜豆 图12－20羽衣甘蓝
小结：
锰缺乏
症状从新叶开始，叶脉间失绿，出现褐色或灰色斑点，逐渐连成条状。严重时叶片失绿坏死。
锰中毒
老叶边缘和叶尖出现许多棕褐色焦枯的小斑，并逐渐扩大。与缺锰不同的是，不出现失绿现象。
12.3.4 Mn in Soil
Soil manganese may be divided into four forms: organically bound manganese, mineral manganese, exchangeable manganese, and soluble manganese.
The most important fractions available to plant nutrition are soluble Mn, exchangeable Mn and easily reduced Mn from Mn oxides, which are called active Mn.
In China, the critical exchangeable Mn content is 2 μg Mn /g, easily reduced Mn 100 μg Mn /g.
表12－6 Rates of soil active Mn in China
12.4 Copper
12.4.1 Content and Distribution of Cu
Cu content in most plants varies from 5-25mg/kg, which major distributes in younger leaves and seed, and less in stem and older leaves.
Cu mobility in plants depends on Cu level applied.When Cu is sufficient, it shows to be mobile,conversely it is immobile.
12.4.2 Physiological Function
12.4.2.1 Role in Redox Reaction
Cu is a transition element
Cu 2+ ←→ Cu+
Cu takes part in redox reaction as a component of enzyme. Such as plastocyanin (质体蓝素), superoxide dismutases (超氧化物歧化酶), cytochrome oxidase (细胞色素氧化酶), phenol oxidase (多酚氧化酶), ascorbate oxidase(抗坏血酸氧化酶), and so on.
12.4.2.2 Copper Proteins and Photosynthesis
About 70% of Cu located in chloroplast, and more than 50% of which is bound to blue protein (plastocyanin).Plastocyanin is a component of the election transport chain of PSI.
Cu protein:
（1） Blue protein (plastocyanin)
（2）Non-blue protein (peroxidase )
（3）Multicopper protein (ascorbate oxidase)
12.4.2.3 N metabolism and N fixation
在复杂的蛋白质形成过程中，铜对氨基酸活化及蛋白质合成有促进作用。铜也可能是共生固氮过程中某些酶的成分。缺铜时豆科植物根瘤减少，固氮能力下降。
12.4.2.4 Pollen Formation and Fertilization
Cu deficiency affects grain, seed, and fruit formation much more than vegetative growth.The main reason for the drease in the formation of generative organs is the nonviability of pollen from Cu deficient plants.
表12－7 缺铜对小麦花药和花粉发育的影响
 |
供铜水平 花药长度 花粉粒 花粉直径 花粉萌发
（mg/L） （mm） 个/每花药 （um） 率（%）
0.065 3.5 2017 52.4 53.0
0.013 2.1 2076 45.9 7.1
图12－21 施铜对缺铜土壤小麦产量的影响
12.4.3 Cu deficiency and Toxicity
Deficiency is rare, but young leaves may become dark green and twisted or misshapen, often with brown, dry spots. Typical symptoms of Cu deficiency are chlorosis (white tip, reclamation disease), necrosis, leaf distortion, and die back.
The most spectacular symptoms of Cu deficiency are reduced seed or fruit yield caused mainly by male sterility.Copper deficiencies are mainly reported on organic soils (peats and mucks), and on sandy soils which are low in organic matter.
Copper uptake decreases as soil pH increases. Increased phosphorus and iron availability in soils decreases copper uptake by plants.
图12－22葱头：缺铜时外部鳞茎皮薄而色黄 图12－23番茄：叶片向内卷曲、皱缩
作物体铜的含量<4mg/kg时，即可能缺铜。
缺铜症状：禾本科作物植株丛生，顶端逐渐发白，通常从叶尖开始严重时不抽穗，或穗萎缩变形，结实率降低，或籽粒不饱满，甚至不结实。果树缺铜，顶梢上的叶片呈叶簇状，叶和果实均褪色。严重时顶梢枯死，并逐渐向下扩展。还有，某些作物的花会褪色。
单子叶植物对缺铜敏感，燕麦和小麦是判断土壤是否缺铜的理想指示作物。
当作物体铜的含量>20mg/kg时即可能中毒。铜中毒症状表现为：新叶失绿，老叶坏死，叶柄和叶的背面出现紫红色。 主根的伸长受阻，侧根变短。
12.5 Zinc
12.5.1 content and distribution
Normally Zn content varies from 25 to 150 mg/kg，which changes among species or cultivars.Zn in plant most distributes in stem tip and young leaves.Zn content is higher in root than in shoot.Crop will show Zn deficiency when Zn content is less than 20 mg/kg. Zn may transfer from old leaves to young leaves at Zn deficiency.
12.5.2 Physiological Function
12.5.2.1 Zn-containing and Zn-activated enzymes
（1）Zn-containing enzymes:
Alcohol Dehydrogenase (乙酸脱氢酶), Carbone anhydrase(碳酸酐酶),CuZn-superoxide dismutase (超氧化物歧化酶), RNA polymerase (RNA聚合酶)
（2）Zn-activated enzymes:
Dehydrogenase(脱氢酶)、 aldolases(醛缩酶)， inorganic pyrophosphatase(焦磷酸酶）。
12.5.2.2 Indoleacetic Acid (IAA) synthesis
Zn can improve the synthesis of tryptophan(色氨酸)from indole(吲哚)and serine (丝氨酸), and results in the IAA synthesis.
The most distict Zn deficiency symptoms is growth stunt and “little leaf”.
12.5.2.3 protein metabolism
Zn is a component of RNA polymerase;Zn is a structural component of ribosomes (核糖体)and essential for their structural integrity.
表12－8 供锌对大豆鲜重、RNA酶活性和蛋白态含量的影响
供锌水平 供锌水平 RNA酶活性* 蛋白态氮含量 （mg/L) （mg/L) （%） （%鲜重） |
0.005 4.0 74 1.82 0.01 5.1 58 2.25 0.05 6.6 48 2.78 0.10 10.0 40 3.65 |
12.5.3 Zn deficiency and toxicity
Zinc is not mobile in plants so zinc-deficiency symptoms occur mainly in new growth. The most visible symptoms of Zn deficiency are short internodes and a decrease in leaf size.
Chlorotic bands along the midribs of corn, mottled leaves of dry bean and chlorosis of rice are characteristic zinc-deficiency symptoms.
Zinc deficiencies occur more often during cold, wet spring weather and are related to reduced root growth and activity as well as lower microbial activity decreases zinc release from soil organic matter.
Zinc uptake by plants decreases with increased soil pH.
Uptake of zinc also is adversely affected by high levels of available phosphorus and iron in soils.
图12－24玉米：脉间绿呈淡黄色和浅绿色的图12－25柑桔：新叶叶片小、细长，脉间浅绿或
条纹，叶脉保持绿色。 黄化，主脉或侧脉仍保持绿色，节间短。
植物缺锌时，生长素和赤酶素含量明显减少，叶绿素形成和生长受阻，尤其是节间生长严重受阻，并表现出叶片的脉间失绿或白化。因而植物常出现叶脉间失率现象。典型症状：果树“小叶病”、“繁叶病”。
植物对缺锌的敏感程度因是种类不同而有差异。禾本科作物中玉米和水稻对锌最为敏感，通常可作为判断土壤有效锌丰缺的指示植物。
一般认为植物含锌量>400mg/kg时，就会出现锌的毒害。
锌过量
新叶失绿发黄，甚至呈灰白色，皱卷曲。
图12－26菠菜 图12－27番茄
小结
锌缺乏：
（1）植株矮小，节间短，生育期延长；
（2）叶小簇生；
（3）中下部叶片中脉附近出现脉间失绿，并发展成褐斑，叶缘扭曲发皱；玉米出现“白苗病”。
锌过量
新叶失绿发黄，甚至呈灰白色，皱卷曲。
12.6 Molybdenum
12.6.1 Content and Distribution in Plant
Normally 1 µg/g dry weight or less of Mo in leaf tissues, Average from 0.33 to 1.5 µg/g in grasses and from 0.73 to 2.3 µg/g in legumes.
The distribution of Mo at the maturity of beans is 0.17 µg/g in leaves, 1.0 µg/g in stems, 0.5 µg/g in pods, 12.0 µg/g in seeds.
A high Mo content in seeds ensures proper seedling growth and high final grain yield in plants growing in soils low in available Mo
Plants take up Mo mainly as molybdate ions MoO42- and HMoO4-,
In plants, Mo is moderately mobile in xylem and phloem for long-distance transport.
Recent research results indicated that Mo is most likely transported as MoO42- rather than in complexed form.
12.6.2 Physiological Function of Molybdenum
The most important physiological function of Mo is the reduction of nitrates and the fixation of molecular nitrogen.
Mechanism of Mo catalizing redox depends on valency change of Mo.In Mo oxidized stage, it exists Mo (VI), and it is reduced to Mo (V) and Mo (IV)。
12.6.2.1 A metal component of Nitratase
图12－28 Redox sustem of the nitrate reductase and the sequence of reactions
12.6.2.2 Nitrogen Fixation
Mo is constituents of nitrogenase.
Nitrogenase is the key enzyme complex unique to all nitrogen fixing microorganisms.
It occurs in the nodules of legumes and nonlegumes and consists of two metallo enzyme proteins, a Mo-Fe-S protein and a FeS cluster protein.
Electrons from reduced ferredoxin are transferred vir the Fe protein to the Mo-Fe-protein from which electrons are transferred directly to N2 to effect the reduction to NH3.
12.6.2.3 Role in other metabolism process
（1）Nitrogen metabolism
（2）Protein biosynthesis
（3）Nucleic acid and phosphorus metabolism
12.6.3 Diagnosis of Mo deficiency
钼在受精和胚胎发育中有特殊作用。玉米缺钼时，花粉的形成和活力均受到影响。
The initial symptoms of Mo deficiency appear as yellow-green or pale-orange interveinal spots.
This is followed later by wither and necrosis at the leaf margins along with a characteristic curving over of the marginal regions of the leaf.
Some plants, however, show also more specific Mo deficiency symptom, such as, “whiptail” (“鞭尾病”) in cauliflower, “yellow spot ” (“黄斑病” ) of citrus.
12.6.4 Mo toxicity symptoms
Mo toxicity symptoms in plants under field conditions are very rare.
In some soils of high pH, plants may accumulate enough Mo to develop molybdenosis (慢性钼中毒） for ruminants.
Molybdenosis is caused by an imbalance of Mo and copper in the ruminant diet,
Ruminants are very sensitive to excessive concentrations of Mo
图12－29番茄：脉间呈浅黄或桔黄色斑块， 图12－30黄瓜：在脉尖呈淡黄绿色至黄色，
叶边缘向内卷曲，小叶顶端干枯，叶片凋萎。 主脉周围有不规则的绿色斑点，在叶基部和叶缘有绿色花斑，叶尖向内卷曲。
小结
钼缺素症状：
（1） 老叶脉间淡绿发黄，有褐色斑点；
（2） 叶缘焦枯卷曲，叶片有畸形，生长不规则；
（3） 豆科不结根瘤或结瘤少；
（4） 十字花科叶片瘦长，螺旋状扭曲，老叶变厚焦枯。
12.6.5 Molybdenum in Soil
Available Mo content ranges from 0.01 to 12.0 mg/kg in world soils.
In China, the available Mo content extracted with Tamm solution ranges from trace to 0.65 mg/kg in soil. The major form of Mo in soil solution is MoO42-.
As the pH falls the Mo concentration decreases because of the adsorption of Mo on the Fe and Al oxides.
Mo has several valency, mainly including Mo4+and Mo6+.
In particular the Mo6+, one acidic oxide, easily reacts with Na, K, Mg to produce water soluble molybdate (MoO42-), or is reduced to MoO2 or Mo2O5,
表12－9 Available soil Mo and grade
Availability of soil Mo is tightly relative to pH in soil.
Soil Mo value = pH + available soil Mo content×10
When soil Mo value less than 6.2, supply of Mo in soil is short;above 8.2,
supply of Mo in soil is sufficient.However, the soil Mo value isn’t suitable for calcareous soils.
12.7 Chlorine
12.7.1 Content and forms
Clin plants are generally in the range of 1 000-20 000 mg/g dry matter, which is similar to macronutrients. In most plant species the chlorine requirement for optimal plant growth, however, is in the range of 150-300 mg/g dry matter.
Cl- mobility in plants is related to the transpiration. Poor transpiration leads to chlorine content in grains or fruits< leaves.
Plants absorb chloride as the Cl- anion through both roots and aerial parts.
Cl uptake is sensitive to both variations in temperature and metabolic inhibitors, which means that Cl- uptake is metabolically controlled.
12.7.2 Physiological function of chlorine
12.7.2.1 involving photosynthesis
Cl- enhances both the evolution of O2 and photophosphorylation. Cl- is required for the fractional assembly of PSⅡ cluster comprising 4 Mn atoms.
12.7.2.2 osmoregulation
Cl is a main osmoticum in the vacuoles of the bulk tissue (50-150 mM Cl-), together with K+.
12.7.2.3 ATPase activation
The proton pimping ATPase located at the tonoplast is not affected by monovalent cations but specifically stimulated by Cl-.
12.7.2.4 inhibition of disease
12.7.3 Chlorine deficiency and toxicity
Wilting of leaves, especially at leaf margins is a typical symptom of chlorine deficiency. With severe deficiency curling of youngest leaves followed by shriveling and necrosis might occur.
Compared with chlorine deficiency, chlorine toxicity is a more serious problem.
Cl- toxicity include burning of leaf tips or margins, bronzing, premature yellowing and abscission of leaves
Plant species differ in their sensitivity to Cl-:Sugar beet, barley, maize, spinach and tomato are highly tolerant.
while tobacco, beans, citrus, vine, potatoes, lettuce and some legumes are very prone to Cl- toxicity.
Reduction in yield and quality in crops is associated with tissue levels of 5-20 g Cl /kg DW for sensitive crops and 40 g Cl /kg or more of tolerant plant species.
大田中一般很少发现作物缺氯症状，氯过多倒是生产上的一个问题。
氯中毒的症状是：叶缘似烧伤，早熟性发黄及叶片脱落。
根据对氯的敏感程度可分为耐氯作物和忌氯作物。
耐氯作物：大麦、玉米、 菠菜和番茄
忌氯作物：烟草、菜豆、马铃薯、莴苣和一些豆科作物。
12.8 Diagnosis on Micronutrients
12.8.1 morphological diagnosis
12.8.1.1 Location showing symptom
tip ——shoot top、root apex：B、Ca
Young leaf：Fe、Mn、Mo、Cu
Old leaf： Zn
12.8.1.2 Leaf size and shape
-Zn：“little leaf”, short internodes
-B：thick, curl, crimple,brittle
12.8.1.3 Chlorosis position
interveinal chlorosis, but vein keeps green ： Zn、Fe、Mn
表12－10 微量元素缺素症状
生产实践中形态诊断存在的问题
（1） 一些微量元素缺素症状相似，难以根据外形作出准确判断；
（2） 当养分是潜在性缺乏时，有时无明显症状，但却存在严重营养障碍；
（3） 作物缺素症状常和某些病害或环境胁迫的症状相混淆，容易造成误诊。
12.8.2 sample assay
（1）Plant sample（2）Soil sample
表12－11 土壤有效态微量元素的分级和评价指标（mg/kg)
元素 |
很低 |
低 |
中等 |
高 |
很高 |
临界值 |
水溶性硼 |
＜0.25 |
0.25-0.5 |
0.51-1.0 |
1.01-2.0 |
＞2.0 |
0.50 |
有效态钼 |
＜0.10 |
0.1-0.15 |
0.16-0.2 |
0.21-0.3 |
＞0.30 |
0.15 |
代换态锰 |
＜ 1.0 |
1.0-2.0 |
2.1-3.0 |
3.1-5.0 |
＞5.0 |
3.0 |
易还原态锰 |
＜50 |
50-100 |
101-200 |
201-300 |
＞300 |
100 |
有效态锌* |
＜1.0 |
1.0-1.5 |
1.6-3.0 |
3.1-5.0 |
＞5.0 |
1.5 |
有效态锌** |
＜0.5 |
0.5-1.0 |
1.1-2.0 |
2.1-5.0 |
＞5.0 |
0.5 |
有效态铜* |
＜1.0 |
1.0-2.0 |
2.1-4.0 |
4.1-6.0 |
＞6.0 |
2.0 |
有效态铜** |
＜0.1 |
0.1-0.2 |
0.3-1.0 |
1.1-1.8 |
＞1.8 |
0.2 |
注：* 适用于酸性土；** 适用于石灰性土壤
Phosphate availability as dependent on soil pH - note low availability of phosphate at both alkaline and acid pH
表12－12我国微量和中量营养元素缺乏面积和施用面积
12.8.3 Foliar Spraying
（1） 叶面喷施；
（2） 叶片浸泡；
（3） 叶面涂抹。
一般： 0.1-0.2%
12. 9 Micronutrient Fertilizers
12.9.1 Micronutrient Fertilizer sort
12.9.1.1 Sorting depending on Nutrient
硼肥；锌肥；等
表12－13 铁肥等微量元素肥料
12.9.1.2 Sorting depending on compound
（1）水溶性：硫酸盐、氯化物、等
（2）溶解度较小的无机盐：磷酸盐、碳酸盐、氧化物
（3）玻璃肥料：将玻璃与微量元素共同熔融，磨碎成粉末即成。
优点：施入土壤后减少与土壤接触面，减少固定；溶解度小，不易随水流失，可供作物缓慢吸收。
螯合态肥料
螯合剂与微量元素螯合后形成螯合物。
螯合剂：EDTA, HEDTA 等
优点：溶于水，有效性高于无机盐类；可减少土壤固定；可根外追肥。
复合或混合肥料
大量元素肥料中加入一种或几种微量元素化合物制成。
优点：养分含量均一，施用方便； 避免微肥因量少而不易施匀的现象。
12.9.2 major micronutrient Fertilizer
表12－14 几种重要的微肥
12.9.2 Application technique
major include:
Soil application(Broadcast , Banding)
Seed application (mixing, soaking, coating )
Foliar application,
or
Basal fertilizer
Seed fertilizer
Top dressing
Foliar spray.
Pay attention to toxicity!!
Higher plants require less in micronutrients than in macronutrients, and there is a narrow range in critical tissue content between micronutrient deficiency and toxicity.
Hence, it is necessary to make soil test and tissue analysis and then confirm the adequate amount of micronutrient fertilizers to be applied.
12.9.3 Application technique
12.9.3.1 Soil application
做基肥或追肥，施用必须均匀（可用含微量元素的大量元素肥料或与有机肥混用）。
12.9.3.2 Application directly on plants
（1）拌种：少量水溶解肥料，拌种，阴干
0.5-1.5g/kg
(2) 浸种：种子浸泡于稀溶液，使肥料进入种皮，晾干。0.01-0.05%浸种12小时
（3）沾秧根（用于水稻或其它移栽作物）
将适量微肥与少量肥沃土壤或优质有机肥制成稀糊状液体，移栽前，秧苗浸入数分钟。
（4）根外喷施
0.01-0.2%
实践中注意：
防止过量！
调查确定后谨慎施用！
配合NPK肥施用提高肥效！
[思考题]
1. 植物体中七种微量营养元素的含量？
2. 植物吸收七种微量营养元素的形态？
3. 七种微量营养元素的主要营养功能？
4. 七种微量营养元素缺乏的主要症状？
5. 主要微量营养肥料及其施用技术？
6. 如何合理施用微量营养肥料？