Handbook of Plant Nutrition - chapter 22 potx

Pilbeam University of Leeds, Leeds, United Kingdom CONTENTS 22.1 Status of Current Knowledge and Research ...599 22.2 Soil Testing and Plant Analysis and Nutrient Availability ...599 22.

Section V

Conclusion

Allen V Barker

University of Massachusetts, Amherst, Massachusetts

David J Pilbeam

University of Leeds, Leeds, United Kingdom

CONTENTS

22.1 Status of Current Knowledge and Research 599

22.2 Soil Testing and Plant Analysis and Nutrient Availability 599

22.3 Accumulation of Elements by Plants 600

22.4 Genetics of Plant Nutrition 601

22.5 General Remarks 602

References 603

22.1 STATUS OF CURRENT KNOWLEDGE AND RESEARCH

Chapters in this handbook summarize research for each of the plant nutrients and several bene ficial elements, and readers should refer to the individual chapters for information on past, current, and future research on these elements However, some conclusions can be drawn about the kinds of cur-rent research that are being carried out in plant nutrition, and literature that addresses this research

in a general way can be identi fied and will be presented in this summary.

Traditionally, research in soil fertility and plant nutrition has addressed soil testing and plant analyses and nutrient availability for plants, nutrient requirements of di fferent crops, fertilizer use, and crop utilization of nutrients in materials applied to soil Interest in these traditional fields con-tinues, but topics including accumulation and transport of nutrients and nonessential elements have received recent attention Research in genetics of plant nutrition has risen with the growth in the field of molecular biology.

22.2 SOIL TESTING AND PLANT ANALYSIS AND NUTRIENT AVAILABILITY

Consideration of the environmental and economic consequences of soil fertility practices is an essential component of research in plant nutrition Soil tests are developed to assess the availability

of plant nutrients in soils, and these tests are calibrated for the major field and vegetable crops, and provide the basis for lime and fertilizer recommendations Recommendations for amounts and application of fertilizers are continually modi fied to optimize economics of production as the costs

of fertilizer application, the value of crop yields, and subsidy regimes change Criteria for inter-preting the results of soil testing and plant analyses are developed through field and glasshouse research that relates test results and plant composition to crop yields Research in soil fertility and plant nutrition also covers application to the land of agricultural, municipal, and industrial wastes

and by-products (1), atmospheric contributions to plant nutrients in soils, short- and long-term availability of plant nutrients, especially nitrogen and phosphorus, and many other factors as well

as soil testing and plant analyses.

Work on soil fertility and plant nutrition often involves multidisciplinary research in other areas

of soil science and plant physiology Basic and applied information in such areas as soil–plant tions, nutritional physiology, and plant nutrition technology have been summarized in books and monographs (2–4) Regular meetings of scientists working on plant nutrition occur, leading to con- tinual developments in the subject For example, 11 symposia on iron nutrition and interactions in plants have been held, with the most recent one covering topics that include the genetics of iron

Some plant nutrients, such as potassium and sodium, are involved in plant responses to salt and water stress (6,7), giving rise to further studies on comparative physiology Research on nutritional stresses include studying the physiological and biochemical detail of the absorption and transport

of nutrients (8–11), and also studying plant composition with respect to factors such as organic acid biosynthesis in relation to nutrient accumulation or de ficiency (12).

The complexity of the relations between plants and soils, and the complexity of the tory pathways and cycling of nutrients within plants, has caused some workers to develop models

assimila-to aid our understanding of the acquisition and uptake of nutrients by plants (13) Some of these models, such as those developed by Warwick HRI for nitrogen, potassium, and phosphorus for a variety of crops in di fferent geographical locations (http://www.qpais.co.uk/nable/nitrogen.htm) are freely available on the internet.

Interest in nutrient absorption and accumulation is derived from the need to increase crop tivity by better nutrition and also to improve the nutritional quality of plants as foods and feeds Investigations occurring in many di fferent research locations are determining and helping to understand factors that a ffect nutrient absorption and accumulation in plants The U.S Plant, Soil and Nutrition Laboratory at Cornell University, Ithaca, New York (http://www.uspsnl.cornell.edu/index.html) con- ducts studies in the chemistry and movement of nutritionally important elements in the soil and the absorption of the elements by plant roots Scientists at the laboratory also investigate factors that a ffect the concentration and bioavailability of nutrients in plant foods and feeds, and are developing methods

produc-to evaluate soil contamination of foods derived from plants The laboraproduc-tory is conducting research on identifying and investigating genes that facilitate and regulate plant nutrient uptake and transport The Plant Physiology Laboratory of the Children’s Nutrition Research Center at Baylor University, Waco, Texas (www.bcm.tmc.edu/cnrc), is a unique cooperative venture between a college of medicine (Baylor) and an agricultural research agency (USDA/ARS) This laboratory is dedicated to under- standing the nutrient transport systems of plants as a means of improving food crops.

22.3 ACCUMULATION OF ELEMENTS BY PLANTS

Understanding how plants accumulate and store metallic elements are research topics of current interest, and the direct toxicity of elements to plants has been a long-standing topic of interest in plant nutrition research Meharg and Hartley-Whitaker (14) reviewed literature on the accumulation and metabolism of arsenic in plants Nable et al (15) discussed research on the toxicity of boron in soils, noting amelioration methods of soil amendments, selection of plant genotypes that are toler- ant of boron, and breeding of boron-tolerant crops.

The mechanisms of toxicity of trace elements are complex, and plants vary considerably in their responses to trace elements in soils To understand and manage the risks to plant and animal life posed by toxic elements in soils, it is essential to know how these elements are absorbed, trans-

located, and accumulated in plants A special issue of New Phytologist was dedicated to metal

accu-mulation, metabolism, and detoxi fication in plants and in the use of plants in remediation of contaminated soils (16) Cobbett and Goldsbrough (17) considered the roles of metal-binding ligands

in plants in metal detoxi fication, and there has been considerable interest in engineering plants for metal accumulation for purposes of phytoremediation of soils (or for providing better nutrition in diets and rations of humans and livestock) (18) Accordingly, the genetics of plants with regard to metal accumulation is a major topic of interest.

Babaoglu et al (19) noted that Gypsophila sphaerocephala Fenzl ex Tchihat has the potential

to accumulate boron (over 3000 mg B/kg in leaves) from soils in which boron is phytotoxic and that the boron-rich plant material may be transported to areas where boron is de ficient Selenium, although often regarded as an element that is dangerous when it accumulates in plants that are ingested by animals, has received considerable attention in programs such as that at Cornell University, as selenium is now seen as being de ficient in the human diet worldwide The fact that its uptake by plants can be enhanced by supply of more selenium to the plants is important in this context (20) These issues are addressed in a chapter on selenium in this handbook Terry et al (21) also reviewed the literature on the physiology of plants with regards to selenium absorption and transport, pathways of assimilation, and mechanisms of toxicity and tolerance of plants to selenium Aluminum toxicity is a long-standing issue for research in plant physiology, and a chapter in this handbook addresses aluminum as a factor in plant and animal nutrition Rout et al (22) also reviewed the physiology and biochemistry of aluminum toxicity in plants and discussed ways of increasing the tolerance of plants to aluminum.

The use of organic materials in metal detoxi fication or in the increase in nutrient availability in soils is also a topic for study (23) Similarly, the role of mycorrhizal associations in alleviating metal toxicity in plants is a topic of current research Jentschke and Godbold (24) discussed the possibil- ities of a role of fungal activities in immobilization of metals or otherwise restricting the e ffects of soil-borne metals on plant growth.

22.4 GENETICS OF PLANT NUTRITION

The genetic and molecular background for plant nutrition is an area in which interest in research is

expanding (5,16,25) A special section of Journal of Experimental Botany contains six invited

papers from a session held at the Society for Experimental Biology Annual Meeting in April 2003, addressing the genetics of plant mineral nutrition A preface to this section mentions the topics cov- ered (26) The topics include a review of the genes that a ffect nitrogen absorption, assimilation, uti-

lization, and metabolism in corn (Zea mays L.), and how manipulation of these genes might

improve grain production Another article describes the physiological and biochemical tics that allow plants to survive in environments containing little available phosphorus The article explains the genetic events that occur when plants lack phosphorus and how knowledge of these events might be used to improve the e fficiency of phosphorus acquisition and utilization by crops The genetics of control of K⫹transport across plant cell membranes is the topic of another article Another discussion is of the generation of salt-tolerant plants through transgenic approaches and through conventional plant breeding Another article surveys the accumulation of nutrients in the shoots of angiosperms under lavish nutrition in hydroponics and under natural environmental con- ditions In another article, the micronutrient requirements of humans and the supply of micronutri- ents from plants to populations at risk from mineral de ficiencies is discussed in relation to the varying micronutrient contents in plants These papers illustrate basic research in plant nutrition and describe how the application of modern genetic techniques contribute to solutions for plant and animal mineral nutrition.

characteris-Research in the genetics of plant nutrition covers major and minor nutrients, metals, plant stress, symbioses, and plant breeding Several publications cover research in this area A book by Reynolds et al (27) has several chapters that address genotypic variation in wheat with respect to zinc and other nutrient e fficiencies A review article by Fox and Guerinot (28) summarizes knowl- edge about genes that in fluence the transport of cationic nutrients and addresses how genes encode

for transporter proteins These proteins can be divided into three main types, primary ion pumps, ion channels and cotransporters (29), and the genes that code for transporter proteins for all the macronutrients and some micronutrients that have been cloned from plants (29–31) This research studies how genetics a ffect plant responses to nutrient availability and may allow for creation of food crops with enhanced nutrient levels or with the ability to exclude toxic metals Smith (10) describes how the expression of genes encoding for high-a ffinity phosphate transporters may improve phosphate utilization by plants growing under regimes of low phosphate availability in soils However, it is probably the case that the in flux of nutrient ions is not the limiting step in nutri- ent acquisition, so ‘improving’ the performance of transporters in plants by breeding may not achieve big increases in plant yield if not accompanied by other changes (29) In terms of improving yields

of plants through improving the uptake and assimilation of nitrogen, expression of genes for lic glutamine synthetase could have as large an impact on nutrient use e fficiency as expression of genes for transporters (32).

cytoso-Keeping phosphate, or other nutrients, available at the root surface is a major problem in

internal mobilization within plants Hinsinger (33) reviewed changes in the rhizosphere that can occur with plant species, plant nutrient availability, and soil conditions that can a ffect the acquisition of phosphorus by plants Root exudates that are important in the acquisition of nutrients through

compo-sition and their e ffects on the development of mycorrhizal fungi, chelation of nutrients, solubilization

of sparingly soluble compounds, and e ffects on soil acidity, among other actions Breeding for improved soil–plant–microorganism interactions, especially under suboptimal environmental condi- tions, may lead to genotypes that are improved for nitrogen fixation and promotion of mycorrhizal symbiosis may bring about increased crop yields under a wide range of environmental conditions Bassirirad (35) considered factors of global change, such as increased atmospheric carbon diox- ide concentrations, higher soil temperatures, and increased atmospheric nitrogen deposition, that may a ffect the kinetics of nutrient absorption by roots, noting that the information on the subject was scanty and that rigorous research was needed on the topic Processes such as transpiration- driven mass flow, root growth, root exudation, biological nitrogen fixation, and tissue dilution are all likely to be a ffected by climate change (36).

Ionomics has been coined as the study of how genes regulate all the ions in a cell (37) This

research is stated to hold promise leading to mineral-e fficient plants that might need little fertilizer,

to crops with better nutritional value for humans, and to plants that may remove contamination from the soil Possibly, a simple genetic change can increase nutrient absorption by green plants and allow crop production under conditions of limited nutrient availability or allow plants to be e fficient

in recovery of fertilizer-borne nutrients Yanagisawa et al (38) suggested that utilization of scription factors might lead to modi fication of metabolism of crops, because a single transcription factor frequently regulates coordinated expression of a set of key genes for several pathways They applied the plant-speci fic transcription factor (Dof1) to improve nitrogen assimilation, including the

tran-primary assimilation of ammonia to biosynthesize amino acids and other organic compounds taining nitrogen The authors proposed that similar genetic modi fications could reduce dependence

con-on nitrogen fertilizers.

22.5 GENERAL REMARKS

Current research on plant nutrition is extensive, and only a few topics can be mentioned here Some

of the topics mentioned on http://www.plantstress.com, which is sponsored by the Rockefeller Foundation, are noted With the world population increasing fast, and many people su ffering from

of plant mineral nutrition so that we can grow crops that utilize mineral nutrients as e fficiently as possible.

4 H Hirt, K Shinozaki, eds Plant Responses to Abiotic Stress Berlin: Springer, 2004.

5 H.A Mills., Exec ed Proceedings of the Eleventh International Symposium on Iron Nutrition and

Interactions in Plants, June 2002, Udine, Italy J Plant Nutr 26: 1889–2319, 2003.

6 S.R Grattan, C.M Grieve Salinity-mineral nutrient relations in horticultural crops Sci Hortic 78:

127–157, 1999

7 R Munns Comparative physiology of salt and water stress Plant Cell Environ 25: 239–250, 2002.

8 D.P Schachtman, R.J Reid, S.M Ayling Phosphorus uptake by plants: From soil to cell Plant Physiol 116: 447–453, 1998.

9 F Gastal, G.N Lemaire N uptake and distribution in crops: An agronomical and ecophysiological

per-spective J Exp Bot., Inorganic Nitrogen Assimilation Special Issue, no 370: 789–799, 2002.

10 F.W Smith The phosphate uptake mechanism Plant Soil 245: 105–114, 2002.

11 F.W Smith, S.R Mudge, A.L RaeM D Glassop Phosphate transport in plants Plant Soil 248: 71–83,

14 A.A Meharg, J Hartley-Whitaker Arsenic uptake and metabolism in arsenic resistant and

nonresis-tant plant species New Phytol 154: 29–43, 2002.

15 R.O Nable, G.S Bañuelos, J.G Paull Boron toxicity Plant Soil 193: 181–198, 1997.

16 C Cobbett Heavy metals and plants — model systems and hyperaccumulators New Phytol 159:

289–293, 2003

17 C Cobbett, P Goldsbrough Phytochelatins and metallothioneins: Roles in heavy metal detoxification

and homeostasis Annu Rev Plant Biol 53: 159–182, 2002.

18 S Clemens, M.G Palmgren, U Krämer A long way ahead: Understanding and engineering plant

metal accumulation Trends Plant Sci 7: 1360–1385, 2002.

19 M Babaoglu, S Gelzin, A Topal, B Sade, H Dural Gypsophila sphaerocephala Fenzl ex Tchihat.:

A boron hyperaccumulator plant species that may phytoremediate soils with toxic boron levels Turk

22 G.R Rout, S Samantaray, P Das Aluminium toxicity in plants: A review Agronomie 21: 3–21, 2001.

23 R.J Haynes, M.S Mokolobate Amelioration of Al toxicity and P deficiency in acid soils by additions

of organic residues: A critical review of the phenomenon and the mechanisms involved Nutr Cycling Agroecosystems 59: 47–63, 2001.

24 G Jentschke, D.L Godbold Metal toxicity and ectomycorrhizas Physiol Plant 109: 107–116, 2001.

25 G.A Gissel-Nielsen, A Jensen, eds Plant Nutrition — Molecular Biology and Genetics Proceedings

of the 6th International Symposium on Genetics and Molecular Biology of Plant Nutrition, Kluwer

Academic Publishers: Dordrecht, 1999

26 P.J White, M.R Broadley Preface to genetics of plant mineral nutrition J Exp Bot 55: i–iv, 2004.

27 M.P Reynolds, J.I Ortiz-Monasterio, A McNab, eds Application of Physiology in Wheat Breeding

30 M.J Chrispeels, N.M Crawford, J.I Schroeder Proteins for transport of water and mineral nutrients

across the membrane of plant cells Plant Cell 11: 661–675, 1999.

31 J.L Hall, L.E Williams Transition metal transporters in plants J Exp Bot 54: 2601–2613, 2003.

32 A.G Good, A.K Shrawat, D.G Muench Can less be more? Is reducing nutrient input into the

envi-ronment compatible with maintaining crop production? Trends Plant Sci 9: 597–605, 2004.

33 P Hinsinger Bioavailability of soil inorganic P in the rhizosphere as affected by root-induced

chemi-cal changes: A review Plant Soil 237: 173–195, 2001.

34 F.D Dakora, D.A Phillips Root exudates as mediators of mineral acquisition in low-nutrient

envi-ronments Plant Soil 245: 35–47, 2002.

35 H Bassirirad Kinetics of nutrient uptake by roots: Responses to global change New Phytol 147:

in Arabidopsis thaliana Nature Biotechnol 21: 1215–1221, 2003.

38 S Yanagisawa, A Akiyama, H Kisaka, H Uchimiya, T Miwa Metabolic engineering with Dof1 scription factor in plants: Improved nitrogen assimilation and growth under low-nitrogen conditions

tran-Proc Natl Acad Sci 101: 7833–7838, 2004.

Alcohol dehydrogenase and zinc deficiency, 11, 412

Aldehyde oxidase and molybdenum, 376, 378

and water uptake, 446, 450, 459

effect on calcium homeostasis, 452

effect on cell division, 445, 447

effect on lignification, 445

effect on photosynthesis, 446

effect on root elongation, 444–445, 449, 454, 458,

479–480inhibition of symbiosis with Rhizobium, 447

Aluminum citrate, 460

Aluminum oxalate, 460

Aluminum oxides

and boron sorption, 262

and copper sorption, 318

and molybdenum sorption, 385, 389

and phosphorus sorption, 54and vanadium sorption, 586Aluminum sulfate in water treatment, 470–471Aluminum toxicity, 154–155, 442, 444–453, 468,476–479, 601

Alunite, 461Amidation, 24–25

-aminolevulinic acid, 588

-aminolevulinic acid synthetase, 330Amino sugars in soil, 34, 38–39Ammoniated superphosphate fertilizer, 42Ammonium

accumulation in plant tissues, 10, 92accumulation in soil, 35, 36, 92assimilation, 23–25

toxicity, 35Ammonium chloride as fertilizer, 287Ammonium metavanadate, 587Ammonium molybdate as fertilizer, 387, 388Ammonium nitrate fertilizer, 41

Ammonium nitrate sulfate fertilizer, 42Ammonium phosphate nitrate fertilizer, 42Ammonium polyphosphate fertilizer, 42, 82Ammonium sulfate fertilizer, 39, 41Anhydrous ammonia fertilizer, 40Anthocyanin accumulation, 5, 7, 199Apatite, 52, 137,139

APS reductase, 185–186Aqua ammonia fertilizer, 40Aridisols, 138

Arsenicaccumulation, 600competition with sulfur, 197metabolism, 600

Ascorbic acid oxidase and copper deficiency, 11, 314Atmospheric emissions, 600, 602

of sulfur dioxide, 183–184, 187

of vanadium, 585, 586, 594 ATPase

activity limited by boron deficiency, 244

in photophosphorylation, 147inhibition by aluminum, 449inhibition by cobalt, 502inhibition by copper, 316inhibition by vanadate, 587, 588, 589role in acidification of rhizosphere, 338role in calcium transport, 124, 131role in potassium uptake and transport, 94, 95, 96–97,98

stimulation by chloride, 280ATP sulfurylase, 185–186Augite, 137, 166

605

Beneficial element, definition, 4, 571

Biological nitrogen fixation, 33, 35; see also Nitrogen

fixationBiotite, 105–106, 166

and nitrate concentration, 243

and nitrate reductase, 243

215–217Brown-heart and boron, 242, 248

and fruit firmness, 124, 127–128, 139

and magnesium competition, 124, 132, 149, 150, 151

and nickel, 403

and phosphorus sorption, 132–133, 138and potassium competition, 100–101, 132and sodium competition, 165, 572and strontium, 125

and vanadate, 589channels, 128, 443, 589competition with vanadium, 587, 589deficiency, 7, 245

role in pollen tube growth, 125transport, 129–131

uptake, 128–129Calcium carbonate equivalent (CCE), 140Calcium chloride and fruit, 139Calcium chloride as fertilizer, 287Calcium magnesium phosphate as fertilizer, 171Calcium nitrate and fruit, 139

Calcium nitrate urea fertilizer, 41Calcium oxalacetate, 128Calcium oxalate, 128Calcium silicate fertilizer, 562

Calcium sulfate fertilizer, 139; see also Gypsum

Calmodulin, 124Cambisols, 263Canonical discriminant analysis, 9Carbamylputrescine, 100Carbonic anhydrase and zinc deficiency, 11, 412Carbon monoxide dehydrogenase and nickel, 397Catalase

and cobalt, 507and iron deficiency, 10–11, 330iron as a component, 330

Cation competition, see Ion antagonism

Cation exchange in soil, 113, 137, 138, 140, 331, 586

in sodic soil, 570Cation exchange in plant cell walls, 129, 131, 133, 447, 458Cellular pH, maintenance of, 52

Cell-to-cell adhesion, 124Cell wall structure, 122–124, 447–448, 554, 556Chalcocite, 312, 317

chalcocite as fertilizer, 312Chalcopyrite, 317

as fertilizer, 312Chenopodiaceae as halophytes, 571–573Chernozems, 317

Children’s nutrition, 600Chitosan, 588

Chlorapatite, 137Chlorideand magnesium, 154and manganese, 282osmotic effect 112, 280, 284role in maintenance of electroneutrality, 280–281role in stomatal opening, 280

Chlorine deficiency, 279, 280, 281–282, 283–284, 285Chlorine toxicity, 283

Chlorite, 107, 166Chlorophyll,copper substitution for magnesium, 316 magnesium as a constituent, 4, 146, 147, 148, 149, 151Chlorophyll a, 588

Chlorophyll b, 588Chlorophyll biosynthesis

Copper chelate as fertilizer, 312

Copper chloride as fertilizer, 312

Copper chlorosis, 335

Copper deficiency, 11, 313, 314–315, 320, 379

and nickel, 403

Copper frits as fertilizer, 312

Copper oxalate as fertilizer, 312

Copper sulfate as fertilizer, 312, 313

Cupric nitrate as fertilizer, 312

Cupric oxide as fertilizer, 312, 313

Diamine oxidase, 314Diammonium phosphate fertilizer, 42, 79Dicalcium phosphate dihydrate (DCPD) fertilizer, 54Dicyandiamide fertilizer/nitrification inhibitor, 41Diet and minerals, 155, 601, 602

and aluminum, 468–469, 474–476and cobalt, 500

and copper, 321–323and iron, 344and manganese, 353and selenium, 524–526Dimethylselenide, 520Dof1, 602

Dolomite, 113, 135, 138, 167, 170, 317Dolomite as fertilizer, 151, 170, 171, 172Dumas method, 33–34

E

Effective calcium carbonate equivalent, 140Electro-ultra-filtration (EUF), 108–112Elovich function, 108, 109

Entisols, 106, 110, 138

Epsom salts, 170–172, 221; see also Magnesium sulfate

Essential element, definition, 3–4, 396, 571Exchangeable sodium percentage, 570

F

Facilitated diffusion, 94, 101FeDTPA, 345

FeEDDHA, 344–345FeEDTA, 344–345FeHEDTA, 345Feldspars, 105–107, 108, 137, 561, 562Ferrasols, 317

Ferric chelate reductase (Fe(III) chelate reductase), 310,336–338, 339, 344

Ferric citrate (Fe(III) citrate) as fertilizer, 344Ferric dihydroxamate (Fe(III) dihydroxamate) as fertilizer,345

Ferric monodihydroxamate (Fe(III) monodihydroxamate)

as fertilizer, 345Ferric reductase (Fe(III) reductase) and copper, 310Ferrimolybdite, 385

Ferrous sulfate (Fe(II) sulfate) as fertilizer, 344–345Fertigation and phosphorus supply, 81–82Fluorapatite, 137

Fluvisols, 317, 383Fluvo-aquic soils, 586, 587Fly ash, 219, 524, 585Foliar application

Grass tetany, see Hypomagnesia

Greenback and potassium, 99

and copper concentration, 317

and molybdenum concentration, 383

and phosphorus concentration, 73, 79

cation exchange capacity, 113

inhibition of transport by aluminum, 452role of calcium in action of IAA, 125Indus civilization, 571

Inositol phosphate, 53; see also myo-Inositol phosphate

Ion antagonism, 100Ionomics, 602Ironand aluminum, 450and cobalt, 506, 509and copper, 310, 311and magnesium, 152and molybdenum, 379, 385, 389and nickel, 403

and phosphorus, 332and potassium, 332Iron deficiency, 6, 10–11, 330, 332–334, 335–336, 339,

342 deficiency with magnesium, 152, 156deficiency with vanadium, 587–588Iron deficiency chlorosis, 133, 335, 337, 342, 343, 355Iron deficiency chlorosis paradox, 336

Iron EDTA, 587Iron efficiency, iron-efficient plants, 336, 343, 600Iron oxides in plants, 335

Iron oxides in soil, 331–332and sorption of boron, 262and sorption of molybdenum, 389and sorption of phosphorus, 54 and sorption of selenium, 523and sorption of vanadium, 586Iron toxicity, 332, 334

Iron uptake, 336–338, 600Irrigation

and boron, 265–266and cobalt, 502and copper, 317and iron, 339, 341and magnesium, 172and nickel, 404and phosphorus, 77, 81–82and salinity, 570–571and sulfur, 205Isobutylidene diurea (IBDU) fertilizer, 41

J

Jarosite, 335Jurbanite, 464

K

Kaolinite, 108, 109, 263, 461, 561Kastanozems, 317

Kieserite as fertilizer, 171

K+fixation, 106

K+-fixing soils, 92, 114 Kjeldahl, 33–34, 36

Labile phosphorus, 54

Law of diminishing returns, 12

Law of the minimum, 12

Leaf area

increase with vanadium, 587

decrease with copper, 311

Leaf canopy reflectance 10, see also Spectral reflectance,

13Lignification

and aluminum tolerance, 468

and cobalt uptake, 503

and water relations, 147

and zinc, 153

deficiency, 8, 148–149, 151, 154

toxicity, 149

Magnesium ammonium phosphate as fertilizer, 171

Magnesium chloride as fertilizer, 287Magnesium nitrate as fertilizer, 171Magnesium oxide as fertilizer, 170, 172

Magnesium sulfate as fertilizer, 170–172; see also Epsom

saltsMagnesium uptake and mycorrhizas, 150Malate dehydrogenase, 457

Manganeseand chloride, 282and cobalt, 504, 505, 506, 507, 509and copper, 311

and lignification, 353, 365and magnesium, 153and nickel, 403and photosynthesis, 353, 365and plant diseases, 357deficiency, 10, 11, 353, 354–355, 357toxicity, 356

Manganese oxide in soil, 353, 586Manganese toxicity, 153, 356–357Manganese uptake, 353

Malachite, 317Mesopotamia, 570Metal

accumulation, 600–601detoxification, 600–601metabolism, 600–601Metallothioneins, 192, 313Methyl coenzyme M reductase and nickel, 397Methylene urea fertilizer, 41

Micas, 105–107, 461, 562Mineralization

of nitrogen, 32, 34, 35, 36, 37, 42–43

of phosphorus, 53–54, 504Mollisols, 106, 113, 138Molybdenite, 385Molybdenumand aluminum, 385, 389and iron, 379, 385, 389 and phosphorus, 385, 389and sulfate, 379, 385, 389deficiency, 11, 378–379, 388Molybdenum frits as fertilizer, 387Molybdenum sulfide as fertilizer, 387Molybdenum toxicity, 379

Molybdenum trioxide as fertilizer, 387, 388Molybdic acid as fertilizer, 387

Molybdopterin, 376–378Monoammonium phosphate fertilizer, 42, 79, 81, 82Monocalcium phosphate fertilizer, 81

Montmorillonite, 168, 263, 318, 319Muscovite, 105–106

Mycorrhizas, 331, 404, 602aluminum toxicity to, 459and magnesium uptake, 150and zinc uptake, 415, 424

in alleviating metal toxicity, 601

myo-Inositol phosphate, 52

N

NADP+-malic enzyme, 573Naumannite, 523

and iron deficiency, 11

and molybdenum requirement, 11, 377, 381, 388

and nitrogen deficiency, 11

and sodium toxicity, 572

and sulfur deficiency, 221

Nitrification, 35, 37–38, 40, 41; see also Mineralization of

nitrogenand chloride, 282

Orthophosphate (orthophosphoric acid) fertilizer, 81, 82

Osmotic adjustment in plants, 147, 570, 573–574

Oxisols, 113, 132, 586, 587 aluminum saturation, 467calcium concentration and cation exchange capacity,138

distribution, 461, 462, 463potassium-binding capacity, 107

P

Patronite, 586Pectin, 122–124, 128, 447–448Peroxidase

and cobalt, 501and iron deficiency, 10–11, 330and manganese deficiency, 10and silicon, 555

iron as a component, 330Peteca, 126–127

Phenolase, 314Phosphate, high affinity transporters, 602 Phosphoenolpyruvate, sodium requirement forregeneration, 573

Phosphoenolpyruvate carboxylase, 124, 336, 412, 457,573

Phosphoinositide, 451Phosphorus accumulation with vanadium, 588acquisition, 601

and aluminum, 442, 446, 459and boron, 244, 262and copper, 310, 311and iron, 332and magnesium, 152and molybdenum, 385, 389and selenium, 517–518and silicon, 554and sulfur, 197–198and zinc, 423 cycle, 53–54deficiency, 7, 8, 11, 54–55nutrition, 601

sorption in soil, 54, 132–133, 138uptake, 78, 600

Photosynthesisinhibition by aluminum, 446inhibition by manganese, 353, 365oxygen evolution, 588

photosystem I, 330, 588photosystem II, 315–316, 453, 504, 505, 588Phytoalexins, 219

Phytochelatins, 192, 313Phytoextraction, phytoremediation, 13, 313–314, 406,520–521, 600–601

Phytoferritin, 335Phytosiderophores, 336–339, 343Plagioclase, 137, 561

Plant analysis, see Tissue analysis

Plant diseaseand aluminum, 442and chloride, 282–283and manganese, 357and nickel, 399, 400

role in enzyme activation, 92–93

role in protein synthesis, 93–94

Potassium magnesium sulfate as fertilizer, 170–171

Potassium metaphosphate fertilizer, 112, 113

Potassium nitrate fertilizer, 112, 113

Potassium silicate fertilizer, 112, 562

Potassium sulfate fertilizer, 112, 113

Powellite, 385

Precision agriculture, 13

Preplant nitrate test, 37

Pre-sidedress soil nitrate test (PSNT), 37–38

Principal component analysis, 9

S

Saline soil, 570–571Salinity

and boron, 263–264 and magnesium, 151, 152, 154, 572and nitrogen nutrition, 572and phosphorus nutrition, 572and potassium nutrition, 115–116, 572and silicon alleviation, 557

visual symptoms, 8Salinization, 570–571Selenium

and copper, 310and nitrogen, 518and phosphorus, 517–518and sulfur, 191, 197, 517, 518–519, 521, 526Selenium deficiency in human diet, 524–526, 601

Selenium toxicity in animals, see Selenosis

Selenium toxicity in plants, 521Selenium uptake, 517–518 Selenosis, 517, 524, 526Sewage sludge, sewage effluent, 382, 404, 405, 406, 586Silicate chrysocolla, 317

Siliconand aluminum, 460, 554and cell walls, 554–557and pests and diseases, 554–557and phosphorus, 554

and salinity, 557Silicon uptake, 553Smectites, 107, 108, 109, 461, 561Sodicity, sodic soil, 570–571Sodium

and inhibition of protein synthesis, 93–94and inhibition of uptake of calcium, 165, 572and inhibition of uptake of magnesium, 152, 165, 572and inhibition of uptake of potassium, 93–94, 100–101,

557, 572and nitrate assimilation, 572and nitrate uptake, 572Sodium absorption ratio, 165, 263Sodium bicarbonate soil test for phosphorus, 73, 75Sodium borates, 246

Sodium-calcium borates, 246Sodium chloride as fertilizer, 287Sodium copper EDTA, 312Sodium molybdate as fertilizer, 387, 388Sodium nitrate fertilizer, 39

Sodium/potassium replacement in plants, 572 Sodium toxicity, 573–574

Soil quality index, 12Soil test, 11–12, 599for aluminum, 465–468for ammonium, 36for boron, 257–260for calcium, 137for chlorine, 286

for nitrogen, 28–32for phosphorus, 55–71for potassium, 101–105for selenium, 518, 527–542, 543for silicon, 558–560

for sodium 574–575for sulfur, 206–217for vanadium 586, 587, 589–594for zinc, 416–421

Tourmaline, 246Transamination, 24Transporter protein genetics, 6022,3,5-triiodobenzoic acid (TIBA), 125Triple superphosphate, 82, 139, 389, 522Tripolyphosphate fertilizer, 81

Trunk injection of zinc, 422

U

Ulexite fertilizer, 267Ultisols, 113, 138, 461, 465, 467distribution, 462, 463Urea as fertilizer, 39, 39–41Urea ammonium phosphate fertilizer, 42Urea formaldehyde fertilizer, 41Urea phosphate, 82

Urease and nickel, 396, 397, 399, 400, 401

V

Vanadinite, 586Vanadium and aluminum accumulation, 588and borate, 589

and calcium, 587and chloride, 589and chromate, 589and copper, 587, 589and increase in leaf area, 587and iron deficiency, 587–588and magnesium, 587and manganese, 587–588, 589and molybdate, 589and molybdenum, 587and nickel, 587, 589and potassium, 587and selenium, 589Vanadium bioavailability, 594Vanadium oxidation states, 585Vanadyl amino compounds, 589Vanadyl cellulose compounds, 589Variscite, 464

Vermiculite, 107, 319, 461, 561Vertisols, 110, 113, 138, 317Viets effect, 94

Vitamin B12deficiency and cobalt, 500Vivianite, 345

Water use and silicon, 557

Water use efficiency and potassium, 99

Zinc nitrate as fertilizer, 424, 425–427Zinc nitrate-ammonium nitrate-urea (NZMTM) fertilizer,

415, 424–427, 429Zinc nutrition, 601Zinc sulfate-induced defoliation, 426–427Zinc sulfate as fertilizer, 422–423, 424, 425–428, 429ZnEDTA, 422

FIGURE 1.1 Interveinal chlorosis of iron-deficient borage (Borago officinalis L.) (Photograph by Allen V.Barker.)

FIGURE 1.2 Deficiency symptoms showing necrosis of leaf margins, as in this case potassium deficiency oncucumber (Cucumis sativus L.) leaf (Photograph by Allen V Barker.)

(b)

FIGURE 1.3 Deficiency symptoms showing necrosis on young leaves of (a) calcium-deficient lettuce (Lactuca sativa L.) and necrosis on young and old leaves of (b) calcium-deficient cucumber (Cucumis sativus L.) Withcucumber the necrosis has extended to all leaves that have not expanded to the potential size of full maturity.(Photographs by Allen V Barker.)

FIGURE 1.4 Stunting and development of red color and loss of green color of phosphorus-deficient tomato(Lycopersicon esculentum Mill.) (Photograph by Allen V Barker.)

Lycoper-FIGURE 5.3 Calcium-deficient maize (Zea mays L.) The younger leaves which are still furled are yellow,but the lamina of the older, emerged leaf behind is green (Photograph by Allen V Barker.)