1. 1 Unit 1 Chapter 5 Mineral Nutrition Note: download slides for previous chapters

2. 2 Mineral nutrition Mineral nutrients are elements such as N, P, K that plants acquire primarily in the form of inorganic ions from the soil. Plants are “miners” of mineral nutrients through roots. Mycorrhizal fungi and nitrogen-fixing bacteria often participate with roots in the acquisition of mineral nutrients.

3. 3 Figure 5.1 Worldwide fertilizer consumption over the past five decades

4. 4 Typically, < 50% fertilizer applied to the soils are used. Leaching or evaporation to the air cause pollution. Nitrate (NO 3 - ) and ammonium (NH 4 + ). Because of the complex nature of plant- soil-atmosphere relationships, studies of mineral nutrition involve scientists in many fields.

5. 5 Essential nutrients Essential elements: -an intrinsic component in the structure or metabolism of a plant, -its absence causes severe abnormalities in plant growth, development, or reproduction. There are a total of 16 essential mineral elements: Macronutrients: N, P, K, Ca, Mg, S, Si Micronutrient Cl, Fe, B, Mn, Na, Zn, Cu, Ni, Mo

11. 11 Figure 5.2 Various types of solution culture systems Solution culture Hydroponics

15. 15 Figure 5.3 Chelator and chelated cation To prevent Fe precipitation, often chelators as EDTA or DTPA are used to make chelated Fe DPTA EDTA

16. 16 Mineral deficiencies  Deficiencies of several elements may occur simutaneously in different tissues  Deficiencies or excessive amounts of one element may induce deficiencies or excessive accumulations of another  Some virus-induced plant disease may produce symptoms similar to those of nutrient deficiencies

17. 17 Mineral deficiencies Nutrient deficiency symptoms in a plant are expression of metabolic disorders resulting from insufficient supply of an essential elements These disorders are related to the roles played by essential elements in normal plant metabolism and function (Table 5.2)

18. Si, Ni, Mn ??

19. Mineral deficiencies If an essential element is mobile, deficiency symptoms tend to appear first in older leaves. Deficiency of an immobile essential element becomes evident first in younger leaves.

20. Nutrient deficiencies Essential elements have multiple roles in plant metabolism. Soil and plant tissue analysis can provide information on the nutritional status of the plant soil system and can suggest corrective actions to avoid deficiencies or toxicities.

21. Extra reading Topic 5.1 Symptoms of Deficiency In Essential Minerals http://5e.plantphys.net/article.php?ch=t&id =289

22. Nutrients Group 1. part of carbon compounds N: component in amino acids, DNA Deficiency: chlorosis in old leaves. S: component in amino acids, vitamins.Deficiency: chlorosis in mature and young leaves. Veins and petioles show a very distinct reddish color.

23. Nutrition Group 2: energy storage or structural integrity P: components in DNA, RNA, phospholipids, ATP, etc Deficiency: stunted growth, dark green coloration containing necrotic spots; slight purple coloration

24. Silicon: components of cell wall Deficiency: lodging and fungal infection Boron: function unclear (cell wall component) Deficiency: necrosis of young leaves and terminal buds

25. Nutrition Group 3: nutrients in ionic form Potassium: marginal chlorosis; necrosis, shown first in old or mature leave. A more advanced deficiency status show necrosis in the interveinal spaces between the main veins along with interveinal chlorosis. This group of symptoms is very characteristic of K deficiency symptoms.

26. Nutrition deficiencies Calcium: necrosis around the base of the leaves. The very low mobility of calcium is a major factor determining the expression of calcium deficiency symptoms in plants. Classic symptoms: blossom-end rot of tomato (burning of the end part of tomato fruits), tip burn of lettuce, blackheart of celery and death of the growing regions in many plants. All these symptoms show soft dead necrotic tissue at rapidly growing areas, which is generally related to poor translocation of calcium to the tissue rather than a low external supply of calcium.

27. Group 3 Leaf chlorosis and necrosis Chlorosis in old leaves Small necrotic spots, chlorosis in young or old leaves

28. Nutrition Group 4: mineral nutrients involved in redox reactions Iron; Zinc; Copper; Nickle; Molybdenum: associated with nitrate metabolism, chlorosis in leaves Dark green leaves, twisted or malformed Intervenous chlorosis in young leaves

29. Nutrient deficiency Diagnosis of mineral nutrient deficiency Soil analysis Plant tissue analysis Crop harvesting removes nutrients from the soil Nutrients can be added back to the soil in the form of fertilizers: Chemical fertilizers, organic fertilizers (plant and animal residues) Fertilizers can be applied to the soil or sprayed on leaves

30. 30 Figure 5.4 Relationship between yield and the nutrient content of the plant tissue

31. 31 Figure 5.5 Influence of soil pH on the availability of nutrient elements in organic soils Soil pH has a large influence on the availability of mineral nutrients to plants

32. 32 Figure 5.6 The principle of cation exchange on the surface of a soil particle Cation exchange capacity: the degree to which a soil can adsorb and exchange ions

34. The soil is a complex substrate – physically, chemically, and biologically. The size of soil particles and the cation exchange capacity of the soil determines the extent to which a soil provides a reservoir for water and nutrients A soil with higher cation exchange capacity generally has a larger reserve of mineral nutrients

35. 35 Figure 5.7 Fibrous root systems of wheat (a monocot)

36. 36 Figure 5.8 Taproot system of two adequately watered dicots

37. 37 Figure 5.9 Diagrammatic longitudinal section of the apical region of the root

38. 38 Figure 5.10 Formation of a nutrient depletion zone in region of soil adjacent to plant root

39. 39 Roots Plants develop extensive root systems to obtain nutrients Roots have a relatively simple structure Roots continually deplete the nutrients from the immediate soil around them, and roots grow continuously. Different areas of the root absorb different ions: –in barley, Ca absorption is restricted to the apical region; K, nitrate, and ammonium can be absorbed at all locations of the root surface. –In corn, elongation zone has the maximum rate of K and nitrate absorption.

40. 40 Figure 5.11 Root biomass as a function of extractable soil NH 4 + and NO 3 – Excessive nutrients decrease root biomass, as carbohydrates become limited.

41. 41 Figure 5.12 Root infected with ectotrophic mycorrhizal fungi Root infected with ectotrophic mycorrhizal fungi – forming a dense sheath or mantle; the hyphae also penetrate the intercellular space of the cortex to form the Hartig net.

42. 42 Figure 5.13 Association of arbuscular mycorrhizal fungi with a section of a plant root Arbuscular mycorrhizal fungi grow into the intercellular space of the cortex and penetrate individual cortical cells

43. 43 Mycorrhizal fungi Plant roots often form associations with mycorrhizal fungi The fine hyphae of mycorrhizae extend the reach of roots into the surrounding soil and facilitate the acquisition of mineral nutrients, particularly those like phosphorus that are relatively immobile in the soil. Plant provides carbohydrates to the mycorrhizae. Plants tend to suppress mycorrhizal association under conditions of high nutrient availability.