Monica Ozores-Hampton University of Florida/IFAS/SWFREC Spring 2013

Transcription

1 Monica Ozores-Hampton University of Florida/IFAS/SWFREC Spring 2013 MACRONUTRIENTS: MICRONUTRIENTS: Nitrogen (NO 3, NH 4 ) Boron (H 2 BO 3- ) Phosphorus (P) Chlorine (Cl) Potassium (K) Copper (Cu) Calcium (Ca) Iron (Fe) Magnesium (Mg) Manganese (Mn) Sulfur (S) Molybdenum (MoO 4- ) Zinc (Zn) Free elements : C, H, O 1

2 Higher crop yields Widespread use of N-P-K fertilizers Higher analysis fertilizers containing less micronutrients The research that concluded we have enough micronutrients for 50 years dates back from the 1930s and 1940s Farming of marginal land 2

3 Fungicide contribution to Cu, Mn and Zn supply may be major Cl supplied by KCl Mo very seldom an issue Fertilized micronutrients: B and Fe 3

4 Soil testing Plant analysis Field demonstrations Field observations Field history Elt. Soil-pH Range 5.5 to to to 7.0 Insuff. Toxic Insuff. Toxic Insuff. Toxic (ppm) B Cu Fe Mn Mo Zn

5 Nutrient Source Foliar rate (lb/acre) Boron Borax 2 to 5 Solubor 1 to1.5 Copper CuSO 4 2 to 5 Iron FeSO 4 2 to 4 Fe-chelate 0.75 to 1 Manganese MnSO 4 2 to 4 Molybdenum Na-molybdate 0.25 to 0.50 Zinc ZnSO 4 2 to 4 Zn-chelate 0.75 to 1 Estimated crop removal (lb/acre) Range in soils, Corn Cotton Nutrient Total (lb/acre) 150 bu 1,000 lb lint Boron Copper Iron 10, , Manganese , Molybdenum Zinc

6 Not affected 4 3 B Cl Cu Fe Mn Mo Zn 6

7 Reduces toxicity of Mn Increases availability of Mo Has no affect on Cl Reduces availability of Fe and Zn 7

8 Element (mobility in plant) B (non mobile) Cl (mobile) Function in the plant Meristematic growth Uracil synthesis Germination Splitting of water (Hill reaction) Tissue content (mg/kg or ppm dry weight) 20 to to 200 (up to 2-3%) Cu (non mobile) Enzyme component Redox reactions: Cu + <-> e - + Cu ++ 2 to 20 (up to 200 ) Element Function in the plant Tissue content (mg/kg or ppm dry weight) Fe (non mobile) Mn (non mobile) Mo (mobile) Zn (non mobile) Electron transfer: Fe ++ <-> e - + Fe to 75 (up to 300) Electron transfer: Mn ++ <-> e - + Mn +++ Superoxide dismutase Nitrate reductase Nitrogenase Carbonic anhydrase IAA synthesis 10 to 50 (up to 200) 0.15 to to 50 (up to 200) 8

9 B mostly taken up by transpirational stream as undissociated boric acid. Some B is taken up actively. In the root, B may be associated with polysaccharides, remain free, or become bound to cell walls B moves in xylem as sugar-borate B immobile in plant B may be lost by guttation 9

10 Meristematic growth (cell differenciation, maturation, division and elongation) B essential for uracil synthesis, which is an RNA component and precursor of uridine di-p glucose Pollen tube growth and germination Involved in lignine biosynthesis and differentiation of lignine Celery Crooked stem Peanuts Hollow heart Apples Corky core Alfalfa Rosetting, yellow top, death of terminal bud Beets Black heart Cotton Ruptured squares, dieback of terminal bud, rosetting 10

11 Potatoes: growth stunted; growing point killed; leaves dull grayish green, changing to yellow before dying off. B deficiency on sunflower 11

12 Most response Medium response Least response Alfalfa Cauliflower Celery Sugarbeets Table beets Turnips Peanuts Cotton Apples Clover Broccoli Cabbage Carrots Lettuce Spinach Sweet corn Tomatoes Asparagus Canola Radish Beans Blueberries Cucumbers Corn Onions Potatoes Small grains Sorghum Sudan grass Soybeans Boron Water Source (%) soluble Borax 11.3 Yes Sodium pentaborate 18.0 Yes Sodium tetraborate Fertilizer Borate Yes Fertilizer Borate Yes Boric acid 17.0 Yes Colemanite 10.0 Low Solubor 20.0 Yes 12

13 Cu uptake is active and metabolically controlled. Cu absorbed as Cu ++ or chelated-cu Cu moves in the plant complexed with AA Immobile in the plant Most (>50%) of the plant Cu is in the chloroplast 13

14 Symptoms Cereals Slight Moderate Severe Limpness or wilting at mid-tillering. x Limpness or wilting at stem elongation. x x Pale yellow, curled young leaves at tillering. x Pigtail - The leaf tip dies and may roll and turn white, sometimes appearing fibrous. Upper one-third or half of the leaf may wither and break abruptly at the x x healthy part. Increased susceptibility to disease. x x The presence of ergots in the grain heads, specifically wheat and barley. x x x Unusually high levels of take-all or "fake-all" like symptoms, particularly in 0slo wheat. x x x Retarded stem elongation. x x Excessive late tillering and high mortality on late tillers. x x Delay in heading - Non-uniform heading occurs, particularly on light loamy soils where crop emergence and early development is uniform. x x Aborted heads and spikelets. x Heads and spikes are nearly normal, but contain many spikelets that are devoid of grain. Anthesis is poor and late. Grain appears shrivelled and the x x endosperm is blackened. Delay in maturity and senescence - Maturity may be delayed for several weeks. x x x Head and stem bending - Stem may break 15 to 30 cm below the head. x x Stem melanosis - Dark brown patches out in wheat fields (particularly in Park wheat) that begin to appear at the milky ripe stage. The stems immediately below the head and lower nodes turn dark brown. The head becomes bleached x x x and then turns dirty gray with empty florets and shrivelled kernels. Probable loss in grain yield (%) Probable loss in straw yield (%). Nil Barley Citrus Necrotic-corky areas 14

15 Copper Deficiency Tomatoes Copper Water Source (%) soluble Copper sulfate 22.5 Yes Copper ammonium phosphate 30.0 Slight Copper chelates Variable Yes Other organics Variable Yes Note: Application method may be foliar or soil 15

16 Little correlation between soil Fe and available Fe Fe moves little in the soil (<1.5 cm) Fe mostly taken up as Fe +++, but some as Fe ++ Fe absorbed by two mechanisms: reduction of Fe +++ into Fe ++ in the root, or Fe ++ is taken up chelated, and then oxidized Fe +++ moves in the xylem in association with citrate towards the chloroplast Fe is immobile in plant 16

17 Imbalance with metals such as Mo, Cu and Mn Excessive soil P Wet, cold soils High soil ph High soil bicarbonate levels Plant genetic differences Fe Interveinal chlorosis: At the base of the younger leaves near the top of the plant there is chlorosis due to immobility and poor translocation of Fe. Bleached leaf: Drastic reduction of the leaf chlorophyll content ending in necrotic spots. 17

18 18

19 Source Fe (%) Iron sulfates Iron oxides Iron ammonium sulfate 14 Iron ammonium polyphosphate 22 Iron chelates and FeEDDHA 5-14 Other organics

20 Mn uptake is competitive and metabolically mediated Mn taken up as Mn ++ and translocated as Mn ++ or combined with organic acids Mn is immobile in the plant Part of the plant enzyme system Activates several metabolic reactions Aids in chlorophyll synthesis Accelerates germination and crop maturity Increases plant availability of P and Ca 20

21 21

22 Source Mn (%) Manganese sulfates Manganese oxides Manganese chelate 12 Manganese carbonate 31 Manganese chloride 17 22

23 Mo taken up as MoO - 4 (molybdate) and translocated to leaves Essential component of Nitrate Reductase and Nitrogenase (that s why Mo deficiency may look like N deficiency) Water Source Mo (%) soluble Ammonium molybdate 54 Yes Sodium molybdate Yes Molybdic acid 47.5 Slight 23

24 The leaves show some mottled spotting along with some interveinal chlorosis. An early symptom for Mo deficiency is a general overall chlorosis, similar to the symptom for N deficiency but generally without the reddish coloration on the undersides of the leaves. This results from the requirement for Mo in the reduction of nitrate, which needs to be reduced prior to its assimilation by the plant. Thus, the initial symptoms of Mo deficiency are in fact those of N deficiency. However, Mo has other metabolic functions within the plant, and hence there are deficiency symptoms even when reduced N is available. In the case of cauliflower, the lamina of the new leaves fail to develop, resulting in a characteristic whiptail appearance. In many plants there is an upward cupping of the leaves and mottled spots developing into large interveinal chlorotic areas under severe deficiency. At high concentrations, Mo has a very distinctive toxicity symptom in that the leaves turn a very brilliant orange. 24

25 Zn taken up as Zn ++ but also as (ZnCl) + and Zn-chelates Zn is mostly immobile in the plant Plant Functions of Zn Aids in the synthesis of enzyme systems Promotes certain metabolic functions Necessary for the production of chlorophyll and carbohydrates 25

26 Tomato Potato Bean Source Zn (%) Zinc sulfates (hydrated) Zinc oxide 78 Basic zinc sulfate 55 Zinc-ammonia complexes 10 Zinc chelates 9-14 Other organics

27 Cl follow water movement in soil and is taken up as Cl - against an electrochemical gradient by a protein carrier Cl is mobile in plant and remains as Cl - 27

28 Involved in energy reactions, including the chemical breakdown of water Activates several enzyme systems Involved in the transport of cations Regulates stomatal guard cells, thus controlling water loss and maintaining turgor Cl deficiency is rare Foliar rates above 0.5% to 2% are toxic Plants require relatively high chlorine concentration in their tissues. Chlorine is very abundant in soils, and reaches high concentrations in saline areas, but it can be deficient in highly leached inland areas. 28

29 The leaves have abnormal shapes, with distinct interveinal chlorosis. The most common symptoms of Clo deficiency are chlorosis and wilting of the young leaves. The chlorosis occurs on smooth flat depressions in the interveinal area of the leaf blade. In more advanced cases there often appears a characteristic bronzing on the upper side of the mature leaves. Plants are generally tolerant of Cl, but some species such as avocados, stone fruits, and grapevines are sensitive to Cl and can show toxicity even at low chloride concentrations in the soil. Smaller quantities does not mean less important Most functions are tied to changes in oxidation state Micronutrients may limit yields 29