Mo Molybdenum
|
part of nitrate reductase; essential
for N fixation
|
Chlorosis or twisting of leaves, whiptail disease in acidic soils.
| Excess Mo causes Fe and Cu deficiencies.
|
|
Cu Copper
|
component of plastocyanin, aplastid
pigment; present in lignin of xylem elements; activates enzymes
|
Young leaves dark green, twisted, and
wilted; tips of roots and shoots remain alive; xylem loses rigidity; rarely deficient
| Excess Cu results in Fe deficiency, especially in acid soils.
|
|
Zn Zinc
|
ecessary for formation of pollen;
involved in auxin synthesis; maintenance of ribosome structure;
activates enzymes
|
Causes most problems in all micronutrients. Chlorosis, smaller leaves, thin;
reduced internodes; distorted leaf margins; older leaves most
affected. New leaves grow contorted and twisted, dropping early.
| Excess Zn causes dark mottled leaves
|
|
Mn Manganese
|
photosynthetic O2 evolution; enzyme
activator; electron transfers
|
Interveinal chlorosis; appears first on
older leaves from base; necrosis common; disorganisation of
lamellar membranes; immobile when pH over 7.5 and often accompanies
Fe deficiency
| Excess Mn arises in acidic media giving
orange-brown mottling
|
|
B Boron
|
ssential for growth of pollen tubes;
regulation of enzyme function; possible role in sugar transport
|
Death of apical meristem; leaves
twisted and pale at base; swollen, discoloured root tips; young
tissue most affected with grey specks, shoots turn grey
| Excess B causes discolouration and death of leaf tips, then margins.
|
|
Fe Iron
|
equired for synthesis of chlorophyll;
component of cytochromes and ferredoxin; cofactor of peroxidase and
some other enzymes
|
Interveinal chlorosis; short and
slender stems; buds remain alive; affects young leaves first,
yellows from base, eventually necrosis; immobile when pH over 7.5 or
high Cu levels
| Excess Fe causes leaf bronzing.
|
|
Cl Chlorine
|
activates photosynthetic elements;
functions in water balance
|
Wilted leaves; chlorosis or bronzing; necrosis;
stunted, thickened roots
| Ecess Cl also causes bronzing.
|
Macronutrients
| Function
| Deficiency
| Toxicity
|
|
S Sulphur
|
part of coenzyme A and the amino acids
and cystine and methionine; can be absorbed through stomata as
gaseous SO2
|
Interveinal chlorosis; usually no
necrosis; affects young leaves, lime green to yellow; stem
elongation; rarely deficient; immobile when high pH or Ca levels
| SO2 causes interveinal chlorosis.
|
|
P Phosphorus
|
part of nucleic acids, sugar
phosphates, and ATP; component of phospholipids of membranes;
coenzymes
|
Stunted growth, dark blue/green to
purple pigmentation; accumulation of anthocyanin pigments, delayed
maturity; leaves contort and drop, often with dark blotches, lower leaf tips may turn brown and curl down;
reddening on underside of stem; affects entire plant; low pH makes P
unavailable as does cold, wet heavy soils; excess Fe and Zn in soil binds with phosphates; second
to N, P is element most likely to be deficient
| Excess P reduces availability of Zn, Fe, Mg, and calcium in young leaves. Watch especially symptoms for Zn
|
|
Mg Magnesium
|
part of chlorophyll; enzyme activator;
protein synthesis
|
Interveinal chlorosis and reddening of
leaves; red spots; leaf lips turn upward; older leaves most
affected, and drop early; made unavailable by high K levels and low
pH
| Excess Mg creates small, dark green leaves with curled edges.
|
|
Ca Calcium
|
membrane integrity; in middle lamella;
functions as “second messenger”to co-ordinate plant's responses
to many environmental stimuli; reversibly binds with calmodulin,
which activates many enzymes
|
Required in large quantities. Death of root and shoot tips; very dark
green foliage and slow growth; young leaves and shoots most affected, distorted and withered
| Excess Ca causes wilting and Mg, K, Fe and Mn deficiencies.
|
|
K Potassium
|
regulates osmotic pressure of guard
cells, thereby controlling opening and closing of stomata; activates
more than 60 enzymes; necessary for starch formation
|
Chlorosis and necrosis, weak stems and
roots; roots more susceptible to disease; young leaves develop mottling, older leaves most
affected, first tips and margins; leaf tip curls (often downwards)
and brown spots and tips develop; common in tomatoes, potatoes, beans and
fruit. Recovery is slow.
| Excess K gives scorching of plants and wilting, may lead to Ca or Mg deficiency.
|
|
N Nitrogen
|
part of nucleic acids, chlorophyll,
amino acids, protein, nucleotides, and co-enzymes
|
N is very mobile and
dissipates quickly - element most likely to be deficient. General chlorosis, stunted growth;
older leaves yellow first, stem(underside) and leaf veins might
develop red/purplish colouration due to accumulation of anthocyanin
pigments; small, brightly coloured fruit;
|
Toxicity shows as excessive lush, green
foliage, stems weak, leaves go copper/brown and drop
|
|
O Oxygen
|
major component of plant's organic
compounds
|
Rarely limiting enough to cause
specific symptoms
| Photorespiration
|
|
C Carbon
|
major component of plant's organic
compounds
|
Rarely limiting enough to cause
specific symptoms
|
|
|
H Hydrogen
|
major component of plant's organic
compounds
|
Rarely limiting enough to cause
specific symptoms
|
|
