15
PHOSPHORUS
Phosphorus (P) has an important role in many fundamental biochemi-
cal and physiological processes. Plants take up phosphorus in the form
of phosphate ion (PO
4
3-
).
PRESENT IN
DNA and RNA, ATP, ADP
ACTION
• stimulates the roots growth
• stimulates blooming
• stimulates fecundation and ripeness
• strengthens the plant tissues
• is necessary in the formation of seeds
SHORTAGE
• delayed ripening
EFFECTS
• slower growth
• small leaves
• decrease of production (smaller fruits and difficult
seeds formation)
• reduction of root system
EXCESS EFFECTS
• premature ripening
• excess of fruit-setting
• negative effects on the absorption of some micro-
elements such as iron, zinc, boron and copper
POTASSIUM
Potassium (K) is essential in proteic synthesis. The problem of lack of
potassium is quite frequent in calcareous soils.
Potassium is absorbed as K
+
.
PRESENT IN
tissues responsible for the growth of plants (primary
and secondary meristems), embryos and cell vacuole
ACTION
• improves the quality of fruits and flowers
• gives more resistance both to frost and to
diseases caused by fungi (increases the cuticular
thickness)
• regulates the cellular turgidity (helps to regulate the
osmotic processes and increases the resistance to
dryness)
• regulates the stomatic opening and closing (it means
a strong influence on transpiration and photo-
synthesis)
SHORTAGE
• slower growth
EFFECTS
• smaller fruits, less colored and less preserved
• increase of transpiration
• less resistance to the cold
38
Phosphorus HR
INTERFERENCES
Calcium above 10000 mg/L as CaCO
3
Chloride above 150000 mg/L as Cl
–
Ferrous iron above 100 mg/L
Magnesium above 40000 mg/L as CaCO
3
Sulfide
x
1
0
• Wait for a few seconds and the
display will show "-0.0-". Now
the meter is zeroed and ready for
measurement.
• Remove the cuvet.
• Add 10 drops of HI 93706A
Molybdate reagent.
• Add the content of one packet of
HI 93706B-0 Phosphorus Reagent
B (Amino Acid) to the cuvet.
Replace the cap and shake gently
until dissolution is complete.
• Reinsert the cuvet into the
instrument.
• Press TIMER and the display will show the countdown prior to the
measurement or, alternatively, wait for 5 minutes and press READ
DIRECT. In both cases "SIP" will blink during measurement.
• The instrument directly displays concentration in mg/L of phosphorus
on the Liquid Crystal Display.
• To convert the reading to mg/L of phosphate (PO
4
3–
), multiply by
a factor of 3.07.
