Hanna Instruments HI 83225-01 - Manual (Page 17)

17
NITROGEN
Nitrogen (N) is mostly absorbed by plants as nitrates (NO
3
¯) and, in smaller amount, in the form of
ammonium (NH
4
+ ). In hydroponics, an adequate ratio between the two forms is generally used in nutritive
solutions.
PRESENT IN proteins, enzymes, chlorophyll, hormones, vitamins, DNA and RNA
ACTION • is fundamental for plants in phase of growth
• promotes the lengthening of trunks and sprouts
• increases the production of foliage
• helps to absorb other nutrients
(in particular phosphorus)
• assists a bigger production for both size and
number of fruits
SHORTAGE • slower growth
EFFECTS • smaller leaves
• yellowing of leaves
• smaller fruits
• premature ripening
EXCESS EFFECTS • reduction in resistance to diseases and atmospheric agents
• increase of water demand (caused by an excessive production of leaves)
• bad quality of fruits
• delayed ripening
• reduction in potassium absorption
INTRODUCTION
THE ROLE OF NUTRIENTS IN THE GROWTH AND PRODUCTION OF PLANTS
The three elements that are mostly needed by the plants are nitrogen (N), phosphorus (P) and potassium
(K). They are called the macronutrients while other elements, needed by plants in smaller amounts, are
called microelements. In hydroponics, plants need a balanced nutritive solution, composed of macro and
microelements.
Shortage or excess of even only one nutritive element may cause an imbalance in plant physiology and in
the absorption of the other nutrients. Nutrients shortages may result in irregular plant growth, low
resistance to diseases, scarce production both in quantity and quality, while nutrients excess may cause
waste of fertilizer, pollution of the groundwater and the possible accumulation of dangerous substances in
the crops produced.