6.3. Mineral requirements of plants

 

Nitrate ion and magnesium are essential minerals for plant growth.

Plants need:

• nitrate ions (NO3−) for making amino acids
• magnesium ions (Mg2+) for making chlorophyll

Nitrate ions (NO3−)

Nitrate ion deficiency

• Function
• needed for making amino acids (building blocks of protein)
• amino acids are formed by sugars + nitrate
• all proteins contain N
• proteins are used to make cytoplasm and enzymes

• Deficiency:
• plant can't synthesize (make) amino acids and proteins
• --> slows down growth
• symptoms
• stems --> weak
• lower leaves --> yellowing --> die
• upper leaves --> pale green

Nitrate ion deficiency in tomato leaf

Magnesium ions (Mg2+)

Magnesium deficiency

• Function:
• needed for making chlorophyll
• each chlorophyll molecule contains one Mg ion
• plants need chlorophyll to trap light to provide energy during photosynthesis

• Deficiency:
• can't synthesize chlorophyll
• reduced photosynthesis
• symptoms
• leaves turn yellow (chlorosis) from the bottom of the stem upwards
• plant growth suffers

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