Dieback in citrus and cracking of apple is due to the deficiency of

Correct option is B

Correct Answer: (b) Copper

Explanation:

• Copper (Cu) deficiency is responsible for dieback symptoms in citrus and fruit cracking in apple.
• In citrus:
• Deficiency leads to dieback of twigs and branches, where terminal shoots dry and die.
• Leaves may show chlorosis and reduced growth.
• In apple:
• Copper deficiency results in poor lignification of tissues, leading to fruit cracking.
• Copper plays a vital role in:
• Enzyme activation
• Lignin synthesis, which strengthens cell walls
• Reproductive growth and disease resistance
• Lack of copper weakens plant tissues, making them prone to cracking and dieback.

Information Booster:

• Copper is a micronutrient required in small quantities but essential for plant metabolism.
• Functions of copper:
• Involved in photosynthesis and respiration
• Helps in formation of chlorophyll (indirectly)
• Enhances disease resistance
• Common copper fertilizers:
• Copper sulphate (CuSO₄)
• Bordeaux mixture

Additional Knowledge:

• Zinc deficiency (Option A): Causes little leaf and rosetting.
• Iron deficiency (Option C): Causes interveinal chlorosis in young leaves.
• Sulphur deficiency (Option D): Causes uniform yellowing of young leaves.
• Copper deficiency symptoms are more common in sandy and organic soils.

Explanation of Incorrect Options:

Option (a):

• Zinc deficiency causes little leaf and stunted growth, not dieback and fruit cracking.

Option (c):

• Iron deficiency leads to chlorosis, not dieback or cracking.

Option (d):

• Sulphur deficiency causes yellowing, not these specific symptoms.

Option (e):

• Incorrect because copper deficiency is the correct cause.