Question

Deficiency of molybdenum causes whiptail disease of cauliflower
(a) True
(b) False

Answer 1

Hint: Molybdenum is a plant microelement and several diseases can be seen in plants in case of deficiency of microelements. Most of these changes are externally observable.

Complete answer:
Molybdenum in plants is absorbed in the form of ${ MoO }_{ 2 }^{ 2+ }$ (molybdenum dioxide) cation. The deficiency of molybdenum causes whiptail disease in cauliflower.
The visible changes that occur during whiptail disease are:
- Chlorosis of leaf margins
- Whitening of leaf
- Incomplete development of leaf blades
- Deformation of apical parts

Several other diseases are also caused due to deficiency of molybdenum in the plant:
a. Mottled chlorosis along with marginal necrosis.
b. Inflorescence loosening.

Additional Information:
- Molybdenum is a microelement, which means it is required in lesser amounts.
- Plant microelements include iron, copper, zinc, boron, manganese, molybdenum, chlorine, and nickel.
- Several disorders are seen due to the deficiency of micronutrients, some of them are as follows:

Iron deficiency results in chlorosis of young leaves and a reduction in growth.
Copper deficiency leads to dieback disease of citrus, reclamation disease, apical necrosis, blackening of stem tubers in potatoes.
Deficiency of zinc leads to interveinal chlorosis, little leaf disorder, stunted growth, khaira disease in rice, and whip tip of maize.
Boron deficiency causes the brown heart of turnip, heart rot of sugar beet, dying of shoot and root tips, stunted growth, miniature-sized fruits, lower nodule formation in leguminous plants, browning of cauliflower.
Due to chlorine deficiency leaves appear bronze in color, root tips get swollen, necrosis and chlorosis are also observed, reduction in fruiting.
The deficiency of nickel causes necrosis of leaf tips.

So, The correct answer is, “Deficiency of molybdenum causes whiptail disease in cauliflower is a true statement.”

Note: Deficiency of zinc causes whip tip of maize and deficiency of molybdenum causes whip tail of cauliflower, this should be remembered. Chlorosis and necrosis are common features for the deficiency of most of the microelements.