(i) Manganese (ii) Copper (iii) Zinc
1. Manganese (Mn) :
i. As a Cofactor : Mangenese primarily functions as activator of several enzymes involved in photosynthesis.
ii. It helps in the splitting of water and liberation of oxygen
iii. Synthesis of chlorophyll : It is also involved in the synthesis of chlorophyll.
Deficiency of manganese causes chlorosis, nacrosis in the interveinal areas of leaves, the veins remain green, the chloroplasts are devoid of chlorophyll and starch grains become yellow green in colour, vacuolated and finally disintegrate.
2. Copper :
Copper is a component of many enzymes involved in redox reactions. It plays a as a key role in the electron transport chain in photosynthesis.
i. Deficiency of copper causes necrosis.
ii. Under severe conditions the whole plant may appear wilted and the leaves may be lost.
3. Zinc :
Zinc plays an important role in the activation of many enzymes especially carboxylases
It is involved in the synthesis of auxin. s
Deficiency of zinc causes
(i) shortening of internodes with the result plant become stunted;
(ii) reduction in the size of leaves so that the leaves become very small.
(iii) chlorosis of older leaves starting at tip and extending to the margins.