Little leaf and ‘rosette’ of apple, ‘white bud’ of maize are the deficiency symptoms of

✅ Explanation: Zinc deficiency is indeed associated with the specific symptoms mentioned in the question:
-Little leaf: Zinc is crucial for the production of auxin, a plant hormone that promotes growth. Its deficiency leads to stunted growth and the development of small, underdeveloped leaves, often referred to as "little leaf."
-Rosette of apple: In apples, zinc deficiency can cause a condition called "rosette," where the leaves become clustered and small, forming a rosette-like pattern.
-White bud of maize: In maize, zinc deficiency can result in the "white bud" symptom, where the young leaves emerging from the whorl are pale or white due to impaired chlorophyll synthesis.

🔑Key Points :
-White Bud disease in plants is caused by deficiency of Zinc.
-Zinc is an essential micronutrient for plants.
-It is required for the activity of carbonic anhydrase, auxin biosynthesis and activator of certain carboxylases and dehydrogenases.
-Its deficiency leads to little leaf disease, leaf rosette formation, short internodes, interveinal chlorosis appearing first marginally on older leaves, followed by necrosis, white bud, and stunted growth. 
-Zinc activates enzymes that are responsible for the synthesis of certain proteins.
-It is used in the formation of chlorophyll and some carbohydrates, conversion of starches to sugars and its presence in plant tissue helps the plant to withstand cold temperatures. 
🛑Additional Information:​

✏️Symptoms of zinc deficiency in plants:
-Chlorosis – yellowing of leaves, often interveinal, in some species, young leaves are the most affected, but in others both old and new leaves are chlorotic.
-Necrotic spots – death of leaf tissue on areas of chlorosis
-Bronzing of leaves – chlorotic areas may turn bronze coloured