Question

heat is the only essential for the ripening and the development grains in the plants then when do we get more heat

Answer 1

during development we get more heat

Answer 2

Hii Friend,

Here Is Your Answer...
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Oftenly, we get more heat from sun at noon time.
But the question you have asked is extremely wrong because heat is not only essential for the development of a plant but also the plant requires sufficient water and minerals to grow into a  beautiful tree.

HOPE IT HELPS ^_^