Dormancy of seed is broken by

Name the plant growth regulator which,upon spraying on sugarcane crop,increases the length of stem,thus increasing the yield of sugarcane crop.

Describe the discovery of gibberellins.

Give scientific reasons: Gibberellic acid induces reversal of dwarfism in many genetically dwarf plants.

The activity of $\alpha$-amylase in the endosperm of barley germinating seed is induced by

$A$ : Seeds do not sprout when $ABA$ is overcome by Gibberellins. $R$ : $GA$ inhibits protein and $RNA$ synthesis.