Positively photoblastic seeds germinate only in the presence of

Seed dormancy is caused by the presence of . . . . . . .

Which hormone is responsible for breaking seed dormancy?

Which of the following factors are responsible for seed dormancy?
$I -$ Hard and tough seed coat
$II -$ Presence of Abscisic Acid $(ABA)$
$III -$ Chemicals like Gibberellic Acid and Nitrates
$IV -$ Phenolic acids and Para-ascorbic acid
$V -$ Immature embryo

Which chemical is sprayed to break the dormancy of buds?

For a seed to germinate,the most important thing needed is