Which of the following is responsible for seed dormancy?

Treatment of seed at low temperature under moist conditions to break its dormancy is called

Which of the following is not a man-made method to overcome seed dormancy?
$(I)$ Seed coat broken by using knives,sandpapers,etc.
$(II)$ Passage of seed through the digestive tract of animals.
$(III)$ Effect of inhibitory substances can be removed by subjecting the seeds to chilling conditions.
$(IV)$ By application of certain chemicals like gibberellic acid and nitrates.

The process of removing seed dormancy by mechanically removing or weakening the seed coat is called:

Positively photoblastic seeds germinate only in the presence of

Treatment of seeds at low temperature under moist conditions to break its dormancy is called