When the dormancy is due to embryo factor i.e. the seed is incubating at low temp. (0- 5o C) over a substratum for 3 to 10 days placing it at optimum temp. Required for germination. E.g. mustard. – (Brassica campestrits)
Some seeds required a brief period of incubation (from a few hours to one to five days) at 40 to 50 oC before germinating at required temp. ( in this method care should be taken that moisture content of the seed is not more than 15% e.g. paddy (Oryza Sativa)
Hot water treatment is also an effective method of breaking hard- seed ness in legumes. In this method the seeds are soaked in water at 80oC temp. For 1 – 5 minutes (depending up on the type of seed) before putting for germination.