Dear Niloy Kumar Das

Pls. find the attached files

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-31222002000200008

http://www.agriinfo.in/?page=topic&superid=3&topicid=81

http://aob.oxfordjournals.org/content/80/4/479.full.pdf

http://scialert.net/fulltext/?doi=biotech.2007.61.63

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3923009/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2997405/

https://libraries.uark.edu/aas/issues/1995v49/v49a3.pdf

http://connection.ebscohost.com/c/articles/25974998/effect-culture-media-seed-dormancy-callus-induction-ability-some-wild-cultivated-rice-genotypes

http://www.nzdl.org/gsdlmod?e=d-00000-00---off-0fnl2.2--00-0----0-10-0---0---0direct-10---4-------0-1l--11-en-50---20-about---00-0-1-00-0--4----0-0-11-10-0utfZz-8-00&a=d&cl=CL1.3&d=HASHd3b46cd4916b56b3547bcc.1.5

Hoping this will be helpful

Regards

Prof. Houda Kawas

Also

Rice seeds can have dormancy upon harvest, which may be lost by dry storage or a heat treatment. I never heard about going from non-dormant to dormant during dry storage. It may be more likely your seeds have lost viablity. You can check viability using tetrazolium staining. 

If you use the fresh seed also you wont get germination due to dormancy

store the seed at 50 degree Celsius for 1-2 days to break the dormancy

IR 64, PB1 Jaya are good for callus formation

Pre germination treatment is also helpful to get good germination; temperature treatments as suggested above; priming for even germination are effective measures. Also refer the attached paper.

Try to use KNO3  0,2 % for 1 hr. before to plant in substrate or in in vitro culture

There are many methods of breaking dormancy of rice seeds. Among these, soaking seed in warm water on two main processes of the seed which are metabolism processes (respiration rate, ethylene production, and α-amylase activity) and germination rate and other different dormancy breaking treatments such as Seeds soaking in thiourea, KNO3, HCl, HNO3, and H2SO4 (Mechanical scarification and acid scarification) methods are some of the many methods.

Article Methods to Break Seed Dormancy of Rhynchosia capitata, a Sum...

Steven Groot is right try dry after ripening.

The half seed test also works well; if dormant it will be broken and thye will germinate if dead they rot. Also basic treatments like nitrite are easy and fast. see Cohn et al 1983

I suggest the Rules for Seed Testing from ISTA, AOSA or the "Regras para a análise de sementes, Brasil, 2009" (free for download). Use the word "arroz" that is rice, and the chapter 5 has the methods for dormancy breaking (the collumn at right of the page with a number in from the scientific name). Apply a tetrazolium test to verify the presence of secondary dormancy. The TT test does not have this aim, but it helps. Along the storage time, rice seeds acquire the possibility of seed germination. I suggest you to make a revision about storage of rice seeds using the environment of a home refrigerator where you can maintain the samples until the tests. The previous references in the question above match many of the useful papers to you. Best regards. Walter

I do not know exactly for rice, you need a reference of ISTA and AOSA rules. But, from my experience i eliminated dormancy in barley seeds by chilling temperatures.

Put your rice seed in 0,2% KNO3  by 1 or 2 hours shaking

Greatings

Heat treatment is the most effective practical way of breaking seed dormancy in rice. I agree with Steve that you need to check your seeds if they are really dormant or have lost viability by using the tetrazolium test

Please read this paper. Not rice but related.

https://www.researchgate.net/publication/348394860_The_effect_of_different_treatments_on_seed_dormancy_breaking_and_germination_inducing_in_Louisiana_variety_of_Okra_Abelmoschus_esculentus_L