Different treatment of rice seed dormancy breaking, germination of both wild species and cultivated varieties (Oryza sativa L.)

The present study was conducted at Genetics Department, Hazara University Garden Campus and during 2008-09 as a part of PhD study. Seed dormancy breaking, germination tests of 2 wild speciesi.e., O. longistaminata and O. rufipogon and 3 local cultivated rice varieties/ germplasm i.e., Swat-1, F. Malakand and JP-5 were conducted under different treatments. Hulled seeds were exposed to: constant temperatures of 28 degree celsius to 38 degree celsius & room temperature (25#1 degree celsius); and alternating temperatures of 40/30 degree celsius to 45/35 degree celsius (12 hours/12 hours) and at a room temperature(25# degree celsius). Third treatment ,intact seeds were exposed to dry heat at 50 degree celsius for 7 and 14 days before germination of hulled and intact seeds under the maximum temperature for each wild species determined from treatments 1 2 species that showed minimum % of germination , various chemical treatment, for germination of intact seeds in 0.001M potassium nitrate, presoaking the seeds for 24 or 48 hours in (0.1 or 0.2 M Nitric acid , I M Hydrogen peroxide , 1000 ppm Gibberellic acid (GA3) and in-combination of 0.1 M HNO, and 1 M H , 0.2 MHNO2O2 , 0.2 M HNO3 and 1 M3H2O2 were conducted . It was observed that: removal of the seed hull is extremely effective for breaking seed dormancy while species respond differently to various constant / alternating temperatures and heat generally promotes germination of the species that respond to certain constant and alternating temperature but no consistent differences observed in seed germination of most species between heat treatments at 50 degree celsius for 7 or 14 days. O rufipogon and Swat-1 both respond to certain chemical treatments effectively under the optimum temperature regimes. An appropriate combination of seed hull removal, dry heat or chemical treatments, and germination under the optimum temperature regimes individual species provides the best results for braking seed dormancy of rice species.