Characteristics associated with out crossing in a short duration improved rice (Oryza sativa L.) variety AT307

Rice is considered as self-pollinated crop but out-crossing is possible. At307 is a high yielding, 90d variety developed at the Rice Research Station, Ambalantota, Sri Lanka possessing good attributes to be recommended as a commercial variety in Sri Lanka. It contains both Indica and Japonica germplasms. At307 has failed to pass the seed certification several times due to lack of its genetic purity perhaps due to out -crossing nature, or mechanical mixing. Therefore the present study was conducted to investigate the characteristics associated with out -crossing of At307. Comparison was done with Bg300, Bg304, At303 and At306 improved 90d rice varieties at Ambalantota rice research station during the Yala season, 2010. Out crossing mainly depends on flowering behavior, floral characteristics of male and female parts and variation in environmental factors. Varietal differences were found to be significant at 5% probability level for spikelet open angle. But spikelet open duration, numbers of spikelet per panicle (NS/P), stigma exsertion percentage, flowering period of plant, culm length), panicle length. Flowering period of panicle, angle of flag leaf, length of flag leaf and width of flag leaf were not significantly different among five selected rice varieties. Out-crossing associated characters of At307 were normal except spikelet opening angle. Increased exposes the stigma more to alien pollens resulting emerges off-types in future generation of At307.