Waterlogging Effects on Survival of Rice and Some Rice Seeds

Abstract

Two experiments of rice seed survival were studied under waterlogging condition to find out the elimination of volunteer or off types plants efficiently in case of changing rice variety for seed production at Pathumthani Rice Research Centre from 2001 to 2003. The first one started with dormant seeds, exposed to waterlogged soil condition at 0 and 5 cm depth below soil surface and water level was maintained at 5- 10 cm above the soil surface with 4 replications. The second experiment began with non dormant seeds (the seeds after releasing dormancy). used in the same condition as above, but were germinated 0, 3, and 10 days before treatments. Six types of red rice seeds and 8 recommended variety of foundation seeds were used in the pot and field experiment. Germination (ability of seed to develop a normal seedling), dormancy after survival including dead seeds were recorded. It was found that red rice seeds were survived at a longer time than recommended variety rice seeds and died only 50 % after 49 days under waterlogging condition. Survived seeds could germinate only 30 % and 10- 17 % was remained dormant. Germination and dormancy percentage of recommended variety rice seeds after survival decreased but dead seed percentage was increased during waterlogging. Rice seeds on the soil surface died 51 and 57 % after 7 and 14 days waterlogging respectively but the seeds at 5 cm depth below soil surface died 44 and 48 % after 7 and 14 day waterlogging respectively. Survived seeds germinated 30- 40 % under favorable condition and 10-20 % remained dormant. Rice seeds died 70-80% after 56-63 days under waterlogging condition; survived seeds were able to germinate 10-20 % under favorable condition and still remained dormant. There was only small different of dormant seeds at 0 and 5 cm depth under waterlogged soil. Moreover, it was found that non dormant seeds with 0 and 3 day old seedlings which were buried 5 cm depth under soil surface died 56 and 86 % after 7 days waterlogging and increased to 93 and 100% death after 14 days waterlogging. Furthermore, 10 day old seedlings which were buried 5 cm depth under soil surface died 99-100 % after 7-14 days waterlogging. For non dormant seed on the soil surface, there was variation of seed death due to germinability of some seeds.