Interference and genetic characterization of red rice (Oryza sativa L.) and rice (O. sativa)

Field and greenhouse experiments were conducted to evaluate the growth responses of cultivated rice and red rice when grown with different densities and laboratory experiment to determine the genetic relationships among red rice and rice. When compared to Kaybonnet rice planted alone, LA3, the tallest red rice, reduced rice tiller density 51%, panicle density 50%, and grain yields 81%. KatyRR, the shortest red rice, had the least effect and reduced rice tillers 30%, panicle density 23%, and grain yields 21%. Yields of Kaybonnet were reduced 60 and 70% at red rice densities of 25 and 51 plants/m 2.;PI 312777 produced 33% higher tiller and 34% higher panicle densities and yielded 33% higher than Kaybonnet, and Guichow was intermediate in tiller and panicle density when in competition with Sgtstraw red rice. When compared to red rice planted alone, PI 312777 reduced red rice tiller density 74%, shoot biomass 72%, panicle density 76%, and seed yields 75%. Guichow, reduced red rice tiller and panicle densities 66%, above ground biomass 72%, and seed yields 68%. Kaybonnet, the tallest, rice reduced red rice tillers only 76%, above ground biomass 58%, panicle density 58%, and seed yields 58%. Seed yield of Sgtstraw grown alone was reduced 72% in 1997 and 36% in 1998 when grown with 50 kg/ha and 90% in 1997 and 64% in 1998 when grown with 150 kg/ha of cultivated rice.;In the greenhouse replacement experiment, relative yield based on shoot biomass of Kaybonnet was lower than that of KatyRR or LA3 while PI 312777 was comparable with KatyRR and LA3. This indicate that Kaybonnet was less competitive than PI 312777 against KatyRR and LA3 red rice ecotypes.;Multidimensional scaling (MIDS) showed that the 26 red rice and rice populations could be separated into six distinct groups. Group I was Bengal, Group 2 was Acc-8, Group 3 were KatyRR and 1996-1, Group 4 were the six strawhull, awnless accessions, Group 5 were Kaybonnet and Katy rice, and Group 6 were four strawhull and 10 blackhull accessions. The 23 red rice and three rice populations were genetically clustered according to morphological traits.