Cytogenetical Studies on the Hybrids of Echinochloa oryzicola Vasing. and the Thai Tetraploid Strain of E. stagnina (Retz.) Beauv. with the West African Species E. obtusiflora Stapf

Abstract

The West African annual diploid E, obtusiflora (2n=2x=18) is characterized by the morphology of its spikelets and is partially self-incompatible. The result of the author's field observation in Nigeria indicated that this species is a companion weed of African rice Oryza glaberrima. The annual tetraploid E. oryzicola (=E. phyllopogon Stapf subsp. oryzicola (Vasing.) Koss., 2n=4x=36) is a companion weed of common rice Oryza sativa, and also is the carrier of two of the three genomes of the annual hexaploid E. crus-galli (2n=6x=54), the wild form of the Asian cultivated species E. utilis. The self-pollinated, stoloniferous perennial species E. stagnina is distributed in tropical Asia and Africa, and includes some cytoytpes. The F1 hybrids of E. oryzicola and the Thai 4x strain (2n=4x=36) of E. stagnina with E. obtusiflora were artificially produced. The results of the cytogenetical studies on these F1 hybrids indicated that the genome of E. obtusiflora may be related to one of the genomes of the Thai 4x strain and that E. obtusiflora has more or less the cytological characteristics which are requisite for a presumable diploid carrier of the third genome of E. crus-galli. © 1983, Japan Mendel Society, International Society of Cytology. All rights reserved.