Cytogenetical studies on African rice, Oryza glaberrima Steud. 3. Primary trisomics produced by pollinating autotriploid with diploid

Abstract

In order to promote cytogenetical studies on Oryza glaberrima (2n=2x=24), I produced primary trisomics in the progeny of the autotriploid. When the autotriploid was pollinated with the diploid, 136F1 seeds (5.8% of the number of spikelets pollinated) were obtained. The numbers of chromosomes of 31 surviving progeny varied from 24 to 28, with plants having 2n=25 occurring at the highest frequency (34.4%). The primary trisomics differed from one another as well as from the normal disomics in many aspects. The differences were attributed to a single extra chromosome in each trisomic type. Nine primary trisomics were classified into 8 types on the basis of morphological and reproductive features. Seeds were obtained from all primary trisomics except for Type D by self pollination, open pollination or pollination with the disomics. I was able to maintain 7 types of primary trisomics by seed propagation. The primary trisomics which are capable of expressing subtle genetic dissimilarities should be useful for studying the relationship between the two cultivated species of rice at the level of individual chromosomes.