Yielding Ability and Phenotypic Traits in the Selfed Progeny of Protoplast-derived Rice Plants

Abstract

The first progeny plants (Pt2 generation) of original protoplast-derived plants of three Japanese rice cultivars, Nipponbare, Fujisaka 5 and Iwaimochi were respectively cultivated in submerged paddy fields on an ordinary scale. They were planted using an automatic planting machine and cultlvated according to the standard paddy field culture method applied in Ishikawa Prefecture. In the protoplast-derived plants of Fujisaka 5, about 25% of semi-1ethal segregants were observed among the flrst progenies of these plants (Pt2 plants). The agronomlc traits in Pt2 plants of Fujisaka 5 were recorded in viable and phenotypi-cally normal Pt2 plants. The common characteristics of the Pt2 plants were as follows, com-pared with the control: slight inc.rease of the number panicles, slight decrease of the number of spikelets per panlcle and similar grain yield. Progenies of the protoplast-derived plants of Nipponbare and Iwaimochi were phenotypically very uniform and stable, respectively. Culm length in the Pt2 plants of Nipponbare was uniform and slightly shorter than that of the control, whereas in the Pt2 plants of Iwaimochi, the culm was uniformly slightly longer. The viable Pt2 plants of Fujisaka 5 exhibited a considerably shorter culm, as compared with the control. The short culm of the Pt2 plants of Fujisaka 5 seems to be a heritable trait. The causes of the uniformity observed in the Pt2 plants of the three cultivars were dlscussed. The present results suggest that the progeny plants of the protoplast-derived rlce plants, except fcr Fujisaka 5, display a similar yielding ability and phenotypic uniformity to those of the control plants.