STUDIES ON STABILITY OF CYTOPLASMIC MALE STERILE LINES AND THEIR FLORAL TRAITS INFLUENCING OUTCROSSING IN RICE (ORY.ZA SATIVA L)

Abstract

One of the problems encountered in the hybrid breeding of crop plants is the pollen shedding in male sterile lines under certain environments; hence, studies on cytoplasmic male sterility (CMS) breakdown and relative stability of CMS lines for their sterility was undertaken. Twelve CMS lines were evaluated over two seasons at Delhi. The CMS lines PMS2A. PMS3A and PMS lOA were completely pollen sterile, had zero spikelet fertility and hence highly stable while PMS SA and IR S802SA were stable. Remaining CMS lines were unstable. 'I1\e CMS lines PMS 3A, PMS lOA and IR S802SA had comparatively longer stigma, style and anthers length favourable for outcrossing during seed production of Ax B and A x R combinations. In general, all CMS lines were semi- Idwarfin height,. had medium to high tillering and medium duration except IR 62829A (early). The differential response of CMS lines possessing one kind of, cytosterile source 'wild abortiv~ twA)' observed was due primarily to differences in nuclear background of CMS lines and interactions of cytoplasm with nuclear genes.