RESPONSE OF EXPERIMENTAL AND COMMERCIAL SORGHUM LINES TO THE A2 GENE-CYTOPLASMIC ANDROSTERILITY

Abstract

New cytoplasmic-genetic male sterility systems have been developed in sorghum (Sorghum bicolor L. Moench) that can increase the variability and reduce the genetic vulnerability of this crop. The purpose of this study was to determine the response of a group of experimental and commercial sorghum lines, origi nated from Río Bravo and "Bajío" (México) and Texas (USA). to an A₂ source ofcytoplasmi~genetic male sterility as the initial step in the introduction of this system into Mexican lines and hybrids. This study was conducted at the Río Bravo Experimental Station during 1982-83-84 using as sterility source the line A₂ Tx2753 derived from IS 12662C(SC-171) of the group Caudatum nigriccans (Guinea race) from Ethiopia. Genotypes response was compared with available data from the same lines on A₁ system.

Results indicate that it is possible to develope hybrids with both systems of cytoplasmic-genetic male sterility (A ₁, A ₂) since their parents showed similar response in both systems. Besides, since there were some lines type R in A ₁, that showed a B response in A₂ it is possible to increase the diversity in hybrid fomation through combinations wich were not be possible when a single system was available.