Commercial viability of alternative cytoplasmic-nuclear male-sterility systems in pearl millet

Commercial viability of three cytoplasmic-nuclear male sterility (CMS) systems (A(4), A(5) and A(v)) as potential alternatives to the most widely used A(1) system in pearl millet ( Pennisetum glaucum (L.) R.Br.) was evaluated in terms of stability of complete male sterility of four isonuclear A-lines (81A(1), 81A(4), 81A(5) and 81A(v)) and the level and stability of male fertility restoration of their 44 single-cross hybrids. Lines 81A(4) and 81A(5) had no pollen shedders (PS), and there were very low frequency of non-PS plants of these A-lines that had a maximum of 1-5% selfed seedset (SSS). In 81A(1) and 81A(v), there were, albeit low frequency (<1%) of PS plants, and relatively higher frequency of the non-PS plants in these two lines, the more so in 81A(v), had 1-5% and even greater SSS. Some hybrids made on each of the three A-lines (81A(1), 81A(4) and 81A(v)) had high and stable male fertility, while others made on the same three A-lines displayed large variation in SSS across the environments, the more so in case of hybrids made on 81A(v). These results indicate that the A(4) CMS system provides a better alternative to the A(1) CMS system, while the A(v) system does not. On the basis of highly stable male sterility and the highest frequency of pollinators behaving as maintainers, the A(5) CMS system appeared to be the best for A-line breeding. The commercial viability of this CMS system in breeding R-lines of grain hybrids, however, still remains to be ascertained as no hybrid on it was fully male fertile in any environment.