Increase in the yield of cytoplasmic male sterile maize revisited

For decades, little attention has been paid to a potential increase in the yield of maize (Zea mays L,) as a result of cytoplasmic male sterility (CMS); however, interest is growing because CMS seed is relatively inexpensive to produce. The present investigations were carried out with two hybrids, 'Corso' and 'Silex', in Switzerland (in 1994 and 1995) and with an open-pollinated cultivar, Suwan 2, in Thailand (1996), These cultivars were tested with non restored T-cytoplasm or with fertile cytoplasm. They were grown with and without nitrogen fertilization at the recommended or at higher plant density; they were grown in Thailand with and without severe preanthesis drought. CMS increased the grain number per ear of all cultivars; in Corso and Suwan 2 a stable kernel weight resulted in an increase in grain yield as well. Plant density, nitrogen application, and drought did not significantly affect changes in the grain yield as caused by CMS. Choosing hybrids with a positive yield response to CMS is suggested; mixtures with a high percentage of CMS hybrids can then be made with their fertile counterparts.