Reaction of diverse CMS sources, testers and their hybrids to downy mildew caused by Plasmopara halstedii in sunflower (Helianthus annuus L.)

摘要

Thirty six sunflower hybrids synthesized in the background of three diverse sources of cytoplasmic male sterility (CMS) viz., Helianthus petiolaris (CMS-F), Helianthus petiolaris ssp. fallax (CMS-PF) and Helianthus annuus ssp. lenticularis (CMS-I) along with their respective male (12) and female parents (3) were screened in disease sick plots under field condition to study their reaction to downy mildew caused by Plasmopara halstedii. Among the three sources CMS-F recorded 86 per cent susceptibility, while CMS-PF and CMS-i exhibited complete resistance. The disease reaction among restorers varied from highly resistant (0-incidence) to complete susceptibility (100% incidence). The hybrids of the cytoplasmic background of CMS-F exhibited susceptibility from 30.33 to 100 per cent, while that of the hybrids of CMS-I revealed 0.00 to 60.00 per cent susceptibility. On the contrary, all hybrids in the background of CMS-PF were free of downy mildew. Overall results indicated that the female parents seems to have greater influence in determining the level of resistance of the hybrid to downy mildew.