Influence of Flowering Event Factors in Cytoplasmic Male Sterile Lines and F₁ Hybrids on Infection by Claviceps fusiformis in Pearl Millet. R. P. Thakur, Cereals Program, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh 502 324, India. V. P. Rao, and S. B. King. Cereals Program, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Andhra Pradesh 502 324, India. Plant Dis. 75:1217-1222. Accepted for publication 8 May 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-1217.

The influence of flowering event factors, such as length of protogyny period, and time between full protogyny (FP) and anthesis initiation (AI) on infection by Claviceps fusiformis was studied in seven cytoplasmic male sterile (CMS) lines (A lines), their corresponding maintainer lines (B lines), nine pollinator lines (R lines), and their 64 F₁ hybrids (A × R and B × R) of pearl millet (Pennisetum glaucum). Three of the seven A lines had significantly longer protogyny than their corresponding B lines. The protogyny periods in R lines (range 38–84 hr) were shorter than in B lines (range 45–135 hr). Significant positive correlations were found between protogyny, the FP-AI period, and ergot severity in susceptible A or B lines and their F₁ hybrids, regardless of the susceptibility or resistance of R lines, but not in resistant A, B, and R lines and their hybrids. Seed set was generally more in B × R hybrids than in A × R hybrids, indicating poor restoration ability of R lines. Stigmas were longer in susceptible lines and their hybrids than in resistant lines and hybrids. The susceptibility of F₁ hybrids was closely associated with flowering event factors of susceptible A lines. No such relationship was found in resistant lines. This indicates that there may be a factor or factors independent of flowering events governing resistance in A lines and their hybrids.