Seed health studies on parental lines of hybrid rice.
The seeds of CMS lines of rice had high incidences of kernel smut (Tilletia barclayana) compared with maintainers (B lines), restorers (R lines) and conventional varieties. A negative correlation existed between the infection grade of kernel smut and seed germination, seedling length and seedling dry weight. Curvularia lunata [Cochliobolus lunatus], Drechslera tetramera [Cochliobolus spicifer] and Fusarium moniliforme [Gibberella fujikuroi] were predominant in the CMS lines compared with other genotypes. All the predominant fungi caused seed rot/seedling mortality. Seed soaking for 8 h in a suspension of Emisan (0.1%) [2-methoxyethylmercury chloride] alone or in combination with streptocycline (0.01%) proved to give effective control of the seed mycoflora. Bavistin (0.2%) [carbendazim] in combination with thiram (0.2%) also gave good control. None of the fungicides had a fungicidal effect on teliospores of T. barclayana. They only showed fungistatic action while in contact with the spores.