Sheath blotch (SBL) of rice
1987
Ahuja, S.C. | Bhan, U. (Rice Research Station, Kaul, Haryana (India))
The host range of Pyrenochaeta oryzae, the cause of SBL [sheath blotch], and the effect of infection on germination, seedling vigor, and yield parameters on potted plants and inoculated grains of four crops were studied. Plants of Zea mays, Oryzae barthii, Echinochloa crus-galli, and Sorghum vulgare were inoculated by inserting a hypha piece between the sheath and culm. P. oryzae could infect Z. mays and O. barthii, causing brown-olivaceous spots 4 d after inoculation. Pycnidia formed after 17 only on O. barthii. Rice varieties HKR101, Palman 579, RP2151-33-4, RP2151-76-1, RP2151-27-1, RP2151-40-1, IET7662, 7688, and HAU47-6045-1 were inoculated at booting by injecting mycelial suspension prepared from oat grain culture. Grains and enclosing sheaths of all varieties showed lesions. Initially, glumes assumed a blood red color, which turned into the color of clotted blood. Rice varieties could not be graded on panicle infection. Germination and seedling vigor of discolored and healthy grains of four selected varieties were tested in petri plates at 30 plus or minus 1 degree Celsius. Varieties differed in reduction of percent germination and root and shoot length. Reduction was maximum in RP2151-76-1 and minimum in RP2151-27-1. Although germination in discolored seeds of Palman 579 was not affected, root length reduction was noticed. Affected and healthy panicles from six plots of Jaya and Pusa 2-21 were collected to study the effect of SBL on yield parameters. Number of filled grains was reduced and number of unfilled and discolored grains was higher in affected panicles. Infection was more pronounced on Pusa 2-21 than on Jaya.
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