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Title: THE INFLUENCE OF SILICON ON COMPONENTS OF RESISTANCE TO BLAST IN SUSCEPTI- BLE, PARTIALLY RESISTANT, AND RESISTANT CULTIVARS IN RICE

Author
item SEEBOLD, K - UNIV. OF FLORIDA
item KUCHAREK, T - UNIV. OF FLORIDA
item DATNOFF, L - UNIV. OF FLORIDA EREC
item CORREA-VICTORIA, F - CIAT
item MARCHETTI, MARCO

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: The use of silicon, usually in the form of calcium silicate, is gaining recognition as an effective soil amendment to increase yields of several agricultural crops, rice among them. It has been known for years that the addition of silicate to silicon-deficient soils improved the general appearance of crops and increased yields in rice, and that diseases such as srice blast caused by the fungus Magnaporthe grisea were less severe in silicate-amended soils. This paper elucidates the effects of silicon on various components of disease development, such as lesion expansion, infection efficiency and spore production and also on the relative effectiveness of silicon in blast development in rice cultivars with inherently different levels of resistance to blast.

Technical Abstract: The application of silicon fertilizers reduces the severity of blast, caused by Magnaporthe grisea, in irrigated and upland rice; however, little research has been conducted to examine the epidemiological and etiological components of this reduction. Four cultivars of rice with differential susceptibilities to race IB-49 of M. grisea were fertilized with three rates of a calcium silicate fertilizer and then inoculated with the pathogen to test the effects of Si on the following components of resistance to blast: incubation period, latent period, infection efficiency, lesion size, rate of lesion expansion, sporulation per lesion, and diseased leaf area. For each cultivar, the incubation period was lengthened by increased rates of Si, and the numbers of sporulating lesions, lesion size, rate of lesion expansion, diseased leaf area, and number of spores per lesion were reduced. Lesion size and sporulation per lesion were lowered by 30-45 percent and the number of sporulating lesions per leaf, and diseased leaf area were reduced by greater than 90 percent at the highest rate of Si. The net effect of Si on these components of resistance is an overall reduction in the production of conidia on plants infected with M. grisea, thereby slowing the epidemic rate of blast.