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Effect of irradiation on resistance of maize to corn smut

By: Zedgenidze, I | Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT) | Tbilisi (Georgia) 14-17 Jun 2004.
Contributor(s): Bedoshvili, D [ed.] | Gvaramadze, K [coaut.] | Shengelia, J [coaut.].
Material type: materialTypeLabelBookAnalytics: Show analyticsPublisher: Tbilisi (Georgia) CIMMYT : 2004Description: p. 379-380.Subject(s): Cultivation | Infestation | Maize | Nutritive value | Pathogenesis | Plant diseases | Quality | Smuts | Ustilago zeae | Varieties | CIMMYTDDC classification: 633.1147 Summary: One of the most harmful diseases of maize is corn smut caused by fungus Ustilago zeae unger. This pathogen is more or less spread in all places, where maize is cultivated. This pathogen causes, on average, 8-10% loss of harvest annually. Any part of the plant can be infected by this pathogen but the ear is the most frequent focus of the smut infection. The loss extent depends on the part of a plant inoculated by the parasite and the stage of vegetation at which the infection occurs. If smut affects the tassel the grain loss makes 5%, if smut attacks the basal part of root the loss reaches 15- 17%, damaged stem results in 20% grain loss and in the case of a diseased ear grain loss exceeds 94% (Mesheryakov 1957, Kalnishkov 1962, Nemlienko 1957). Corn smut along with the yield reduction considerably decreases grain quality and the nutrition value of green mass. Sugar content in a grain and green mass decreases by 5% and more. Chlamydospores of the parasite produce strong toxins. We have studied the influence of pre-sowing gamma radiation on the disease prevention in some of maize varieties (Ajametis Tetri, Kartuli Krugi, Imeruli Hybrid and K viteli Kazhovana). Low doses (500 and 1000 rad) proved to increase at some extent plant resistance towards this pathogen compared to the non-irradiated plants, while larger doses (1500 and 2000 rad) increase disease susceptibility. Namely, only 12,2% of the new plants produced from the untreated seeds of Ajameti Tetri and 15,3% of the ears were diseased. At stimulation doses the diseased plants and ears made 8.1% and 13.5%, respectively, at the larger doses of 1500 rad the share of infected plants and ears was 13.4% and 20%, and at 2000 rad 32.2% and 32.6%, respectively. The above described pattern was demonstrated by all the experimental varieties. The similar experiments have been carried out on the same varieties in subtropical zone of West Georgia. It has been ascertained that increased radiation doses cause the intensification of a plant and an ear infections. In this environment at 2000 rad plants were diseased by 35-71% and ears by 35-63%. In addition, expression of the disease symptoms was accelerated in this zone. The propagation of the parasite upon disease manifestation was also accelerated. Intensive formation of the small grouping blisters as well as of the large separate ones was registered. In the humid environment of West Georgia the parasites attack the basal part of root, stems and, more frequently, leaf axils where plants break and perish soon. Thus, we can conclude that the large doses of radiation considerably intensify disease development both in maize plants and in ears.Collection: CIMMYT Publications Collection
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Conference proceedings CIMMYT Knowledge Center: John Woolston Library

Lic. Jose Juan Caballero Flores

 

CIMMYT Publications Collection 633.1147 BED (Browse shelf) 1 Available 5Q630072
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Abstract only

One of the most harmful diseases of maize is corn smut caused by fungus Ustilago zeae unger. This pathogen is more or less spread in all places, where maize is cultivated. This pathogen causes, on average, 8-10% loss of harvest annually. Any part of the plant can be infected by this pathogen but the ear is the most frequent focus of the smut infection. The loss extent depends on the part of a plant inoculated by the parasite and the stage of vegetation at which the infection occurs. If smut affects the tassel the grain loss makes 5%, if smut attacks the basal part of root the loss reaches 15- 17%, damaged stem results in 20% grain loss and in the case of a diseased ear grain loss exceeds 94% (Mesheryakov 1957, Kalnishkov 1962, Nemlienko 1957). Corn smut along with the yield reduction considerably decreases grain quality and the nutrition value of green mass. Sugar content in a grain and green mass decreases by 5% and more. Chlamydospores of the parasite produce strong toxins. We have studied the influence of pre-sowing gamma radiation on the disease prevention in some of maize varieties (Ajametis Tetri, Kartuli Krugi, Imeruli Hybrid and K viteli Kazhovana). Low doses (500 and 1000 rad) proved to increase at some extent plant resistance towards this pathogen compared to the non-irradiated plants, while larger doses (1500 and 2000 rad) increase disease susceptibility. Namely, only 12,2% of the new plants produced from the untreated seeds of Ajameti Tetri and 15,3% of the ears were diseased. At stimulation doses the diseased plants and ears made 8.1% and 13.5%, respectively, at the larger doses of 1500 rad the share of infected plants and ears was 13.4% and 20%, and at 2000 rad 32.2% and 32.6%, respectively. The above described pattern was demonstrated by all the experimental varieties. The similar experiments have been carried out on the same varieties in subtropical zone of West Georgia. It has been ascertained that increased radiation doses cause the intensification of a plant and an ear infections. In this environment at 2000 rad plants were diseased by 35-71% and ears by 35-63%. In addition, expression of the disease symptoms was accelerated in this zone. The propagation of the parasite upon disease manifestation was also accelerated. Intensive formation of the small grouping blisters as well as of the large separate ones was registered. In the humid environment of West Georgia the parasites attack the basal part of root, stems and, more frequently, leaf axils where plants break and perish soon. Thus, we can conclude that the large doses of radiation considerably intensify disease development both in maize plants and in ears.

English

0409|AGRIS 0401|AL-Maize Program

Juan Carlos Mendieta

CIMMYT Publications Collection

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