Host plant resistance for rice blast management in the Tropics

Bonman J.M., . (1990) Host plant resistance for rice blast management in the Tropics. [Proceedings Paper]

Blast disease caused by the fungus Pyricularia oryzae Cav. is found throughout the tropics and is a problem to various degrees in the irrigated rainfed deepwater and upland rice environments. The disease has a variety of symptoms of which leaf blast infection of the leaf blade and neck blast infection of the panicle neck node and panicle branches are the most common. Except in a few rice-growing areas neck blast is the more destructive symptom. Cultivars resistant to neck blast even if susceptible to leaf blast may be acceptable in environments with low blast potential. Resistance to leaf and neck blast is correlated and indirect selection for neck blast resistance thus can be made during vegetative growth. Climate soil hydrology and the farmer's agronomic practices greatly influence the frequency and destructiveness of blast. Although it is generally true that upland environments have higher potential for blast than tropical areas where flooded rice is grown many exceptions exist. In less blast-conducive environments host plant resistance has been the most successful and widely used management tactic. Tropical irrigated areas for instance are the least subject to blast and cultivars with partial resistance have shown great durability. These cultivars exhibit typical blast symptoms when inoculated with a matching pathogen race but lesion number and size are reduced. There are few cultivars that have shown durable resistance in upland environments with high blast potential. Many of these cultivars have both a high level of partial resistance and resistance to many races of P. oryzae. In the most blast-conducive environments resistance alone may be insufficient to manage the disease and other means of blast management might be required. This paper reviews the use of host resistance for blast disease management in tropical rice. Three main themes are discussed: 1 the relative importance of resistance to neck blast versus resistance to leaf blast 2 the crucial influence of the environment on how resistant germplasm can be used and 3 durable resistance and its association with partial resistance

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Abstract

Blast disease caused by the fungus Pyricularia oryzae Cav. is found throughout the tropics and is a problem to various degrees in the irrigated rainfed deepwater and upland rice environments. The disease has a variety of symptoms of which leaf blast infection of the leaf blade and neck blast infection of the panicle neck node and panicle branches are the most common. Except in a few rice-growing areas neck blast is the more destructive symptom. Cultivars resistant to neck blast even if susceptible to leaf blast may be acceptable in environments with low blast potential. Resistance to leaf and neck blast is correlated and indirect selection for neck blast resistance thus can be made during vegetative growth. Climate soil hydrology and the farmer's agronomic practices greatly influence the frequency and destructiveness of blast. Although it is generally true that upland environments have higher potential for blast than tropical areas where flooded rice is grown many exceptions exist. In less blast-conducive environments host plant resistance has been the most successful and widely used management tactic. Tropical irrigated areas for instance are the least subject to blast and cultivars with partial resistance have shown great durability. These cultivars exhibit typical blast symptoms when inoculated with a matching pathogen race but lesion number and size are reduced. There are few cultivars that have shown durable resistance in upland environments with high blast potential. Many of these cultivars have both a high level of partial resistance and resistance to many races of P. oryzae. In the most blast-conducive environments resistance alone may be insufficient to manage the disease and other means of blast management might be required. This paper reviews the use of host resistance for blast disease management in tropical rice. Three main themes are discussed: 1 the relative importance of resistance to neck blast versus resistance to leaf blast 2 the crucial influence of the environment on how resistant germplasm can be used and 3 durable resistance and its association with partial resistance

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Item Type:	Proceedings Paper
Additional Information:	3 ill.; 19 refs. Summary En
AGROVOC Term:	ORYZA
AGROVOC Term:	RESISTENCIA A LA ENFERMEDAD
AGROVOC Term:	CONTROL DE ENFERMEDADES
AGROVOC Term:	ZONA TROPICAL/ TIZON
AGROVOC Term:	PYRICULARIA ORYZAE
AGROVOC Term:	SELECCION
AGROVOC Term:	FACTORES AMBIENTALES
AGROVOC Term:	VARIEDADES
Geographical Term:	MALAYSIA
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:26
URI:	http://webagris.upm.edu.my/id/eprint/14874

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