Performance of upland rice cultivars under two nitrogen levels in relation to leaf blast.
1996
PRABHU, A. S. | SOUZA, N. S. | FILIPPI, M. C. | BARROS, L. G. | AZEVEDO, D. P. M. | ANNE SITARAMA PRABHU, CNPAF; NAPOLEAO S. SOUZA, EMPAER-MT; MARTA CRISTINA CORSI DE FILIPPI, CNPAF; LUIZ G. BARROS, EMPAER-MT; DIOGENES P. M. AZEVEDO.
The performance of improved rice cultivars, in relation to the development of leaf blast, was compared under low and high nitrogen levels in a field experiment conducted in Goiania (GO), Jaciara (MT) and Vilhena (RO), during three successive years (1986-1989). The treatments consisted of two nitrogen levels (10 and 60 kg!ha of nitrogen) and six upland rice cultivars (Centro América, Cuiabana, Guarani, IAC 47, IAC 165, Rio Paranaíba). The criteria utilized for measuring slow leaf blasting included area under disease progress curve, the rate of disease increase until it attains maximum and the maximum leaf blast severity during the course of the epidemic. Nitrogen application at the rate of 60 kg/ha resulted in overall increase of leafblast. The improved early maturing cultivars Centro America and Guarani, and medium maturing cultivars Cuiabana and Rio Paranaiba, were superior to IAC 165 and IAC 47, respectively, in relation to the rate of leaf blast increase both at low and high nitrogen levels. The effectiveness of leaf blast resistance was greater at Goiania, where they were developed, than in Jaciara and Vilhena.
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