Reação de cultivares de milho-pipoca a Helmintosporiose
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2002-09
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Revista Ceres
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Avaliou:se a reaÇav de nove populações de milho-pipoca a Exserohilum turricum por meio de infec9ao natural em qualro epocas de semeadura. D delineamento experimental utilizada foi o de blows ao acaso, com Tres repet4oes. Foram realizadas de tries a cinco avaliações em oito plantar por parcels, a partir do florescimento, com intervalo de sete dias. Foi utilizada escala de notas de I a 5, correspondendo as porcentagens de area foliar afetada de 0 e 1U0%, respectivamente. Foi calculada a area abaixo da curva de Progresso da doença e realizada a analise de variancia das notas de severidade da doença. Os cultivares que em todas as semeaduras apresentaram-se nos grupos estatisticos com menor suscetibilidade a helmintosporiose foram SAC 112, CMS 43, CMS 42, Branco, Beija-flor e Rosa Clam, diferindo do cultivar RS 20. No entanto, somente IAC 112 diferiu estatisticamente do cultivar S 20 em todas as épocas de semeadura. Os cultivares CMS 42 e 43 apresentaram-se com menores rea0es a helmintosporiose em relação ao RS 20 somente nas semeaduras realizadas m novembro e dezembro. Os cultivates Beija-flor e Branco apro n se corn menores rearfves a IwJniintospoiiose em relaÇao ao RS 20 somente na semeadura de dmbro Concluiu-se que, quarto a rear* a IIeIInIIItOSpOnOSe, os cultivarec comportaram-se de modo difente, sen+do rye IAC 112; mediaznente ante CMS 43; moderadamente suscetiveis CMS 42, Branco, Beija-flor, Viçosa e Rosa-Claro; e suscetiveis Zélia e RS 2D. A avalia9Ao semanal que melhor discriininou os cultivar+es de milho-pipoca ocorreu aos 21 dias apps o florescimento. A época de semeadura que se mostrou favorável ao desenvolvimento da doenÇa foi outubro.
The objective of this work was to evaluate the reaction of nine popcom populations to Exserjohilum turcicum by natural infection in four sowing dates. The trials were arranged in & randomized complete-block design with three replications. Eight plants were evaluated during three to tive seasons, from the flowering stage, in intervals of seven days. The rating scale used ranged from 1 to 5, where ] indicated no disease and 5 indicated a serious infection. The area under the disease progress curve was calculated and the disease severity variance analysis was performed. IAC 112, CMS 43, CMS 42, Branco, Beija-Hor, and Rosa Claro were the most resistant cultivars in every sowing date, differing from RS 20 cultivar. However, only [AC 112 was statistically different of RS 20 in every sowing dates. CMS 42 and CMS 43 showed a lower reaction to E. turcicum than RS 20 only in November and December. Beija-flor and Branco showed a lower reaction to the disease than RS 20 only in December. It was concluded that cultivars have different behaviors: [AC 112 is resistant; CMS 43 is moderately resistant; CMS 42, Branco, Beija-Hor, Viçosa and Rosa Claro are moderately susceptible', and Zélia and RS 20 are susceptible. The best weekly evaluation for popcorn cultivars occurred 21 days and the flowering stage. The most efficimt sowing dates for disease development was in Octoba.
The objective of this work was to evaluate the reaction of nine popcom populations to Exserjohilum turcicum by natural infection in four sowing dates. The trials were arranged in & randomized complete-block design with three replications. Eight plants were evaluated during three to tive seasons, from the flowering stage, in intervals of seven days. The rating scale used ranged from 1 to 5, where ] indicated no disease and 5 indicated a serious infection. The area under the disease progress curve was calculated and the disease severity variance analysis was performed. IAC 112, CMS 43, CMS 42, Branco, Beija-Hor, and Rosa Claro were the most resistant cultivars in every sowing date, differing from RS 20 cultivar. However, only [AC 112 was statistically different of RS 20 in every sowing dates. CMS 42 and CMS 43 showed a lower reaction to E. turcicum than RS 20 only in November and December. Beija-flor and Branco showed a lower reaction to the disease than RS 20 only in December. It was concluded that cultivars have different behaviors: [AC 112 is resistant; CMS 43 is moderately resistant; CMS 42, Branco, Beija-Hor, Viçosa and Rosa Claro are moderately susceptible', and Zélia and RS 20 are susceptible. The best weekly evaluation for popcorn cultivars occurred 21 days and the flowering stage. The most efficimt sowing dates for disease development was in Octoba.
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Zea mays, Queimadas-folhas, Exserohilum turcicum, Doença foliar, Época de semeadura.