INTERACTIONS BETWEEN Fusarium solani f. sp. phaseoli AND Rhizoctonia solani ON THE SEVERITY OF DRY BEAN ROOT ROT INTERAÇÕES ENTRE Fusarium solani f. sp. phaseoli E Rhizoctonia solani NA SEVERIDADE DA PODRIDÃO RADICULAR DO FEIJOEIRO

Abstract

<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:HyphenationZone>21</w:HyphenationZone> <w:PunctuationKerning /> <w:ValidateAgainstSchemas /> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables /> <w:SnapToGridInCell /> <w:WrapTextWithPunct /> <w:UseAsianBreakRules /> <w:DontGrowAutofit /> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if !mso]><object classid="clsid:38481807-CA0E-42D2-BF39-B33AF135CC4D" id=ieooui></object> <style> st1:*{behavior:url(#ieooui) } </style> <![endif]--> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:595.3pt 841.9pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> <!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabela normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} </style> <![endif]--> <p class="MsoNormal" style="text-align: justify;">The present work aimed to evaluate the effect of inoculum densities of Fusarium solani f. sp. phaseoli (Fsp) and Rhizoctonia solani (Rs) and their interactions on the severity of root rot and on the dry mass of bean plants. Soil was infested by the addition of Rs or Fsp-colonized sorghum seeds, in the amounts of 0.00 g; 0.06 g; 0.12 g; 0.25 g; 0.50 g; and 1.00 g for Rs, and 0 g; 1g; 2 g; 4 g; 8 g; and 16 g for Fsp per pot (1.4 kg of soil). The densities used for the joint soil infestations with both pathogens were the same used in the separate pathogen infestations. A progressive rise in the severity of root rots was observed with the increase of inoculum density for both pathogens. Maximum disease severities for Rs were 67% and 22%, in separate or combined infections with Fsp, respectively. Maximum disease severities with Fusarium were 14% and 38%, in separate or combined infections with Rs, respectively. The results suggest that Rhizoctonia solani stimulated the expression of symptoms of Fusarium solani f. sp. phaseoli, while Fsp inhibited the expression of symptoms caused by Rs. Negative correlations between the inoculum density and bean dry weight were generally observed, except for the single infestation with Fsp.</p> <p class="MsoNormal" style="text-align: justify;"><br /> KEY-WORDS: Soilborne fungus; bean diseases; soil infestation.</p> <span></span><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:HyphenationZone>21</w:HyphenationZone> <w:PunctuationKerning /> <w:ValidateAgainstSchemas /> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables /> <w:SnapToGridInCell /> <w:WrapTextWithPunct /> <w:UseAsianBreakRules /> <w:DontGrowAutofit /> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if !mso]><object classid="clsid:38481807-CA0E-42D2-BF39-B33AF135CC4D" id=ieooui></object> <style> st1:*{behavior:url(#ieooui) } </style> <![endif]--> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:595.3pt 841.9pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> <!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabela normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} </style> <![endif]--> <p class="MsoNormal" style="text-align: justify;">O estudo teve como objetivo avaliar o efeito da densidade de Fusarium solani f. sp. phaseoli (Fsp) e de Rhizoctonia solani (Rs) e de suas interações na severidade de podridão radicular e na massa da matéria seca do feijoeiro. Sementes de sorgo, colonizadas com Rs, foram infestadas nas quantidades de 0,00 g; 0,06 g; 0,12 g; 0,25 g; 0,50 g; e 1,00 g e com Fsp nas quantidades de 0 g; 1g; 2 g; 4 g; 8 g; e 16 g por vaso (1,4 kg de solo). As densidades utilizadas nas infestações conjuntas foram as mesmas das infestações separadas. Observou-se um aumento progressivo na severidade da podridão radicular, com o aumento da densidade de inóculo, para ambos os patógenos. As severidades máximas alcançadas para Rs foram 67% e 22%, em infestação separada e combinada com Fsp, respectivamente. As severidades de podridão radicular máximas alcançadas com Fusarium foram 14% e 38%, em infestação separada e combinada com Rs, respectivamente. Isto sugere que Rhizoctonia solani estimula a expressão dos sintomas de Fsp e que Fsp inibe os sintomas de Rs. Foram observadas correlações negativas entre a densidade de inóculo de Rs, em inoculações isoladas ou combinadas com Fsp, e a massa da matéria seca da parte aérea.</p> <p class="MsoNormal" style="text-align: justify;"><br /> PALAVRAS-CHAVE: Fungo de solo; doenças do feijão; infestação do solo.</p>

Keywords

• Fungo de solo
• doenças do feijão
• infestação do solo.