Alelopatia Entre Leguminosas Arbóreas E Feijão-Caupi

Abstract

RESUMOO conhecimento das interações entre as leguminosas arbóreas e as culturas anuais é de grande importância para o manejo dos sistemas agroflorestais. Este trabalho avaliou o efeito de extratos aquosos de folhas e raízes de leucena e de guandu sobre sementes de feijão-caupi, bem como a possibilidade das substâncias húmicas reverterem o efeito inibitório desses extratos. Destarte foram conduzidos dois experimentos, no primeiro os tratamentos constaram de extratos de folhas e raízes de guandu e leucena nas dosagens de 0; 2; 4; 6; 8 e 10%; e no segundo constaram de extratos de raízes de guandu e leucena na dosagem de 5%, na presença de substâncias húmicas extraídas do solo nas dosagens de 10, 20, 30 e 40%. Os extratos aquosos de folhas e raízes das duas leguminosas provocaram reduções na germinação de feijão caupi, sendo esta, mais drástica quando se aplicou extratos de raízes. Observou-se um efeito quadrático das doses de extratos aquosos de folhas e de raízes de leucena sobre a redução da germinação de sementes de feijão caupi. A aplicação de extratos de solo contendo substâncias húmicas nas dosagens de 20 e 30% reverteu o efeito inibidor sobre a germinação do feijão-caupi provocado pelo extrato de raiz de guandu, mas não reverteu a inibição da germinação causada pelo extrato aquoso de raiz de leucena a 5%.Palavras-chave: leucena; guandu; extratos aquosos. ABSTRACTThe knowledge of the interactions between leguminous tree and crops is of great importance to manage agroforests systems. This work evaluates the effect of leaves and roots aqueous extract of leucaena (Leucaena leucocephala) and pigeon pea(Cajanus cajan) in of cowpea seeds germination and the possibility of the humic substances revert these inhibitory effects. In this sense were carried two experiments, in the first the treatments appear the aqueous extract of leaves and roots of leucaena and pigeon pea at 0, 2, 4, 6, 8 and 10% (v/v); in the second appear the root aqueous extract of guandu e leucaena in 5%(v/v) dosage, with humic substances at 0, 10, 20, 30 and 40% (v/v) concentrations. The aqueous extracts of leguminous leaves and roots caused reductions in the cowpea germination, being this, more dramatic when root extracts were applied. There was a quadratic effect of doses of leucena leaves and root aqueous extracts on the cowpea seeds germination The application of soil extracts containing humic substances in dosages of 20 and 30% reversed the inhibitory effect on the germination of cowpea caused by the pigeon pea root extracts, but not reversed the allelopathic effects caused by the leucaena roots aqueous extract (5% v/v).

Allelopathic potential of aqueous extracts of leaves and branches of mint under the initial development of cowpea beans

“…It was observed that the aqueous extract from branches of mint, according to different concentrations, stimulated the emergence of seedlings and shoot dry matter in relation to the control treatment (0%), evidencing a positive effect. The results corroborate those of Brito and Santos (2012), who studied the allelopathic effects of tree species from the Caatinga on germination and seed vigor of cowpea and verified that the extracts of quince and Jurema did not interfere with emergence of seedlings; on the other hand, Santos et al (2010) observed a negative allelopathic effect on germination of cowpea seeds in function of the application of aqueous extract of pigeon pea. Ribeiro et al (2009), evaluating the allelopathic effects of aqueous extracts of Crinum americanum L on vegetable species, verified that the action of different extracts of Crinum americanum interfered significantly with the development of shoots and roots of lettuce, radish and sesame seedlings.…”

“…The concentration of 40% of aqueous extract of mint was beneficial for root growth; as for the other variables, there was no significant difference between the treatments, as shown in Table 2. Santos et al (2010), evaluating the allelopathic effect of leguminous trees on the germination of seeds of cowpea, observed that there was a reduction in germination of cowpea seeds in function of the application of aqueous extract of leaves of pigeon pea. Bach et al (2010), evaluating the allelopathic effect of the aqueous extract of boldus and picão preto on the germination and development of seedlings of lettuce, concluded that the concentrations of 20, 30 and 40% exerted more severe effects on shorter shoot length of seedlings of lettuce (Lactuca sativa).…”

EFECTO ALELOPÁTICO DE ESCOBA DE BRUJA (Moniliophthora perniciosa Stahel.) INOCULADAS EN SIETE ESPECIES DE MALEZAS

“…El promedio de las tres fechas de evaluación, los testigos T1 (4.02) y T2 (4.24) presentaron resultados cercanos a los demás datos obtenidos, esta respuesta probablemente se debe a que en los tratamientos (T3, T4 y T5) se utilizó etanol al 80%, posiblemente la extracción alcohólica presenta una ventaja expresiva en la inhibición de la severidad, germinación de ramas y raíces en plantas, podía deberse a que el etanol químicamente en los organismos suele cumplir una función de deshidratación, al contacto de los tejidos aéreos de las malezas, este estimula una respuesta de defensa cerrando sus estomas y disminuyendo su actividad metabólica para no perder líquidos, lo cual provocaría una disminución del crecimiento como lo sostienen con otras especies (Evans, 1980;Piña-Rodríguez y López, 2001;Rodrígues, 2002;SouzaFilho, 2002;Nürnberger et al, 2004;García, 2005;Aguiar-Capobiango et al, 2009;Santos et al, 2010 Error Estándar 0.023 0.015 0.01 T1 Extracto acuoso de ramas sanas aplicadas en malezas de hoja ancha. T2 Extracto acuoso de ramas sanas aplicadas en malezas de hoja angosta.…”

EFECTO ALELOPÁTICO DE ESCOBA DE BRUJA (Moniliophthora perniciosa Stahel.) INOCULADAS EN SIETE ESPECIES DE MALEZAS

“…El promedio de las tres fechas de evaluación, los testigos T1 (4.02) y T2 (4.24) presentaron resultados cercanos a los demás datos obtenidos, esta respuesta probablemente se debe a que en los tratamientos (T3, T4 y T5) se utilizó etanol al 80%, posiblemente la extracción alcohólica presenta una ventaja expresiva en la inhibición de la severidad, germinación de ramas y raíces en plantas, podía deberse a que el etanol químicamente en los organismos suele cumplir una función de deshidratación, al contacto de los tejidos aéreos de las malezas, este estimula una respuesta de defensa cerrando sus estomas y disminuyendo su actividad metabólica para no perder líquidos, lo cual provocaría una disminución del crecimiento como lo sostienen con otras especies (Evans, 1980;Piña-Rodríguez y López, 2001;Rodrígues, 2002;Souza-Filho, 2002;Nürnberger et al, 2004;García, 2005;Aguiar-Capobiango et al, 2009;Santos et al, 2010 T1 Extracto acuoso de ramas sanas aplicadas en malezas de hoja ancha. T2 Extracto acuoso de ramas sanas aplicadas en malezas de hoja angosta.…”