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Influência de auxinas e citocininas na enxertia de videira (Vitis vinifera L.)
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As taxas de sucesso obtidas na propagação de videiras são inconsistentes e reduzidas (40% a 60%), sendo um problema crónico dos viveiros. A propagação é feita por enxertia, um processo complexo e delicado, que leva a um grande número de videiras perdidas, isto porque não se desenvolvem devidamente em função da frágil ligação entre garfo e porta-enxerto. Esta ligação é intermediada por fito-hormonas (nomeadamente auxinas e citocininas) que, numa complexa interação, promovem a formação do callus e ligam os sistemas vasculares das duas plantas. O aumento da concentração de auxinas e/ou citocininas, na zona de enxertia, cria a possibilidade de promover um melhor desenvolvimento das videiras após enxertia e, assim, garantir melhores taxas de sucesso. Nesta dissertação foram testadas soluções contendo diferentes concentrações de auxina (ácido índole-3- butírico) (1000 mg/L e 2000 mg/L) e/ou citocininas (cinetina e benziladenina) (250 mg/L, 500 mg/L e 1000 mg/L) em 3 castas (Touriga Nacional, Touriga Franca, Viosinho) enxertadas em dois portaenxertos (1103 Paulsen, 110 Richter). As videiras foram inoculadas com as soluções após enxertia e mantidas em câmara de ambiente controlado para calogénese, sendo depois transferidas para viveiro ao ar livre. Foram avaliados vários parâmetros: taxa de sucesso, grau e percentagem de formação de callus e raízes, número e comprimento de rebentos e raízes. As soluções com auxina (1000 mg/L e 2000 mg/L) promoveram, essencialmente, o desenvolvimento do sistema radicular, mas impactaram negativamente a formação de callus e rebentos (sempre próximos do 0). As citocininas reduziram ligeiramente a formação de callus, mas otimizaram o desenvolvimento de rebentos. A cinetina com uma concentração de 250 mg/L obteve a melhor taxa de sucesso (22,5%). Esta concentração de citocinina revelou os melhores resultados na maioria dos parâmetros avaliados. As taxas de sucesso obtidas foram, no entanto, muito baixas.
The success rates obtained in the propagation of grapevine plants are inconsistent and low (40% to 60%), being a chronic problem of the nurseries. Propagation is commonly done by grafting, a complex and delicate process, which leads to a large number of lost plants, because they do not develop properly due to the fragile connection between the scion and the rootstock. This connection is mediated by phytohormones (namely auxins and cytokinins) which, in a complex interaction, promote callus formation and connect the vascular systems of the two plants. The increase in the concentration of auxins and/or cytokinins in the grafting area creates the possibility of promoting better development of the vines after grafting, ensuring better success rates. In this dissertation, solutions containing different concentrations of auxin (indole-3-butyric acid) (1000 mg/L and 2000 mg/L) and/or cytokinins (kinetin and benzyladenine) (250 mg/L, 500 mg/L and 1000 mg/L) were tested in 3 grapevine cultivars (Touriga Nacional, Touriga Franca, Viosinho) grafted in two rootstocks (1103 Paulsen and 110 Richter). The grapevines graft combinations were inoculated with the solutions after grafting and kept in a controlled environment chamber for callogenesis and then transferred to an open-air nursery. Several parameters were evaluated: success rate, degree and rate of callus and root formation, number and length of shoots and roots. Solutions with auxin (1000 mg/L and 2000 mg/L) essentially promoted the development of the root system but negatively impacted the formation of callus and shoots (always close to 0). Cytokinins reduced partially callus formation, but optimized shoot development. Kinetin with a concentration of 250 mg/L had the best success rate (22.5%). This concentration of cytokinins revealed the best results in most of the parameters evaluated. The success rates obtained were, however, very low.
The success rates obtained in the propagation of grapevine plants are inconsistent and low (40% to 60%), being a chronic problem of the nurseries. Propagation is commonly done by grafting, a complex and delicate process, which leads to a large number of lost plants, because they do not develop properly due to the fragile connection between the scion and the rootstock. This connection is mediated by phytohormones (namely auxins and cytokinins) which, in a complex interaction, promote callus formation and connect the vascular systems of the two plants. The increase in the concentration of auxins and/or cytokinins in the grafting area creates the possibility of promoting better development of the vines after grafting, ensuring better success rates. In this dissertation, solutions containing different concentrations of auxin (indole-3-butyric acid) (1000 mg/L and 2000 mg/L) and/or cytokinins (kinetin and benzyladenine) (250 mg/L, 500 mg/L and 1000 mg/L) were tested in 3 grapevine cultivars (Touriga Nacional, Touriga Franca, Viosinho) grafted in two rootstocks (1103 Paulsen and 110 Richter). The grapevines graft combinations were inoculated with the solutions after grafting and kept in a controlled environment chamber for callogenesis and then transferred to an open-air nursery. Several parameters were evaluated: success rate, degree and rate of callus and root formation, number and length of shoots and roots. Solutions with auxin (1000 mg/L and 2000 mg/L) essentially promoted the development of the root system but negatively impacted the formation of callus and shoots (always close to 0). Cytokinins reduced partially callus formation, but optimized shoot development. Kinetin with a concentration of 250 mg/L had the best success rate (22.5%). This concentration of cytokinins revealed the best results in most of the parameters evaluated. The success rates obtained were, however, very low.
Descrição
Dissertação de Mestrado, Engenharia Agronómica, 2025, Universidade de Lisboa, Instituto Superior de Agronomia.
Palavras-chave
enxertos prontos calogénese ácido indole-3-butírico cinetina benziladenina graft combinations callogenesis indole-3-butyric-acid kinetin benzyladenine