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Estudo de algumas características em melhoramento de framboesa: resistência à ferrugem tardia, precocidade e cor do fruto
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No âmbito do programa de melhoramento de framboesa, implementado pelo INIAV, I.P. em parceria com a empresa BeiraBaga, foram realizados três cruzamentos com o objetivo de introduzir características de interesse num genótipo com potencial comercial (progenitor feminino), desenvolvido pelo programa.
Do cruzamento com vista a introduzir resistência à doença da ferrugem tardia (Thekopsora americana) foram avaliadas, em estufa, 773 plantas previamente inoculadas com o fungo, relativamente à severidade da doença, que apresentou um valor mínimo de 0,2 % e máximo de 46,8%. Destas, foram selecionadas 78 plantas (10,1%), com severidade até 5%, para instalação em campo. A avaliação de campo mostrou diferenças significativas (p<0,05) nos valores de severidade entre as famílias resultantes dos três cruzamentos, o progenitor feminino e o progenitor dador de resistência, o que poderá indicar que esta foi efetivamente introduzida.
Do cruzamento com vista a introduzir precocidade, foram avaliadas 1827 plantas em campo, das quais 242 (13,2%) produziram até seis semanas antes do progenitor feminino. Os indivíduos precoces compuseram 12 grupos de precocidade, demorando entre 13 e 18 semanas a produzir, desde a plantação até à primeira colheita, e necessitando de 1359,8 a 1925,7 GDC (TB5°C). Tal como o primeiro, este cruzamento foi bem-sucedido na produção de genótipos precoces com potencial, que poderão passar à próxima fase de avaliação e seleção.
O terceiro cruzamento tinha o objetivo de produzir descendência com frutos de coloração mais clara que o progenitor feminino. Apenas 5 indivíduos do total de 95 avaliados produziram frutos cujos parâmetros de cor medidos (L*, a*, b*, C*, h°) apresentaram diferenças significativas (p<0,05) relativamente aos do referido progenitor. Estas diferenças traduziram-se em frutos que cumprem o objetivo delineado, particularmente no caso do indivíduo 449 que apresenta o maior valor de luminosidade (L*449=43,57) e o terceiro maior valor de saturação (C*PF=49,37).
Integrated in the raspberry breeding program implemented by INIAV, I.P. in partnership with Beira Baga company, three crosses were made aiming at introducing desirable traits in a high-quality variety (female parent) with commercial potential, developed by the program. From the cross aiming at introducing resistance to the late leaf rust disease (Thekopsora americana), 773 previously inoculated plants were evaluated regarding disease severity, in the greenhouse screening phase. The minimum and maximum registered values were 0,2% and 46,8%, respectively. From those, 78 (10,1%) plants with a maximum severity of 5% were selected, to be installed in the field. The field assessment showed significant differences (p<0,05) in disease severity between the three families, the female parent and the resistance donor parent, which might indicate that some degree of resistance was transmitted to the offspring. From the cross meant to segregate for earliness, 1827 plants were evaluated in the field, from which 242 (13,2%) were first harvested up to six weeks prior to the female parent. The early individuals composed 12 earliness groups, taking from 13 to 18 weeks from plantation to harvest of the king fruit, requiring 1359,8 to 1925,7 GDD (BT5°). As in the first cross, this second one was successful in producing genotypes with potential to be selected to the next selection stage. The third and last cross was meant to produce offspring showing fruits of lighter color than that of the fruits of the female parent. Only 5 individuals from a total of 95 evaluated ones exhibited fruits whose measured color parameters (L*, a*, b*, C*, h°) showed significant differences (p<0,05) when compared to those of the female parent. These differences translate into fruit colors that meet the outlined goals, in particular individual 449, which exhibited fruits with the highest lightness value (L*449=43,57) and the third highest value for chroma (C*PF=49,37).
Integrated in the raspberry breeding program implemented by INIAV, I.P. in partnership with Beira Baga company, three crosses were made aiming at introducing desirable traits in a high-quality variety (female parent) with commercial potential, developed by the program. From the cross aiming at introducing resistance to the late leaf rust disease (Thekopsora americana), 773 previously inoculated plants were evaluated regarding disease severity, in the greenhouse screening phase. The minimum and maximum registered values were 0,2% and 46,8%, respectively. From those, 78 (10,1%) plants with a maximum severity of 5% were selected, to be installed in the field. The field assessment showed significant differences (p<0,05) in disease severity between the three families, the female parent and the resistance donor parent, which might indicate that some degree of resistance was transmitted to the offspring. From the cross meant to segregate for earliness, 1827 plants were evaluated in the field, from which 242 (13,2%) were first harvested up to six weeks prior to the female parent. The early individuals composed 12 earliness groups, taking from 13 to 18 weeks from plantation to harvest of the king fruit, requiring 1359,8 to 1925,7 GDD (BT5°). As in the first cross, this second one was successful in producing genotypes with potential to be selected to the next selection stage. The third and last cross was meant to produce offspring showing fruits of lighter color than that of the fruits of the female parent. Only 5 individuals from a total of 95 evaluated ones exhibited fruits whose measured color parameters (L*, a*, b*, C*, h°) showed significant differences (p<0,05) when compared to those of the female parent. These differences translate into fruit colors that meet the outlined goals, in particular individual 449, which exhibited fruits with the highest lightness value (L*449=43,57) and the third highest value for chroma (C*PF=49,37).
Descrição
Mestrado em Engenharia Agronómica. Universidade de Lisboa, Instituto Superior de Agronomia
Palavras-chave
Rubus idaeus Thekopsora americana produção precoce sistema CIE seleção precoce early production CIE variables early stage selection
Contexto Educativo
Citação
Novo, H.I.V.C.R. Estudo de algumas características em melhoramento de framboesa: resistência à ferrugem tardia, precocidade e cor do fruto. Lisboa: ISA-Universidade de Lisboa, 2023. Dissertação de Mestrado
Editora
Instituto Superior de Agronomia, Universidade de Lisboa