Seleção de porta-enxertos para quiabeiro visando resistência múltipla à nematoides de galhas
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Data
2016-07-16
Autores
Silva, Edgard Henrique Costa [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Dentre os fitopatógenos de maior importância econômica para o quiabeiro, destacam-se os nematoides de galhas (Meloidogyne spp.). Várias técnicas e abordagem de manejo vem sendo estudadas, no entanto, com potencial agroeconômico restrito. A resistência genética é vista como o manejo mais eficiente e sustentável, todavia não se tem relatos de resistência à nematoides de galhas dentro do gênero Abelmoschus. Uma alternativa promissora para manejar Meloidogyne spp. na cultura do quiabeiro seria a enxertia com porta-enxertos da mesma família botânica. Nesse sentido, objetivou-se com este trabalho, em duas etapas, verificar a reação de genótipos de quiabeiro e vinagreira aos nematoides de galhas Meloidogyne enterolobii, M. javanica e M. incognita raça 3 e de acessos de algodoeiro à M. incognita raça 3, e avaliar a compatibilidade para enxertia dos materiais resistentes com o quiabeiro. Na etapa 1, adotou-se delineamento inteiramente casualizado, com sete repetições. No ato do transplantio, as mudas foram inoculadas com 5.000 ovos e juvenis de segundo estádio de cada espécie de nematoide separadamente. Considerou-se uma planta por vaso como uma repetição. As plantas foram avaliadas aos 90 dias após a inoculação. Estimou-se a população final e o número de ovos e juvenis de segundo estádio por grama de raiz, bem como, o fator e o índice de reprodução para classificação de resistência ou suscetibilidade. Na etapa 2, os materiais resistentes na etapa anterior foram avaliados em duas sub-etapas, quanto à compatibilidade inicial e ao desenvolvimento inicial das plantas enxertadas. Adotou-se delineamento inteiramente casualizado em esquema fatorial 20x4, onde o primeiro fator foi constituído dos candidatos à porta-enxertos, e o segundo de intervalo de semeadura entre enxerto e porta-enxerto (-5D, o porta-enxerto foi semeado cinco dias antes do enxerto; 0D, o porta-enxerto e o enxerto foram semeados no mesmo dia; +5D e +10D, o porta-enxerto foi semeado 5 e 10 dias após o enxerto, respectivamente). Utilizou-se dez repetições, sendo uma repetição representada por uma planta. Os enxertos foram padronizados para 3 cm de comprimento e enxertados pelo método de garfagem fenda cheia. As mudas enxertadas foram acondicionadas em câmara úmida do tipo “floating” durante 20 dias. As mudas foram transplantadas para campo aberto no espaçamento 1x0,25 m. Mensurou-se o comprimento do enxerto e o número de folhas no transplantio e a taxa de sobrevivência cinco dias após o transplantio. Aos 40 dias após o transplantio, aferiu-se a massa fresca, massa seca, comprimento e diâmetro do enxerto e do porta-enxerto, massa fresca, massa seca e diâmetro da região da enxertia e número de folhas. Os resultados obtidos foram submetidos à análise de variância e as médias foram comparadas pelo teste de Tukey ou Scott-Knott à 5% de probabilidade. Todos os genótipos de quiabeiro foram suscetíveis às três espécies de nematoides. As vinagreiras roxa e flor-de-veludo foram resistentes às três espécies estudadas, e a vinagreira comum foi resistente à M. incognita raça 3. Foram resistentes à M. incognita raça 3 os acessos de aldogoeiro TMG 43 WS, IAC 20-233, PRO 136, Nou PAL-RR, LD 990 11213, Stoneville Cluster, Dunn 224, IAC 25, PA 04-158, IAPAR 97-141, Parrot, Acala 22, Wild Mexican Jack Jones, Coodetec 404, AP 0460, AUB 612 RNR, BJ 3128, SA 2572 e CS 8601. Os genótipos de algodoeiro e a vinagreira comum não são compatíveis para enxertia com quiabeiro. As vinagreiras roxa e flor-de-veludo são compatíveis para enxertia com quiabeiro ‘Santa Cruz 47’, sendo porta-enxertos promissores que devem ter o potencial agronômico do quiabeiro avaliado. Melhores resultados foram encontrados quando o enxerto ‘Santa Cruz 47’ e os porta-enxertos vinagreiras roxa e flor-de-veludo foram semeados no mesmo dia.
Among the pathogens of major economic importance to okra, it highlights the root-knot nematodes (Meloidogyne spp.). Various techniques and management approach has been studied, however, with restricted agroeconomic potential. Genetic resistance is seen as the most efficient and sustainable management, but there is no root-knot nematode resistance reported in Abelmoschus. A promising alternative to manage Meloidogyne spp. in okra crop would be grafting with rootstocks of the same botanical family. In this sense, the aim of this work, in two steps, was to screen okra and Hibiscus genotypes to Meloidogyne enterolobii, M. javanica and M. incognita race 3 and cotton access to M. incognita race 3, and to evaluate the compatibility of grafting of resistant materials with okra. In step 1, we adopted a randomized complete block design with seven replicates. At the time of transplanting, the seedlings were inoculated with 5.000 eggs and second stage juveniles of each species of nematode separately. It was considered one plant per pot as a repetition. The plants were evaluated 90 days after inoculation. We estimated the final population and the number of eggs and second stage juveniles as well as the factor and the reproduction rate for resistance or susceptibility classification. In step 2, the resistant material in the previous step were evaluated in two sub-steps, as for the initial compatibility and the initial development of grafted plants. A randomized complete block design in a factorial 20x4 was adopted. The first factor was composed of rootstocks candidates, and the second was seeding interval between scion and rootstock (-5D, the rootstock was sown five days before the scion, 0D, the rootstock and scion were sown on the same day; +5D and +10D, the rootstock was seeded with 5 and 10 days after the scion, respectively). We used ten replicates, with a repetition represented by a plant. Scions were standardized to 3 cm long and grafted by the cleft grafting method. Grafted seedlings were placed in a moist chamber of the floating type, for 20 days. Seedlings were transplanted to open field, spaced 1x0,25 m. It was measured the scion length and the number of leaves at transplanting and the survival rate five days after transplanting. At 40 days after transplanting, we assessed the fresh weight, dried weight, length and diameter of the scion and rootstock, fresh weight, dry weight and diameter of the graft area and number of leaves. The results were submitted to analysis of variance and means were compared by the Tukey or ScottKnott tests at 5% probability. All okra genotypes were susceptible to the three nematode species. The kenaf and false roselle were resistant to the three studied species, and the roselle was resistant to M. incognita race 3. The cotton access TMG 43 WS, IAC 20-233, PRO 136, Nou PAL-RR, LD 990 11213, Stoneville Cluster, Dunn 224, IAC 25, PA 04-158, IAPAR 97-141, Parrot, Acala 22, Wild Mexican Jack Jones, Coodetec 404, AP 0460, AUB 612 RNR BJ 3128, SA 2572 and CS 8601 were resistant to M. incognita race 3. The cotton genotypes are not compatible for grafting with okra. The roselle, despite initial compatibility, showed up, over time, incompatible. The kenaf and false roselle are compatible for grafting with okra 'Santa Cruz 47', and promising rootstocks that should have the agronomic potential assessed. Best results were found when the scion and rootstock were sown on the same day.
Among the pathogens of major economic importance to okra, it highlights the root-knot nematodes (Meloidogyne spp.). Various techniques and management approach has been studied, however, with restricted agroeconomic potential. Genetic resistance is seen as the most efficient and sustainable management, but there is no root-knot nematode resistance reported in Abelmoschus. A promising alternative to manage Meloidogyne spp. in okra crop would be grafting with rootstocks of the same botanical family. In this sense, the aim of this work, in two steps, was to screen okra and Hibiscus genotypes to Meloidogyne enterolobii, M. javanica and M. incognita race 3 and cotton access to M. incognita race 3, and to evaluate the compatibility of grafting of resistant materials with okra. In step 1, we adopted a randomized complete block design with seven replicates. At the time of transplanting, the seedlings were inoculated with 5.000 eggs and second stage juveniles of each species of nematode separately. It was considered one plant per pot as a repetition. The plants were evaluated 90 days after inoculation. We estimated the final population and the number of eggs and second stage juveniles as well as the factor and the reproduction rate for resistance or susceptibility classification. In step 2, the resistant material in the previous step were evaluated in two sub-steps, as for the initial compatibility and the initial development of grafted plants. A randomized complete block design in a factorial 20x4 was adopted. The first factor was composed of rootstocks candidates, and the second was seeding interval between scion and rootstock (-5D, the rootstock was sown five days before the scion, 0D, the rootstock and scion were sown on the same day; +5D and +10D, the rootstock was seeded with 5 and 10 days after the scion, respectively). We used ten replicates, with a repetition represented by a plant. Scions were standardized to 3 cm long and grafted by the cleft grafting method. Grafted seedlings were placed in a moist chamber of the floating type, for 20 days. Seedlings were transplanted to open field, spaced 1x0,25 m. It was measured the scion length and the number of leaves at transplanting and the survival rate five days after transplanting. At 40 days after transplanting, we assessed the fresh weight, dried weight, length and diameter of the scion and rootstock, fresh weight, dry weight and diameter of the graft area and number of leaves. The results were submitted to analysis of variance and means were compared by the Tukey or ScottKnott tests at 5% probability. All okra genotypes were susceptible to the three nematode species. The kenaf and false roselle were resistant to the three studied species, and the roselle was resistant to M. incognita race 3. The cotton access TMG 43 WS, IAC 20-233, PRO 136, Nou PAL-RR, LD 990 11213, Stoneville Cluster, Dunn 224, IAC 25, PA 04-158, IAPAR 97-141, Parrot, Acala 22, Wild Mexican Jack Jones, Coodetec 404, AP 0460, AUB 612 RNR BJ 3128, SA 2572 and CS 8601 were resistant to M. incognita race 3. The cotton genotypes are not compatible for grafting with okra. The roselle, despite initial compatibility, showed up, over time, incompatible. The kenaf and false roselle are compatible for grafting with okra 'Santa Cruz 47', and promising rootstocks that should have the agronomic potential assessed. Best results were found when the scion and rootstock were sown on the same day.
Descrição
Palavras-chave
Abelmoschus esculentus, Enxertia, Meloidogyne spp., Resistência genética, Grafting, Genetic resistance