Propagação de híbridos somáticos de citros e reação à infecção por Phytophthora nicotianae e vírus da tristeza dos citros. / Propagation of citrus somatic hybrids and response to Phytophthora nicotianae and Citrus Tristeza Virus infection.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Somatic hybridization is a new alternative in citric species breeding, yielding somatic hybrids which may integrally keep the genetic combination of both progenitors involved in the hybridization. Thus, the objective of this work was to study the propagation and growth of somatic hybrids parental combinations with potential to be used as rootstock and to verify possible resistance/tolerance to trunk and roots infection by Phytophthora nicotianae and citrus tristeza virus (CTV). This work applied the following somatic hybrids: Cravo lemon + sour orange, Caipira orange + Cravo lemon, Caipira orange + Cleopatra tangerine, Caipira orange + Volkamerian lemon, Caipira orange + Rough lemon, Cleopatra tangerine + Volkamerian lemon, Cleopatra tangerine + sour orange, Cravo lemon + Sunki tangerine, Ruby Blood orange + Volkamerian lemon, Rohde Red orange + Volkamerian lemon and Valência orange + Fortunella obovata. In hybrids propagation, stem cuttings of approximately 15 cm length were excised from matrix plants of respective somatic hybrids and submmited to rooting in intermitent nebulization chamber for 100 days. Later, the stem cuttings root system and air part were analyzed. In sequence, they were transplanted to plastic bags, conduced in only one hast and kept in greenhouse during 210 days, when monthly evaluations were performed concerning the air part and, in the end, root system evaluations. For the Phytophthora nicotianae and CTV infection essays, plants derived from the respective somatic hybrids originated from stem cuttings were used, as well as control plants. For the resistance/tolerance to P. nicotianae analysis, the needle method for the trunk infection test was applied, being the lesions quantified after 25 days post-inoculation. For the roots and radicels flashening test, substrate was infected with pathogen structures and the air part of the plants was analyzed at every 15 days; roots were analyzed 60 days after the essay implementation. To evaluate the somatic hybrids tolerance to CTV, it was adopted the method of tissues union (grafting), where the air part of the plants was analyzed once a month in three evaluations. On the stem cuttings rooting, the hybrids of Caipira orange + Cleopatra tangerine, Caipira orange + Volkamerian lemon, Cravo lemon + Sunki tangerine and Rohde Red orange + Volkamerian lemon presented the best results, with the hybrids of Caipira orange + Volkamerian lemon and Rohde Red orange + Volkamerian lemon being the top concerning the stem cuttings development after transplanting. The somatic hybrids of Cleopatra tangerine + sour orange, Cravo lemon + Sunki tangerine, Cleopatra tangerine + Volkamerian lemon, Ruby Blood orange + Volkamerian lemon, Rohde Red orange + Volkamerian lemon and Caipira orange + Volkamerian lemon showed good results related to reducing the trunk flashening, and the somatic hybrids of Cleopatra tangerine + Volkamerian lemon, Cleopatra tangerine + sour orange, Caipira orange + Volkamerian lemon and Caipira orange + Cravo lemon presented tolerance to roots and radicels flashening caused by P. nicotianae. The hybrids of Cleopatra tangerine + sour orange and Valência orange + Fortunella obovata showed to be intolerant to citrus tristeza virus.

ASSUNTO(S)

fruta cítrica propagação vegetal tristeza cítrica vegetal hibridization estaca (planta) citric tristeza vegetal propagation gomose vegetal genetic breeding cutting (plant) citric fruit vegetal genetic resistence rootstock melhoramento genético vegetal hibridação vegetal gummosis resistência genética vegetal porta-enxerto

ACESSO AO ARTIGO

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