Comparison between diploid and tetraploid citrus rootstocks: morphological characterization and growth evaluation

Abstract

Tetraploid citrus rootstocks may present different morphological characteristics and growth when compared to diploid ones. This worked aimed at comparing morphological characteristics and height growth of diploid and tetraploid plants from the rootstocks ‘Swingle’ citrumelo [C. paradise Macf. x Poncirus trifoliate (L.) Raf], citrange ‘Troyer’ (C. sinensis (L.) Osb. x P. trifoliata) and citranges ‘Fepagro C 13’ and ‘Fepagro C 37’ [C. sinensis cv. Pêra x P. trifoliata] during twelve months. Diploid (2n=18) and tetraploid (2n=36) plants originated from the same seed were identified, cultivated and evaluated every 45 days regarding color, height, petiole length, leaf length and central leaflet width. Significant differences were observed for the evaluated characteristics: the average of petiole length was 1.78 cm in the diploid and 0.99 cm in the tetraploid plants; the average of leaf length was 2.32 cm in the diploid and 2.95 cm in the tetraploid plants; the average of central leaflet width was 1.33 cm in the diploid and 1.69 cm in the tetraploid plants. Moreover, tetraploid plants had darker and thicker leaves than the diploid ones. Variation regarding height was observed and the diploid plants presented higher growth than the tetraploid ones. As tetraploid plants are smaller, have a slow height growth and wider and longer leaves.

Porta-enxertos cítricos tetraploides podem apresentar características morfológicas e desenvolvimento diferenciados comparados a plantas diploides. Este trabalho teve como objetivo avaliar características morfológicas e o crescimento em altura de plantas diploides e tetraploides dos porta-enxertos citrumelo Swingle [C. paradisi Macf. x Poncirus trifoliata (L.) Raf], citrange Troyer [C. sinensis (L.) Osb. x P. trifoliata] e dos citranges Fepagro C 13 e Fepagro C 37 (C. sinensis cv. Pêra x P. trifoliata) por um período de 12 meses. Plantas diploides (2n=18) e tetraploides (2n=36) oriundas da mesma semente foram identificadas, estabelecidas e avaliadas a cada 45 dias quanto a cor, altura, comprimento do pecíolo, da folha e largura do limbo do folíolo central. Diferenças significativas foram observadas nos caracteres avaliados: a média do comprimento do pecíolo nas plantas diploides foi de 1,78 cm e, nas tetraploides, de 0,99 cm; a média do comprimento das folhas nas diploides foi de 2,32cm e nas tetraploides de 2,95 cm; a média de largura dos folíolos centrais das folhas das plantas diploides foi de 1,33 cm e, nas tetraploides, de 1,69 cm; além disso, as plantas tetraploides apresentaram folhas com coloração mais escura e mais espessas do que as das diploides. Variações foram observadas na altura, com as plantas diploides apresentando maior crescimento que as tetraploides. Portanto, plantas tetraploides apresentam menor tamanho, crescimento em altura mais lento e folhas mais largas e compridas.