Obtenção de plantas autotetraplóides de variedades de porta-enxertos de citros / Obtention of autotetraploids plants of varieties of rootstocks of Citrus
AUTOR(ES)
Aparecido da Silva Júnior
DATA DE PUBLICAÇÃO
2008
RESUMO
The Brazilian citriculture stands out as the greatest expression worldwide, with about 27.9% of world production of oranges and 59% of global production of frozen orange juice concentrate. However, it presents a vulnerability that is the predominance of a single species of rootstock, the Cravolemon, with approximately 85% of citrus planted on it. Thus, greater diversification of rootstocks is necessary, which also depends on obtaining and provision of superior kind of lemon Cravo. The rootstock is of fundamental importance in shaping the citrus scion, since it interferes with various aspects of graft, such as the vigour of the graft and plant size. Currently, due the appearance of new diseases and the need to maximize resources allocated in the citrus farm, more dense citrus orchards have been used, increasing the interest in the production of smaller plants. One of the possibilities of obtaining plants of small size is through the use of dwarf or semi-dwarf rootstocks, and some authors have found that plants autotetraploids, when used as rootstock, induce the formation of small-sized plants. The initial objective of this study was to obtain and identify plants autopoliploids of Cravolemon, Cleopatraand Sunkitangerines, using the method of in vitro culture of segments of epicotyl temporarily in the culture medium containing colchicine, followed by shoots regeneration in medium without the alkaloid. The colchicine caused toxicity in explants, at the different times of cultivation and concentrations tested. Several plants were obtained and among these, 27 were selected for morphological characteristics similar to polyploid plants. Afterwards, trials were conducted with six selected plants (two of each kind) to confirm the nucelar ploidy origin, and to characterize the morphology of the leaves, stomatal density and some physiological parameters. Among the six plants, only four were confirmed as autotetraploids by method of flow cytometry. These, generally presented leaves with small length, greater thickness of the leaf lamina and lower stomatal density in leaves. All six plants showed some change in physiological parameters, but data could not determine whether these changes could affect the plants growth rates
ASSUNTO(S)
tissue culture autotetraploid citrus porta-enxerto autotetraplóide citros colchicine rootstock cultura de tecido colchicina
