Produção de mudas de Pitaya Através da micropropagação

Abstract

The objective of this study was to develop protocols for the production of pitaya seedlings through micropropagation. First, five experiments were carried out. The objective was to generate a protocol for seedling production of Hylocereus undatus and Hylocereus polyrhizus, with the establishment, multiplication, rooting and acclimatization stages. In the second work, we aimed to evaluate the cladode and 6-benzylaminopurine portions in Hylocereus undatus multiplication. The works were developed in the Laboratory of Propagation of Fruit Plants of the Federal University of Pelotas. Cladodes were segmented and rooted in flowerbeds, the shoots were used for the establishment. The culture medium at all stages was MS (Murashige & Skoog) and pH adjusted to 5.8. At the establishment, the experiment was in a 2x5 factorial scheme (two genotypes and doses of 6-benzylaminopurine (0, 1, 2, 3 and 4mg L-1)), with one areola per explant. After 90 days, the number of shoots and the percentage of regenerated explants were evaluated. In the multiplication were two experiments; the first one was conducted in a 2x5 factorial scheme (genotypes and doses of Zeatin (0, 0.2, 0.4, 0.6 and 0.8mg L-1) and after 60 days were evaluated: number and length of shoots, multiplication rate, number and length of roots and mass of total dry matter. In the second study, a 2x4 factorial scheme (two genotypes and doses of 6-benzylaminopurine (0, 0.3, 0.6 and 0.9mg L-1), after 60 days were evaluated: number of shoots and multiplication rate. In the rooting stage, doses of indolebutyric acid (0, 0.2, 0.4 and 0.6mg L-1) were tested in Hylocereus undatus, after 60 days were evaluated: number and length of roots and number and length of shoots. For acclimatization, two genotypes and the substrates were bark of charred rice, vermiculite, coconut fiber and peat ® Fertil. The experiment was conducted in a greenhouse with controlled temperature, 25 °C ± 2 °C. After 60 days, shoot length, number of areolas, number of primary and secondary roots, root length and dry mass of root and shoot were evaluated. In another experiment, the influence of the cladode portions (apical, median and basal) and doses of 6-benzylaminopurine (0, 1, 2, 3 and 4mg L-1) on the multiplication of Hylocereus undatus were tested. In the establishment the dose of 2mg L-1 of 6-benzylminopurine to Hylocereus polyrhizus and 4mg L-1 to Hylocereus undatus promoted the induction of shoots and number of shoots. It is not necessary to use indolebutyric acid in the rooting of Hylocereus undatus. Zeatin presented a negative effect on multiplication, with 6-benzylminopurine the highest number of shoots and multiplication rate occurred between doses 0.6 and 0.9mg L-1. For the acclimatization the bark of charred rice and vermiculite favored the development of the roots of the two genotypes. The median and basal portions present a higher number of shoots and the dose 2mg L-1 of 6-benzylminopurine are indicated for multiplication of Hylocereus undatus.