LIMA, F. N.; http://lattes.cnpq.br/5923728757958142; LIMA, Francileide do Nascimento.
Resumo:
Dragon fruit are cacti grown in tropical and subtropical regions. Its cultivation in Brazil
is still incipient with areas located in the states of the South and Southeast and, more
recently, in semi-arid regions of the Northeast, where water resources are scarce.
Despite being characterized as a species tolerant to water deficiency, pitaya shows
great sensitivity to this factor during the germination process. Because it is necessary
to evaluate the germination performance under stress conditions, the present work
aims to evaluate the effect of water stress on the germination performance of dragon
fruit species. The experiment was conducted in a completely randomized design in a
2 x 6 factorial scheme, corresponding to two pitaya species (Hylocereus undatus,
Hylocereus costaricensis) and six water potential gradients (0; -0.2; -0.4; -0, 6; -0.8
and -1.0 MPa) using Polyethylene glycol 6000 as an osmotically active agent, using
four replicates of 50 seeds per treatment. The following variables were analyzed:
percentage, first count, speed index, average time, average germination speed, radicle
length, shoot length and seedling fresh mass. The data obtained were submitted to
analysis of variance by the F test with 5% of significance. The averages obtained for
the species were compared by Tukey test, while the data for water potentials were
submitted to regression analysis. The reduction of the osmotic potentials of the
imbibition water causes decreases in the quality and vigor of the seeds of H. undatus
and H. costaricensis. Osmotic potentials below -0.6 MPa completely restrict the
physiological manifestations of H. undatus and H. costaricensis seeds.