Pre-germination treatments in pitaya (Hylocereus spp.) seeds to attenuate salt stress

Resumo

Pitaya (Hylocereus undatus and H. costaricensis) is found in the group of exotic fruits and its cultivation in
Brazil is expanding, especially in the semi-arid region of the Northeast. In this region, the problems of water quantity and
quality usually cause environmental stresses which limit the survival of plants, especially during germination and seedling
establishment. Thus, the objective was to evaluate the mitigating action of pre-germination treatments in pitaya seeds under
salt stress. The experiment was conducted in a completely randomized design, in a 2 × 6 factorial scheme, corresponding to
two species of pitaya (H. undatus and H. costaricensis) and six pre-germination treatments (T1 = 0.0 MPa (control); T2 = salt
stress (-0.4 MPa); T3 = hydropriming + salt stress; T4 = gibberellic acid + salt stress; T5 = salicylic acid + salt stress; T6 =
thiamethoxam + salt stress). After 20 days of sowing, germination, germination speed index, shoot length, primary root length,
total dry mass, total soluble sugars and total free amino acids were analyzed. H. costaricensis was more tolerant to salinity
than H. undatus. Salicylic acid stimulated the germination and growth of H. undatus, besides increasing the soluble sugar
content in H. costaricensis. Seed hydropriming attenuated salt stress during germination of H. undatus and favored dry mass
gain. Gibberellic acid stimulated the germination of H. undatus and the growth of H. undatus and H. costaricensis seedlings, in
addition to increasing the levels of soluble sugars in H. undatus.