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

Abstract

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.

Maternal Environment and Priming Agents Effect Germination and Seedling Quality in Pitaya under Salt Stress

“…However, research on how pitaya species/cultivars/genotypes perform under these stress factors is scarce. Pitaya seeds germinated under saline conditions reduced germination rate and seedling length up to 33% and 38%, respectively, according to cultivars [16]. It was emphasized that not only the shoot but also the root development regressed in all investigated hybrid pitaya genotypes under salt concentrations [17].…”

“…Seeds were obtained from fresh fruits of similar size that fully ripened on the plants. The fruits were peeled, and the seeds were separated from the pulp manually and washed with tap water several times to remove mucilage and the left-over pulp [16]. Seeds were treated with 2% sodium hypochlorite for 3 min for surface sterilization.…”

“…The seeds of each replicate were homogeneously distributed in 3 layers of Whatman filter paper, 2 on the bottom and 1 on top of the seeds, and 7 mL of salt solution (2500 ppm, 5000 ppm, 10,000 ppm) or pure water (control) was applied to each filter paper (21 mL for each replicate at the start). The homogeneously soaked filter papers were folded into zip-lock bags to minimize moisture loss and placed in a growth chamber set at 25 • C, ~650 lux and 12/12 h photoperiod for germination [16,43]. Moisture was controlled, and the salt solutions were added to the filter papers according to their groups when necessary.…”

“…On the 45th day following the establishment of the experiment, ten seedlings randomly selected from each replicate were measured for seedling shoot length (mm) using a caliper (Traceable-6, VWR International, Milan, Italy) sensitive to 0.01 mm and seedling fresh weight (mg) using a precision balance (Sartorius-CPA 16001S, Göttingen, Germany) sensitive to 0.001 g. Then, the samples were kept in an oven at 70 • C for 48 h, and their dry weights were determined with the help of the same precision balance. As a result of the ratio of dry weight to fresh weight multiplied by 100, the amount of dry matter per unit amount was found as a percentage (%) [16].…”

Guarda Municipal Em Ações Ambientais Efetivas Na Comunidade De Nossa Senhora Do Livramento Da Reserva De Desenvolvimento Sustentável Do Tupé: Uma Análise À Luz Da Constituição Federal E Das Leis Específicas Garantidoras De Um Patrulhamento Ambiental Alternativo Nas Unidades De Conservação De Manaus

“…costaricensis, em 46%(CARVALHO, et al, 2022). Para condições de estresse, o hidrocondicionamento acaba promovendo o aumento na velocidade de germinação, já que as sementes irão requerer menos água para completar o processo (PESKE; VILLELA; MENEGHELLO, 2019).As cactáceas podem ainda manter seu crescimento e rendimento satisfatório mesmo submetidas ao estresse salino.…”