Imbibition of Seeds of Mexican Seepweed (Suaeda mexicana) and Purslane (Portulaca oleracea) in Saline Solutions and its Effect on Germination and Initial Growth

Objective: To evaluate the effect of salinity sources and concentrations, as well as the interaction of these study factors on the increase in seed mass during imbibition, germination and initial growth of Mexican seepweed (Suaeda mexicana) and purslane (Portulaca oleracea) seedlings were measured. Design/methodology/approach: Seeds of Mexican seepweed (Suaeda mexicana) and purslane (Portulaca oleracea) from the agricultural area of Tláhuac and San Gregorio Atlapulco, Xochimilco, Mexico City were used. They were incubated for 3 h in 15 saline solutions, which resulted from the combination of three sources: NaCl, Na2SO4, and CaCl2; and five concentrations: 0, 0.25, 0.50, 0.75, and 1.00 M. The seeds were incubated in Petri dishes at 28 °C in 80%relative humidity. The increase in seed mass gained after the imbibition period, germination percentage, and radicle and shoot length of the seedling were determined. Results: The 0.25 M NaCl treatment increased germination in Mexican seepweed; in contrast, doses higher than 0.25 M of CaCl2 and Na2SO4 significantly reduced germination, as well as shoot growth. NaCl causes less inhibition of Mexican seepweed radicle growth than the other sources. In purslane, the 0.25 M CaCl2 treatment significantly reduced germination; but it stimulates radicle growth. The Na2SO4 and NaCl sources at doses starting at 0.5 M inhibited germination in purslane. Limitations of the study/implications: No certified germplasm was used for this study, since the seed was obtained directly from producers who maintain semi-domesticated native accessions. Findings/conclusions: Mexican seepweed is tolerant to NaCl and Na2SO4, but sensitive to CaCl2; this was also observed in purslane, although the ranges of tolerance to the concentration vary between salinity sources.