Ionic effects of NaCl counter osmotic inhibition of germination and seedling growth ofScorzonera hispanicaand subsequent plantlet growth is not affected by salt

Abstract

Scorzonera (Scorzonera hispanica L.) is experiencing range reduction in Portugal while its distribution in the Iberian Peninsula largely coincides with areas affected by salinization. Thus, two experiments were conducted to evaluate the response of scorzonera to salinity. In the first experiment, seed germination and seedling growth were investigated under osmotic potentials down to –1.21 MPa using NaCl or iso-osmotic polyethylene glycol (PEG) solutions. Results of PEG treatments show that osmotic potential alone reduces germination and seedling growth while on NaCl reductions were much lower. Ionic effects of NaCl are stimulatory and clearly counteract osmotic effects. Most seeds completed germination after being transferred from PEG to distilled water. Conversely, on NaCl, recovery results essentially from more time allowed for seeds to complete germination. In the second experiment, young plantlets were treated with NaCl solutions up to 250 mmol·L−1. In general, plantlets were insensitive to NaCl except for a concentration-dependent increase of relative chlorophyll content, suggesting that scorzonera tolerance to NaCl might depend upon nitrogen availability. Altogether, results support the conclusion that scorzonera may be a naturally salt tolerant species able to accumulate and sequester NaCl, with its tolerance increasing as plants grow older.

Physiological and Biochemical Analyses of Sorghum Varieties Reveal Differential Responses to Salinity Stress

“…Salt stress affects seed germination mainly by reducing the soil solution's osmotic potential to delay seed water absorption, causing embryo toxicity to sodium and/or chloride, or changing protein synthesis. Again, poor seedling emergence might be caused by hypocotyls mortality associated with the salt accumulation at the soil surface [13]. Even though germination rate of all varieties was considerably altered by high level of salinity stress, the most severe effects were recorded in genotype Serena and Sc Sila, whereas Gadam had the best performance with regard to this trait.…”

Evaluation of Morphological and Biochemical Characteristics of Sorghum [Sorghum bicolor [L.] Moench] Varieties in Response Salinity Stress

“…Salt stress affects seed germination mainly by reducing the soil solution's osmotic potential to delay seed water absorption, causing embryo toxicity to sodium and/or chloride, or changing protein synthesis. Again, poor seedling emergence might be caused by hypocotyls mortality associated with the salt accumulation at the soil surface [17]. Even though germination rate of all varieties was considerably altered by high level of salinity stress, the most severe effects were recorded in genotype Serena and Sc Sila, whereas Gadam had the best performance with regard to this trait.…”

Effects of dark or of red, blue or white light on germination of subterranean clover seeds

“…To evaluate the recovery of germination the replicates of red, blue and white light treatments were divided 7 days after sowing (DAS) in two groups as described elsewhere (Dias et al, 2015). One group included replicates with the highest and lowest germination and the other the two replicates with intermediate values.…”

“…where G R is the number of seeds germinated after being transferred from light treatments to dark conditions, G F the number of non-germinated seeds when the transferral was done, G C being the equivalent to G R for seeds that continued in the same light treatment, from which true recovery TR was determined by subtracting from RG the mean value of CG (Dias et al, 2015(Dias et al, , 2016.…”

“…However, large recovery values like those observed after blue and white light treatments could also result just from more time having been allowed to seed germination and not represent a true recovery of germination resulting from the removal of the inhibitory factor(s), in this case the removal of blue light and transferral to dark (Dias et al, 2015(Dias et al, , 2016. Therefore the need to determine the effect of more time to germinate, provided by continuance groups.…”