Abstract
Although knowledge about halophytic Solanaceae is scarce, it is known that several species within genus Lycium tolerate salinity. Lycium humile grows in highly saline soils in mudflats near saline Andean lakes. This study evaluated the germination responses of L. humile under different scarification methods, photoperiods, temperatures and saline conditions and, simultaneously, tested seedling survival under different iso-osmotic conditions. Dormancy and germination were found to be regulated by interactions with different factors, with the highest germination percentages being obtained by immersion in sulfuric acid, with a temperature of 25 °C and a temperature regime of 5/25 °C, under which seeds were neutrally photoblastic. As osmotic potential of saline solutions decreased, germination also decreased drastically but the seedling survival percentage was higher than 30 % at 600 mM NaCl. No seeds germinated in any of the polyethylene glycol (PEG) solutions and no seedling survival was observed from -1.2 MPa PEG solutions. More than 90 % of seeds incubated in NaCl were able to recover germination after being transferred to distilled water, independently of NaCl treatments. We concluded that the effects of extreme environmental conditions on germination responses and seed tolerance to salinity may determine the occurrence and restricted distribution of L. humile.
Highlights
Salinity is one of the major abiotic stresses that adversely affect worldwide crop productivity, as well as the growth and development of plants (Llanes et al 2016), the importance of finding new sources to improve crop salt tolerance through biotechnological strategies (Reginato et al 2012), especially in families with great productive value
The aims of the present study were: (1) to evaluate the germination responses of L. humile under different scarification methods, temperatures and photoperiods; (2) to establish the effect of increasing salinity with monosaline and bisaline iso-osmotic solutions of NaCl and KCl on germination and seedling survival, and at the same time, differentiating the osmotic effects from the ion toxicity effects; (3) to assess the ability of L. humile seeds to recover their germination in distilled water after being exposed to NaCl solutions; and (4) to discuss the possible causes that explain the occurrence and restricted distribution of L. humile
Our results show that the germination percentage of L. humile seeds without scarification was very low and the sulfuric acid treatment for 15 minutes was the most effective method for L. humile; suggesting that in natural conditions, L. humile seeds are dormant, i.e. seeds that do not have the ability to germinate under otherwise favorable environmental conditions (Baskin & Baskin 2004), and may require passage through animal digestive tracts, such as birds or mammals, where gastric acids are found
Summary
Salinity is one of the major abiotic stresses that adversely affect worldwide crop productivity, as well as the growth and development of plants (Llanes et al 2016), the importance of finding new sources to improve crop salt tolerance through biotechnological strategies (Reginato et al 2012), especially in families with great productive value. Low germination and decreased seedling growth result in poor plant establishment and, occasionally, in crop failure (Bajehbaj 2010). Salinity can inhibit the germination and growth of plants because it induces low external water potential (preventing water uptake) and ion toxicity; it interferes with nutrient uptake (Munns & Tester 2008; Guma et al 2010; Nasri et al 2015; Silva et al 2015). Plants adaptation to salinity during germination and early seedling stages is essential for a successful establishment and depends on the tolerance to Germination responses of Lycium humile, an extreme halophytic Solanaceae: understanding its distribution in saline mudflats of the southern Puna both osmotic and ionic effects. Ionic effects depend on the chemical nature of the ions involved, which may interact in a synergistic or antagonistic way (Llanes et al 2005)
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