The adaptation of Medicago polymorpha to a range of edaphic and environmental conditions: effect of temperature on growth, and acidity stress on nodulation and nod gene induction

Abstract

Three experiments were conducted with Medicago polymorpha collected from a diverse range of sites in Sardinia, to investigate the relationship between edaphic and environmental conditions at collection sites, and the growth and nodulation of the genotype. Growth response to 2 temperature regimes (20/15�C, 11/9�C) was greater for genotypes collected from high altitude than for those from 1350 m. Shoot yield was more depressed by low temperature and more stimulated by high temperature in high altitude than low altitude genotypes. All genotypes nodulated when exposed to considerable acidity stress (pH 5.4) and 1 mmol Ca/L in solution culture. However, there were differences between genotypes in nodulation reduction caused by exposure to acidity. These differences were not well related to the soil pH at the site of collection, or to the effects of pH on the ability of root exudates from the genotypes to stimulate nod gene expression in Rhizobium meliloti.

Diversity of Naturalized Hairy Vetch (Vicia villosa Roth) Populations in Central Argentina as a Source of Potential Adaptive Traits for Breeding

“…Observed large variability within available germplasm could be used by breeders to select parental accessions for HV improvement breeding program that maximizes the winterspring biomass with low PY for cover crops (Wilke and Snapp, 2008;Wayman et al, 2016), or with high PY for´ley farmingś ystems (Loi et al, 2005;Renzi et al, 2017;Renzi et al, 2018). No significant correspondence was found between the geographic distance matrix and the phenotypic distance matrix (P > 0.15) among the naturalized AR populations and these results differ from Medicago polymorpha L., in which a correspondence between collection site and phenotypic traits (Loi et al, 1993;Helliwell et al, 2018) was observed.…”

“…On the other hand, Jannink et al (1997) found that accessions of HV were more winter-hardy than woolly-pod vetch, and late flowering may be positively genetically correlated with winter hardiness (Maul et al, 2011). The susceptibility of HV to low-temperature increases with more advanced phenological stages (Brandsaeter et al, 2002) while slow growth during winter can be an adaptation attribute to avoid frost damage (Loi et al, 1993). Prompt maturity is a desirable trait for earlier biomass production as well as N accumulation in regions with a shorter growing season.…”

Developmental Responses to Temperature and Photoperiod in Ecotypes of Medicago polymorpha L. Collected Along an Environmental Gradient in Central Chile

“…Yet little is known of its ecophysiology, adaptive strategies under varying environmental conditions, or range of genetic expression. Ehrman andCocks (1990, 1996) did include burr medic in their ecogeographic study of 71 annual legumes in Syria, and an in-depth study of this species has been carried out in Sardinia (Loi et al, 1993(Loi et al, , 1995. Some relevant ecological and agronomic literature exists on several other annual medics and clovers (e.g.…”

Morpho-phenological diversity among natural populations of Medicago polymorpha of different Tunisian ecological areas

“…Accordingly, Del Pozo et al (2002) demonstrated that days to first flower were positively correlated with both latitude and longitude, as well as mean annual precipitation of collecting site of 69 Chilean accessions of M. polymorpha. Ecotypic differentiation related to environmental parameters along an aridity gradient in Syria or in a heterogeneous area of distribution such as Sardinia have been found in numerous annual legumes, for traits such as flowering time and degrees of hard seededness (Ehrman and Cocks, 1990;Piano et al, 1996) and shoot growth (Loi et al, 1993;Prosperi et al, 1991;Ovalle et al, 1993;Norman et al, 1998). Adaptive genetic variation is defined as the variation in genes that affects the fitness of an organism (Holderegger et al, 2006).…”

“…M. polymorpha can be a useful pasture plant, in particular, in regions with a Mediterranean climate (Salhi Hannachi et al, 1998). It had aroused great interest due to high nutritious quality, highly palatability and N-fixing plan in neutral soil (Loi et al, 1993(Loi et al, , 1995. M. polymorpha is a species of Mediterranean origin, but its species range is wide spread throughout the world.…”