Salt stress resistance of peach and four North American Prunus species

Four species of Prunus native to stress-prone habitats in North America were evaluated for their ability to exclude or tolerate Na+ or Cl- ions, relative to the peach (Prunus persica (L.) Batsch.) rootstock 'Nemaguard'. An 8-week experiment was conducted in a greenhouse using hydroponic growth conditions, with 50 mM NaCl added to the nutrient solution of half the plants of each species. Root, stem and total biomass were reduced by about 30-50% for P. persica, P. maritima Marsh., and P. mexicana Wats., but were not affected in P. andersonii Gray or P. havardii (Wight) Mason. However, leaf biomass was reduced for all five species in response to salt stress. P. maritima had higher thresholds of Na+ or Cl- ion content in leaves for foliar injury than P. persica or P. mexicana, and had 26-29% less canopy injury than the latter two species. There were no differences in Na+ or Cl- ion exclusion ability of roots among the five species. P. mexicana partitioned about 15% less of total plant Cl- to leaves than P. persica or P. maritima, and P. persica partitioned about 8-10% less total plant Na+, to leaves than P. mexicana or P. maritinia. The beach plum, P. maritima, may offer the best potential of the species studied for improvement of leaf Na+ or Cl- tolerance in peach.