Effects of NaCl and NaHCO3 stress on the growth of in vitro culture seedlings of Fragaria x ananassa Duch

The tissue culture seedlings from two strawberry cultivars of `Sweet Charlie' and `Benihoppe' were used as materials. The growth and rooting of the seedlings were investigated and the indices of salt tolerance and alkali tolerance under in vitro culture screening were determined in the medium supplemented different concentrations of NaCl and NaHCO3 and pH solution treatment. The results showed that the rooting ability of strawberry seedlings in vitro was restrained, and the rooting rate, the average root number and root length decreased, and the leaves showed distinctive symptoms of saline and alkali injury under NaCl and NaHCO3 treatment. NaCl tolerance and NaHCO3 tolerance to 'Benihoppe' were higher than that of 'Sweet Charlie'. The 120 mmol L-1 NaCl and 10 mmol L-1 NaHCO3 can be used respectively as an index that salt tolerance and alkali tolerance for the in vitro screening of strawberry seedlings. The growth of strawberry seedlings in vitro was supressed as pH value of the solution increased. NaHCO3 and pH stress together may lead to greater injury than NaCl stress alone.