Growth and physiological responses of five Malus species to the pH of hydroponic solutions

.) generation and antioxidant enzyme activities in the roots. When the pH was raised from 7.0 to 8.5, seedlings of M. sieversii displayed significant increases in their growth parameters whereas values for all other traits were significantly decreased. The opposite trend was observed with M. prunifolia and M. hupehensis . When the pH was decreased from 7.0 to 5.5, seedlings of M. sieversii showed a significant decline in their dry weights but a significant improvement in root MDA, H 2O2, AsA, and GSH contents, O 2 .generation and enzyme activities. In conclusions, these results suggest that growth is not severely inhibited for M. prunifolia , M. mandshurica , and M. hupehensis under acidic conditions (pH 5.5) or alkaline conditions for M. sieversii , M. robusta and M. mandshurica (pH 8.5). In fact, M. sieversii grew better at pH 8.5, whereas growth was significantly inhibited for M. sieversii and M. robusta at pH 5.5 and for M. prunifolia and M. hupehensis at pH 8.5.