Effect Of Acidity And/or Aluminum Stress On Elongation Of Alfalfa Primary Root

In this study, the effects of acidity and/or aluminum(Al) on alfalfa primary root were investigated by different ways of experiment, the result indicates that alfalfa primary root is high sensitive to acidity and Al, and both acidity and Al are stress factors to elongation of alfalfa primary root. In low-pH medium, alfalfa primary roots would suffer an irreversible damage and lost viability within 6 h exposure to pH 4.1 medium containing 0.5 mmoI.L-1 Ca. The major symptoms developed by low-pH includes curvature and etiolation in root apical. In contrast to low-pH stress, The symptoms by Al induces curvature, turgor and changing color to brown in root apical, and results in a thinner mucilage secreted from root tip. At pH4.5, elongation of alfalfa primary root exposed to 3mol.L-1 Al for 8 h was inhibited by more than 50%. Experiment using cell wall of alfalfa primary root tip showed that both low-pH and Al could inhibit cell wall autolytic activity. Additional calcium could not only alleviate stress on primary root induced by acidity and Al effectively, but also alleviate the inhibition of cell wall autolysis resulted from acidity (partly) and Al(fully).