Response of Eucalyptus camaldulensis Dehnh., E. globulus Labill. ssp. globulus and E. grandis W. Hill to excess boron and sodium chloride.

摘要

The effects of boron (0.01, 0.19, 0.46 and 0.93 mol B -3, as H3BO3), sodium chloride (0, 100 and 200 mol NaCl m-3) and combined B and NaCl, over 36 days, on growth, water use and foliar ion concentrations of nine week-old seedlings of Eucalyptus camaldulensis, E. globulus ssp. globulus and E. grandis were investigated in a sand culture experiment. Shoot dry weight was significantly reduced by high concentrations of NaCl (P<0.001) and by B and NaCl in combination (P<=0.05) but not by B alone. Root dry weight was significantly reduced by both NaCl (P<0.001) and B (P<0.001), but not by combined B and NaCl. Foliar B concentrations increased with higher concentrations of applied B and decreased with higher NaCl concentrations. Foliar Na concentrations were greater with higher NaCl concentrations, whereas B application had no significant effect on foliar Na concentrations. All three species accumulated relatively high B concentrations in leaves. Severe boron toxicity symptoms (BTS) were apparent only when leaf B concentrations exceeded 50 mol X 10-6 g-1, but even at these high concentrations plant growth was only slightly reduced. E. camaldulensis showed least development of BTS, the lowest leaf B concentrations and least reduction in height growth dueto B and NaCl. The results suggest that there was a correlation between both B tolerance and B accumulation in leaves and between tolerance to B and NaCl.