Influence of copper on root growth and morphology of Pinus pinea L. and Pinus pinaster Air. seedlings
1995
Arduini, I. (Universita degli Studi Pisa, Pisa, Italy.) | Godbold, D.L. | Onnis, A.
We assessed the effects of Cu on root growth and morphology of stone pine (Pinus pinea L.) and maritime pine (Pinus pinaster Ait.) seedlings grown in culture solutions supplied with 0.012 (control), 0.1, 1 or 5 micromolar CuSO4. The presence of 5 micromolar Cu in the nutrient solution completely inhibited root growth of both species within 3 days. In both species, taproot elongation was reduced in the presence of 1 micromolar Cu, although partial growth recovery occurred after 7 days of treatment. The presence of 0.1 micromolar Cu in the culture solution slightly enhanced root elongation in P. pinaster, but did not significantly influence root elongation in P. pinea. In both species, root weight per unit length increased in response to Cu exposure, and in P. pinaster, root diameter was significantly increased. The Cu treatments also affected lateral root number and length. In the presence of 1 micromolar Cu, both species formed only short lateral primordia. The 1 micromolar Cu treatment increased the lateral root index (number of roots per cm of root length) of P. pinaster, but decreased that of P. pinea, compared with control values. Neither the 0.1 nor 1 micromolar Cu treatment had a significant effect on the mitotic index of either species. We conclude that cell elongation is more sensitive to Cu than cell division. Cell membrane damage, as indicated by Trypan blue staining, occurred after 10 days of exposure to 1 micromolar Cu
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