Abstract:

Effects of lead stress on absorption and distribution of mineral nutrients in Pleioblastus fortunei were studied using a clone that was cultivated in 1/2 Hoagland nutrient solution supplemented with different Pb²⁺ concentration (0, 828.8, 1 657.6, 2 486.4 and 3 315.2 mg·kg^-1). Roots, rhizomes, stems and leaves were harvested after the seedlings became wilting, and the contents of lead (Pb), sodium (Na), potassium (K), phosphorus (P), magnesium (Mg), calcium (Ca), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B) and molybdenum (Mo) in different organs were measured. The results showed that the contents of mineral nutrients in the organs significantly changed with Pb increasing. The Na content in P. fortunei was positively correlated with Pb concentration in the solution, the correlation coefficient were 0.876,0.938,0.938 and 0.954 respectively for root,rhizome,stem and leaf. However the content of B and K obviously decreased with Pb concentration rising. Among the measured elements the concentrations of Na and K changed the most obviously. Meanwhile Mg, P, Ca and Fe also changed to some extent in different organs. It was suggested that the normal balance among mineral elements was broken by lead stress, especially between Na⁺ and K⁺,which might be the major cause for lead potentially toxic to the plant. P. fortunei had a maximum tolerance to Pb of 828.8 mg·kg^-1, and it was able to effectively accumulate Pb and the enrichment coefficient reached to 1.87 and 2.48 in roots and leaves. Some elements related with chlorophyll synthesis, such as Ca, Mg, Fe and Cu, did not reduce, which, therefore, suggested that chlorosis of the leaves by lead stress was not caused by deficit of Ca, Mg, Fe and Cu.

Key words: lead stress, Pleioblastus fortunei, mineral nutrition, Na⁺/K⁺ balance