| The reaction of the physiological and biochemical and growth of Acer ginnala Maxim, Pyrus ussuriensis, Acer mono Maxim and Malus bacata Borkh were studied under thestress of heavy metals (Cd2+ and Pb2+ ) in the soil by the seedlings in pots in greenhouse, the distribution and accumulation of heavy metals were analyzed in the four species and the resistance of the four species to heavy metals was evaluated. Every species was designed under different concentration gradient, Cd2+: 10 50 100 200mg kg-1(pure Cd2+), Pb2+ 100, 500 , 1000 2000 mg kg -1 (pure Pb2+), simultaneity CK was designed (showed CK Cd10 Cd50 Cd100 Cd200 Pb100 Pb500, Pb1000 Pb2000 in text). The results were as follows:1 The effects of Cd2+ and Pb2+ on photosynthesis of the seedlings With enhancing of the concentration of the Cd2+ and Pb2+, chlorophyll content in leaves of four tree species declined, It was achieved significant level in contrast with the hig -hest concentration treatment(Cd200, Pb2000) and CK ( P<0.05 ) . Acer mono Maxim was the most distinct, Pyrus ussuriensis Maxim and Acer ginnala Maxim were at second place, Malus bacata Borkh was the least. With the decline of chlorophyll, pure photosynthetic rate of plant leaves change. With Cd2+ concentration enhanced, photosynthetic rate of Acer mono Maxim decline, other three tree species first increase then descend, the variety of Malus bacata Borkh was the most, followed by Malus bac -ata Borkh, Pyrus ussuriensis Maxim was the least; pure photosynthetic rate of Pyrus ussuriensis Maxim continually decrease, with enhancing of the Pb2* concentration, that of other three tree species were first raised then decreased. Under the stress ofCd2* an -d Pb2+, chlorophyll fluorescence parameters Fv/Fm psII qP and qNP of most treespecies differently decreased, but variety was relative less.2 The effects of Cd2+ and Pb2+ on the cell membrane lipid peroxidation and theactivity of protectiase of the seedlingsRelative conductivity rate of four tree species leaves enhanced with increase of heavy metals and the difference among tree species was significant. Under the stress of Cd2+, Acer mono Maxim was the most sensitive, followed by Pyrus ussuriensis Maxim and Malus bacata Borkh, Acer ginnala Maxim was least; Under the stress of Pb2+, the variety of Acer mono Maxim was most, followed by Malus bacata Borkh and Acer gin -nala Maxim, the variety of Malus bacata Borkh was least. The activity of SOD offour tree species seedlings first enhanced then decreased with the enhancing of the concentration of Cd2+ and Pb2+, while under the highest concentration treatment (Cd200 Pb2000) , the decreasing degree was Pyrus ussuriensis Maxim and Acer mono Maxim >Acer ginnala Maxim and Malus bacata Bork. POD activity raised conti -nually with the increasing of Cd2* and Pb2"1" concentration. The variety of Pyrus ussuriensis Maxi -m was maximal, followed by Acer ginnala Maxim and Acer mono Maxim, the variety of Malus bacata Borkh was minimal.3 The effects of Cd2+ and Pb2+ pollution on growth and biomass of the seedlings From the appearances of plant, leaves appeared chlorosis symptom under the stress of heavy metals, Cd2+ treatment was the most obvious, the symptoms of Acer ginnala Ma -xim and Acer mono Maxim were the most outstanding among four tree species. The lo -wer concentration of Cd2+ and Pb2+ can stimulate the growth of base diameters, seedli -ng heights, new branches and leaves of most tree species. With the enhancing of Cd2+ and Pb2+ concentration, each indexes decreased, thereinto, the effect on Acer mono Ma -xim was maximal, while the effect on other three tree species were insignificant. The poison of Cd2+ and Pb2+ on underground roots was ahead of that on the overground, the new root growth quantity of Acer ginnala Maxim and Malus bacata Borkh decreased with the Cd2+ and Pb2+ concentration increased; the new root growth quantityof other t -wo tree species was different under different heavy metals treatments. Under the stress of Cd2+, the new root growth quantity of Pyrus ussuriensis Maxim fi...
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