| Firstly, the rooting properties of eight poplar materials were observed through hydroponics screening and selected three poplars of higher rooting rate, which was Populus deltoides’zhonglin2025’(2025), P. deltides’Harvord’(1-63) and P. simonii Carr. Secondly, the selected materials were exposed to0,50μM and75μM arsenate. The growth status as well as the accumulation, distribution and translocation characteristics of arsenic, As(III) and As(V) in three poplars were investigated. Meanwhile the antioxidant enzyme activities of roots and leaves and the contents of glutathione, ascorbic acid, chlorophyll, soluble protein and malondialdehyde (MDA) were evaluated. Results were as follows:(1) The root primordium of Populus Xeuramericana cv.’Nanlin895’, P. deltoides Bartr. cv.’Lux’ and DORKAMP (P. nigra×P. deltoides) was induced in stead of latent root primordium and the rooting percentage was low. Parts of the root primordium of Si,2025, P. deltoids cv.Zhonghua hongye’, P. deltoidesCL.’Danhong’ and I-63were latent primordium which already existed in the cuttings and their rooting performances were better than the induced primordium. There were three poplar materials with the highest rooting percentage:Si,2025and1-63. Rooting characteristics of the three poplars were evaluated by rooting effect index, results showed that the rooting property of I-63was the best.(2) After exposed to arsenate for four weeks, growth ratio of roots length and shoots height were significantly decreased compared to the control. The roots growth and shoots height ratio of2025,1-63, Si decreased13.7%,26.7%,10.6%and33.9%,52.1%,31.7%under50μM arsenate stress, respectively. When exposed to75μM arsenate, the roots growth and shoots height ratio of2025,1-63, Si decreased26.4%,46.5%,35.5%and44.3%,58.5%,53.4%.(3) Analysis of the chlorophyll content showed that the chlorophyll content was significantly decreased with the rise of arsenate concentration. Compared to control, chlorophyll content of2025,1-63, Si decreased18.6%,61.8%,37.6%and35.0%,72.8%,43.4%under50μM and75μM arsenate stress, respectively.(4) The concentration of arsenic in roots and leaves all increased with the enhancement of arsenate-treatment. When exposed to75μM arsenate, arsenic content of2025,1-63, Si in roots and leaves increased76.5%,75.6%,40.4%and29.3%,37.2%,58.4%compared to50μM arsenate, respectively. Arsenic content of1-63in roots and leaves was the highest while2025was the lowest with arsenic concentration accumulated in I-63was twice higher than2025. The roots absored and accumulated most of the arsenic and very few transported to the leaves. The translocation index of2025,1-63, Si was0.186,0.211,0.147and0.137,0.165,0.165under50μM and75μM arsenate stress, respectively.(5) Concentration and form of arsenic in tissues of three poplars were investigated. The result indicated that As(III) was the main species with the percentage of As(Ⅲ) in total arsenic content was93%. The percentage of As(III) in roots was more than80%in three poplars, which indicante that the conversion of As(V) to As(Ⅲ) was mainly in roots. The accumulation, distribution and tranportation characteristics of As(Ⅲ) and As(V) in three poplars was the same as arsenic.(6) The response of enzymatic antioxidant and non-enzymatic antioxidant of three poplars were investigated. The SOD activities in both roots and leaves of three poplars increased when exposed to50μM arsenate concentration, whereas it decreased upon the exposure to75μM arsenate concentration. Simultaneously, the POD activities and the contents of GSH and AsA in both roots and leaves of three poplars were on the rise with the increase of arsenate concentrations, which were statistically positive correlation with the arsenate concentration. The SOD and POD activities of2025were the highest while I-63were the lowest. On the contrary, the contents of GSH and AsA of2025were the lowest while I-63were the highest. The SOD and POD activities and the content of AsA in leaves were higher than that in roots while the content of GSH was the opposite.(7) The content of soluble protein in roots and leaves was declined with the rising of arsenate concentrations and the content of soluble protein in leaves was higher than that in roots. The concentration of soluble protein in2025was the highest while I-63was the lowest.(8) The content of MDA in roots and leaves was increased with the rising of arsenate concentrations and the content of MDA in roots was higher than than in leaves. The concentration of MDA in2025was the lowest while I-63was the highest.Consequently,I-63possessed the strongest ability to absorb and accumulation As. Although leaves suffered from a certain degree of toxicity, plants still maintain the normal growth, indicating that I-63was an effective accumulator and tolerant of As to some extent. |
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