Effect Of Graphene Oxide On Germiantion And Growth Of Seedlings In Crops

To study the effect of Graphene Oxide (GO) on germination and growth of seedlings in plants, five varieties of rice (Nipponbare, Minhui63, Shuangkangmingzhan, R527 and 9311), which represent Monocotyledon and five varieties of rape (Zhongshuang 11, Zhongshuang5, Zhongshuang9, Zhongshuang7 and Zhongyoull9), which represent dicotyledon, were selected as experimental materials. Different concentrations of Graphene Oxide were used to treat rice seeds and rape seeds. The Germination potential, germination rate and morphology (root length, stem length, adventitious root number, root fresh weight, fresh weight of over ground part and root cap ratio) of rice and rape seedlings, enzyme activities (SOD, POD and CAT), MDA content and chlorophyll content were measured. The results were as follows:GO had accelerated germination of Nipponbare. After treating for 1 d, the germination potential of 150 mg/L GO was 1.6 times of CK. But germination of Minghui63 was significantly delayed. Germination potential of 150 mg/L GO was 28.33%, being 46.67% lower than CK. For Shuangkangmingzhan,10 mg/L, 50 mg/L and 150 mg/L GO had accelerated its germination, other concentrations of GO had no influence on the seeds. R527 and 9311 focused on the first day to germinate. After been treated for 1 d, the germination potential of R527 and 9311 were at least 88.33% and 80%.10 mg/L and 50 mg/L GO had accelerated the germination of R527, and 10 mg/L GO had delayed the germination of 9311. For rape seeds, GO had accelerated germination of Zhongshuangll, Zhongshuang5 and Zhongyoul19. After been treated, the highest germination potential of the three rape varieties reached 2.1 times,1.7 times and 1.5 times of CK. The germination of Zhongshuang9 had been momentarily accelerated, and 10 mg/L GO had delayed the germination of Zhongshuang7. In the second day of treatment, the germination potential of 10 mg/L GO was 15.83% lower than CK. After been treated by GO, germination rates of five varieties of rice were all above 90%, and germination rates of five varieties of rape were all above 95%.With the increase of GO concentration, root length of Nipponbare reached 0.3323 g after been treated by GO of 150 mg/L. However, the fresh root weight was only 0.2663 g. Root length of Minghui63 had tendency of going down at first and increasing latter, The root length of R527 had tendency of going down at first and increasing latter. Its root length at 150 mg/L GO was 4.23 cm longer than CK, For 9311, the fresh root weight had no significant change, root length shortened firstly and then lengthened. The root length of 100 mg/L GO treatment had reached 11.7067cm, being 3.9467 longer than CK. GO had different influences on the phynotype of these five varieties of rice.For Zhongshuangll, Zhongshuang 9 and Zhongshuang 7, with the increase of GO concentration, the root length shortened gradually, Compared with CK, the shortest root length were only 0.47 times,0.69 times and 0.54 times of CK. Fresh root weight decreased, and stem length lengthened gradually, weight of overground part increased gradually, but the root cap ratio decreased gradually; For Zhongshuang5, the root length shortened gradually, the root length of 150 mg/L GO treatment was 12.8067 cm shorter than CK. Fresh root weight decreased, and stem length lengthened gradually, weight of overground part had no significant change, and the root cap ratio decreased gradually; After been treated for 16 d, the root length of Zhongyou 119 had a tendency of first increasing and then decreasing, fresh root weight decreased, and stem length lengthened gradually, weight of overground part increased gradually, but the root cap ratio decreased gradually.After been treated for 16 d, CAT activities in five varieties of rice seedlings increased. However, SOD, POD activities and MDA content had no obvious regularity. For rape seedlings, the activity of SOD, CAT, POD or MDA content have the tendency of increasing. It may be due to the difference of rice variety, resulting in the difference of reactive oxygen species. However, rape is xerophytes. Growth in solution itself has a stress effect on it.When the concentration of GO was below 10 mg/L, there was no significant difference in the concent of chlorophyll within the three varieties of Nipponbare, Shuangkangmingzhan and R527. Chlorophyll content of 9311 was the highest at concentration of 5 mg/L. However, there was an increase of chlorophyll in Minghui63. After been treated by 10 mg/L GO, the chlorophyll concent reached the highest, and had significant difference with CK. This suggested that 10 mg/L GO had promoted the synthesis of chlorophyll. When the concentration of GO was higher than 10 mg/L, chlorophyll content in the leaves of five varieties of rice all decreased. Chlorophyll content in the leaves of Minghui63, R527 and 9311 were far lower than CK, being respectively 1.2872 mg/g、2.2598 mg/g �'� 1.6992 mg/g lower. For rapes, with the increase of GO concentration, the concent of chlorophyll in Zhongshuangll and Zhongshuang5 had tendency of rising at first and going down latter, and both reached the maximum at 50 mg/L. There was the same phenomenon in the leaves of Zhongshuang7. And the chlorophyll content of GO treatments were higher than CK. However, with the increase of GO concentration, chlorophyll content in leaves of Zhongshuang 9 and Zhongyou 119 rised gradually, the chlorophyll content in this varity was 0.2142 g higher than CK. Research results suggested that, the influence of GO on the germination speed varies between different rice seeds and rape seeds, and no influence on germination rate. With the increase of GO, the phenotype of five varities of rice were different, and inhibitory effect on overground part of the four varieties. For rape seedlings, GO has inhibition effects on the root of five varieties, and acceleration effects on the overground part. After been treated by GO, both rice seedlings and rape seedlings produce different levels of oxidative stress reaction, and GO treatment has influenced the photosynthesis of rice seedlings and rape seedlings. From the results of enzymes, it can be seen that GO had induced oxidative stress reaction, and it is possible that GO had influenced the absorption of nutrient substance and water, leading to the different phenotype of root and chlorine in leaves.