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| Cadmium tolerance evaluation and evaluation index screening in nitrogen metabolism of different alfalfa cultivars |
| Received:September 02, 2018 |
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| KeyWord:alfalfa (Medicago sativa L.);nitrogen metabolism;cadmium tolerance;principal component analysis;evaluation index |
| Author Name | Affiliation | E-mail | | YANG Shu | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China
College of Science, Yunnan Agricultural University, Kunming 650201, China | | | ZU Yan-qun | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | LI Bo | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | BI Yu-fen | Faculty of Animal Science and Technology, Yunnan Agricultural University, Kunming 650201, China | | | HE Yong-mei | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | JIA Le | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | | | LI Yuan | College of Resources and Environment, Yunnan Agricultural University, Kunming 650201, China | liyuan@ynau.edu.cn |
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| Abstract: |
| To evaluate cadmium tolerance in nitrogen metabolism of different alfalfa (Medicago sativa L.) cultivars, greenhouse potted experiments of 20 alfalfa cultivars were conducted, with soils treated with 0 (control) and 50 mg·kg-1 cadmium stress. Eleven evaluation indexes, including plant height, biomass, total nitrogen content, nitrogenous compounds content in different forms (nitrate, proline, free amino acid, and soluble protein), and nitrogen metabolism key enzyme activities (nitrate reductase, glutamine synthetase, glutamate synthase, and glutamate dehydrogenase) were measured. The change rates of the above indexes were calculated between the control and treatment groups. Correlations between each two index change rates were analyzed. The comprehensive evaluation value (D) of each cultivar, which was used to evaluate the cadmium tolerance, was calculated based on principal component analysis and membership function method. The multiple linear regression analysis of D was then used to screen the main indexes to establish the mathematic model for the D calculation. The results showed that the change rates of all 11 indicators varied with different cultivars, among which the largest increase (122.24%) was in nitrate content and the largest decrease (-83.00%) was in nitrate reductase activity that were observed in WL525HQ. Correlation analysis showed that there were significant positive pairwise correlations (P<0.05 or P<0.01) among the change rates of plant height, biomass, total nitrogen content, soluble protein content, proline content, nitrate reductase activity, glutamine synthetase activity, and glutamate synthase activity. Out of the 20 alfalfa cultivars, Juren had the largest cadmium tolerance in nitrogen metabolism (D value was 0.89); whereas, Sandeli had the weakest cadmium tolerance (D value was 0.04). Based on the multiple linear regression analysis, plant height, glutamine synthetase activity, glutamate dehydrogenase activity, nitrate reductase activity, nitrate content, and biomass were screened as the main indexes. Based on these six indexes. A regression model was established, which could be used to evaluate cadmium tolerance of alfalfa. |
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