外源硅对狼尾草属牧草镉胁迫的缓解效应及其机制
发布时间：2018-08-18 07:42
【摘要】：镉(Cd)是土壤主要重金属污染物之一,具有生物毒性强、迁移性大的特点,其在植物体内积累到一定量会影响植物的物质积累和能量代谢而影响植物正常生长。狼尾草属(Pennisetum Rich.)牧草是一年生或多年生禾本科植物,具有生物量大、耐性强、营养含量高等优良特性,是热带、亚热带和温带地区的重要牧草,也是优质的能源草和观赏草,适宜在我国南方种植。本试验以美洲狼尾草(Pennisetum americanum)和杂交狼尾草(P.americanum×Ppurpureum)为材料,采用土壤盆栽的方法,研究了镉对狼尾草的毒害机理,并探讨了硅对镉胁迫下两种狼尾草的缓解效应及其机制,试验结果如下:(1)随着Cd2+浓度增加,两种狼尾草的株高、鲜重以及干重逐渐降低,但叶宽没有显著性变化;两种狼尾草叶片细胞膜透性、丙二醛(MDA)含量、可溶性糖含量及脯氨酸含量呈递增趋势,在高浓度Cd(Cd40、Cd80)处理下,细胞膜透性、丙二醛(MDA)含量、可溶性糖含量及脯氨酸含量均显著增加;低浓度Cd(Cd10、Cd20)处理对两种狼尾草的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性有促进作用,高浓度Cd(Cd40、Cd80)处理对两种狼尾草的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性有明显抑制;Cd处理使两种狼尾草的净光合速率(Pn)、蒸腾速率(Tr)及气孔导度(Gs)显著下降,而胞间二氧化碳浓度(Ci)升高,且在高浓度Cd(Cd40、Cd80)处理下,两种狼尾草的叶绿素含量显著降低。(2)加硅处理明显缓解了镉对两种狼尾草生长的抑制,提高了镉胁迫下两种狼尾草的株高、鲜重和干重,其中硅浓度为4.0 mmol·L-1时,对两种狼尾草株高和鲜干重缓解效果最显著;不同浓度的硅(1.0、2.0、4.0 mmol·L-1)处理能够减少两种狼尾草的丙二醛(MDA)含量,维持脯氨酸含量与可溶性糖含量在一定水平上,提高超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,减轻了膜脂过氧化程度,其中硅浓度为2.Ommol·L-1时,能够显著提高杂交狼尾草狼尾草在Cd40处理下过氧化物酶(POD)和过氧化氢酶(CAT)活性,硅浓度为4.0 mmol·L-1时,能够显著提高两种狼尾草在Cd80处理下超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性。其次,硅处理能够提高镉毒害下两种狼尾草叶绿素含量和光合能力,随着硅浓度增加,两种狼尾草的净光合速率、气孔导度以及蒸腾速率上升,胞间CO2浓度下降,当硅浓度为4.0 mmol·L-1时,高浓度Cd(Cd40、Cd80)组的叶绿素含量显著增加。(3)随着Cd2+浓度增加,两种狼尾草的地上部分Cd含量和根系Cd含量逐渐增加,且根系Cd含量大于地上部分Cd含量;加硅处理后,地上部分Cd含量和根系Cd含量下降,随着硅浓度增加,地上部分Cd含量显著下降。
[Abstract]:Cadmium (Cd) is one of the major heavy metal pollutants in soil, which has the characteristics of strong biotoxicity and large migration. Its accumulation in plants will affect the accumulation of substances and energy metabolism and affect the normal growth of plants. (Pennisetum Rich.) Forage is an annual or perennial gramineous plant with excellent characteristics of large biomass, strong tolerance and high nutrient content. It is an important forage in tropical, subtropical and temperate regions, and is also an excellent energy and ornamental grass. Suitable for planting in the south of China. In this experiment, (Pennisetum americanum) and P.americanum 脳 Ppurpureum were used as materials to study the mechanism of cadmium toxicity to the two species under cadmium stress, and to explore the mitigation effect and mechanism of the two species under cadmium stress. The results were as follows: (1) with the increase of Cd2 concentration, the plant height, fresh weight and dry weight of the two species decreased gradually, but the leaf width did not change significantly. The content of soluble sugar and proline showed an increasing trend. The cell membrane permeability, malondialdehyde (MDA) content, soluble sugar content and proline content increased significantly under high concentration of CD (CD40) CD80. The activities of (SOD), peroxidase (POD) and catalase (CAT) were promoted by low concentration of CD (CD10 + CD20). The activities of superoxide dismutase (SOD),) peroxidase (POD) and catalase (CAT) were significantly inhibited by high concentration of CD (CD40 + CD80), and the net photosynthetic rate (Pn),) transpiration rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) of the two species were significantly decreased. However, the concentration of (Ci) increased, and the chlorophyll content of the two species significantly decreased under the high concentration of CD (CD40) CD80. (2) the inhibition of cadmium on the growth of the two species was alleviated, and the plant height of the two species was increased under cadmium stress. Fresh weight and dry weight, of which Si concentration was 4.0 mmol L-1, had the most significant relief effects on the height and fresh dry weight of the two species, and different concentrations of Si (1.0 ~ 2.0 ~ 4.0 mmol ~ (-1) could reduce the malondialdehyde (MDA) content of the two species. The content of proline and soluble sugar were maintained at a certain level, the activities of (SOD), peroxidase (POD) and catalase (CAT) were increased, and the degree of membrane lipid peroxidation was alleviated, especially when the concentration of silicon was 2.Ommol L-1. The activity of peroxidase (POD) and catalase (CAT) were significantly increased by Cd40 treatment, and the activity of peroxidase (POD) and catalase (CAT) were significantly increased when the concentration of silicon was 4.0 mmol L-1. The activity of superoxide dismutase (SOD),) peroxidase (POD) and catalase (CAT) were significantly increased by Cd80 treatment. Secondly, silicon treatment could increase chlorophyll content and photosynthetic ability of the two species under cadmium toxicity. With the increase of silicon concentration, the net photosynthetic rate, stomatal conductance and transpiration rate of the two species increased, while the intercellular CO2 concentration decreased. When the concentration of silicon was 4.0 mmol L-1, the chlorophyll content of the high concentration CD (CD40) CD80 group increased significantly. (3) with the increase of Cd2 concentration, the CD content in the aboveground part and the root system of the two species increased gradually, and the CD content in the roots was higher than that in the aboveground part of CD. After the addition of silicon, the CD content of the aboveground part and the root system decreased, and with the increase of the silicon concentration, the CD content of the aboveground part decreased significantly.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X173;S54
，
本文编号：2188796
[Abstract]:Cadmium (Cd) is one of the major heavy metal pollutants in soil, which has the characteristics of strong biotoxicity and large migration. Its accumulation in plants will affect the accumulation of substances and energy metabolism and affect the normal growth of plants. (Pennisetum Rich.) Forage is an annual or perennial gramineous plant with excellent characteristics of large biomass, strong tolerance and high nutrient content. It is an important forage in tropical, subtropical and temperate regions, and is also an excellent energy and ornamental grass. Suitable for planting in the south of China. In this experiment, (Pennisetum americanum) and P.americanum 脳 Ppurpureum were used as materials to study the mechanism of cadmium toxicity to the two species under cadmium stress, and to explore the mitigation effect and mechanism of the two species under cadmium stress. The results were as follows: (1) with the increase of Cd2 concentration, the plant height, fresh weight and dry weight of the two species decreased gradually, but the leaf width did not change significantly. The content of soluble sugar and proline showed an increasing trend. The cell membrane permeability, malondialdehyde (MDA) content, soluble sugar content and proline content increased significantly under high concentration of CD (CD40) CD80. The activities of (SOD), peroxidase (POD) and catalase (CAT) were promoted by low concentration of CD (CD10 + CD20). The activities of superoxide dismutase (SOD),) peroxidase (POD) and catalase (CAT) were significantly inhibited by high concentration of CD (CD40 + CD80), and the net photosynthetic rate (Pn),) transpiration rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) of the two species were significantly decreased. However, the concentration of (Ci) increased, and the chlorophyll content of the two species significantly decreased under the high concentration of CD (CD40) CD80. (2) the inhibition of cadmium on the growth of the two species was alleviated, and the plant height of the two species was increased under cadmium stress. Fresh weight and dry weight, of which Si concentration was 4.0 mmol L-1, had the most significant relief effects on the height and fresh dry weight of the two species, and different concentrations of Si (1.0 ~ 2.0 ~ 4.0 mmol ~ (-1) could reduce the malondialdehyde (MDA) content of the two species. The content of proline and soluble sugar were maintained at a certain level, the activities of (SOD), peroxidase (POD) and catalase (CAT) were increased, and the degree of membrane lipid peroxidation was alleviated, especially when the concentration of silicon was 2.Ommol L-1. The activity of peroxidase (POD) and catalase (CAT) were significantly increased by Cd40 treatment, and the activity of peroxidase (POD) and catalase (CAT) were significantly increased when the concentration of silicon was 4.0 mmol L-1. The activity of superoxide dismutase (SOD),) peroxidase (POD) and catalase (CAT) were significantly increased by Cd80 treatment. Secondly, silicon treatment could increase chlorophyll content and photosynthetic ability of the two species under cadmium toxicity. With the increase of silicon concentration, the net photosynthetic rate, stomatal conductance and transpiration rate of the two species increased, while the intercellular CO2 concentration decreased. When the concentration of silicon was 4.0 mmol L-1, the chlorophyll content of the high concentration CD (CD40) CD80 group increased significantly. (3) with the increase of Cd2 concentration, the CD content in the aboveground part and the root system of the two species increased gradually, and the CD content in the roots was higher than that in the aboveground part of CD. After the addition of silicon, the CD content of the aboveground part and the root system decreased, and with the increase of the silicon concentration, the CD content of the aboveground part decreased significantly.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X173;S54
，
本文编号：2188796
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