铜对作物幼苗的毒害机理及铁钙缓解铜毒害的研究

【作者】 翟福勤；

【导师】 封克；

【作者基本信息】 扬州大学 ， 植物营养学， 2007， 硕士

【摘要】 环境中越来越多的重金属铜对植物的生长和发育造成了严重的伤害作用。本研究采用水培的方法,以小麦(扬麦12)、玉米(登海11)为实验材料,研究了重金属铜对小麦和玉米幼苗根系和叶片生理生化的影响,并在此基础上探讨了钙对铜所造成的毒害的缓解或恢复作用;并且研究了缺铁和供铁条件下,小麦、玉米幼苗对不同形态铜的吸收特征,以及不同浓度铜和不同形态铜对小麦和玉米幼苗吸收铁的影响。通过研究主要得到如下结论:(1)随着铜浓度的增大,作物幼苗的生长发育受到了不同程度的抑制。作物幼苗受铜毒害的表观现象主要是生物量的降低以及根系的发育受阻。小麦和玉米地上部和地下部的生物量都随着铜浓度的增加而下降;作物幼苗的根系在外源铜存在时受到的伤害最大,主要表现为:铜浓度增大时,小麦和玉米幼苗根系的长度、根系的表面积、根系的体积都缩小了。外源铜的存在也引起了作物幼苗体内的生理生化指标的变化:小麦和玉米叶片和根系的相对膜透性和MDA含量随着铜浓度的增加而升高;小麦和玉米的根系活力和叶绿素含量随着铜浓度的增加而降低;小麦和玉米叶片和根系的铜含量随着铜浓度的增加而增加,并且根系的铜含量显著高于叶片的铜含量。铜能引起作物幼苗根细胞膜电位的变化,膜电位的去极化程度随着铜浓度的增加而加强,膜电位发生改变的时间随铜浓度的增加而缩短。(2)钙的加入对于缓解铜对作物幼苗造成的伤害有一定的作用。钙能提高小麦和玉米幼苗地上部和地下部的生物量,使小麦和玉米幼苗的根系长度、根系表面积以及根系体积加大,同时也能通过对小麦和玉米体内生理生化过程的影响缓解铜的毒害作用:降低了小麦和玉米幼苗植株对铜的吸收量,降低小麦和玉米幼苗叶片和根系的相对膜透性和MDA的含量,提高了小麦和玉米的根系活力和叶绿素含量。(3)缺铁条件下,小麦和玉米幼苗吸收铜的量随着铜浓度的升高显著增加;小麦和玉米幼苗根系铜含量和积累量显著高于地上部铜含量和积累量;无机铜是最容易被小麦和玉米幼苗吸收的形态,而且向地上部的转运也最多。EDTA-铜最不易被吸收,向地上部的转移也少;有机络合铜被吸收的总量较大,但多积累于根部,向地上部运输的比例很小,在有机络合铜中,EDTA络合铜被吸收的量最少,但在体内向地上部的相对转运比例最大。(4)供铁的小麦和玉米幼苗植株对铁的吸收随着铜浓度的增加而显著降低,无论在低铜还是高铜供应条件下,铁在植物体内的分布浓度总是根部高于地上部;介质中不同形态铜的存在对小麦幼苗吸收铁存在一定影响,有机形态铜处理时铁容易被作物幼苗吸收,而无机铜处理时铁被作物幼苗吸收的较少,并且无论供应无机铜还是有机铜,铁在植物体内的分布浓度总是根部高于地上部。(5)在一定浓度范围内,增加铁的使用可以大大减少进入植物体内的铜量,并使已进入植物根系的铜更多地分布在根部,从而减少了地上部铜的含量,减小了铜对作物幼苗的毒害;有机酸-铜络合物的形成对外源铜的吸收有促进作用,但所吸收的铜主要累积在作物根部,说明有机酸络合铜不利于铜向地上部的转运。更多还原

【Abstract】 The growth and development of plants are seriously damaged by increasing of copper in environment. The experiments were carried out with wheat (yangmai 12)、maize(denghai 11), we have studied the effects of copper to physiological-biochemical in roots and leaves of young wheat and yang maize by hydroponic culture, and in the same time we studied detoxification of calcium to the copper toxicity under the same hydroponic culture; We also studied the absorption characters of different copper forms on young wheat and maize plant under Fe deficiency and Fe sufficient treatments, besides we studied effects on iron uptake by young plant of wheat and maize under different concentration coppers and different copper forms. The results were summarized as follows:(1) The growth and development of crop seedlings were restrained in different degrees with the increasing concentration of copper. Decrease of biomass and suffocation of roots growth were the apparent phenomenon of damage of crop seedlings by copper. with the increasing concentration of copper, the biomass of wheat and maize were decreased; the roots of crop seedlings were damaged seriously under the copper treatments: with the increasing concentration of copper, the length,the surface area and the volume of roots of wheat and maize seedlings were all shortened. And the copper also gave effects on the effects of physiological-biochemical in the crop seedlings, the relative permeability of cell membrane and malondialdehyde (MDA) contents in wheat and maize leaves and roots were promoted with increasing copper concentration; the root activity and the chlorophyll contents were decreased under higher copper concentration; the contents of Cu of wheat and maize leaves and roots were promoted with increasing copper concentration. And the change of membrane potential of crop roots was also affected by copper, the depolarization patterns of membrane potential were enhanced with increasing copper concentration, and the happen of membrane potential time was shortened with increasing copper concentration.(2)Addition of calcium into nutrient solution could alleviate the copper toxicity to young wheat plants. Calcium could enhance the biomass of crop seedlings, and increase the length,the surface area and the volume of roots of crop seedlings, and in the same time, calcium could reduce the copper toxicity by changing the physiological-biochemical of wheat and maize: calcium could decrease the assimilation of copper by wheat and maize, reduce the relative permeability of cell membrane and the contents of MDA in wheat and maize leaves and roots of wheat and maize, improve the root activity and the contents of the chlorophyll of wheat and maize.(3)Copper contents in wheat and maize seedlings were added with increasing copper concentration under Fe deficiency treatment; and the contents of copper in roots were notably higher than shoots of wheat and maize. Inorganic copper was the easiest absorbed by young plant of wheat and maize, and most of Cu contents were transferred to shoots. EDTA-Cu was the most difficulty assimilated by crop seedlings, and the transfer of copper to shoots was the least. The gross of assimilation of copper by organic complex coppers was higher, and most of copper was accumulated in roots of wheat and maize, the transfer proportion to shoots was lower. Between five different organic complex coppers treatments, the assimilation of copper by wheat and maize was the lowest under EDTA-Cu treatment, but the relative contents of copper by transferred to shoots were the highest.(4)Copper contents in crop seedlings were increased with increasing copper concentration under Fe sufficient treatment, and the contents of iron in roots were notably higher than shoots under any concentration of copper; the accumulation of iron in crop seedlings was affected by the forms of copper, iron was easier absorbed by yang plants under organic complex coppers treatments than under inorganic copper treatment, moreover, the accumulation of iron in roots was higher than in shoots under organic complex coppers treatments or under inorganic copper treatment.(5)Increasing Fe can visibly decrease copper contents in the plant, and more copper contents stayed in the roots, less were transferred to shoots, so organic complex coppers can decrease copper toxicity to young maize plant. Organic complex coppers gave accelerating effects on copper contents by crop seedlings assimilated, and the assimilated copper was mostly accumulated in roots, result showed that organic complex copper was not propitious to transfer copper to shoots.更多还原