【作者】 陈璐；

【导师】 王昌全；

【作者基本信息】 四川农业大学 ， 土壤学， 2010， 硕士

【摘要】 随着工矿业的发展、农业污水灌溉、污泥和磷肥的施用等,农田土壤Cd污染日趋严重,特别是稻田污染,稻米安全受到影响。Cd污染问题已成为威胁土壤生态安全和制约农业可持续发展的重要因素。如何减轻Cd对水稻的毒害,成为当前亟需解决的问题之一。因此,本文以两份对镉积累吸收能力不同的水稻保持系材料(宜香B、E2B)为供试材料,通过水培试验研究不同钙水平处理对镉胁迫下水稻幼苗根系形态、镉化学形态分布及谷胱甘肽含量的影响。主要研究结果如下：(1)水稻幼苗根系形态在不同Ca、Cd浓度下反应各异,材料间存在差异。单Cd胁迫下,两份水稻材料幼苗根系形态表现出低Cd浓度促进根系生长,高Cd浓度则抑制其生长；在Cd胁迫下,施入外缘Ca,两份水稻材料幼苗根系形态随着Ca浓度的增加呈现出先增加后减少的情况,材料间存在差异。具体表现为,在单Cd胁迫下,低镉处理(1mg/L)对水稻幼苗根系生长有一定的促进作用,均略有升高,但高镉(5mg/L)处理下,水稻幼苗根干重、根总长、根表面积、根体积、根尖数明显受到抑制。无论是在低镉(1mg/L)还是高镉(5mg/L)胁迫下,低中浓度Ca(80,160mg/L)明显促进了水稻幼苗根干重、根总长、根表面积、根体积、根尖数的增加,而高浓度Ca(320mmg/L)抑制了其根系的生长。在镉胁迫时不同供钙水平下,两种水稻幼苗均以直径小于或等于0.4mm的根系为主,对其直径小于或等于0.2mm的根系生长影响最大。Ca(80mg/L、160mg/L)有利于促进水稻幼苗的根系生长,缓解镉对水稻的毒害。无论是钙镉单独处理还是钙镉交互处理对于E2B根系生长影响效应明显大于宜香B,耐镉型水稻材料E2B根系各项指标总是高于镉敏感型水稻宜香B。(2)随着Cd胁迫水平的提高,两份水稻材料幼苗的总Cd含量和不同化学形态Cd含量均增加,材料间存在差异;在Cd胁迫下,施入外缘Ca后,总Cd含量和不同化学形态Cd含量随着Ca浓度的增加先降低后升高,材料间变化各异,各处理间均达显著性差异。在单镉胁迫下水稻幼苗根系和叶片中氯化钠提取态和醋酸提取态是优势形态,其次是水提取态和乙醇提取态,盐酸提取态最少；随Cd处理浓度的增加,水稻幼苗体内总镉含量升高,水稻幼苗根系中乙醇提取态和水提取态的比例略有下降,而在水稻幼苗叶片中,水提取态的比例逐步上升。两种材料相比较,E2B体内总Cd含量和不同化学形态Cd含量比宜香B体内的低；E2B体内乙醇加水提取态的比例比宜香B低,而醋酸加盐酸提取态的比例比宜香B高,说明其体内的Cd处于难以移动的状态。在镉胁迫下施入一定量的钙元素(80mg/L、160mg/L)后,水稻幼苗根系和叶片总镉含量呈现先降低后升高的趋势。水稻幼苗根系和叶片中氯化钠提取态和醋酸提取态依然是优势形态,其次是水提取态和乙醇提取态；水稻幼苗根系和叶片中乙醇提取态和水提取态的比例下降；水稻幼苗中醋酸和盐酸提取态的比例增加大。当钙达到320mg/L时,水稻幼苗中镉总量反而较正常供钙时高,镉的乙醇提取态和水提取态的比例较正常供钙时增加。无论是钙镉单独处理还是钙镉交互处理对于E2B体内镉总量和镉化学形态影响效应明显大于宜香B。(3)水稻幼苗体内谷胱甘肽(GSH)含量在不同Ca、Cd浓度和时期对Ca、Cd的反应各异,材料间存在差异,各处理间达到显著性差异。在单Cd胁迫时,水稻幼苗中GSH含量随着胁迫浓度的增加先升后降。在不同Ca、Cd处理下,低中浓度Ca(80,160mmg/L)提高了镉胁迫下水稻体内GSH含量,减缓了GSH下降的速率,降低了镉对水稻的毒害。低中浓度Ca(80,160mg/L)对低镉(1mg/L)胁迫下水稻材料的缓解效果好于高镉(5mg/L)胁迫下的水稻。高浓度Ca(320mmg/L)则抑制GSH的合成。在单镉胁迫时,水稻幼苗根系和叶片中GSH均随着时间的增加呈现先升后降的趋势；随着处理时间的延长,镉胁迫严重抑制了谷胱甘肽的合成。钙镉处理7天时水稻体内GSH含量明显大于14天时。钙对镉胁迫下水稻根系中的GSH的影响明显大于在其叶片。在整个胁迫过程中,耐镉型水稻材料E2B体内GSH含量总是高于镉敏感型水稻材料宜香B。钙镉处理7天时对宜香B影响效应比E2B大,而钙镉处理14天时则对E2B影响效应大于宜香B。更多还原

【Abstract】 Along with the development of agriculture, irrigation of agricultural wastewater, fertilization of sludge and phosphatic fertilizer, Cd pollution for farmland soil become more and more serious. In particular, the rice safety is affected by the pollution of paddy field. Cd pollution problem has become a threat to the soil ecological safety and an important factor of restricting the sustainable development of agriculture. How to reduce the infect of Cd on rice become a urgent problems to be solved. Therefore, this article used two copies of rice with different cumulative absorbility of cadmium as experimental material, and researched the influence of the root morphology of rice seedlings, distribution of chemical form of Cd and content of GSH under Cd stress with handling by different concentration of Ca. Main research results are as follows:(1) The root morphology of rice seedlings has different reaction under different concentration of Ca, Cd. Only under the stress of Cd, two copies of root morphologies of rice seedlings shows that low Cd concentration promote root growth, high Cd concentration inhibit the growth. Under the stress of Cd and adding Ca, two copies of root morphologies of rice seedlings shows the situation of increasing first, then decreasing along with the increasing of Ca concentration. There is discrepancy between different materials. The specific performance is as below: Under the stress of Cd, handling with low cadmium (1mg/L) promote the growth of rice seedling root, but If handling with higher cadmium (5mg/L), it obviously retrains rice seedlings, root dry weight, total root root, Surface area and volume number. Whether in low cadmium (1mg/L) or higher cadmium (5mg/L), low concentration of Ca (80,160 mg/L) obviously promote the increasing of root dry weight, rice seedlings, total root surface, root volume, root number. And high concentration of Ca (320mg) inhibit the growth of root. Under the stress of Cd and different concentration of Ca, different under two kinds of rice seedlings, with 0.4 mm diameter than the root, the diameter of than 0.2 mm the root growth..Ca (80mg/L, 160mg/L) could promote growth of rice seedling roots and ease the infect of cadmium to rice. Either handling with Cd alone or with calcium and cadmium, the influence to E2B is significantly greater than Yixiang B, and the indexes of E2B is higher than Yixiang B.(2)With the increasing concentration of the cadmium ion, the total content and different charges of cadmium ion content in two kinds of rice seedlings increased. And the discrepancy was existed between two kinds of rice seedlings. When the concentration of the calcium ion increased in the instances mentioned before, the total content and different charges of cadmium ion content descended firstly and rose after separately. After the change, the significant differences existed in two kinds of rice seedlings. When the leaves and roots of rice seedlings was treated with cadmium ion solution only, the extract of sodium chloride solution and acetic acid solution is advantage form, followed by water, ethanol extract and the hydrochloric acid extract. With the increase of the concentration of the ambient cadmium ion solution, the proportion of preponderant state in the water and ethanol fraction of rice seedlings roots descended, while the proportion of preponderant state rose gradually in the water fraction of rice seedling leaves. Compared with the two kinds of examples, E2B total compared with different chemical form Cd content Cd content than the lower body is sweet B, Ethanol extraction ratio of water, add hydrochloric acid and the highest proportion of extraction, the body is difficult to move the Cd. Under cadmium stress in the amount of the element calcium 80mg/L, 160mg/L after seedling leaves and roots of rice in sodium chloride and acetic acid extraction state extraction is still advantage, followed by water extraction form ethanol extract and configuration, When 80mg/L for calcium concentration or 160mg/L, rice seedlings of ethanol extract roots and water extraction, while the proportion of rice seedlings in leaf extract and water is ethanol extraction proportion of big changes, Rice seedlings and acetic acid hydrochloric acid extraction of increasing proportion of state. When 320mg/L calcium to rice seedlings, instead of the normal amount of cadmium than for calcium, cadmium ethanol and water extraction proportion of state for calcium than normal. Either alone or with calcium cadmium to interact with E2B calcium cadmium and cadmium in chemical form of cadmium effect significantly greater than Yixiang B is.(3) the glutathione (GSH) content has different reaction in different concentration of Ca, Cd. There is discrepancy between different materials. When the rice seedlings were stressed by single cadmium (Cd) for 7days, the increasing cadmium concentration would enhance the content of GSH. The content level of GSH in rice seedlings being stressed for 14 days began to drop after rising first. Its roots and leaves both showed the same trends. The results showed that the synthesis of GSH was severely restrained by cadmium. The longer the stress was, the clearer the final effects were. The calcium of low and moderate concentration (80, 160 mg/L) would improve the level of GSH in rice stressed by cadmium, which slowed the degression speed of GSH and alleviated cadmium (Cd) toxicity to rice seedlings. At the same time, the results indicated that the calcium of low and moderate concentration (80, 160 mg/L) showed better alleviation to the rice seeding of low cadmium concentration (1mg/L) than that in high concentration (1mg/L). But the calcium of high concentration (320 mg/L) would restrict the synthesis of GSH. The amounts of GSH in rice plants treated by calcium and cadmium for 7 days were obviously higher than that treated for 14 days. The effects of calcium on the roots were clearly greater than on the leaves. During the whole process, the content of GSH in Cd-resistant rice species E2B always showed higher than the sensitive species YixiangB. The effects of the stress on YixiangB were more notable than E2B, when treated calcium and cadmium for 7 days. On the contrary, the effect on E2B was more remarkable than the other when treated for 14 days.更多还原