不同钾水平对苗期玉米铬的吸收和生理特性的影响

采用溶液培养的方法,研究了不同钾素水平对苗期玉米地上、地下部铬的吸收、转运及其生理特性的影响.结果显示,在六价铬作用下,玉米幼苗的各项生理指标均受到一定的影响,生物量随着铬浓度的升高而呈现降低趋势.在铬浓度0-100μmool·L~(-1)之间,植株地上、地下部六价铬的含量随外界铬处理浓度的增加而增加,在100μmol·L~(-1)时,铬含量达到最大;叶绿素含量、根系活力随六价铬浓度的增加而降低,在100μmol·L~(-1),叶绿素、根系活力最小;丙二醛(MDA)含量呈先降低后上升趋势,在40μmol·L~(-1)时,丙二醛含量最小.钾素可缓解重金属铬对玉米幼苗的毒害作用,在400-1 600μmol·L~(-1)间,不同钾水平处理均可显著减少玉米幼苗地下部对铬的吸收,钾浓度为1 600μmol·L~(-1),铬含量最小.随着钾浓度的提高,叶绿素含量、根系活力都增加,但丙二醛(MDA)含量变化没有呈现明显的规律.值得注意的是,当溶液中铬浓度在0-20μmol·L~(-1)间时,地上部铬含量随着钾浓度的增大而逐渐减小,当铬浓度为40-100μmol·L~(-1),随着钾浓度的增大而呈增加趋势,说明高浓度铬处理时,钾町不同程度地促进铬由地下向地上部的转运.

Effects of Different Potassium Levels on Cr Absorbed and Physiological Characteristics of the Maize Seedlings

Cr is known as a toxic agent that is accumulated in the crops over a life time.Solution culture was used to study the effects of different concentration potassium on chromium absorption, transport and physiological characteristics of maize seedlings. The results showed that the physiological indicators of maize seedlings were affected to a certain extent when they were subjected to the appilied concentration of the hexavalent chromium. The biomass decreased with the chromium concentration increasing.The amounts of hexavalent chromium absorbed by maize shoot and root system increased with the concentration in solution. Chlorophyll contents and root activity decreased with the concentration of hexavalent chromium increasing. Malondialdehyde content decressed at first and then rising with the chromium increasing, and malon-dialdehyde content were the minimum at 40 μmol·L~(-1) of chromium. Application of potassium could alleviate chromium poisoning effects. Absorption of chromium in maize seedlings root system could be significantly reduced at different concentration of potassium. With application of potassium increasing, the chlorophyll content and root activity increased, but the malondialdehyde content changed irregularly. The shoot system was worth to be noticed, when chromium concentration were between 0-20 μmol·L~(-1), the amount of chromium decreased gradually with the potassium concentration increasing,when chromium concentration were between 40-100 μmol·L~(-1), the amount of chromium increased with the potassium concentration increasing.This illuminated that different potassium concentration could promote the chromium transiting from the root system to the shoot at high chromium concentration.