不同锰处理对镉胁迫下2种油菜重金属累积和根系形态的影响

采用水培试验,研究Cd胁迫(10μmol·L~(-1))条件下,不同浓度Mn(0,0.1,1,10,100μmol·L~(-1))处理对2种镉累积能力不同的油菜生物量、Cd和Mn含量以及根系形态参数的影响。结果表明,与正常营养处理Mn1相比,缺Mn和Mn过量处理显著降低2种油菜的地上部和镉低积累油菜"华骏"的根部生物量,而对普通油菜"寒绿"的根部生物量没有显著影响。与Mn1处理相比,缺Mn处理下2种油菜的Cd累积总量和"华骏"地上部Cd含量显著降低;Mn过量处理下2种油菜根部和地上部Cd含量均呈升高趋势,2种油菜的Cd累积总量无显著变化或显著降低。随Mn处理浓度升高,2种油菜地上部和根部Mn含量显著升高,缺Mn处理下2种油菜根部的Mn含量低于Mn缺乏的临界值。与Mn1处理相比,缺Mn处理下"华骏"的根长、表面积、体积、平均直径和根尖数显著降低;Mn过量处理下"寒绿"的根长以及"华骏"的根系表面积、体积显著降低;缺Mn处理下2种油菜细根表面积所占的比例增加,粗根表面积比例降低;Mn过量时,"寒绿"的粗根表面积比例增加,细根比例降低,而"华骏"则相反。总的来看,缺Mn处理影响油菜根系和地上部生长,减少地上部Cd含量和植株Cd累积总量;Mn过量处理下油菜生长也受到抑制,但是油菜地上部和根部Cd含量有所升高;2种油菜的根系形态学参数在不同Mn处理下变化规律不同,表现出不同的响应策略。

Effects of Different Manganese Treatments on Heavy Metals Accumulation and Root Morphology of Two Cultivars of Brassica chinensis under Cadmium Stress

A solution-culture experiment was conducted to investigate the effects of different manganese ( Mn ) treatments (0, 0.1, 1.0, 10.0 and 100.0μmol·L-1) on the biomass of two cultivars of Brassicachinenesiswith differ-ent cadmium (Cd) accumulation, as well as the influence on Mn and Cd concentrations in Brassica chinenesis and the root morphological parameters under Cd treatment (10.0μmol·L-1). Results show that the biomass of shoots of the two cultivars and roots of the low Cd accumulating cultivar"Huajun" was significantly reduced under low and high Mn treatments when compared with normal Mn treatment (1 μmol·L-1 ), but it was not significantly different for root biomass of the common cultivar"Hanlv". The total Cd accumulation of the two cultivars and the Cd con-centrations in shoots of Huajun under low Mn treatments were significantly lower than those under Mn1 treatment. Under high Mn treatments, Cd concentrations in roots and shoots of the two cultivars were increased, but the total Cd accumulation did not significantly change or decrease in comparison with Mn1 treatment. Mn concentrations in shoots and roots of the two cultivars significantly increased with the increasing Mn levels in the solution. Under low Mn treatments, the Mn concentrations in roots of the two cultivars were lower than the critical value of Mn de-ficiency. Under low Mn treatments, root length, surface area, volume, average diameter and root tip number of"Huajun" significantly decreased compared to those under Mn1 treatment. In contrast with Mn1 treatment, root length of "Hanlv", root surface area and volume of "Huajun" decreased significantly under high Mn treatments. Under low Mn treatments, the percentage of root surface area of fine roots (≤0.4 mm) in the two cultivars in-creased, and the percentage of thick roots (≥1.0 mm) decreased, when compared to Mn1 treatment. Under high Mn treatments, the percentage of root surface area of thick roots in "Hanlv" increased and that of fine roots de-creased, and the opposite trend was seen in "Huajun". In general, under low Mn treatments, the growth in roots and shoots of the two cultivars was affected, Cd concentrations in shoots and total Cd accumulation decreased. Un-der high Mn treatments, the growth of the two cultivars was also inhibited, but Cd concentrations in shoots and roots increased. The root morphological parameters of the two cultivars exhibited different response strategies under different Mn treatments.