锰对水稻亚铁毒害的缓解作用

The Ameliorative Role of Manganese on Ferrous Toxicity in Rice Plants

以两个籼型水稻密阳46和珍汕97B为研究材料,设置不同水平的亚铁处理和锰处理,研究了锰对亚铁胁迫下的水稻生长和植株铁、锰、锌、磷、钾等元素含量的影响。结果表明,锰处理和铁处理对水稻的株高、根长和植株(地上部和根系)干物质量都有显著影响。随着亚铁处理浓度(2、50、100和200 mg/kg)的升高,密阳46和珍汕97B的株高和根长均显著降低;而随着锰处理水平(0、0.5、25 mg/kg)的上升,两材料株高均明显增加,但根长并未见有明显差异,而100 mg/kg锰处理对植株株高则具有抑制作用。在同一亚铁处理下,与0.5 mg/kg锰处理相比,25和100 mg/kg锰处理显著提高了两材料的地上部和根系干物质量,尤其在亚铁胁迫(50、100和200 mg/kg)时。这表明锰对水稻的亚铁毒害具有缓解作用,但目前实验结果尚不能解释0.5 mg/kg锰处理下的两水稻地上部和根系干物质量均显著低于0 mg/kg锰处理这一现象。结果显示,亚铁处理和锰处理对根膜、根系和地上部铁锰含量以及磷、钾和锌含量都具有明显的影响。密阳46和珍汕97B的根膜、根系和地上部的铁含量,随着亚铁处理水平的提高而显著增加;而在同一亚铁胁迫处理(50、100 mg/kg)下则两材料根膜中的铁含量随着锰水平的上升而呈现减少的趋势,但根系和地上部的铁含量却表现出增加的趋势。在200 mg/kg亚铁胁迫下,密阳46和珍汕97B的根膜、根系和地上部中的铁含量均随着锰处理水平(0.5、25和100 mg/kg)的上升而降低。两材料根膜、根系和地上部的锰含量则随着亚铁胁迫处理的提高而显著降低,而随着锰处理水平的上升而显著增加,表明锰处理浓度上升显著改善了因亚铁胁迫而导致的植株锰营养缺乏,是锰缓解亚铁毒害的重要机制之一。

Two indica rice genotypes, Milyang 46 and Zhenshan 97B were used as materials to study the rice growth and their Fe, Mn, Zn, P, K concentrations in plants under combined treatments with varied concentrations of Fe2＋ and Mn2＋. The results showed that the plant height, root length, dry weight of shoots and roots of both rice genotypes were signifi- cantly affected by Fe and Mn treatments. With increasing levels of Fe2＋ , the plant height and root length of Zhenshan 97B and Milyang 46 were significantly reduced, indicating that both rice genotypes severely sufferred from ferrous stress. However, the plant height of both rice genotypes were markedly increased with the increasing Mn concentration （0,0.5 and 25 mg/kg）, while the root length was not affected; the Mn level of 100 mg/kg inhibited both rice geno- typesrplant height. In the same ferrous treatment, compared with 0.5, 25 and 100 mg/kg Mn levels significantly im- proved the dry weight of the two rice plants （shoots and roots）, especially under ferrous stress （50, 100, and 200 mg/ kg）, implying that the growth of rice suffered from iron stress could be alleviated by application of Mn. The present ex- perimental results coud not explain the phenomenon that the dry weight of the two rice shoots and roots was signifi- cantly lower at 0.5mg/kg Mn level than that at 0 mg/kg Mn level. The results also showed that Fe2＋ and Mn2＋ treat- ment could significantly affect Fe and Mn concentration in root iron plaque and plants（roots and shoots）, as well as the concentration of P,K and Zn. Under the same level of ferrous stress（50,100mg/Kg）, iron concentration decreased in i- ron plaque, while increased in roots and shoots with varied Mn levels. Under 200 mg/kg iron treatment, the concentra- tion of Fe in iron plaque and plants decreased with the increasing Mn concentration （0.5,25,100 mg/kg）, which likely indicates a direct mechanism by which Mn could alleviate ferrous toxicity in rice plants. The concentration of Mn in iron plaque and plant remarkably reduced with varied Fe2＋ levels, while significantly increased with varied Mn levels. The increased manganese concentration in solution significantly improved ferrous-stress-induced Mn deficiency. Mn could al- leviate ferrous stress.