铁、锰对广西宿根甘蔗幼苗黄化的影响

Effects of iron and manganese on ratoon sugarcane seedlings chlorosis in Guangxi

【目的】明确铁、锰对宿根甘蔗幼苗黄化的影响,为有效解决广西宿根甘蔗幼苗黄化病问题提供科学依据。【方法】以新台糖22号为试验材料,采集其宿根甘蔗幼苗黄化叶片和正常叶片,通过成对数据t检验和相关分析法对比分析21组样品的叶绿素、全铁、活性铁、全锰、活性锰、铁和锰亚细胞组分含量及活性铁/锰比值的差异。【结果】宿根甘蔗幼苗黄化叶片的叶绿素含量(0.42 mg/g)极显著低于正常叶片(2.20 mg/g)(P<0.01,下同),活性铁含量(5.94 mg/kg)极显著低于正常叶片(13.42 mg/kg),但黄化叶片全铁含量(323.36 mg/kg)、全锰含量(572.59 mg/kg)和活性锰含量(92.47 mg/kg)均极显著高于正常叶片。相关分析结果表明,甘蔗幼苗叶片的叶绿素含量与活性铁含量呈极显著正相关性,与活性锰含量呈极显著负相关性;活性锰含量与活性铁含量呈极显著负相关性,黄化叶片的活性铁/锰比值(7.89)极显著低于正常叶片(61.68)。黄化叶片亚细胞器中铁含量排序依次为:细胞壁>细胞核>线粒体>叶绿体>可溶性部分,而正常叶片的叶绿体中铁含量仅次于细胞壁。宿根甘蔗黄化叶片的亚细胞组分铁含量(63.30 mg/kg)虽略高于正常叶片(62.97 mg/kg),但叶绿体中铁含量(3.24 mg/kg)显著低于正常叶片(7.82 mg/kg)(P<0.05)。宿根甘蔗黄化叶片亚细胞组分锰总量(93.04 mg/kg)是正常叶片的3.95倍,但黄化叶片89.01%的锰主要分布在细胞壁和可溶性组分,只有10.99%的锰存在于生理活性区。【结论】叶片活性铁/锰比值低,高锰抑制铁的活性,铁向叶绿体运输受阻是宿根甘蔗幼苗生理性缺铁黄化的主要原因之一,过量的锰贮存在细胞壁和可溶性部分可能有利于宿根甘蔗幼苗对锰毒的忍耐。

【Objective】The effects of iron and manganese on ratoon sugarcane seedlings chlorosis were clarified to provide scientific basis for solving the chlorosis disease of ratoon sugarcane seedlings in Guangxi.【Method】Using 21 pairs of chlorotic leaves and normal leaves of ratoon sugarcane seedlings(Xintaitang 22)as materials,the differences of chlorophyll,total iron,available iron,total manganese,available manganese,iron and manganese subcellular components content and the ratio of available iron/manganese ratio were compared and analyzed by paired data t-test and correlation analysis.【Result】Chlorophyll content(0.42 mg/g)in the chlorotic leaves of ratoon sugarcane seedlings was extremely significantly lower than normal(2.20 mg/g)(P<0.01,the same below),and available iron content(5.94 mg/kg)was extremely significantly lower than normal(13.42 mg/kg),but total iron content(323.36 mg/kg),total manganese content(572.59 mg/kg)and available manganese content(92.47 mg/kg)in the chlorotic leaves were extremely significantly higher than normal leaves.The correlation analysis results showed that chlorophyll content exhibited extremely significant positive correlation with available iron content and extremely significant negative correlation with available manganese content in the leaves of ratoon sugarcane seedlings.Available manganese content exhibited extremely significant positive correlation with available iron content in the leaves,and available iron/manganese ratio(7.89)in the chlorotic leaves was extremely significantly lower than normal leaves(61.68).The sequence of iron content in subcelluar organelles of chlorotic leaves was cytoderm>karyon>mitochondrion>chloroplast>soluble fraction,while iron content in the chloroplast of normal leaves was second only to cytoderm.The total iron content of the subcellular component in the chlorotic leaves(63.30 mg/kg)was slightly higher than normal leaves(62.97 mg/kg),but the iron content(3.24 mg/kg)in the chloroplast was significantly lower than normal leaves(7.82 mg/kg)(P<0.05).The total manganese content of the subcellular component in the chlorotic leaves(93.04 mg/kg)was as 3.95 times as that of normal,but 89.01%manganese content of chlorotic leaves were stored in cytoderm and soluble fraction,while only 10.99%manganese content had physiological active zones.【Conclusion】Available iron/manganese ratio is low,overactive manganese inhibits iron activity,the transport of iron to chloroplast is blocked,which is one of the main causes of physiological iron deficiency on ratoon sugarcane seedlings chlorosis,and excess manganese is stored in cytoderm and soluble fraction,which can be beneficial to tolerance of ratoon sugarcane seedlings to manganese toxicity.