Abstract: In order to explore the root characteristics of different flue-cured tobacco genotypes and their effects on morphological changes of soil potassium in rhizosphere soil, this paper set a pot experiment by 2 treatments of exogenous potassium (NK) and normal potassium supply (UK) on 4 flue-cured tobacco genotypes, including Nongda 202, NC628, Yunyan 87 and NC89. Root morphology, root exudates and rhizospheric potassium activation of 4 genotypes were determined. The results showed that the chemical composition of root secreta had the most kinds of organic acids, but there were differences in genotypes. Under UK treatment, Nongda 202 had the highest content of rhizosphere organic acids, which was 1.36 times of that of NC89. The conversion of slow-release potassium to available potassium was the most and the potassium content in leaves were the highest. Under UK treatment, Nongda 202 had a large and vigorous root system. Its total root length, total surface area, root system activity and root system ATPase activity were 1.49~1.90 times of that of NC89. Under NK treatment, the total root length, total surface area, root system activity, root system ATPase activity of Nongda 202 decreased over 30% compared with that under UK treatment. Under UK treatment, the correlation coefficients of potassium content in middle leaves with rhizosphere organic acids, root system activity, total root length and total root surface area reached 0.837~0.942, respectively. The contents of organic acids, root system activity, ATPase activity and total root length, total surface area had 0.6 or over 0.6 correlation. Therefore, genotypes with longer root length and larger total surface area were most likely the genotypes with large secretion of organic acids in root system, high root system activity and high potassium content in leaves, which might be used as important reference for evaluating high-potassium genotype of flue-cured tobacco.

Key words: flue-cured tobacco, genotype, potassium content, root exudates, root system morphological physiology

摘要： 为了探究不同烤烟基因型的根系特性及其对根际土壤钾素形态变化的影响，通过盆栽试验，设置无外源钾(NK)和正常供钾(UK)2个处理，测定了4个不同烤烟基因型农大202、NC628、云烟87和NC89的根系形态指标、根系分泌物及根际土壤钾素活化状况。结果表明：烤烟根系分泌物化学组成上有机酸种类最多，但具有基因型差异；UK处理下农大202根际有机酸含量最高，是NC89的1.36倍，土壤缓效钾向速效钾的转化最多，并且烟叶钾含量最高。UK处理下农大202具有庞大的根系和旺盛的根系生理活动，其总根长、总表面积、根系活力、根系ATP酶活性是NC89的1.49~1.90倍；NK处理下，农大202的总根长、总表面积、根系活力、根系ATP酶活性较UK处理均下降30%以上。UK处理下，中部叶钾含量与根际有机酸、根系活力、根系总长、根总表面积的相关系数分别都达到0.837~0.942，根际有机酸含量、根系活力、ATP酶活性与根总长、总表面积均有0.6以上的相关性。因此，根系总长较长、总表面积较大的基因型很可能是根系分泌有机酸量大、根系活力高、叶高钾含量的基因型，可作为高钾烤烟基因型评价的重要参考。

关键词: 烤烟, 基因型, 钾含量, 根系分泌物, 根系形态生理