富钾基因型烤烟的钾积累及根系生理特性

Potassium Accumulation and Root Physiological Characteristics of Potassium-Enriched Flue-Cured Tobacco Genotypes

采用室内营养液培养(钾浓度为3mmolL-1)的方法,以富钾基因型烤烟农大202与2个一般型品种净叶黄、NC89为材料,研究富钾基因型烤烟钾积累及根系生理特性。结果表明,3个烤烟品种根和茎中钾积累量无显著差异,但农大202的叶片钾积累量、根系活力和根系总活力、根系H+分泌量、根系阳离子交换量(CEC)、根系可溶性蛋白含量和ATPase活性均极显著高于另两个品种。净叶黄、NC89间除根系活力和根系H+分泌量差异达显著水平外,其他根系生理特性差异均不显著。根系钾吸收动力学参数结果显示,农大202苗期钾离子最大吸收速率(Vmax)较高而米氏常数(Km)和钾离子吸收临界浓度(Cmin)较低,而旺长期的Vmax、Km及Cmin均较高,说明其根系具有较高的钾吸收速率,但旺长期后耐低钾能力较差。

High quality of flue-cured tobacco in production in China is currently limited by low potassium content in leaf. It is necessary to screen the potassium-enriched flue-cured tobacco genotypes for alleviating the shortage of available potassium in soil. However, there is no standard procedure for such screening. Three different genotypes of flue-cured tobacco including one potassium-enriched cultivar Nongda 202 and two common cultivars of Jingyehuang and NC89 were surveyed in potassium accumulation and root physiology with a hydroponic culture at normal K level （3 mmol L^-1）. The results showed that the potassium accumulation of root and stalk among three cultivars were not significantly different, whereas, the leaf potassium concentration of Nongda 202 was significantly higher than that of Jingyehuang and NC89. The indices of root physiology consisting of root vigor and total root vigor, excreted H^＋, CEC, soluable protein content, and ATPase activity in Nongda 202 were significantly higher than those in Jingyehuang and NC89, but there were no significant differences in those except root vigor and H^＋ excretion between Jingyehuang and NC89. Compared with Jingyehuang and NC89 in the K^＋ dynamic uptake parameters of root, Nongda 202 had higher Vmax and lower Km, Cmin at seeding stage, but higher Vmax, Kin, and Cmin at vigorous growing stage, indicating that the potassium absorption velocity of Nongda 202 was higher, but its tolerance to low potassium was weaker at vigorous growing stage. In conclusion, the potassium accumulation capability of leaves is strong, the physiological activity is vigorous and the potassium absorption rate of roots are high in potassium-enriched flue-cured tobacco genotype.