低钾胁迫下不同钾效率甘薯的钾吸收利用规律研究

以钾高效品种徐薯28和低效品种济薯22为材料,采用室内土培试验研究了不同施钾量下,甘薯钾的积累与分配及利用规律。结果显示:不施钾显著促进甘薯地上部生长,抑制块根膨大,但品种间变幅不同,钾高效型徐薯28具有更强的根系膨大能力。徐薯28苗期地上部钾浓度显著高于济薯22,叶片和叶柄钾含量分别比济薯22高33.1%、33.9%;但收获期徐薯28植株钾含量为8.7 g/kg,显著低于济薯22的9.8 g/kg。施钾或不施钾下,收获期徐薯28钾分配系数分别为4.2、3.2,济薯22分别为2.0、1.5,表明徐薯28将钾更多分配到块根部分,而济薯22更多分配到茎叶部分。各处理的块根钾利用效率(KIUE-T)为65.1~135.9,施钾及不施钾下,徐薯28块根钾利用效率都显著高于对应的济薯22处理。甘薯植株内钾含量高低是决定济薯22及徐薯28钾利用效率高低的关键因素。因此,两甘薯基因型间钾的利用效率差异主要体现在:徐薯28即使在不施钾下,苗期地上部尤其是茎叶能维持较高的钾含量,为后期块根膨大奠定基础,而收获期维持较高的钾分配系数及植株较低的钾浓度,而济薯22则相反。

Different Responses to Potassium Stress Between Sweet Potato Genotypes with High and Low Potassium Use Efficiencies

Different responses of potassium accumulation and distribution characteristics to potassium stress were studied between sweet potato genotypes Xu28 of high potassium utilization efficiency and sweet potato genotypes Ji22 of low potassium utilization efficiency. The results showed that potassium stress increased the growth of above-part, restrained the root growth, while the change extents were different between the two genotypes. Xu28 had stronger ability in root expanding than Ji22. Potassium concentration in Xu28 seedlings was significant higher than that of Ji22, especially in leaves and petioles, 33.1% and 33.9% higher, respectively. While at harvest period, potassium concentration in Xu28 whole plant was 8.7 g/kg, significantly lower than Ji22 with 9.8 g/kg. Under potassium application or potassium stress, the ratio of potassium distribution of root to shoot were 4.2 and 3.2 for Xu28 and were 2.0 and 1.5 for Ji22, respectively, indicating Xu28 had an ability to dislocate potassium and dry matter to tube root more effectively than Ji22. Potassium use efficiency (KIUE) of two genotypes ranged from 65.1 to 135.9. Xu28 both had significant increase in KIUE under potassium application or potassium stress. The concentrations of potassium in sweet potato shoot, root and whole plant are the dominated factor for potassium use efficiency, indicating higher potassium use efficiency of Xu28 is due to its higher potassium concentrations in leaves, petioles and shoots at seedling stage as well as the higher ratio of potassium accumulation in root to shoot and low potassium concentration in plant.