Objective The study was conducted to screen banana varieties with low postassium (K) tolerance and high K efficiency, with a view to providing theoretical basis for the promotion of banana varieties with low K tolerance and high K efficiency in Guangdong Province, where K deficiency is common and serious.

Method With Fenza No.1, Nantianhuang and Baxi, the main banana varieties in Guangdong Province, as tested materials, the normal K (NK) and low K (LK) hydroponic experiments were designed to measure the physiological indexes related to K nutrition, and to conduct in-depth comparison and screening from the aspects of biomass, physiological characteristics and mineral nutrition.

Result Compared with NK, the decrease of pseudostem diameter, plant height, fresh weight and dry weight of Nantianhuang was the lowest under LK treatment for 30 days, and the total dry weight of Nantianhuang decreased by 9.87%, which was 49.87% and 54.32% of that of Fenza No.1 and Baxi, respectively. Although the root activity and soluble sugar content of the whole plant of Fenza No.1 were higher than those of Baxi and Nantianhuang after LK treatment, while there was no significant difference in N and P accumulation of Nantianhuang, but there was significant difference between the other two varieties. The potassium accumulation of Nantianhuang decreased by 47 g per seedling, which was 65.28% and 75.81% of that of Fenza No.1 and Baxi, respectively, and only the potassium distribution ratio of Nantianhuang shoot increased after Low K treatment. The two results showed that the K efficiency coefficient of Nantianhuang was the highest, followed by Fenza No.1, and Baxi was the lowest.

Conclusion Nantianhuang is more tolerant to Low K than Fenza No.1 and Baxi, and is insensitive to Low K stress, while Fenza No.1 and Baxi are sensitive to Low K stress. Therefore, Nantianhuang is most resistant to low K among the three varieties.