Improving sugarcane agronomy: Field evidence for ultrasonic treatment enhancing yield, growth, and physiological and biochemical characteristics

Abstract

Ultrasonic treatment (UT) is a safe and efficient physical stimulus used to improve crop germination and growth. However, previous studies have concentrated on the germination and seedling stages of ultrasonically treated crops, while field tests of the effects of ultrasound on sugarcane growth have not been reported. In this study, we compared the growth, photosynthetic characteristics, and antioxidant properties of three sugarcane varieties, ‘ROC22’, ‘LC05–136’, and ‘YT93–159’, under no UT (T1), UT (20–40 kHz mixed frequency, dry treatment) for 1 min (T2), UT for 2 min (T3), and UT for 5 min (T4). The field experiments were conducted from January 2021 to January 2023.The effect of UT on newly-planted sugarcane was greater than on ratoon sugarcane for all measured parameters in both years. Compared with the T1 treatment, in 2021 the increases in cane yield and sugar yield under UT (T3 and T4) were 9.76%–28.57% and 7.80%–21.21%, respectively, while in 2022, the increases were 1.19%–12.64% and 2.16%–8.39%, respectively. From the two-year data, compared with the T1 treatment, the sucrose content of sugarcane under the T3 treatment in V1 increased by 0.38%–15.26%; the T3 and T4 treatments in V2 increased the sucrose content by 0.48%–4.90%, and the T4 treatment in V3 increased the content by 1.17%–5.85%. Moreover, suitable UT increased plant height, stem diameter, root length, and germination rate. Suitable UT also increased the chlorophyll content, net photosynthetic rate, stomatal conductance, transpiration rate, superoxide dismutase activity, peroxidase activity, catalase activity, soluble protein content, and soluble sugar content while decreasing the malondialdehyde content in sugarcane leaves. Meanwhile, a multi-analysis showed that a more developed root system, a more efficient photosynthetic rate, and better antioxidant properties after UT treatment led to increased sugar yield of sugarcane. This study is the first to demonstrate that suitable UT (2–5 min, 20–40 kHz mixed frequency, dry treatment) can significantly increase the yield and quality of sugarcane based on field tests. Furthermore, this study shows that ultrasonic seed treatment technology has promising applications in sugarcane cultivation and significant potential in agricultural production.