Optimal potassium fertilization mitigates drought stress effects on sugarcane growth and physiology

Sugarcane is a key global crop, providing up to 60 % of raw sugar material. However, abiotic stress factors, especially water scarcity, significantly limit its productivity by reducing nutrient uptake and transport within the plant. Ensuring proper nutrition is essential to improve stress tolerance and maintain sugarcane yield. This study conducted a two-factor experiment following a completely randomized design in a greenhouse to evaluate the effects of potassium application (in soil) on the growth and physiology of a sugarcane cultivar named ROC27 (ROC27 cv.) under a drought condition. The first factor was potassium application (in the form of potassium oxide) with 4 different rates, including K1 (0 kg/ha), K2 (100 kg/ha), K3 (150 kg/ha) and K4 (200 kg/ha), while the second factor was irrigation with 2 treatments: control (normal irrigation daily); drought (no irrigation from 100-120 days after planting). Here, we revealed that drought significantly affected sugarcanes' growth and physiological characteristics as it decreased plant height, stem diameter, chlorophyll content, photosynthetic efficiency, total plant dry weight and stem fresh weight. Different rates of potassium oxide application in the soil also showed different influences on the growth and development of sugarcane. Applying 100 kg/ha potassium oxide resulted in the highest growth and physiological performance under drought conditions. Furthermore, plants from this treatment also recorded the highest stem fresh weight of ROC27 at the end of the recovery period (20 days of re-watering after drought treatments). Taken together, these results indicate that an appropriate amount of potassium oxide application significantly enhanced sugarcane physiological traits and mitigated the adverse effects of drought on plant growth and development.