Reduction of Potassium Supply Alters the Production and Quality Traits of Ipomoea batatas cv. BAU Sweetpotato-5 Tubers

In Bangladesh, sweetpotato is the fourth most important source of carbohydrates behind rice, wheat, and potatoes. Potassium is vital for sweetpotato growth, boosting tuber size, sweetness, disease resistance, and yield quality, with deficiencies leading to poor tuber formation and increased stress susceptibility. The present study evaluated the effect of varying dosages of potassium fertilizer (Muriate of Potash, MoP) on the growth, yield, and biochemical qualities of sweetpotato. As a genetic material, BAU sweetpotato-5 was chosen as it is recognized for its high yield, short duration, and nutritional advantages. There were three treatments—full dosage of MoP (321.6 kg ha−1, T0), half dosage of MoP (160.8 kg ha−1, T1) and no MoP (T2). Four replications of a randomized complete block design (RCBD) were used in the experiment. According to analysis of variance, the morphological and biochemical parameters, such as the fresh weight plant−1, number of tuber plant−1, chlorophyll content, total phenolic content, vitamin C, carotenoid, anthocyanin, Zn, and Fe content varied significantly among treatments. The application of the full recommended dosage of MoP resulted in the highest values for several traits, including the fresh weight plant−1, number of tuber plant−1, chlorophyll content, carotenoid, anthocyanin, and Fe content. Conversely, total phenolic content and vitamin C were highest without MoP application. Principal component analysis (PCA) differentiated treatment T0 from T1 and T2 due to higher positive coefficients of the number of leaves at 115 days after transplantation, vine length at 115 days after transplantation, number of branches, stem diameter, fresh weight plant−1, tuber length, tuber diameter, tuber weight, number of tuber plant−1, SPAD, carotenoid, anthocyanin, Fe, and negative coefficients of total phenolic content, vitamin C, and Zn. The findings suggest that potassium is integral to maximizing both yield and key nutritional components in sweetpotato cultivation.