Physiological studies on anthocyanin accumulation, quality and yield of purple sweet potato tubers with different forms of potassium fertilizer
Jingwei Huang, Qiang Wang, Qingcheng Qiu, Liang Zou, Xueshan Shen, Yan Wan, Huijuan Qu
Abstract
• Purple sweet potatoes have different sensitivities to different forms of potassium fertilizer. • Potassium fertilizer increases the anthocyanin content of tubers by enhancing the activity of key enzymes involved in anthocyanin biosynthesis. • Potassium fertilizer application increased the yield of purple sweet potato tubers. • We found that the use of KCl as a potassium fertilizer is more suitable for the actual production of purple sweet potatoes. Purple sweet potato (PSP) is a nutrient-rich, potassium-favoring grain crop. The judicious application of potassium fertilizer significantly influences the quality and yield of PSP tubers. We conducted two years of field experiments to scientifically determine the optimal types of potassium fertilizers and enhance the quality and efficiency of PSP production. Using no potassium fertilizer as the control (CK), we established four treatments: KCl, K 2 SO 4 , K 2 HPO 4 , and KH 2 PO 4 . The results indicate that different forms of potassium fertilizer enhance the activity of key anthocyanin synthases, including phenylalanine ammonia-lyase (PAL, EC 4.3.1.5), chalcone isomerase (CHI, EC 5.5.1.6), dihydroflavonol 4-reductase (DFR, EC 1.1.1.219), and UDP-galactose flavonoid 3-O-galactosyltransferase (UFGT, EC 2.4.1.91), thereby increasing the anthocyanin content of the tubers. Furthermore, these fertilizers can enhance the quality and yield of PSP tubers to a certain extent. We further combined hierarchical clustering, principal component analysis (PCA), and comprehensive fuzzy mathematics evaluation. Our results indicate that the anthocyanin content, accumulation, yield, and quality composition indicators of “Mianzishu No.9″ are more sensitive to KCl than to other potassium fertilizers. This suggests that using KCl as a potassium fertilizer is more conducive to the actual production of PSP. This study is the first to analyze the impact of different forms of potassium fertilizers on the biosynthesis of PSP anthocyanins and the research results further elucidate the applicability of KCl in sustainable agricultural practices.