Effects of nitrogen, phosphorus, and potassium fertilization on plant growth, element levels in plants and soil, and the relationships among nutrient concentrations, plant yield, and nutrient status in Erythropalum scandens (Blume)

Abstract

Erythropalum scandens is a leafy vegetable that grows in southern and southwestern China. While nitrogen (N), phosphorus (P), and potassium (K) fertilization as well as organic fertilization in early-stage plants have been well-studied, little is known about the nutrient requirements of it. We therefore conducted a series of pot experiments based on the 3414 strategy (3 factors, 4 levels, and 14 treatments) for N, P, and K fertilization to examine the effects on the soil properties, plant growth morphology, and NPK status of 1.5-year-old E. scandens seedlings. The Diagnosis Recommendation Integrated System was applied at the end of the fertilization period to determine the relationships between nutrient concentration, plant yield, and nutrient status. The results showed that, compared to the control, a better growth status was achieved in response to all treatments except the N0P2K2 treatment. The N, P, and K concentrations and contents in the roots, stems, and leaves of the seedlings differed depending on the treatment. Excessive fertilization, especially excess P, led to soil acidification (N2P3K2, pH 5.88). The optimum concentration ranges of N, P, and K in leaves were 17.138–18.434, 0.002–1.106, and 6.325–10.087 g/kg, respectively. Our study indicates that E. scandens seedlings have a stronger sensitivity to N levels than to K or P levels. A deficiency of N caused yellow, scarce leaves, and a low yield whereas excessive N poisoned the roots and adversely affected the growth of aboveground parts of the plants. Most treatments in the high-yield group resulted in a balanced nutrient status.