ABSTRACT

Flax (Linum usitatissimum L.) is an important industrial crop in fiber production. This study is aimed to isolate specific germplazms with high potassium efficiency. Totally 50 flax germplazms were planted in an experimental field in Heilongjiang, China (126°28′E, 46°27′N). Fertilizer was applied under the soil before seeding with two potassium levels (K0, 0 kg/ha K₂SO₄; K50, 50 kg/ha K₂SO₄). The potassium utilization efficiency was calculated as fiber yield/(aboveground dry weight × potassium content), and the partial factor productivity was calculated as fiber yield/unit of K₂SO₄ applied (K50). The application of potassium fertilizer improved the agronomic and yield traits of most flax germplazms, including the plant height, technical length (length from cotyledon trace to base of the first branch), fiber content and yield, stem yield, and seed yield. However, the application of potassium fertilizer did not influence the plant length in 7 germplazms, technical length in nine germplazms, and stem yield in four germplazms. Based on the potassium utilization efficiency, flax germplazms were classified into four categories, including I (low efficiency, K0:17.62–34.38; K50:16.82–29.67), II/III (middle efficiency, K0:36.51–75.34; K50:32.56–58.74), and IV (high efficiency, K0:83.41–91.42; K50:61.38–71.39). Sofie, Yuan-2012-306, Yuan-2012-295, D93005-15-3 were identified to be high potassium utilization efficiency under both K0 and K50. The above agronomic and yield traits of flax were positively correlated with the potassium utilization efficiency. In addition, the partial factor productivity was greater than 70 kg/kg in 8 germplazms, and was lower than 50 kg/kg in 7 germplazms. The top five germplazms in partial factor productivity were Sofie, 92,104-9-3, y0332-1, D93005-15-3, and 98,019–10. To sum up, Sofie and D93005-15-3 with both high partial factor productivity and potassium utilization efficiency were isolated, presenting a promising prospect in agricultural production.