Dry matter partitioning and K distribution of vegetable soybean genotypes with higher potassium efficiency

Field and pot experiments were conducted to select and identify the characteristics of potassium (K) high efficiency vegetable soybean genotypes. Forty genotypes under two potassium application levels (0, 120 kg ha⁻¹ K₂SO₄) showed variations in K concentration, K accumulation, K internal use efficiency (KIUE) and K harvest index (KHI) in field experiment conducted in 2016. According to the distinct KIUE for yield (KIUE-Y) and KHI, two K high efficiency (KHE) genotypes (T117, L113) and two K low efficiency (KLE) genotypes (DZ1, ZX8) were used in pot experiment with two K levels (0, 120 kg ha⁻¹ K₂SO₄) in 2017 for further investigation. Results indicated that KIUE-Y was significantly correlated with harvest index (HI) and KHI. Both K and dry matter (DW) were optimally distributed in the seed of KHE genotypes. In contrast, more DW and K were accumulated in vegetative organs of KLE genotypes, which was the main reason limiting K efficiency. Under K deficiency, KHE genotypes better regulate their DW and K distribution, and have higher specific leaf weight with unaffected leaf area.