Localized phosphorus promotes nutrient productivity of Brassica chinensis genotype with strong root morphological plasticity

Abstract

Crops adjust root morphological and/or exudation traits in response to phosphorus (P) availability and localized P, governing crop productivity. However, how the intraspecific plasticity of root P-acquisition strategies influences plant adaptation to localized P fertilization across doses remains obscure. Root P-acquisition traits were assessed in Brassica chinensis L. Xiaqing and Yanchun grown in soil with four mineral P fertilization levels (0, 15, 24, and 30 kg P ha−1) and with broadcasted and localized P across two levels (15 and 24 kg P ha−1) to characterize efficient strategies in relation to large plant P productivity. The Xiaqing genotype stimulated the growth of roots with large specific lengths and increased the exudation of acid phosphatase and carboxylates under 15 kg P ha−1 fertilization compared to those in 24 and 30 kg P ha−1 soil. Conversely, Yanchun only increased root elongation in 15 kg P ha−1 soil compared with crops in soil fertilized with 30 kg P ha−1. Xiaqing and Yanchun stimulated local root growth in P-rich soil with 15 and 24 kg P ha−1, but with longer roots in the former than the latter genotype. Localized P at the 15 kg P ha−1 level, compared with 24 kg P ha−1, increased root length density in the patchy soil zone and promoted P acquisition in Xiaqing and Yanchun. In conclusion, the Xiaqing genotype exhibited strong root plasticity in response to low and localized P application compared with the Yanchun genotype. Nutrient-efficient genotype coupling with localized fertilization is important to increase crop yield and save fertilizer in vegetable cropping systems.