Physiological Response of Phosphorus-Efficient and Inefficient Soybean Genotypes under Phosphorus-Deficiency

Abstract

Phosphorus (P) deficiency in soil is becoming more common, and low P efficiency restrains soybean growth and production. To explore critical factors determining efficient P use, root growth and physiological characteristics were investigated in the P-efficient soybean (Glycine max (L.) Merr.) L13 and P-inefficient soybean T3 in a sand culture experiment with two P deficient treatments (0.25 and 0.0 mM P) and a control-standard P (0.5 mM P) treatment. Results showed a decrease in soybean yield under P deficiency, but the yield reduction of genotype L13 was much less than that of T3. The grain yield of L13 was 40.5, 64.2 and 141.6% higher than that of T3, under 0.5, 0.25 and 0.0 mM P treatments, respectively. Genotype L13 activated sugar metabolism in roots and released H+ into the root hair zone to acidify the rhizosphere to resist P deficiency. P deficiency induced an increase in aspartic acid concentrations in root, the increase being substantially greater in the P efficient genotype. These findings suggested that the P-efficient genotype L13 has established more responsive mechanisms and better countermeasures against P deficiency. The findings of this study will be useful in further research aimed at optimizing soybean responses to P deficiency.