root surface area and active absorption area can be used to evaluate characteristics of P efficiency, and four-leaf age is the right age to screen soybean genotypes with tolerance to P deficiency.

• 四叶期可作为大豆耐低磷胁迫的筛选期,根表面积和活跃吸收面积可作为衡量磷效率特性的特异性指标。