Fig. 2.

Genetic correlation analysis of grain yield and root morphology traits. Grain yield data (kg ha^− 1) was acquired for plants grown on a low-P soil. The root morphology traits assessed after 13 days in nutrient solution with low-P are total root length (cm), root diameter (RD), total root surface area (SA), surface area of roots in the diameter classes of 0–1 mm (SA1, designated as very fine roots), 1–2 mm (SA2, fine roots) and 2–4.5 mm (SA3, thicker roots), and volume of fine roots between 1 and 2 mm in diameter (root volume 2, in cm³). Surface area measurements are expressed in cm². Pearson correlation coefficients (r) and p-values (p) are shown