Performance of mesocotyls at three sowing environments. (A) Schematic diagram of experimental population construction and analysis. (B) Performance of the mesocotyl length (MES) of LM pool (the 30 largest MES-pool) and SM pool (the 30 shortest MES-pool) at a 20 cm sowing environment. (C) MES of the parents (W64A and K12) and their F1 hybrid under 3, 15, and 20 cm sowing environments, respectively; different lowercase letters with different materials in a single environment indicated a significant difference with p < 0.05 (ANOVA). (D) Boxplot of MES showing the difference between LM pool and SM pool used for a BSA under 20 cm sowing environment; asterisks indicated significant differences (** p < 0.01; ANOVA). (E) Compared to 3 cm sowing conditions, the rate of change (RC) of MES in two parents, F1 hybrid, and F2:3 population under 15 and 20 cm sowing conditions, respectively; asterisks indicated significant differences (** p < 0.01; ANOVA). (F) Heterosis analysis (HI: F1 heterosis index, RH: relative heterosis, MH: mid-parent heterosis, OH: over-parent heterosis, ARR: F2:3 advantage reduction rate) of MES.