Fig 1. Frequency distribution of leaf relative injury (LRI) among three F₂ populations with 147 individuals (A), 56 individuals (B), and 60 individuals (C).

L1: heat tolerant parent P17; L6: heat sensitive parent P23. Distribution of L1 near the origin of the x-axis indicates negative transgressive segregants, while distribution of L6 indicates positive transgressive segregants under heat-stress conditions. DNA of eighteen seedlings was selected from an F₂ population with 147 individuals (A) with extreme phenotypes (low and high LRI values) to develop tolerant and sensitive pools.