The heat tolerance screening of a diverse Brassica napus population using a prototype heat screening facility at UWA's Field Station at Shenton Park

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The data set reported here is an important part of a 5-year (2019-2024) national-wide research project entitled of “Improving canola heat tolerance - a coordinated multidisciplinary approach (UWA1905-007RTX)”. Previous research at UWA on heat stress in several Brassica species has shown that heat stress caused flower abortion, pod abortion and thus seed yield reduction. Heat stress tolerance is controlled by many QTLs distributed across the genome and dispersed in diverse genetic background. Based on these findings, we established a protocol for heat tolerance screening and constructed a prototype heat screening facility (HSF) at UWA. A total of 322 genotypes were assessed for heat tolerance at UWA’s Field Station at Shenton Park, Western Australia (31°56′54′′ S, 115°47′44′′ E). In the prototype HSF, 200 genotypes were assessed for heat tolerance in 2020, and 210 genotypes in 2021 with 88 genotypes in common in both years. In 2022, we further confirmed the heat tolerance of 100 genotypes selected from the previous 2 years (2020 & 2021). This data set consists of the original data from the heat tolerance screening in these 3 years. In this experiment, two environments were related to sowing timings: the early season was sown in mid-April and the late season was sown in early June. The genotypes were randomised in heat treatment pairs, i.e. pots with different heat treatments were placed side-by-side for a given genotype. All genotypes were evaluated for heat tolerance at 25 ⁰C day/15 ⁰C night as control treatment and at 32 ⁰C 4 hours at mid-day/22 ⁰C night as heat stress treatment for seven days from the date of first open flower. All plants were harvested at maturity. Five traits were measured based on main stem: seed yield on main stem, pod number on main stem, seed number on main stem, seed number per pod and 100 seed weight on main stem. Three traits were measured based on whole plant: seed yield on whole plant, above-ground biomass and harvest index. All the traits were analysed using linear mixed effects models. Stress tolerance index (STI) and percentage change (PC), across eight traits were used to determine the heat tolerance/sensitivity level.