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. 2019 Oct 25;10:1342. doi: 10.3389/fpls.2019.01342

Figure 1.

Figure 1

B. napus winter accessions show variability on seed germination kinetics. (A) WOSR accessions show significant differences in germination speed. Although most accessions started to germinate, defined as the radicle breaking through the testa, at 12 hai, main differences arise at T50 (required time to reach 50% of germination) with values that differ from 27 to 42 hai. The graph represents germination rates obtained for WOSR accessions C166, C129, C124, C033, and C032 for each time point tested (2, 12, 36, and 72 hai). (B) WOS accessions seeds with representative germination rates (high, medium, or low; C129, C033, and C032, respectively) were photographed during the time course to show visual differences in germination stages: seed imbibition (12 h), radicle breaking through the testa (24 h), radicle growth and cotyledon expansion (36 h), emerged seedling (48 h), and green seedling (72 h). Mean germination rates for each time point are written at the top right corner of each picture. (C) Dendrogram plot of WOSR accessions groups them in three clusters according to their germination kinetics. We used hierarchical clustering where Y-axes represent similarity based on Pearson correlation coefficients. (D) Biplot of principal component analysis (PCA) based on seed and germination traits shows that major contributors to variability in WOSR accessions (labeled in bold black) are seed germination kinetic parameters (blue boxes), whereas seed and seed imbibition traits show less contribution. Values were obtained from the GEVES automated phenotyping platform and measured for the C166, C129, C124, C110, C033, and C032 WOSR accessions. All traits are labeled in blue. All data were obtained using four biological replicates (25 seeds per replicate). For complete value data set, see Supplementary Table S1. GR, germination rate at 72 h; GR36, germination rate at 36 h; MGT, mean germination time; T10 to T70, time to reach 10% to 70% GR, respectively; FG, first germination time; ES, root elongation speed; MC, moisture content; IS, imbibition speed; VI, volume increase; CF, chlorophyll fluorescence; TSW, 10,000 seed weight; Lt0, seed length at time 0; Vt0, seed volume at time 0.