Fig 1.
Safflower plants at different drought treatments, growing at Plant Phenomics Victoria, Horsham.
(A) Plants in the white pots and carriers on the conveyor system during flowering stage. (B) Plant receiving water at an automated weighing and watering station. (C) Plant in the digital imaging cabinet during image acquisition.
Fig 2.
Simplified analysis pipeline for digital images.
The principal steps and their transitional output images are displayed: (A) input image; (B) region of interest selection; (C) transformation of image to different colour scale such as HSI (hue, saturation intensity), (D) thresholding applied; (E) multiple individual objects identified; (F) merging of individual objects into one object as image object composition; (G) plant colour classification; and (H) detection of plant.
Table 1.
Safflower traits estimated and measured by destructive and digital methods.
Table 2.
The primary and secondary drought indices used in the safflower experiment conducted at PPV, Horsham.
Fig 3.
Growth of safflower plants under four different drought treatments.
(A) The variations in growth of different safflower varieties under the four drought treatments, taken during flowering stage. (B) Estimation of shoot biomass and dynamic growth curves of safflower plants under different drought stress levels. Red dotted boxes Box 1 and Box 2 represent initial branching (IB) and flowering (FL) stages when drought stress treatments were imposed. C—control; IB40–40% field capacity (FC) at IB; F140–40% FC at FL; IB50+FL50–50% FC at both IB and FL. Data represent mean + SEM.
Fig 4.
Performance of safflower genotypes under four different drought treatments.
(A) Dry biomass for all four genotypes at the time of the maturity (g/plant). (B) Seed yield for all four genotypes at harvest (g/plant). (C) Estimated green shoot biomass and (D) estimated non-green shoot biomass from digital image analysis during flowering period. (E) Total estimated digital shoot biomass at end of imaging. C—control; TB40–40% field capacity (FC) at initial branching (IB); FL40–40% FC at flowering (FL); IB50+FL50–50% FC at both IB and FL. Each stress treatment was compared against the control. Data show mean + SEM. Different letters above each bar in the bar chart indicate significant differences between treatments (p < 0.05). The boxes in the boxplot represent lower and upper quartile, vertical lines attached to each bar is whisker. The black horizontal line indicates median; diamond plus represents mean.
Fig 5.
Correlations between dry biomass with other plant traits calculated from the screening of 200 diverse safflower genotypes.
DB. dry biomass; CHA, convex hull area, CL. caliper length, MAR. minimum area rectangle; SY. seed yield; ESB. estimated shoot biomass; r, coefficient of correlation. Blue line indicates the line of best fit as a result of linear regression. The grey shaded area represents the confidence interval. The asterisks show the significance level (*** p< 0.001).
Fig 6.
Estimation of plant digital traits.
(A) Identification of colour classified whole plant; ESB, (B) convex hull area; CHA, (C) caliper length; CL. (D) minimum area rectangle; MRA. Each vertical panel represents plants grown at IB40–40% field capacity (FC) at initial branching (IB); FL40–40% FC at flowering (FL); IB50+FL50–50% FC at both IB and FL; and C—control.
Fig 7.
Performance of genotypes against stress related indices.
(A) Correlation matrix and (B) heatmap of stress indices showing the performance of morphological and yield related traits under control and stress levels. In correlation matrix values are correlation coefficients (r), *** P < 0.001, ** P< 0.01, * P < 0.05, cross (x) on the r values indicate non significant, GMP, Geometric mean productivity. MP, mean productivity; STI, stress tolerance index; SYI. seed yield index; YI, yield index; SNI. seed number index; BdNIbud number index; BrNI, branch number index; ESBI, estimated shoot biomass index; ESB, estimated shoot biomass; DBI. dry biomass index, PHI, plant height index; TOL, tolerance index. In the heatmap, the green cell colour with higher index values indicates no effect or improvement under stress treatment, while orange to red cell colours with lower index values shows negative affects of stress treatment. C—control; IB40–40% field capacity (FC) at initial branching (IB); FL40–40% FC at flowering (FL); IB50+FLS0–50% FC at both IB and FL.