Visual estimation of drought survival. (a) False-colour representations of Fv/Fm measurements of Columbia plants following 15 days' drought treatment. The individual specimens were labeled 1 through 8, as indicated by the number below each plant. Note that false-colour images were not generated at Fv/Fm values of < ~0.125; for details, refer to Experimental Procedures. The image of plant #4 has been omitted for provision of the false-colour scale, however its Fv/Fm measurements were comparable to those of plant #1. (b) Photograph of the plants shown in (a). Fv/Fm measurements obtained from each plant are shown in the lower left corner of each punnet. The average Fv/Fm of control plants (not shown) was 0.800, providing a threshold Fv/Fm of 0.264. The 4 plants in the left column were classified as viable by application of the threshold test (Fv/Fm > 0.264), while the 4 plants in the right column were classified as non-viable (Fv/Fm < 0.264). (c) Photograph of the same 8 plants after watering was resumed for 3 days; n.s. = no signal detected.