Mechanical strength of inflorescence stems. A, Diagram of the apparatus and bending stem segment. B, The force required to flex stem segments excised ∼3 cm (upper stem) and 7 cm (lower stem) from the shoot apical meristem was measured with an electronic force transducer. C, The mean force (± se) obtained from 6–14 separate segments for each position and genotype are plotted. L1 and L2 refer to independent transgenic lines that are homozygous for the L92A/I94A variation in region II and homozygous for the atlazy1 knockout mutation. The genotype means in each position were not significantly different as determined by two-way ANOVA.