Comparison of apparent nectar secretion between different types of sunflower genotypes, from three studies. A line: genic or cytoplasmic male sterile line; B line: male fertile line; R line: male fertile line provided with the restorer nuclear gene of fertility. Male sterile F1 hybrid: result of a cross between a cytoplasmic male sterile line and a B line. Male fertile F1 hybrid: result of a cross between a genic male sterile line (recessive allele) and a B line, or between a cytoplasmic male sterile line and an R line. The reference studies are given with the sampled floret stage and the method of nectar extraction. The sugar mass data of Tepedino and Parker (1982) and Vear et al. (1990) were calculated using the formula of Cruden and Hermann (1983) from the nectar volume and the sugar concentration (measured by gas chromatography in Vear et al., 1990) given for each genotype in the respective Tables 1 of these studies. The data of Mallinger and Prasifka (2017) were recovered using Plot Digitizer 2.6.8 (http://plotdigitizer.sourceforge.net/) from their Figure 1a.