Fig. 7. Correlations between the total number of pollen grains produced per tassel and main stem length, total branch length, main stem diameter, and Tassel Area Index measured on individual plants at Stage 6. Data correspond to 2001 hybrids (Exp. 2), 2002 hybrids (Exp. 3), and 2002 inbreds (Exp. 4).

Image from Crop Management article:
Tassel Morphology as an Indicator of Potential Pollen Production in Maize