The invention provides transgenic maize event MON 87427 and plants, plant cells, seeds, plant parts, and commodity products derived from event MON 87427. The invention also provides nucleotides specific for transgenic maize event MON 87427 and plants, plant cells, seeds, plant parts, and commodity products comprising nucleotides specific for transgenic maize event MON 87427. The invention also provides methods related to transgenic maize event MON 87427 and to the Roundup® Hybridization System (RHS). The invention also provides a Relative Development Scale useful for monitoring and determining reproductive development in maize that reconciles developmental differences across various maize varieties. This is useful for determining the optimal timing of a treatment regimen in which tassel development stage is an important factor, including various methods in making hybrid seed.