Why crossing is often done in early morning ?

Crossing in plants is often done in the early morning to take advantage of optimal environmental conditions and maximize successful pollination.  Studies investigated the timing of flowering and nectar production in plant species, focusing on the foraging behavior of bumblebees. It found that many plants exhibit peak flower opening and nectar production rates in the early morning, coinciding with the activity period of bumblebees. This synchronization between plant reproductive activity and pollinator foraging behavior enhances the likelihood of successful pollination and seed set. Therefore, crossing plants in the early morning when flowers are most receptive and nectar production is highest increases the chances of successful pollination and seed production, ultimately benefiting plant breeding efforts.