Pecan (Carya illinoinensis), belonging to the Juglandaceae fam-ily, originally grows in south-central North America and is one ofthe most important horticultural nut crops in the world (Wetzsteinet al., 1996). It is a wind-pollinated monoecious plant with stami-nate flowers organized into an ament or catkin and female flowersborne on a spike (Wetzstein and Sparks, 1986). Because of the het-erodichogamy and short flowering period, breeding programs oftenhave to use stored pollen to perform particular pecan crossing. Effi-cient and reproducible viability testing before crossing is essentialto avoid the use of nonviable stored pollen, or it will result in theloss of the cross for the year (Sparks and Madden, 1985). Germi-nation tests have generally been considered to be the best in vitroindicator of pollen usefulness, which assess the viability of pollensamples by germinating a sample of pollen grains in an artificialmedia (Galleta, 1983). Previous studies have proved that the in vitro