Optimization of In Vitro Pecan Pollen Germination

Abstract

Storage of pollen from 1 year to the next is often needed to enable desired crosses to be made in a pecan [ Carya illinoinensis (Wangenh.) K. Koch] breeding program. Stored pollen is usually tested for viability through the use of in vitro germination tests. An in vitro germination testing system was developed for this purpose using cellophane booklets to provide a solid support for the pollen grains. Optimized germination media contained 5% sucrose, 20% polyethylene glycol 8000, 0.05% Ca(NO 3 ) 2 , 0.025% H 3 BO 3, and 10 m m 2-( N -morpholino)ethanesulfonic acid pH 6.0. Pollen should be rehydrated for 2 to 4 h in a humidified chamber before germination testing. A germination time of 4 to 24 h produces similar final germination percentages. Testing of pollen samples stored at –80 °C indicates that pecan pollen can be stored for at least 8 years without a decrease in viability. Chemical names used: polyethylene glycol (PEG); 2-( N -morpholino)ethanesulfonic acid (MES).