THE STORAGE AND ARTIFICIAL GERMINATION OF FOREST TREE POLLENS

Abstract

The physical and nutritional requirements for pollen germination in several forest tree species were studied by using a variety of nutrient combinations in agar, silica gel, and distilled water media. It was found that 10% sucrose in 0.75% agar was the best of these media for Pinus pollen, while 1.13% bean pod agar was best for Picea.Results from studies on light and dark incubation of Pinus, Picea, and Quercus pollens showed no significant difference in percentage germination, but indicated a stimulation of pollen tube growth by light.Pollens of several species were stored under different conditions of relative humidity (graded series, 0 to 75%), temperature (2 °C. and room temperature), and light (light and dark). Data on germination after storage for one year showed: that pollen longevity of all viable species was greatly favoured by low temperature and darkness; that the best relative humidity was: for Pinus, 15 to 35% at room temperature and 50 to 75% at 2 °C., for Picea 15% at room temperature and 10 to 75% at 2 °C., and for Quercus 25 to 35% at 2 °C. (no germination at room temperature).Highest percentage germination after storage for one year ranged from 95 to 99% for Pinus species, 58 to 63% for Picea species, and 46% for a Quercus species (2 °C., dark, in each case).In all species successfully stored, pollen germination was higher after 12 months' storage than after eight months' storage.