Vekcha-thielo, Irina Germination of Guayule (parthenium Argentatum Gray) Pollen on an Artificial Medium

The pollen of five diploid and two tetraploid guayule (Parthenium argentatum Gray) plants was cultured on nutrient media. It was observed that guayule pollen is released as tetrads of spores which will not ger­ minate on the media unless they are separated into individual pollen grains. For each plant, the results of the germination tests varied with the day and the time of day of the pollen collection. Pollen was cultured on media containing 0 to 30 percent concen­ trations of either sucrose or mannitol. The 25 percent sucrose yielded the best results. Mannitol had no influence on pollen germination. An addition of the mineral elements B, Ca, and K, and the growth-promoting substances, gibberellic acid and auxin, increased the germination percen­ tages of the pollen of some plants. The variability in the pollen size, characterized by the coef­ ficient of variation of the pollen diameter, of the two tetraploid and some diploid plants was very high.