Effect of morphactin (IT 3456) on pollen germination and pollen tube growth in four species of Angiospermae

The action of morphactin in 10, 100 and 1000 ppm on pollen germination and tube growth was studied in four species: <em>Antirrhinum majus, Campanula rapunculoides, Eschscholtzia californica</em> and <em>Narcissus poeticus</em>. Pollen grains showed different sensitivity to particular concentrations of morphactin. Although the concentration of 1000 ppm inhibited completely pollen germination in <em>A. majus</em> and <em>C. rapunculoides</em>, it was not sufficient to suppress this process in <em>E. californica</em> and <em>N. poeticus</em>. Morphactin has a different effect on the percentage of germinated and ruptured pollen, tube length and its rate of growth. This effect was either inhibitory, neutral or stimulatory, depending on the morphactin concentration, the time of culture and species studied. The action of morphactin on the germination process is discussed.