The significance of the methods of stigmatal and placental pollinationin vitro inAntirrhinum majus L.; seed and callus formation on placentae

A study was made on certain problems connected with the application of methods of stigmatal and placental pollinationin vitro in the snapdragon. Germinable pollen without microbial contamination could be obtained only from the flowers which were left, after surface sterilization, on the stem till the dehiscence of anthers. The germination of pollen, and especially the growth of pollen tubes was better in a 0.3 M lactose solution with 10^?3 per cent H₃BO₃ than in usual sucrose media. The seedsin vitro could be obtained only after normal pollination and the successive artificial cultivation of the entire pistil (the method of stigmatal pollinationin vitro). The seeds did not differ either in their morphology or in their size from those developed under natural conditions, they were viable and without dormancy. Though the pollinated pistils were cultivated in the medium without growth substances, callus formation from uncovered ovules and placenta was observed in some cases. A dependence was revealed of the proliferation on pollination and on the cultivar employed. When using the method of placental pollinationin vitro we failed to obtain seeds. The main difficulty in the use of this method seems to consist in the fact that pollen tubes are not capable of growing from the surface of ovules and placenta into the micropyle.