Pathway of Pollen Tube Growth and the Duration of Different Phases of Fertilization Process in Wheat Comparison and Analysis of Effects of Antisense Oligodeoxynucleotide Inhibition of NtGNL1 in Three Culture Systems of Tobacco Fertilization Process in Flax and Its Performance Time for Each Stage EFFECTSOF Li+, NEOMYCIN AND Ca2+ ON POLLEN GERMINATION AND POLLEN TUBE GROWTH OF APPLE Fertilization Process in Sorghum and Its Performance Time for Each Stage