OPTIMIZATION OF INDUCING 2n POLLEN GRAIN OF Poupulus ussuriensis Kom BY COLCHICINES Pollen Tube Growth after Crossing between Different Ploids Dianthus caryophyllus by Fluorescence Microscopy and Seed Setting Studies on Abnormal Meiosis Producing 2n Pollens in Nonastringent Persimmon (Diospyros Kaki Thunb.) Studies on Overcoming Low Seed-setting in Cross between Sweetpotato and 2n Pollen Clones of It‘s Closerel ated Triploidy Hybrid with Plant Growth Regulator POLLEN CHROMOSOME DOUBLING UNDER HIGH TEMPERATURE IN Populus alba L. STUDIES ON ALLOTRIPLOID BREEDING OF POPULUS TOMENTOSA B301 CLONES Studies on Abnormal Meiosis Producing 2n Pollens in Nonastringent Persimmon (Diospyros Kaki Thunb.)