Pollination of two japanese plum varieties are observed, the study confirmed that 'Royal Diamond' and 'Autumn Giant' are completely sef-sterile and partially fertile respectively. 'Black Amber', 'Black Star', 'Golden Japan', 'Royal Diamond', 'Songold' and 'TC Sun' proved to be compatible with 'Autumn Giant' , and 'Autumn Giant', ’Black Star', 'Golden Japan', 'Larry Ann', 'Songold' and 'TC Sun' proved to be compatible with 'Royal Diamond'.
The time of full bloom of these varieties were also studied between 1999 and 2001.