External source substances were used to spray two-Line hybrid rice during its beading stage so as to increase its seed set.The results showed that not a few external source substances such as adenosine triphosphate, MST. etc.made it possible that the seed sed rate and 1000-grain-weight of two-line hybrid rice were increased at different degrees, and MST, nickel chloride, salicylic acid helped to lower its plant height.The plant growth.regulator prepared hi the author was also capable of delaying ageing of leaves and increasing seed set rate
