8Pegler R A D.Harvestripenessingrassseedcrops[J].J.of the Bri.Grassld.Soc.,1976,31:7-13.
9Hill M J,Watkin B R.Seed production studies on perennial ryegrass,timothy and prairie grass 2.Change sinphysiologic components during seed development and time and method of harvesting for maximum seed yield[J].J.of the Bri.Grassld Soc.,1975,30:131-140.
10Hyde E O C,Mc Leave M A,Harris G S.Seed development in ryegrass and inred and white clover[J].N.Z.Jl.Agric Res.,1959,2:947-952.