Abstract
Aboveground and underground biomass are important indicators of turfgrass growth and establishment.The aboveground and underground biomass of cool-season turfgrass mixtures were measured in field experiments under four different irrigation levels(0,200,400,600 mm) during the entire experimenta1 periods.The results show that the aboveground biomass in the middle and late growing periods under treatments of 400 and 600 mm were significantly higher than that of treatments of 200 and 0mm,but there was no significant difference between irrigation 600 and 400 mm.Root distribution was charactered with the highest density in the layer of 0-5cm,while the least density in the layer of 20-25 cm.The significant differences of underground biomass among treatments only existed in shallow soil layer of 0-5 cm.With proceeding of the growing period,both aboveground and underground biomass increased,but aboveground biomass changed faster.The ratio of root to stem tended to decline in the whole growing period.Aboveground biomass was largely determined by the underground biomass and the statistical determination coefficient for each treatment was above 0.8.Along with the increase of aboveground biomass,the accumulated evapotranspiration(ET) of different irrigation treatments increased and showed very significant difference among different treatments(P<0.01).The ET increased rapidly in the early growing period but slower in late.Statistical results indicate that ET was largely determined by aboveground biomass and the determination coefficient of each treatment was above 0.65.The regression model between aboveground biomass and ET was Y=a×ebX.