Photosynthesis-light response characteristics of five tropical forage cultivars

Photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs) and water use efficiency(WUE) of 5 tropical forage cultivars were measured by using LI-6400 portable photosynthesis system in Guilin.The results were as follows:1) The Pn,Tr and Gs of the five cultivars were increased with the enhancement of the PAR,and the WUE of the 5 cultivars were firstly increased and then decreased as the PAR was gradually enhanced.Guimu No.1(Pennisetum purpureum cv.Mott) ×(P.americanum × P.purureum) reached the maximum WUE at 1 500 μmol/(m2·s) while the others at 600 μmol/(m2·s).2) The maximum photosynthetic rate(Amax) and the light saturation point(LSP) of 3 hybrid cultivars were significantly higher than that of the two Paspalum cultivars,and it was same for net Pn and Tr.It could be concluded that the tested 5 cultivars were well adapted to the local environment.