Analysis on the influnce factors to utilizing efficiency of light and water for alfalfa

To explore the influence factors of light use efficiency (LUE) and water use efficiency (WUE) of alfalfa, the related physiological ecology indexes (Pn, Tr, Gs, Ci, Ta, Tl, RH and PAR) were measured using portable C340df photosynthesis instrument in the morning of sunny days at early flowering period on 12 fouryearold alfalfa varieties under field conditions. The results showed that: 1) The physiological factors (Ci and Gs) are the key factors that affect the LUE of Alfalfa, while some external enviornmental factors (PAR, Ta and RH) played a role effect on WUE; 2) WUE and LUE of a variety, Medicago sativa cv. Pondus, were significantly (P0.05) higher than others, and with highest dry matter.