A two-factor pot experiment under strictly controlled conditions (air temperature and humidity) was carried out in vegetation hall at UWM in Olsztyn in 2004. The tested factors were alfalfa varieties: sowing (Medicago sativa L. ssp. sativa - Legend cv.) and hybrid (Medicago sativa L. ssp. sativa x ssp. falcata - Radius cv.), as well as seed stimulation using He-Ne laser light at surface power density of divergent beam in a plane of free falling: R0 (control - with no radiation), R3 and R6 mW cm(-2), applied 1, 3 and 5 times. The period of a single radiation impulse was 0.1 s. The experiment was conducted by means of complete randomization in four replications in pots of 9 dm3 capacity each. Each pot contained four plants after emergence. Soil humidity was at the level of 60-65% ppw. During the vegetation of three shoots, alfalfa plants were subjected to measurements of photosynthetic and transpiration intensity (three measurements after each cut) that were made using a portable gas analyser LI-COR 6400. The highest photosynthetic intensity was recorded in 1st alfalfa shoot of both varieties. These results significantly exceeded corresponding values for 2nd and 3rd cuts. Significantly higher photosynthetic intensities for Legend and Radius cv. were found in objects R6x3 and R6x5, as compared to the control. The highest plant transpiration occurred in the 1st, and the lowest in the 3rd cut. Dry matter efficiencies, that did not significantly differ, related to the 1st and 2nd cuts; the third cut efficiency was significantly lower, regardless of the variety. Total yield was significantly higher in objects R6x3 and R6x5 (Legend cv.), as well as R3x5, R6x1, R6x3 and R6x5 (Radius cv.). These varieties did not significantly differentiate the alfalfa dry matter yield.