The field experiment which involved the alfalfa seed laser bio-stimulation (M. sativa: ‘Legend’ and M. madia: ‘Radius’) was performed over 2002-2004 by means of randomized blocks. The divergent laser beam power surface density doses were 0 (control) as well as 3 and 6 mW·cm^-2 (R0, R3 and R6, respectively). Seeds were irradiated once, three and five times, directly before sowing. The highest green and dry matter yields in the alfalfa sowing year (2002) were recorded for R3x5 (27.8 and 6.62 t·ha^-1, respectively) and for R6x5 (27.2 and 6.41 t·ha^-1). The laser irradiation significantly increased the shoot density per 1 m², and decreased the weight of a single shoot. For R6x5, R6x1, R6x3 and R3x3 (2003-2004 full performance years) the seed irradiation significantly increased the alfalfa shoot density per 1 m² and for R6x3 and R6x5 – the green and dry matter yields, as compared with the control. Besides the R6x1, R6x3 and R6x5 seed laser stimulation increased the share of the first cut (by 4.6-5.5%) in the annual yield, and decreased – of the third and fourth cut mostly, as compared with the control.

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