Effects of 660 nm laser irradiation of soybean seeds on germination, emergence and seedling growth

The aim of the experiments was to study the influence of irradiating soybean seeds (Glycine max, cultivar BRS 537) with a 660 nm laser diode array. The seeds were treated with laser light provided by a device assembled for the experiments with a power output of I = 3.5±0.2 mW cm–2. The effects of biostimulation were analysed by determining the germination percentage and dry mass of normal seedlings in a germination experiment. Also, the seedlings emergence percentage, emergence rate and mean emergence time were determined in an indoor greenhouse experiment. The irradiation of the seeds with laser light showed the effects of positive biostimulation for two of the three treatments with light when compared to the control (without irradiation). The light dose of 1.6 J cm–2 (t = 457.14 s) significantly increased the germination percentage (5.5%), dry mass (58%) and emergence rate (29%) of normal seedlings and reduced the mean emergence time by 10%, while a dose of 3.2 J cm–2 (t = 914.28 s) significantly increased the dry mass (84%) and emergence rate (13%) at p-value ≤ 0.05