He-Ne laser-induced changes in germination, thermodynamic parameters, internal energy, enzyme activities and physiological attributes of wheat during germination and early growth

Using low power continuous wave He-Ne laser irradiation of seeds, the germination characteristics, thermodynamic changes and enzyme activities as well as changes in morphological attributes were explored for wheat (Triticum aestivum L. cv. S-24) cultivar. The changes in thermodynamic properties such as change in enthalpy (Delta H), entropy generation [(Delta S-e)], entropy flux [(Delta S-c)], entropy generation ratio [(Delta S)e/Delta t],and entropy flux ratio [(Delta S)(c)/Delta t] showed significant (P < 0.05) changes at an energy level of 500 mJ. The germination energy (GE), germination percentage (G%), germination index (GI) as well as alpha-amylase and protease activities was also found to be higher at 500 mJ, while the mean emergence time (MET) and time for 50% germination (E-50) decreased for 300 mJ irradiance. The internal energy of the seeds increased significantly at all laser energy levels, but was highest for 500 mJ 72 h after sowing. The enzyme activities increased up to 24 h after sowing and then declined. The activities of alpha-amylase and protease were found to be positively correlated with the plant physiological attributes. These results indicate that low power continuous wave He-Ne laser (632 nm) treatment has considerable biological effects on seed metabolism during germination as well as on later vegetative growth.