Biochemical composition and photosynthetic activity of Pongamia pinnata（L.） Pierre in response to acute 60Co γ-irradiation

To elucidate the potential and sensitivity of cirradiation in Pongamia pinnata,the present study has been done by irradiating the air-dried seeds to differentγ-irradiation doses(100 Gy,200 Gy,400 Gy and 600 Gy),using 60Co source.Significant increase(p≤0.05)in the germination,growth,and vigor was recorded under the100 Gy treatment than the control set.The chlorophylla and total chlorophyll content(mgg-1 FW)in the leaves of P.pinnata showed a significant decrease under the higher irradiation treatments(200 Gy,400 Gy and 600 Gy).In contrast,chlorophyllb showed a radio-resistance up to 200 Gy dose,and above which its concentration declined significantly(p≤0.05).Photosynthetic rate,stomatal conductance,intercellular CO2 concentration,and transpiration rate were stimulated by 100 Gy irradiation treatment and the higher doses inhibited these parameters.Antioxidant activity in the leaves of P.pinnata tended to increase after irradiation in a dose-dependent manner.All the plants under different treatments ofγ-irradiation showed stimulation in production of proline,flavonoid,and phenolic content in comparision to the control.The findings of the present study showed thatγ-irradiation treatment stimulates the secondary metabolite production(proline,flavonoid and phenolic)and favours faster growth of P.pinnata.