The effect of microgravity conditions and light spectral composition on some physiological and biochemical characteristics of Physalis alkekengi L

This study was performed to evaluate some growth indices, antioxidant activity, total flavonoids, accumulation of soluble sugars and changes in total protein under microgravity conditions and light spectrum composition with four replications on P. alkekengi. Seedlings grown in vitro were exposed to the microgravity treatments under two different light conditions, including white (C) and red+blue (R+B). The results of this study showed that the treatment of R+B light spectrum increased seed germination and leaf relative water content (RWC) by 23.9% and 32.1% respectively, compared to control. Microgravity treatment under white light (Microgravity) and microgravity treatment under red+blue light (R+B+Microgravity) biomass increased 78.1% and 97.4% respectively, compared to the white control. The level of antioxidant activity in the treatment groups showed a significant increase in the leaves, which was the highest value under microgravity under R+B light (10.1%). R+B+Microgravity treatment significantly improved the total flavonoid content by about 19.6% compared to the control. The highest activity of phenylalanine ammonialyase (PAL) enzyme was measured at 9.7% in the root under microgravity conditions. R+B light and microgravity treatment increased the amount of total protein and soluble sugar and also the simultaneous use of these two treatment showed the highest amount (71.8% and 45.1% respectively). The R+B light spectrum can be used improve seed germination and the RWC. In general, R+B+Microgravity treatment synergistically increases biomass, antioxidant activity, total protein and soluble sugars compared to white control.