Regeneration mechanism of Toyonoka strawberry under different color plastic films

This paper describes the effects of plant growth regulators and different color plastic films on shoot regeneration from leaf discs of strawberry (Fragaria × ananassa Duch. cv. Toyonoka) and physiological changes during shoot regeneration under color films. The optimum medium for shoot regeneration was MS supplemented with 1.5 mg l−1 thidiazuron (TDZ) and 0.4 mg l−1 indole-3-butyric acid (IBA). In contrast to the control, color plastic films had significant effects on shoot regeneration. The highest percentage of shoot regeneration (>95%) and the maximum number of shoots per explant (>25) were observed under red and green films. Different spectrum range of the plastic films was 300-700 nm. Light intensity under fluorescent light was highest followed by blue as compared to the lowest under green films. Red and green plastic films induced a lower chlorophyll a/b ratio and a higher level of chlorophyll b in strawberry tissue culture. Superoxide dismutase (SOD), guaicacol peroxidase (G-POD) and catalase (CAT) activities were highest under the red films, followed by green as compared to the lowest under yellow ones. Changes in antioxidant activities were positively correlated with shoot regeneration. After 15 days in culture, gibberellic acid (GA3) content was found highest under fluorescent light followed by red and green plastic films. Zeatin (ZT) and GA3 contents were highest under red plastic films; however, indole-3-acetic acid (IAA) content was highest under blue plastic films after 45 days in culture.