The effect of light intensity and duration on Vitamin C concentration in tomato fruits

Increasing health related phytochemicals (HRP) in fruits may create an added value for consumers. We are currently developing greenhouse cultivation protocols for growers to fine tune plant growth and create products with higher amounts of HRP. Tomato (Solanum lycopersicum) greenhouse experiments were carried out to investigate the effect of light intensity and light quality on HRP during the growing period. Vitamin C concentration of different tomato cultivars was increased in a model growing system with red and blue light-emitting diodes (LEDs), increasing logarithmically with increasing radiation. At moderate light intensities of 140, 200 and 285 μmol m-2 s-1 and a light sum of 10-30 mol day-1, the Vitamin C concentration increased by 65% in comparison to the controls. The light sum is best applied at low intensity for a longer period (20 h) than at higher intensities for a shorter period (14 h). The total amount of antioxidants, estimated as oxygen radical absorbance capacity (ORAC) values, also increased. With these results, practical cultivation systems can be developed to increase the Vitamin C concentration, enabling growers to give their products an added value.