*2.1. Plant Material and Growth Conditions*

For the first experiment, mature green (MG) and red (R) 'Merlice' tomatoes were harvested from a commercial greenhouse in Bleiswijk, the Netherlands in November 2016. The colour stage of the fruit was assessed using the NAI index (see Section 2.5). MG tomatoes were defined as tomatoes with a NAI value between −0.77 and −0.6 at harvest. R tomatoes were defined as having NAI values between 0.25 and 0.55 at harvest. For the second experiment, MG 'Merlice' tomatoes were harvested from a greenhouse at Wageningen University in May 2019 of plants grown under white LED lighting (WL) or WL with 8.3 μmol m−<sup>2</sup> s−<sup>1</sup> FR lighting, with a peak at 730 nm. For the FR treatment, 6% of the photons in the red region were replaced with FR. This resulted in 13 μmol m−<sup>2</sup> s−<sup>1</sup> FR in the FR treatment and hence this treatment was called WL + 13FR and the photon flux density was kept constant at 215 μmol m−<sup>2</sup> s<sup>−</sup>1. The greenhouse compartment was divided into four plots. The light intensity was 215 μmol m−<sup>2</sup> s−<sup>1</sup> at the top of the canopy. In this experiment, VYPRx PLUS modules (Fluence, TX, USA) were used as top lighting. For each of the plots there were six modules installed. Overhead lamps were switched on 16 h before sunset and switched off at sunset. Additionally, LED lighting was automatically switched off when the incoming sunlight exceeded 300 μmol m−<sup>2</sup> s−1. The spectral composition of the light treatments is shown in Figure S1. Light treatments were separated by double sided, non-transparent, white reflective plastic sheets. At harvest, uniform MG fruits were selected with a NAI value between −0.77 and −0.6. Further greenhouse management (fertigation, pollination) was conducted according to standard commercial practice.
