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First harvest hybrid exposure trial Tomato

September this year, new tomatoes were planted for the Hybrid Lighting Tomato project
at Delphy Improvement Centre. In this project, coarse vine tomatoes are grown under a combination of LED and SONT lighting. This week, the first tomatoes were harvested. The main variety is De Ruiter's Merlice. This is no coincidence, as Merlice is one of the strongest and most productive varieties under lights.

Objectives
Among other things, the projects at Delphy Improvement Centre gather information on how De Ruiter varieties respond in future-proof growing conditions. De Ruiter and Delphy Improvement Centre have been working closely together for years, from the beginning in 2005. As partners, several varieties have been trialled over the past 13 years, including Ever, Komeett, Timotion and DRC7028. After SONT, with an intermediate step to hybrid lighting, cultivation with 100% LED lighting took place for 5 years. This cultivation system was tested for both the coarse truss (Komeett and Merlice), and for a variety from the flavour segment (Juanita). Besides the main variety, a number of trial fields are always planted with other varieties/new numbers, to gain breeding knowledge on varieties.

In the Hybrid Lighting project, the partners aim to maximise (winter) production with Merlice. They set a total production target of 107 kg/m2 year. The department is equipped with 235 µmol/m2/s illumination (90 µmol/m2/s SON-t + 90 µmol/m2/s TopLED + 55 µmol/m2/s interlight). The starting point for the illumination was the connection required for a 180 umol SonT installation, i.e. 106 W/m². By replacing 50% of the SonT lamps with LED lighting, the maximum light level can be increased by 40%. In order to aim for maximum winter production, we started with a 3-member plant and 3.3 stems/m2. Last week (week 46), as planned, the first fruits were harvested.

Cultivation progress
The start of cultivation, with a planting date in week 37, was good . The first bunch was just short of flowering at the start. The 3 stems on the plant showed nice uniformity. From a week after planting, the lighting hours were slowly built up and from week 44 the lighting was deployed 18 hours a day. Every Thursday, the trial is visited by the participants and about three growers to determine the right direction. 3 weeks ago, it was questionable whether the first fruits would realise the desired fruit weight, but the average fruit weight of the first bunches at the time of harvesting is 160 grams. Because it is possible to harvest directly from the full 3.3 stems, a difference is made immediately in these first weeks of cultivation. The 3.3 stalks/m2 must start producing over 2 kg/m2/week over the winter period to reach the target production. In the coming week, the aim is to start increasing the stem density to 4 stems/m2, which with the exposure level of 235 µmol/m2/s in total should ensure maximum winter production with good quality.

The project is a collaboration between Signify (formerly Philips Lighting), De Ruiter (Bayer), Saint-Gobain Cultilène, Gremon systems and Delphy. During cultivation, the partners will organise several open days for growers to show the development of the crop and further explain the cultivation system. This will also include visits to the De Ruiter Experience Centre, where the exposed crop was planted on 18 October 2018.