TUmate - TU Berlin's Open-Source Tomato

The TUmato variety "Vivaroma" has an open source license and is a classic red salad tomato with an extraordinarily intense aroma that is suitable for outdoor growing.

Sowing: Beginning mid-February. The aim is to plant the flowering seedlings after the last frost. Planting depth: 0.2-0.5cm

Nutrient and location requirements: Requires little fertilizer and watering, sunny and airy outdoors

Seed spacing: 60 x 60 cm or one plant in a 10-liter bucket

Transplanting: Transplant seedlings once they grow their first leaves. Seedlings should be planted right up to the first leaves in order to form sufficient roots.

Germination and harvest: 18 – 24 °C, 10 – 14 days, beginning July

There are three simple rules to observe when using Open Source seeds:

Rule 1: Anyone may use open-source seed, grow it, propagate it, and develop it further through breeding. In addition, the seed and any further developments of it may be sold, exchanged or given away within the framework of existing laws.

Rule 2: No one is allowed to privatize the seed and its further developments; patent and plant-variety protection are thus excluded.

Rule 3: Each recipient transfers the same rights and obligations to future users of the seed and its further developments.

You can find further details about the Open Source Seed License on the Open Source Seeds website.

Tomatoes are considered one of the most important food crops around the world. Even though it is actually a berry, the tomato is primarily used as a vegetable. What about them fascinates you?

Today, tomatoes are a mundane part of our everyday life. However, this plant, which can be traced back to just a single species, Solanum lycopersicum, shows the tremendous cultivation work of many generations of gardeners that was needed to produce such a multitude of different varieties. Tomatoes also demonstrate the positive effects of globalization – what would Italy be without tomatoes? Meanwhile they are a staple in kitchens around the world and help feed the global population.

Love apple, apple of paradise, golden apple: Can you tell us something about the cultivation history of the tomato and the role it played in earlier gardens as well as how such exciting names originated?

Tomatoes were originally brought to Europe as ornamental plants– like potatoes, I might add. The red fruit was considered poisonous. Because they were so attractive, they were included in orangeries and were even used in garden design, such as in the borders of Baroque gardens. Only with time did they move to vegetable gardens, where they can still be found today.

At the beginning of the modern era in Europe, especially in Central Europe, people were not familiar with other similarly colorful fruits. Oranges were rare and additionally extremely difficult to cultivate. Tomatoes, on the other hand, could be sown as annual plants in spring, grew comparatively unproblematically, and produced a guaranteed yield. The fact that they were soon held in very high esteem is also evident from the names given to tomatoes. In Italy they are still called pomodoro – from pomo d’oro or golden apple – and in Austria apple of paradise – presumably because people believed to have found the forbidden fruit of paradise in the red, large, juicy, and fleshy fruit. The German (and English) word "tomato" can ultimately be traced back to the name indigenous Mexicans gave this fruit.

Nowadays, we can choose from a large variety of tomatoes. How many different types of tomatoes are there and what do you think of this variety?

There are over 3,000 kinds of tomatoes with new varieties added each year. Until the 1970s, tomatoes were purely a summer crop in Germany. Either you grew it in your own garden, bought it at the produce market, or canned and stored it for the rest of the year. Now, it's possible to buy fresh tomatoes year-round. Even in the winter we have access to numerous different kinds – from small cocktail tomatoes and those on the vine to larger beefsteak tomatoes. And it's always possible to find a certain selection at the grocery store.

In economic terms, too, the tomato is considered to be possibly the most valuable field crop. How does this affect the diversity of the tomato plant?

Most tomatoes are grown in greenhouses, where they are cultivated in plastic bags filled with perlite or rock wool and fed liquid fertilizer. This is especially the case in the Netherlands and Spain, whereas Italy continues to grow tomatoes largely outdoors. F1 hybrids, i.e. hybrids of the first generation of parents, are cultivated in mass production as this achieves particularly prominent characteristics. Nowadays, breeding objectives once again include taste and smell, in addition to high yield and plant health.

Is the tomato at all sustainable through this cultivation?

Sustainability depends on several factors (economic, social, ecological). Looking at only resource efficiency, the most important factors are water and energy consumption and the plastic waste resulting from the production conditions. Of course, transport costs for this easily spoiled good must also be considered. Local produce, especially if it also comes from soil-based production and is organically grown, is certainly preferable for this reason. Consequently, we would also need to refrain from buying fresh tomatoes during the winter.

Let's turn our attention to our Open Source TUmato. What do you find so interesting about the Open Source Seed License?

Companies operating worldwide have dedicated themselves to breeding new varieties. To make this immense effort worthwhile, they are only sold under license, i.e. growers not only have to pay for the plants themselves but also a license fee. The high cost of high-tech production allows only a few varieties, which we can then find on supermarket shelves. These are mostly F1 hybrids, which cannot be propagated further by generation. If you sow them, they spread genetically, and you no longer get the desired characteristics. This means growers must buy new seeds or plants every year.

True-to-seed varieties, on the other hand, are the result of continuous self-crossing. Their characteristics are less stable so they are less attractive to breeders and growers. However, these varieties can be further propagated generatively by anyone by taking the seed from the fruit and drying and sowing it. Because tomatoes tend to be self-pollinating, meaning the pollen of a flower fertilizes that same flower, the genetic material is preserved. Centuries of cultivation has produced countless varieties whose different size, shape, color, taste, and smell fascinate us. They are to be valued as part of biological diversity.

However, even though so many tomato varieties already exist, it is important to continue cultivating them, as harmful organisms like viruses, bacteria, and fungi also continue to further develop. In Central Europe, mainly late blight, that is Phytophtora infestans, attacks nightshade crops. New varieties have a lower susceptibility (i.e. a higher resistance). Additional measures such as roofing help to keep the plants healthy even during longer periods of rain in summer.

How do you feel an Open Source Seed License could benefit the diverse variety of tomatoes and contribute to more sustainable practices?

The major problem with tomatoes and other cultivated crops is producers' high dependence on the corresponding global seed producers. These supply not only seeds, but also fertilizers and pesticides. In return, these varieties are highly efficient.

As a result, the same varieties are grown and sold around the world. Local cultivation traditions die out and local varieties are lost. The Summit on Biological Diversity in Rio de Janeiro in 1992 not only lamented the loss of natural diversity but also highlighted the loss of crop varieties. The UN Convention on Biological Diversity is therefore also committed to preserving the diversity of cultivated plants.

Open source plants follow the traditional path of breeding, they are seed-proof. They make use of traditional biodiversity and improve the varieties' properties.

You also grow tomatoes outside of your work. What matters most in your own garden? How much knowledge or skill is required to grow vegetables?

Tomatoes are fairly easy to grow. You can pre-cultivate them (beginning mid-March) or buy plants after Eisheilige (a German holiday in May referring to the final frost) and re-plant them in your garden or put them out on your balcony or patio. Above all they require sun, water, and sufficient nutrients. They're considered heavy feeders. Essentially, anyone can grow them as long as they reliably and regularly take care of the plants.

Do you have tips for other hobby gardeners to ensure success growing the TUmato?

It's important to protect the plants from direct rain, even if it is a more robust variety. And it's important to regularly thin them out by removing lateral shoots. This ensures the plant grows slender upwards.

How do you hope to spread the idea of the TUmato?

I like the idea of a TUmato, because it familiarizes TU staff, students, and other enthusiasts to an extent with fruit and vegetable production. Even though they are easy to grow, they require constant attention, care, and months of planning so that seeds sown in March actually produce fruit in July. Really, it's quite mundane but basic things like sun, water, and nutrients which help them grow. They don't require a digital control system, smartphone, or laptop but they do need dedication, care, and accountability. In this way, everyone can gain some respect for nature, which ultimately provides our livelihoods.

Interviewer: Anna Groh