Paul: How does someone who has little to no experience in gardening with tomatoes, how do they decide what is the right variety or varieties for them to select?
Greg: That's a difficult question because like you said, if you open up a seed catalog, you'll see tens or maybe even hundreds, if you look across different see catalogs, varieties of tomatoes, which is an amazing thing because we have so many options to choose from. But at the same time, it's overwhelming because how do you know what you want, right?
There are different categories that you can divide varieties into. One of those categories is based on fruit size. Whether you want a cherry tomato or a grape, tomato, or a plum or Roma tomato, or a slice or a beefsteak tomato. So you might choose varieties first based on what you want to eat. Those varieties tend to have different flavors and textures.
Then there's categories based on plant growth habit. One of the biggest distinctions there would be determinate versus indeterminate varieties. So determinate varieties are varieties where the shoots grow to a certain point, they produce leaves and flowers that grow into fruits, and then they terminate in a flower cluster and the shoots don't grow any further. So those varieties tend to be more bushy, smaller, and they have more of a concentrated flowering and fruiting period.
An indeterminate variety, on the other hand, is a vining variety where the shoots will actually never naturally terminate. They'll just grow and grow and grow, and produce leaves, and flowers, and fruits. In your garden outside, eventually, the plants will die from frost or disease. In commercial tomato greenhouses, they'll grow indeterminate varieties for 10 months. Yep, they'll grow to be dozens of feet long. They'll snake through the whole greenhouse.
So there's advantages and disadvantages. Indeterminates require a little bit more work in terms of staking them, pruning them, getting them to grow in a manageable way. Oftentimes, people think that indeterminates produce better-tasting fruit because there's a better ratio of leaves to fruit so there's more photosynthate going into the fruit, so higher sugar content in the fruit. I don't think that's a hard and fast rule. I think there are good-tasting determinate varieties and not-so-great tasting indeterminate varieties. But generally, I think it's easier to get a better-tasting indeterminate variety than it is to get a good-tasting determinate variety.
Paul: Is there any correlation between the size of the plant and the size of the fruit?
Greg: No, there's not. Genetically, those traits are controlled differently. So you have indeterminate plants that are cherry tomatoes, indeterminate plants that are large beefsteak tomatoes, and you can do the same thing with determinate plants.
Paul: Across New York State, we have different growing zones, right? So what works in Central New York may not be the most appropriate for the Hudson Valley, is that true?
Greg: Our lab does variety trials in different regions. And we do find that there are some varieties that do well across multiple regions. And then sometimes we have a variety that does really well in one region on one farm and not so great in another place. So there definitely are differences in terms of how varieties perform in different locations.
In terms of sauce tomatoes, there's different preferences, I guess you could say. Many people, when they want a sauce tomato, they want a plum or a Roma tomato. These are meatier tomatoes. They have a greater ratio of flesh to juice. That's good for making a sauce, that they're not too watery. You can make a sauce out of any kind of tomato really, and you can make delicious sauces out of other different kinds of tomatoes. Personally in the summertime, I love making tomato sauce out of even like cherry or grape tomatoes. You can get a really sweet, delicious sauce that way. But generally, I think people like, for sauces, plum and Roma types.
Paul: It's interesting when you start thinking about it's not fair for me to ask you to recommend the best of any tomato because-- but I guess the real question is, how do you ensure when you have decided that you're going to grow a good paste tomato or a good slicer, how do you decide-- what are the factors that are going to affect your ability to grow a good tomato?
Greg: Yeah. So there's two things, I guess you could say, that go into producing a good-tasting tomato. One is the variety, the genetics of the variety. And the other one is how you grow it. That plays a big difference, too. Generally, a healthier plant is going to give you better-tasting fruit. If you have a plant that is heavily diseased and a lot of the leaves are dying, then you don't have leaves that are photosynthesizing and producing sugars that are then going to go into the fruit. You're going to get poorer quality fruit.
Also, pruning can play a role. If you prune your plants excessively, you have the same issue, not enough leaves to go to produce sugars for the fruit. There are some varieties that you need to prune, though, because if you don't prune them, you might end up with slightly smaller fruit and the plants will just be difficult to manage.
Paul: We know that tomatoes have been around for a while. And we also know that folks are developing different varieties in their backyard. Can you talk about what are the pluses and minuses of lab-grown versus backyard-developed varieties?
Greg: The overall process that we use in our lab to breed new varieties of tomato is essentially the same process that people have been doing for thousands of years. Tomato was domesticated somewhere around 7,000 years ago in what's now Mexico. The wild plant that tomato was domesticated from is actually native to South America, so the Andes mountains. The native people there domesticated that plant partially. And then it migrated to Mexico, where it was further domesticated to produce what we would now recognize as tomatoes. So the wild ancestor of tomato produces fruit that are maybe the size of a pea. And then in Mexico is where humans selected naturally-occurring mutations that resulted in the larger fruits that we now know of as tomato today.
Since then, people have been growing tomato plants, looking at the variation that there is, choosing the ones that they like for whatever trait that they're interested in, whether it's the flavor of the fruit, the color, the size, saving seeds of those and that's how new varieties are developed.
We now do it in a slightly more intentional way, perhaps, than it was done a few thousand years ago, in that we have varieties that we know have certain traits. We control the pollination. We cross those together. We develop populations that are from this cross. And when I say cross, I mean we take the pollen from one and apply it to the stigma of the other. So we just control how the pollen is moved. But at the end of the day, we're just growing thousands of plants, looking at them, and choosing the ones that we like.
