During his participation in the seminar organized by Blueberries Consulting in Lima, Gerardo Núñez was able to make a technical tour in farms of Ica, where he talked about the importance of the study of the roots in the academy and the relevance of its results for the commercialization of the fruit.

Why haven't scholars paid attention to blueberry roots during their research?

Sometimes both academics and growers forget that the plant grows from the bottom up. Studies of the root are rarely done, even when the treatments are of the root. I think the reason is because studying roots is more difficult than studying other parts of the plant. The blueberry is in a botanical family that has the finest roots in the entire plant kingdom. So studying those roots takes a lot of optical power and a lot of resolution in cameras, as well as a lot of processing power in computers and a lot of time.

 How the study of the roots can help in the production of blueberries?

For my taste it is a holistic study; those who study the root try to incorporate the whole plant. My interest in studying blueberry roots is to find mechanisms, because unfortunately when we make applications and only measure fruit quality -which I understand is logical for a commercial purpose- we are not clear about the mechanism through which the plant is responding. As long as new varieties keep coming out, if you don't know the mechanism through which the plant responds, all the time you will have to continue testing, variety by variety and agrochemical by agrochemical. And that is not something that is available to most farms. For this reason, it seems to me that studying the response mechanisms of the roots helps us to understand a little better the responses that we observe in the plant.

In this sense, what discoveries have you made in your laboratory that can help improve product application strategies?

We are preparing a publication describing the location and relative abundance of blueberry roots throughout the year. I think this has a lot of impact on irrigation and fertilization. The location of the roots affects the duration of the irrigation events, the number of pulses, how long each pulse lasts. Also, root abundance affects fertilization rates and when to fertilize. The idea is to reach a point where each gram of fertilizer that is purchased is a gram that is well used by the plant. And I think that in blueberries we are still far from that goal.

The idea is to reach a point where each gram of fertilizer that is purchased is a gram that is well used by the plant. And I think that in blueberries we are still far from that goal.

So, the study of the roots is to refine the knowledge on how the products work on blueberries…

Exact. First, create a foundation or theoretical framework to then understand how different applications of products, fertilizers or water affect the response of the plant. But you can't describe an effect on something that no one has seen before. So, because of that, the first step for us was to describe where the roots are, what they are like. Sometimes we even had to create the protocols to study this root system. And now that we happily have that, we are going to dedicate ourselves to testing different applications.

How directly the state of a root can affect the blueberry fruit?

The ideal for the blueberry is a deep and cheap root. The idea is that these roots grow deep enough to anchor the plant and that they have large angles because that increases the absorption of water and nutrients. Also, ideal roots consume little energy so the plant doesn't spend a lot of sugar from photosynthesis and a lot of minerals from fertilizer to create this root system.

That way, a root of low consumption is the best thing that can happen to the fruit, because what it does is that it takes away a competitor. It makes sure that all the sugar will end up in the fruit, that all the minerals and water will end up in the fruit.

Can a producer know the state of his plants, for example, or the possible characteristics of his fruits, just by looking at the roots?

Unfortunately, there are no general indicators that connect the roots directly with the harvest or the quality of the fruit. It sounds illogical, but what you are looking for is to have a mature plant with a young root system. The best analogy I make to people is how we human beings think about our skin. We want an adult with youthful skin. By itself, what you are looking for is a full-size blueberry plant, with the foliage of a mature plant, but with a young root system. Because this young root system is more efficient.

How can you keep the root system young?

We know that any factor that stresses the root causes it to age faster. What we try to do is limit stress at the root level by optimizing pH, alkalinity in the water and its electrical conductivity. In addition, there are genetic factors that affect the root system. Several investigations have been done at the University of Florida to have better cultivars with better roots.

To learn more about the importance of the roots in the cultivation of blueberries, and the care that can be taken from the farms, do not miss the next International Blueberry Seminar Mexico 2022, will be held on May 25 and 26 at Expo Guadalajara.