Alja, Plant Physiology Scientist at Vivent Biosignals, is researching electrical biosignals.
Electrophysiological sensors for plant-oriented cultivation
Wageningen University & Research (WUR) has conducted research on using electrical biosignals for early detection of diseases and pests. Biosensors from Vivent Biosignals were used for this. Alja van der Schuren, Plant Physiology Scientist at Vivent Biosignals and Kirsten Leiss, Senior Researcher Plant Health at WUR talk about the research process, the promising results and the possibilities this new method offers growers.
Alja: ‘Plants use various internal communication mechanisms. For instance, a plant can indicate that its roots are being attacked or that the climate conditions have changed, so that the rest of the plant can prepare for this. One of those communication mechanisms is the electrical biosignal. At Vivent, we developed a method to read that signal. We produced several algorithms to be able to read small fragments of information from the electrical signal. This information indicates whether a plant is affected by disease. We then worked with Kirsten to examine fragments of the signal that show an attack by a virus, insect or fungus.’
Kirsten: ‘That’s right! We tested electrophysiological sensors in cooperation with the Club of 100. This makes us the first to have researched biosensors for detecting stress caused by invading pests or fungi. This form of stress is also known as biotic stress. Plants respond in very specific ways to insects and fungi. The question is: how can we recognise this response at an early stage?’
Alja: ‘We can do that by measuring the electrical signals. You need a control group for this, comprising plants that are free from pests and diseases. There’s also a group of test plants,
which are infected. We measure and then compare the electrical biosignals from both groups of plants. It’s not always easy to ensure that plants are infested. Occasionally the insects don’t do their job, and plants don’t get infested. Of course, that’s in nature’s hands.’
Kirsten: ‘We have indeed noticed that many experiments are needed to build a sound dataset. It is and remains research and to be able to make a good comparison, there needs to be a clear difference between the control and the test plants. Some datasets won’t be usable so it’s essential that we conduct many experiments.’
Alja: ‘From the data we ultimately collected, we compared the signal from the test plants with those of the control plants. We also compared the signals in both groups with signals from the previous periods, to make sure we were studying the plant in the right phase. The computer then searched for differences between the signals. In doing this, we looked at around 700 signal characteristics, such as the level of the signal or how often the signal moves. The characteristics of signals that vary most between the two groups of plants, form the basis of the model we’re developing.’
Kirsten Leiss, Senior Researcher Plant Health at WUR (left) and Alja van der Schuren, Plant Physiology Scientist at Vivent Biosignals (right)
Kirsten: ‘We chose two model plants for the research. For ornamentals, we worked with gerberas, and for fruiting vegetables, we used tomato plants. As we wanted to know if our models work on different organisms, we released a virus, a fungus, and an insect on these two plant species. We started with the virus. We were unfortunately unable to infect the plants enough and the plants didn’t present with enough symptoms to build a model with. A different problem occurred with the fungus, mildew. The control group actually proved to be infected too.’
Alja: ‘That was a real pity! The control plants really need to serve as a control. As soon as an infection is visible there, the data are no longer usable. Otherwise, the model might start seeing the early signs of mildew as control and that is something we want to avoid.”
Kirsten: ‘The results from the insects were the most promising. We used thrips for this: tiny insects that suck out the cells of leaves, allowing air into them. This gives the leaves a kind of silver sheen. This cosmetic damage is a problem but also the virus that the thrips spread weakens the entire plant. The symptoms are only visible after 5-6 days, but with the electrical biosignals, we were able to detect the infection after just 2-3 days.’
Alja: ‘This will be a huge help to growers. Ideally you want to detect a disease before it’s visible on the plant and has had a chance to spread, as this enables the grower to intervene in time. We’re testing all kinds of tactics with different parties in the chain, and things are looking promising! For the research with WUR, we used biosensors connected to the plant via a cable. For an experiment that’s fine, but in practice a device without cables is preferred, which is why we recently developed a mini biosensor that works on batteries. This is easier to place these in various parts of the greenhouse.’
Kirsten: ‘The information from the plant then has to be sent to the grower as quickly as possible so they can take timely action. Am I correct in thinking that you’re also developing something for this?’
Alja: ‘We are indeed testing a live dashboard with the first growers. As soon as the sensors identify a pest, the grower receives a push message on their telephone or computer. The signals arrive with just a few minutes’ delay so they’re getting almost live data from the greenhouse! This development enables us to switch to plant-oriented growing, putting the plant more at the centre of cultivation decision-making. Whereas the generation that is gradually retiring often relied on their own experience, the new generation of growers will be working with the latest technologies.’
Kirsten: ‘From a researcher’s perspective that’s something I can really understand. I want to be able to read the plant from the inside and understand its language. That’s a challenge but it also offers huge potential. Vivent’s electrophysical sensor doesn’t only measure biotic stress, it also measures abiotic stress, or stress caused by the climate. This is a unique combination and offers so many opportunities for new research! That’s why I’m so delighted that the Club of 100 has enabled this research.’
Alja: ‘I hope we can continue this research with the Club of 100 and WUR in the future so we can keep offering smart cultivation solutions!’
The article is published in Horticoop Magazine BLAD Issue 4.
During the test with mildew on tomato plants both the test as well as the control group proved to be infected.
Want to learn more about Alja’s latest work on early detection of diseases and pests? Or are you curious about future research and the upcoming Vivent Biosignals live dashboard? Let’s connect!