HaifaStream: Not just availability - Nutrient ratios and EC are critical for your crops success

Filippo [00:00:08-00:00:00]
Welcome everybody in IFA Stream Greenhouses, it is still Filippo from IFA Italy based in Bologna and today we are going to talk about the nutrient ratio management and they see and how they deal with the plant response and how we can act and today we are going to talk with a colleague but also a friend. Dimitris, I let you introduce.
 
Dimitris [00:00:37-00:01:24]
Hi everybody, I'm Dimitris from IFA South East Europe and I'm from Greece and also, I want to thank you Filippo that you invite me in order to do it together. Today we are going to talk about the nutrient management in the greenhouses with a particular focus on nutrient ratio and EC and of course their connection to plant behaviour. This topic is crucial since in the most time it is difficult for growers to translate the problems that they are seeing in the greenhouses even though that they are providing a complete nutrition. Actually, the key element of a balanced nutrition is not only the total supply of nutrients during the season or a specific phenological stage but it's also a matter of their ratio.
 
Filippo [00:01:26-00:01:35]
You were explaining to us Dimitrios that the nutrient ratio is really important when looking to phenological stage. Why we have to look into nutrient ratio?
 
Dimitris [00:01:37-00:02:49]
First, because the plants don't absorb nutrients always in the same ratio during all their So it's important to say that the plants absorb all the elements during the whole cycle. What changes during the cultivation is the ratio between them. For example, when we are looking at the nutrient ratio, one of the most important is for sure the ratio between the potassium, calcium and magnesium. In fact, plants during their stage are likely to uptake more calcium and magnesium rather than in the last part of their cycle. While when they are finishing their crop life and proceeding through maturation, they tend to absorb more potassium than in the beginning. This happens because when plants are younger they grow faster and so they need more magnesium and calcium to support the new tissue formation. While when they are achieving the last stages, they need more potassium to complete tissue or fruit maturation.
 
Filippo [00:02:51-00:03:08]
The nutrient ratio is important when looking to the phenological stages but also do we have to change the nutrient ratio? For example, looking to potassium and calcium and magnesium according to the climate conditions we have in the greenhouse?
 
Dimitris [00:03:10-00:04:05]
Certainly, we should always give plant nutrients in a specific ratio not only balanced for crop stages but also according to the climate they are facing. Since this drives their development during the season, focusing again on potassium and calcium-magnesium ratio, we can say that in the hot season, with high sunlight, when plants would probably increase their growth rate, we should at this point increase the supply of calcium and magnesium because they are crucial for a proper tissue formation. In the opposite way, when our plants are in a cool season, with low sunlight, we must support them by increasing the supply of potassium in order to have a better plant resistance to low temperature.
 
Filippo [00:04:07-00:04:27]
I agree with you. You have explained to us with these two questions how important is the nutrient ratio when looking both to phenological stages and climate conditions in the greenhouse. Do you have any advice also concerning the EC? What is its role in the plant uptake?
 
Dimitris [00:04:29-00:05:22]
The electrical conductivity is a parameter that expresses the tendency of certain solutions to conduct the electricity. This capability is strictly related to the presence of charged molecules inside the water, in our case the nutrients. Plants actually absorb water and they stabilize the nutrients inside it. Based on that, we can say that plants are much easier to uptake water when they have a low EC or in other words a low concentration of nutrients. In the opposite side, the higher the amount of nutrients inside the drip water, the higher the EC and the lower would be the water absorption by plant depending on species.
 
Filippo [00:05:24-00:05:35]
You were talking about plant species. Plants have different sensibility to the EC depending on this. Can you give us some small insights about this?
 
Dimitris [00:05:37-00:06:21]
Yes, actually we can divide the major crops into three main groups. The sensitive to EC like strawberry, onion, carrot, beans where we should try to stay between 1 and 1.2 dZ per meter in the soil substrate. Also, we can say that they are lightly sensitive to seed, for example lettuce, pepper, spinach where it would be better to stay between 1.3 and 2 in the growing medium. Also, low sensitivity to EC as cucumber, tomatoes, eggplant that can grow well even till 3.5 dZ per meter.
 
Filippo [00:06:23-00:06:31]
Do you have any concerning about EC on how we should modulate it regarding the crop stage or also the climate conditions?
 
Dimitris (06:34-00:07:58]
The EC level should be kept lower during first growth stage, right after the sowing or the truss plant while following plant development can be increased till levels that are not toxic for the plant. Also, EC level should be regulated depending on the climate conditions that are present in the greenhouse. Since the plant responds to temperature and temperature to humidity, we will drive the water uptake and sow the nutrients. In particular, during hot season when plants would have a higher water supply the C should be lower because with the increase of water uptake also the nutrient uptake would increase. In order to maintain the same nutrient supply, we will have to reduce their concentration inside the drip water. The EC reduction during hot season is also a manner to make water uptake by plant easier to enhance their performance during the stages when they lose water the most.
 
Filippo [00:07:50-00:08:11]
Really thanks Dimitrios for this concept we have put together and to sum up, could we have a brief sum up of our today's topic before finishing the episode? Just to clarify the most important concept we have treated that we want to bring home.
 
Dimitris [00:08:12-00:09:36]
Ok, to keep it short we can say that it's crucial during the season to manage properly nutrients ratios. In particular, the ratio between potassium and magnesium and calcium is one of the most important. During the early growth stages and in presence of hot season and high growth rates should be around 0.3 and 0.5 while during maturation phase in presence of cool temperature and low sunlight it should be increased till 0.7. So, during this period it should be around 0.7 and 0.8. Furthermore, something another that we have to say is that balancing the EC to the plant species of course we have to take in consideration the growth stage and the climate that exists in the greenhouse at the moment. In particular, it's better to have low values of EC during first growth stage and when the temperature is higher with plants that have higher transpiration rate requiring more water supply. EC can be increased accordingly to plant development during all the phenological stages.
 
Filippo (09:38): [00:09:54]
 Thank you again Dimitrios. That's all for today. Thanks to you but thanks also to our listeners. So, subscribe to our podcast IFA Stream Greenhouses and do not miss the next episode. Ciao!