Which crops do we need to graft in CEA and why?

Vegetable production with grafted young plants originated in Japan and Korea as a way to avoid serious crop loss caused by soil-borne disease, aggravated by successive cropping.

Which crops do we need to graft in CEA and why?

Grapes of course are a well known grafted crop, as are apples and other stone fruits. They have been grafted for centuries to avoid similar issues originating from soil-borne disease. It’s taken a while for us to catch up, but with every area in CEA being scrutinized for additional efficiency, it is no surprise grafting is becoming the norm in the industry. Tomatoes are the latest to have benefited from grafting onto more vigorous rootstock to prevent disease and boost harvests. 

The tomato in the image above came from a grafted plant. It looks no different from any other tomato, right? Except, it is different, and the farmer of this crop does not have the same heartache or stress of his crop succumbing to diseases.

Grafting has been popular for decades in Asian countries, and now provides success in many hydroponic crops including watermelon, cucumber, tomatoes, peppers, squash and eggplant. 

According to Dr Chieri Kubota, a professor and OHCEAC director at Ohio State University, over 90% of watermelons are now grafted onto squash rootstock to avoid fusarium wilt.

Grafting also minimizes the uptake of undesirable agrochemical residues and grafted plants can adapt more easily to low soil temperature and high soil salts, especially under protected cultivations where successive cropping or continuous farming is routinely practiced. 

Squeeze every ounce of efficiency for profit

To be profitable, VFs must utilize every technique to maximize yield and profits. Grafting can be a labor-intensive technique, but many are starting to automate the grafting process. Improved quality and availability of plug-grown grafted transplants will contribute further to the increased use of grafted vegetables in CEA, helping farmers have more choice in soil mixes and substrates. Optimizing the conditions for long distance transportation of grafted plants is an important factor to avoid any drop in quality by the time it reaches the farmer. 

Grafting is becoming more widespread as companies compete for retail sales, and automation is required for scaling up in large glasshouse’s. The graft itself is made up of a high quality scion that is grafted to vigorous rootstock resistant to common tomato diseases. The join must remain above the soil or rockwool, otherwise the rootstock will grow out. Popular tomato rootstocks include Maxifort and Estimino, more likely to overcome pH changes, water shortage, fluctuations in temperature and provide more efficient uptake of nutrients.

Janet Colston PhD is pharmacologist with an interest in growing ‘functional’ foods that have additional phytonutrients and display medicinal qualities that are beneficial to human health. She grows these using a range of techniques including plant tissue micropropagation and controlled environmental agriculture to ensure the highest quality control.