History of Vegetable Grafting
Grafting of woody plants has been common for centuries, but herbaceous grafting has only become popular recently in agricultural systems. The cultivation of grafted vegetable plants began in Korea and Japan at the end of the 1920s when watermelon plants were grafted onto squash rootstock. Since this time, this technique has spread throughout Asia and Europe. Currently, 81% of Korean and 54% of Japanese vegetable cultivation uses grafting. The use of this cultural technique is mainly carried out for intensive cropping systems like greenhouse and tunnel production. This method is especially popular for vegetable production in the orient, and the number of vegetables in 1998 was estimated to be 540 million transplants in Korea and 750 million in Japan.This technique has moved to the Mediterranean region as well, where the use of grafting has been proposed as a major component of an integrated management strategy for managing soilborne disease and increasing crop productivity. Grafted tomato transplant production has increased in Spain from less than one million plants in 1999-2000 to over 45 million plants in 2003-2004. Grafted tomato is also cultivated in France and Italy, and over 20 million tomato plants were grafted in Morocco in 2004 as a way to reduce soilborne disease and increase crop production.
Grafting can take place on a number of crops. However, because of the added expense, it is typically associated with melons, cucurbits, and members of the Solanaceae family such as eggplant and tomato. Tomato grafting became popular in the 1960s as a way to reduce certain diseases caused by soilborne plant pathogens such as Raletonia solanacearum . Currently, however, grafting is used to offer not only protection from certain diseases, but also tolerance to abiotic stress like flooding, drought, and salinity
The first grafts in the early 20th century were made in order to diminish attacks by infectious organisms, such as Fusarium oxysporum on watermelons. However, research has shown that this technique can be effective against a variety of fungal, bacterial, viral, and nematode diseases. Furthermore, many researchers are looking to utilize specific rootstocks as an alternative to methyl bromide-a soil fumigant that has been widely used until recently. Grafting has been highly effective at overcoming abiotic sources of stress, such as soil salinity, temperature extremes, and excessive soil moisture. Grafting has also been utilized to reduce the effects of flooding in areas where a wet season may occur.
Grafting tomatoes with tolerant rootstocks has been highly effective at producing a saline-tolerant plants. Research indicates that several rootstocks prevent the translocation of sodium and chloride into the shoot. Many of the most economically important vegetable crops like tomato, squash, cucumber, and watermelon are highly sensitive to thermal stress in the roots throughout vegetative development and reproduction. Whether using rootstock tolerant of hot or cold temperatures, the use of temperature tolerant rootstocks often leads to the extension of the growing season in either direction, resulting in better yield and economic stability through the year. Although the vegetable grafting is typically associated with reduction of disease or abiotic stress, yield is often increased without the presence of these identified sources of stress.
In tomatoes, increases in fruit yield are typically the results of increased fruit size.Research has shown that possible mechanisms for increased yield are likely due to increased water and nutrient uptake among vigorous rootstock genotypes. Conductance through the stoma was improved in tomato plants when grafted onto vigorous rootstock. Nutrient uptake for the macronutrients, such as phosphorus and nitrogen, were enhanced by grafting.
Tomato Grafting Methods
There are a variety of methods for grafting vegetable crops. Cleft grafting occurs when a V-shape is cut into the rootstock and a complementing wedge-shaped scion is inserted. The graft is then held with a small clip until healing occurs. Approach grafting involves notching opposing sides of the stems of the rootstock and scion, and then using a clip to hold the stems together while they fuse. Once the graft has healed, the original scion is then cut off of the desired rootstock and the unused rootstock is detached from the scion. Micrografting is a new technique that has been recently integrated into micropropagation production for hybrid tomato. This method uses micropropagated scion shoots that grafted onto 3 week-old rootstock seedlings. The most common commercial technique for grafting tomato is tube grafting. Tube grafting takes place when the scion and rootstock are severed as seedlings and reattached with a small, silicone tube or clip.This technique has been highly effective as it can be carried out when plants are very small, thereby eliminating the need for large healing chambers while increasing the output. Tube grafting has been adopted as the primary method for vegetable grafting on the farm as it can be easily carried out with small healing chambers with typical success rates ranging from 85 to 90 percent.
Approach Grafting is done by cutting opposing and complementary notches in the stem of the rootstock and scion. The complementary notches are fit together and held with a spring clip or some type of tape. Once the graft union has healed, the root system is cut from the scion plant and the shoot is removed from the rootstock plant.
Cleft Grafting is carried out when the plants are slightly larger, and a V-shaped cut is made in the stem of the scion. The scion is then inserted into the rootstock, which has a vertical slice cut down the center of the stem. The rootstock and scion are then held together by a spring clip while the graft union forms.
Tube Grafting or Japanese Top-Grafting is carried out when the plants are very small and the rootstock and scion are held together with a 1.5–2 mm silicone clip or tube.
taken from https://en.wikipedia.org/wiki/Tomato_grafting
Interest in tomato grafting is high among gardeners these days. Grafted plants can be expensive and sources of supply are few. Learning how to do it yourself not only saves money but gives you unlimited options for what varieties you choose to graft. With a little practice, you can become skilled at this worthwhile technique. The benefits of learning include a more productive and disease-resistant tomato crop.
This blog post covers the steps that go into the process commonly called “head grafting,” also known as Japanese grafting, because this is where the technique was first developed. This method allows you to graft your chosen tomato variety (the scion) with rootstock. Rootstock does not produce fruit or foliage but is vigorous and resistant to diseases.
Materials for Grafting Tomatoes
1) Silicone grafting clips (the most popular sizes are 1.5 and 2.0mm);
2) A new, straight edged razor blade;
3) A spray bottle filled with water;
4) Rootstock seeds (we offer a certified organic variety called Estamino that is vigorous and produces well-balanced plants);
5) Scion seeds (heirlooms are popular for grafting because their production can be uneven and they have no disease resistance)
6) A clear plastic bin with lid to hold a tray of grafted plugs.
Plant Your Scion and Rootstock
Your rootstock and scion plugs may grow at varying rates. The first time around, estimate it will take 21 days from seed-planting to stems on each plant that is large enough to graft. Through trial and error, you will find the ideal timing so that the diameter of the scion stem matches the diameter of the rootstock. Your grafts will not all be successful. It is recommended that you plant 2-3 times as many scion and rootstock plants as you think you will actually need.
The scion is ready when it has 2 or 3 true leaves. When you are ready to begin, prepare a clean working surface with all your materials at hand. Make a mental note of your placement of the scion tray and the rootstock tray and make it a habit to put them in the same spot (one left, one right) whenever you graft — you don’t want to confuse them when you begin cutting. Finally, wash your hands. You don’t want to inadvertently introduce harmful organisms to the cut surfaces.
Remove one rootstock plug from the tray. Look it over carefully and decide where to cut. The cut shouldGraft Tomato Plants At Home always be just below the cotyledons (the small set of leaves first from the bottom) and at least 1/2" above the soil line. Use your razor blade to remove the cotyledons. Then cut just below them at an angle between 30 and 45 degrees. After cutting, slide a silicone tube over the cut end of the rootstock. The tube should fit firmly for the best results.
Next, examine your scion plugs and select one with a stem diameter that matches your rootstock. Remove all but the top leaves to reduce transpiration while the graft is healing. Cut at an angle matching the angle of the rootstock, either about 1/3" above or below the cotyledons. You want an exact fit between the scion and the rootstock.
Align the scion with the rootstock and slide the scion into the tube so the two cut surfaces meet cleanly. The grafting tube should hold the scion and rootstock together firmly.
Move the grafted plant to a clean cell tray. Spray the grafted surface with a fine mist after completing each graft to prevent it from drying out. Keep them in the shade and away from strong wind currents while you proceed with additional grafts.
Healing Grafted PlantsGrafting Tomatoes For Gardening
Next comes healing, a critical part of the process. If all goes well, your grafted plants will heal in 4 to 7 days. Ideal conditions for healing are high humidity — upwards of 100% — and steady warmth, with temperatures between 82 and 84 degrees. For the first 24-48 hours, keep the plants in total darkness to prevent transpiration from the scion. Thereafter, they need moderate light roughly equivalent to the intensity of two side-by-side fluorescent tubes.
If you have a greenhouse, these conditions can be met by placing a table beneath a bench and covering it with plastic to retain humidity. Or you can put your grafted plugs in a propagation chamber for the first 48 hours and then beneath a shaded bench and misters for the duration. Home gardeners need a similar arrangement. The easiest solution is a clear plastic storage bin with a lid, the type found at many hardware centers. Choose one large enough to hold your plug tray with grafted seedlings.
While your plants are healing, too much water applied to the soil can create a thin layer of water on the grafted surface. This moisture can create a barrier which interferes with the union between the scion and rootstock. The best way to water during the healing period is to mist the graft union at regular intervals. If you are using a clear storage bin, fill the bottom with about 1/2" of water before you put your grafted plants inside. This should provide enough moisture and create a high level of humidity inside the container. Make sure the lid on your container has a good seal. If in doubt, tape over any openings. Approximately one week after making your grafts, you should begin to expose your plants to more light and increased airflow by gradually opening the lid. The entire process will take about two weeks.
The grafting tubes will fall away from the graft as your tomato plants grow. To prevent the introduction of disease, do not reuse your grafting tubes.
One final note: When you transplant your grafted plants into your garden, keep the graft line at least 1/2" above the soil surface to prevent the introduction of disease.
We wish you success!
taken from https://www.motherearthnews.com/organic-gardening/how-to-graft-tomatoes-
till next time this is Becky Litterer, Becky's Greenhouse Dougherty Iowa firstname.lastname@example.org