Use of grafted seedlings for vegetable production in North America

Grafting of vegetable seedlings is a unique Asian horticultural technology practiced commercially for many years to overcome issues associated with intensive cultivation using limited arable land. This technology was introduced in Europe in the late 20^th century, along with improved grafting methods suitable for commercial production of grafted vegetable seedlings. Grafting was later introduced in North America from Europe and it is now attracting many growers in Canada, US, Mexico, and even beyond. Grafting onto specific rootstocks generally provides resistance to soil-borne diseases and nematodes. In addition to such traditional advantages, increased yield by using grafted seedlings has been attracting the interest of greenhouse hydroponic (soil-less culture) tomato growers. This increased yield is due to the rootstock acting as a superior conductor of water, providing more water and nutrients to the stems, leaves and fruits, mainly because of the better developed root system. Currently, an estimated 40 million grafted seedlings are being used in North American greenhouses. There are several issues identified that currently limit the further promotion of using grafted seedlings in North America. Some of these issues are: limited number of propagators and rootstock varieties, long distance transportation, high market price of seeds and grafted seedlings, and the relatively large amount of seedlings requiring processing at one time due to demand by large vegetable production operations. Introduction of more grafted seedlings to open-field vegetable production is rather slow, but is expected in the near future along with the development of technologies to resolve the above mentioned issues.