Features Crops Flowers
Inside View: July 2009

June 17, 2009 By Gary Jones

Pondering the theme of this issue, what drives development of new varieties? For greenhouse vegetables in particular, growers primarily want a marketable product in size, weight and shelf life. Given those factors, varieties need high yield (obviously!), suitable plant habit, vigour, flavour and pest/disease resistance. Here are some examples of trends in the “veggie” greenhouse.

Some older cultivars are finding renewed grower acceptance, often as a result of marketplace changes. For example, some older cucumber varieties are finding a new lease of life as the market specifications call for longer fruit rather than simply lots of small-sized fruit typical of Dutch-style production. As the market has changed its requirements, varieties that were once good but have been superseded can be more suitable once again.
Demand for less pesticide use means the need for more disease resistance. Breeders are continually introducing cucumbers and tomatoes with higher resistance to powdery mildew. Others are developing tomatoes resistant to other (“new”) diseases such as Pepino Mosaic Virus. Likewise, sweet pepper growers are almost unanimously seeking cultivars with the “TM3” characteristic. New varieties like these provide growers new opportunities to reduce pesticide inputs.
Plant vigour and balance are always important for long-season vegetable crops that have to withstand the summer heat and still produce acceptable yields and high fruit quality into the fall. Of course, one does not know the spring light levels that are going to happen before sowing seeds, but some of the “more established” cultivars have outperformed new varieties this year in this respect. Such resurgence of older varieties is a very compelling reason for growers to increase the number of cultivars they grow (or even better, the number of crop species!), to maintain as diverse a range of genetic material as possible. Because a variety is more than five years old doesn’t mean it’s “done.” Heading down the narrow monocrop route is a risky long-term strategy.
As breeders seek to make the most efficient use of their resources, it’s natural for them to find as many uses for a variety as possible. In particular, this applies to vigour (as already discussed) and plant habit. Growers with older, lower greenhouses can use shorter varieties, but these are equally “labour-friendly” in taller houses.
In a market where there was once limited choice (remember when there were only one or two sizes of tomato?), consumers are given so many options these days that growers must seek that “little something extra” to differentiate their product. This is particularly true of the “newer” shapes and colours of tomatoes (mini-plums, strawberry, striped, purple), an increasing range of colours for bell peppers, exotic hot peppers in all shapes and sizes, and multitudes of eggplant cultivars. Many of these “new” traits are taken from older cultivars, and that genetic resource is tremendously valuable. Which leads to …
Now, there’s a good reason to consider some “new” heritage varieties … While many of the newer varieties have good flavour, or the environment/feed can be manipulated to enhance this characteristic, older varieties often ooze flavour and should be considered possible options for mainstream plantings. Growers in Australia, for example, are not slow to see the potential of “hydroponic heritage” production.
So, should varieties simply be stored in huge mountain repositories for the use of future generations? While this may have some applications, remember that plant breeding is a continual process, and varieties themselves are changing to suit their situations. It’s likely that the environment we will be growing crops in 50 years from now will be much different, and if the genetic material in gene banks has been held in suspended animation until then, one wonders how suitable that genetic material will be in the environment at that time. Think of it as a muscle that withers if it’s not used. So, by all means use the varieties your seed companies develop, but take care not to simply abandon the older cultivar to some seed bank dungeon. You never know when you might need it. ■
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Gary Jones is Chair of Production Horticulture at Kwantlen University, Langley, B.C. He serves on several industry committees and would welcome comments at Gary.Jones@Kwantlen.ca.