Science and nature
  Hybridizing plants means always having new, better varieties


March 9, 2006
MARY and PAUL MEREDITH - Victoria County Master Gardeners
How to best develop, breed and grow plants has long been discussed. Some of us contemplate whether we achieve more of the desired yield or effects through the plants' characteristics or how we cultivate them.
Plants' characteristics are dictated by their "genetics" or "nature," and include how tall they grow, how they bloom and when, how much water, nutrition, and light they need. Plant cultivation is called "culture" or "nurture," and includes the type of soil they're planted in, what nutrients or chemicals are applied and when, and the amount of water, temperature, and light they receive, among other things.
Neither "nature" nor "nurture" turns out to be the best option. Gardeners must consider both. Getting good results means planting the right plants and cultivating them correctly.

For example, if you want to be disappointed, try growing northern highbush blueberries in our climate. Southern rabbiteye blueberries grow and produce in conditions like ours, and they produce much bigger berries than the northern plants.

South Georgia scientists cross-bred existing plants to get successful hybrids for conditions similar to those in their area. Now, University of Minnesota hybridizers are cross-breeding blueberry plants to get cold-hardy hybrids producing bigger berries. They want cold-hardiness with the rabbiteye's large, tasty fruit for their area. But to date, all blueberries still require acid soils to prosper.

Here's an extreme example of what ignoring the effects of plants' genetics does: The USSR's minister of agriculture under Stalin, Lysenko, believed that good crop production only emphasized how farmers tend crops. Those pseudo-science theories said, for example, wheat plants produced rye grain when nurtured in a particular way. Likewise, according to their philosophy, if dogs give birth in the wild, they will give birth to foxes.

Lysenko, however, did improve the cultivation of Soviet crops and, initially, the harvests rose substantially. This earned him much recognition, enough to let him use his influence to force the Soviet botanical scientists to make studying genetics an act of treason; scientists were imprisoned or killed for studying genetics.

Lysenko's actions caused repetitive planting of the same wheat strain and resulted in inbreeding of the seed. The Soviet wheat crop failed several years in a row in the middle of the 20th century because disease-resistant wheat strains were not developed there. They had to buy U.S. surplus wheat to feed citizens and keep their people alive. And those purchases used up Soviet funds needed for their other industries. Economists claim the resulting financial problems contributed to the Soviet Union's demise in the late 1980s.

Today's French wine grape vines (vinifera) epitomize the use of science and genetics and represent another type of hybridizing. When many French vines producing wine grapes died from phylloxera infection in the late 1800s the remedy discovered was grafting French vines onto stems and roots of American grape vine species not affected by the disease. So today, French grape vines grow on American "feet," a process that literally saved the French vineyards and their wine industry.

Neglecting nurturing conditions also can have substantial effects. Getting water-loving, acid-loving plants to grow in many of our areas is a very difficult task in years like this past one.

Acid-loving plants require supplementing in almost all Victoria's soil types. Plants we purchased in South Florida have about a 50 percent success rate of growing in South Louisiana and here, by our actual trials. Most plants we killed needed warmer winter temperatures or much more moisture than we could provide. We have learned to grow plants in six different eco-regions where we lived. We have lost several plants during our years of gardening by ignoring the climate, pH, moisture or light requirements of those plants. We over-watered two tulip trees to death. But we destroyed native azaleas by not watering them enough. And we sunburned and ruined many lilies, gingers and cacti by providing them too little sun. Some of our prior learning experiences confirm that culture counts.

Over- or under-feeding will also damage or kill plants. Knowing the needs of plants we select at the nursery is the best way to get what we want from them. Some soils you can run water on for more than 24 hours and never have it accumulate. We once lived on such soil, a sand dune left over from the latest ice age. Likewise, over-fertilizing is many times worse than under-fertilizing, though neither is good!

Victoria's spring and fall growing seasons, with intense drought in between, take a toll on many plants. Our climate makes planning how and when to plant, fertilize, etc., somewhat challenging. The only way to better your chances with plants you want to cultivate is through increasing your knowledge about the needs of the plants.

It may be difficult for some to understand how a plant can grow beautifully in Mission Valley, for example, but not nearly as well in Bloomington. One factor in such variation is soil type. We have at least seven areas of different soils in Victoria County. Once we understand the complexity of soil types and their influence, we also need to learn about variation in plant growth and performance based on something called "degree-days" of cold weather.

For example, if your location does not have a sufficient number of "chill" or degree-days for a particular variety of fruit, then nothing you can do will get it to produce a good crop.

So the long discussion provides us with knowledge of a rich diversity of plants with inborn characteristics and cultural needs. Our results can be great when we select, plant and nurture hybrid plants. While nature has provided us with the base of plant genetic material to live by, let's not forget that modern science has allowed us to take this material and develop new varieties to sustain 4 billion people on this earth.