Water -- or rather, the lack of it -- was the topic of choice in Lincoln, Neb. last week, when the big boys of agricultural biotechnology came together to discuss how to make more food with less water in coming years. In one Friday morning session, representatives from Monsanto, Syngenta and Pioneer showcased their latest research on drought-tolerant corn at the 2012 Water for Food Conference.
The industry presenters were reticent about the details of the science behind their latest varieties, but all three have new products this year for corn, either for commercial use or field tests. Monsanto is putting the first corn genetically engineered to be drought tolerant -- DroughtGard Hybrids -- into trial fields spread out over 250 farms this spring. Syngenta's Agrisure Artesian hybrids and Pioneer's Optimum AQUAmax hybrids, both based on native, non-transgenic traits, are both available for commercial planting this spring. Compared to other varieties not developed for drought tolerance, the trial phases of these new products have shown mild yield bumps in drought-stressed corn, with no corresponding yield drops in well-watered corn.
Promising, yes, but as USDA plant geneticist Mel Oliver once told me, "We're never going to grow corn in a desert." Some may argue that in parts of the west, we're doing just that, but Oliver's point that corn is a crop that simply cannot grow unaided by irrigation in desert conditions is an important one to remember. The industry representatives referenced different genetic mechanisms in their crop technologies, but they all agreed on one thing: Drought, and the stress it causes in plants, is an extremely complex event, and there is no miracle gene out there.
The impact of drought on corn plants is a well established and growing concern as global water resources contract and the world's population booms. The many ways drought affects a plant complicates efforts to isolate the most effective drought-tolerant genes. Lack of water can affect qualities such as plant height, ear length, width, development, grain size, number and quality, root structure and size, and the photosynthetic process and chlorophyll content, just to name a few.
Finding and isolating drought-tolerant traits is a Herculean task that is further complicated by the timing of the drought. The severity of yield loss depends on whether the plant suffers drought stress in its early growing stages, during tasseling and pollination, or in the grain-filling stage. Generally, water stress during and after pollination produces the greatest yield losses, but it all depends on the duration and severity of the dry weather. In light of this, Mark Edge, the Monsanto representative, aptly described drought as "a moving target" for researchers.
In addition to stressing the complexity of the search for drought-tolerant genes, all the industry speakers at this conference noted a secondary problem: How to test the traits once you find them. Getting research out of a highly controlled and carefully monitored lab environment and into the messy, unpredictable, real world can be a challenge. Even field trials in traditionally dry regions can be complicated by unexpected rain which ruins the test for drought tolerance. Extreme drought conditions can destroy the chance of any crop growing -- even one bred for less water use. Rain-out shelters -- essentially large, mobile greenhouses that can move along a rail system -- can solve some of these problems by allowing researchers to control the quantity and timing of rain. However, serious field trials require thousands of acres for accurate testing and these shelters have a size limit and a significant price tag.
Crop drought researchers have found some promising genes and produced hybrids that show some drought tolerance. However, as they continue to untangle the science behind drought stress, it's unlikely they'll ever find a good substitute for a simple, soil-soaking rain.
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