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Project director, Dr. Richard Beeson grew up on his grandfather’s dairy farm in the 1960s. Always inquisitive, he watched as his father and uncle built equipment and farmed; and helped where he could. However, running a dairy farm didn’t provide much financial success. Later in the mid-70’s, an elderly uncle, those hobby was rhododendrons, convinced his family to sell the cows and grow azaleas and ‘rhodes’. With enhanced income, Richard was able to graduate with BSc. at NC State. As always the farmer, he achieved his PhD. in Oregon State with blue spruce grafting. Coming to Florida, he worked with ornamental nurseries on substrates to irrigation issues before taken the lead helping greenhouse citrus growers rebuilding their industry.

 

Project Ph.D. student Hang Duong has been working on plants and water relations since she started as a lecturer in Vietnam National University of Agriculture. She was studying drought tolerant traits in hybrid rice to provide useful information for rice breeders in Vietnam to produce drought tolerant varieties that survive and produce during Vietnam’s spring dry season, a climate fairly similar to central Florida.  Her passion for water-plant studies grew over time. She completed a MS from Utah State University on turfgrass drought stress. Currently, she’s working toward her PhD degree at the University of Florida, in the department of Environmental Horticulture.

 

Trees are the most vital and expensive element in Florida’s landscapes, and the most valuable Florida Friendly Landscape (FFL) element, both in actual and potential water saving. Landscape trees often need irrigation to maintain their values. However, the FFL program – a program created to conserve water in irrigated landscape, provides very general guidelines for watering landscape plants including trees, that doesn’t account for species- and weather factors such as drought. During dry periods, how much water should be applied to trees?

 

Woody plants drought response falls in two broad strategies: “use it or lose it” or “save it for a rainy day” that balances water use in terms of how leaf transpiration controls depletion of soil water. A use-it/lose-it species has high transpiration rates as long as possible during drought, outcompeting other plants for root zone water at the risk of water stress that can injure if the plant becomes too dry. In contrast, a rainy-day species rapidly reduces transpiration to slow down root zone water depletion, but at the risk of lower photosynthesis and growth, and other species stealing its water.

 

We are studying how two signature Florida landscape tree species respond to drought. We have found that Live oak quickly used up water in its root zone and became drought stressed--“use it or lose it” strategy—but its leaves just as quickly dried out and dropped when the water was gone. By contrast, magnolia slowly depleted root zone water--“save it-for a rainy day” strategy—and even when extremely dry leaves did not wilt like live oak. However, in nature live oak can tolerate drought as well as magnolias, but how? We think it is due to deep roots, and are studying that question. Would urban trees be allowed to grow deep roots to increase drought tolerance, especially a “use it or lose it” species? In turn, would a “save it-for a rainy day” species like magnolia with leaves that don’t wilt be a better choice where root zone depth is limited? And what is the minimum amount of water each species needs to survive a drought? Our research aims to answer those questions.

 

We are also analyzing historical daily rainfall and evapotranspiration data from 1970 from 50 weather stations across Florida for drought length, intensity and trend over time through a powerful machine learning-based approach that handles big-climate data sets. We will then link results from water use studies of the two tree water species to develop seasonal irrigation recommendations that can improve both planning and management of water in Florida Friendly Landscapes.