Grad Students: Making a Difference in Our World

Kelly GarbachThey come from all over the globe, pursuing graduate degrees in a wide and fascinating array of fields. Though their topics are diverse - ecosystem management, food safety, crop domestication, soil science and so much more – their conviction is the same: They seek to make a difference. And they do. Graduate student researchers in the Department of Plant Sciences are advancing the state of knowledge and helping make our crops more nutritious, our food more safe, our resources more sustainable and our planet a healthier place for us all to thrive. Here is just a sampling of the vast work under way.

Kelly Garbach, a fourth-year graduate student working with Rangeland Ecologist Valerie Eviner, is back from Costa Rica researching the effectiveness of a Payment for Ecosystem Services (PES) program. PES is the practice of offering incentives to farmers or landowners to manage their land for ecological good. The World Bank and others have contributed substantial funding for restoration programs on farms to combat negative impacts of agriculture on the environment. The PES program in Costa Rica promotes planting trees as “live fences” in cattle pastures to offset negative impacts, but the truth is, consensus has not been reached as to whether this practice benefits biodiversity and whether it negatively affects pasture productivity.

Enter Garbach. Last year she surveyed more than 100 farmers in Costa Rica to understand their perceptions of what ecosystem services are most important and effective. Then she and her team gathered information on how practices such as planting trees as live fences along cattle fields influenced soil fertility, productivity of pasture grass and resource use among bird species.

“The results may help forecast how conservation policies could be strategically implemented, assessing tradeoffs among local priorities, agricultural production, and conservation of multiple ecosystem services,” she says.

One of the most interesting preliminary findings is that bird-species richness, an indicator of wildlife biodiversity, is highest in live fences with unpruned canopies. More than 90 percent of the forest-dwelling and migratory birds were seen in unpruned live fences.

“That’s an exciting possibility, considering that just a subtle change in management of existing plantings may support significantly greater faunal diversity,” Garbach says. 

Eduardo GutierrezEduardo Gutierrez, working with Cooperative Extension Specialist Trevor Suslow, is looking at the role of nitrogen fertilization on quality and safety of spinach and leafy greens and the role of microbial diversity and overall microbial community on the survival and proliferation of Escherichia coli O157:H7.

Most studies on pathogen survival in leafy greens have been conducted by inoculating greens taken from a store shelf or from plants raised in a greenhouse at inoculum levels not representative of field conditions. Gutierrez has done extensive greenhouse studies, raising spinach from seedlings in a hydroponic system and in soil, but also comparing the behavior of E. coli under these controlled conditions with survival and dispersal characteristics in an open-field environment at low inoculum levels.

“We’re finding that when high levels of nitrogen are used for fertilization, pathogens can accumulate, at low levels, internally, inside the tissues of the plants, where current postharvest treatments are not able to penetrate and kill the bacteria,” says Gutierrez.

What’s more, the third-year graduate student is finding that high levels of nitrogen may affect the nutritional value and shelf life of spinach, increasing nitrate and oxalate levels to potentially unhealthy levels. Excessive nitrogen use can also lead to nitrogen leaching into the soil and groundwater, causing myriad environmental woes.

“The findings indicate we need to find ways to manage nitrogen demands optimally and efficiently, but we also have to pay attention to economic yield,” Gutierrez says. “Growers need to make a profit so it’s important to find the solutions that work for consumers, growers and the environment.”

Kraig Kraft, under the guidance of Professor Paul Gepts, recently received his Ph.D. for “The domestication of the chile pepper, Capsicum annuum: genetic, ecological, and anthropogenic patterns of genetic diversity.”Kraig Kraft

Kraft’s project involved three important steps: 1) collecting and characterizing wild capsicum in Mexico and comparing them genetically to domesticated chile peppers to find where they were domesticated, 2) using a GIS mapping/species prediction program in a novel way, and 3) running a survey to investigate how traditional farmers in Aguascalientes, Mexico, managed their seed and different varieties of chile pepper.

“Farmers were not as rigorous in their selection as I thought,” Kraft says. “There was also a very clean break in terms of seed sources between the different types of chiles grown - green, or fresh, chiles always came from hybrid seeds, while all dried chile peppers came from landraces, or saved seeds.”

On the basis of his collection and the genetic relationships uncovered, Kraft determined C. annuum was most likely domesticated in northeastern Mexico, somewhere near the borders of Veracruz, Tamaulipas and Nuevo León.

That’s big news for plant breeders and chile lovers alike. The more we know about when, where and how crops were domesticated, the better we can protect genetic diversity of germplasm, the raw ingredient breeders need to develop high-quality crops that can resist constantly evolving pests, diseases and environmental stresses.