Graduate student sees future of worldwide crop production in new cultivars

FORT PIERCE, Fla. — Martin Zapien scans long rows of tree canopies each morning and thinks about how the future of food production will advance with new citrus cultivars.

All of the more than 5,000 trees in the 20-acre UF/IFAS citrus research grove range from one-to-two-years-old. Each tree is a new cultivar developed by research scientists. Researchers hope the varieties will triumph over the latest challenges to Florida citrus: citrus greening, climate change and destructive insects.

Zapien is a graduate student whose research with the new citrus cultivars is part of his work toward a master’s degree in horticultural sciences. Enrolled with the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Zapien’s research takes place at the Indian River Research and Education Center (IRREC) in Fort Pierce, Florida.

It is the heart of Florida’s premier grapefruit crop production region. Zapien is a native of Zamora Michoacán, in central Mexico. Like Fort Pierce, Michoacán is at the center of Mexico’s strawberry production industry. There, Zapien’s family and most of their neighbors depend on strawberry crop production. But he sees a decline in the industry there.

“Here, in the Indian River District, citrus was once a prosperous industry,” said Zapien. “We have the same situation in central Mexico with strawberries—the crops are in decline because of plant diseases.”

Zapien points to an insect for the Indian River District’s grapefruit decline. He explains that an invasive insect, the Asian citrus psyllid, transmits the bacterium that causes Huanglongbing, or HLB, also known as citrus greening. It is the most serious citrus disease worldwide.

The new cultivars are what both researchers and growers believe will reveal which trees to plant in the local region. Zapien calls the experimental grove he planted for his master’s studies “the largest and more comprehensive grapefruit variety performance trial” in the Indian River District, a growing region renowned for the world’s highest quality grapefruit.

“Commercially available varieties have been grafted on commercial rootstocks and are expected to perform well in this region,” said Zapien. “In the Indian River District, the citrus trees must keep yields of high-quality fruit despite HLB.”

Zapien’s graduate advisor is Rhuanito “Johnny” Ferrarezi, assistant professor of citrus horticulture at IRREC. Ferrarezi said the experimental grove is essential to local growers because the cultivars will generate results specific to the region.

“The variety trial will provide us the science-based information Indian River growers need to make their planting decisions,” said Ferrarezi. “We expect the research results will assist growers when they decide which cultivars to plant.”

Ferrarezi oversees Zapien’s academic work and mentors his professional development and research activities. They measure data continually. Some of the trees thrive. Others show HLB symptoms. One cultivar that performs well in Texas does not flourish in the UF/IFAS experimental grove due to herbicide sensitivity.

Nearly every day, Zapien performs one or several research activities in the grove. His mornings always begin with careful field inspections. He looks for new infections: the presence of HLB symptoms, damage from leaf miners, other pests, and diseases such as canker. Each quarter, Zapien measures tree trunks and branches in specific areas. Collected research data is voluminous and precise.

“We need specific results for each cultivar. Breeders put a lot of new cultivars in the research ‘pipeline’ to screen,” said Zapien.

Ferrarezi will group each of the new cultivars that perform at the top. Zapien said he feels he is learning at a top agricultural research university.

“When I began my studies, I wanted to help strawberry growers in Michoacán, but my ambitions grew as I realized the University of Florida leads the world in citrus research,” Zapien said. “Now I want to pursue a doctorate and contribute with novel techniques and help lead us to more sustainable agricultural practices amidst the challenges of our time.”

–Robin Koestoyo, UF/IFAS

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