BROWNSVILLE — Weslaco High School student Marc Serna said his interest in agriculture sprouted after a teacher, also a farmer, began bringing seeds to class.

But the 17-year-old Serna soon noted a problem with traditional greenhouses. Without ventilation, overheated plants wilt. Leave a window open too long, and uninvited rodents make themselves at home.

So he designed a solution: a solar-powered fan that automatically turns on when the greenhouse gets too hot.

Serna was one of 700 students from across South Texas who took their ideas to the 58th annual RGV Regional Science and Engineering Fair at the University of Texas Rio Grande Valley.

Fifty-one students each in the high school and middle school categories will move on to the state competition held in March in San Antonio.

“Some of the research is beyond what’s being done at the college level,” said Javier Garcia, the university’s regional science fair director.

Garcia said three grand champions will head to the 2018 International Science and Engineering Fair in Pittsburg to compete against students from 75 countries in May.

NASA space scientist Mike Zolensky traveled from Houston to help select students for the international competition.

“This year, it seems like the projects are the best ever,” he said. “It gives me a lot of optimism for the future.”

Categories range from chemistry and microbiology to behavioral and social sciences.

Rim Touhami, 15, and Jorge Campos, 18, are seniors at the Mathematics and Science Academy at UTRGV. They spent about four months using an atomic force microscope to research how temperature affects bacteria’s ability to adhere to surfaces.

That stickiness is what allows bacteria to build up and rot food or erode ship hulls, Campos said.

“If we can find out how to change (the bacteria), we can stop its growth,” Touhami said.

Texas Southmost College professor Ruben Reyes, once a science fair participant, returned to the event as a judge.

“It’s such a huge difference,” he said of how the science fair has grown. “These kids are our future biomedical scientists, our future doctors, pushing that field to the next level.”