Hamilton Chiango: Drought and Physiological Changes in Maize

Hamilton Chiango presented his USDA-FAS Borlaug Fellowship findings for a CALS SAIGE International Seminar

WRITTEN BY Amelia Cook, alcook3@ncsu.edu

Selected to do research at a U.S. institution, Hamilton Chiango, Assistant Lecturer and Researcher from the Univerdidade Eduardo Mondlane in Mozambique and the 2019 USDA Borlaug Fellow at NC State, traveled to NC State University in the Spring of 2019. While on campus he worked with Dr. Thomas Sinclair of the Crop and Soil Sciences Department to study the drought and physiological properties in maize with the ultimate goal of improving yields in maize in Mozambique.

Potentially significant geneotypes for Mozambique selected by Chiango

Before traveling to Raleigh, Chiango identified which Genotypes would be most important to research abroad for Mozambique. Mozambique relies on maize as a major food source but suffers from drought during long stretches of the year resulting in a hunger problem across the country. The genotypes selected were developed from Mozambique materials and shipped to NC State University’s campus. This data was compiled before traveling to Raleigh to work with Dr. Sinclair.

During his time at NC State, Chiango worked on two major experiments. The first studied the transpiration responses to vapor pressure deficits and the second studied the transpiration responses to soil drying.

Chiango conducting vapor pressure deficit research in Dr. Sinclair’s lab at NC State.

In the first experiment completed with Dr. Sinclair, various vapor pressure deficits were stimulated to trigger transpiration of the plants. Their goal was to identify those that were most effectively closing their stomata to prevent water loss through transpiration. The results showed which genotypes lost more water than others and therefore indicated which were more suitable for dry climates.

Transpiration responses to vapor pressure deficit of Umbelu 8930 and CML 586

Chiango selected two genotypes, Umbelu 8930 and CML 586 as examples to compare different types of responses of transpiration. The right graph shows a linear response depicting a behavior that is not preferred. This type of response means that as the vapor pressure deficit (VPD) increases and continues to stimulate transpiration throughout the day, the genotype will continue to transpire until it contains no more water and dies. The response on the left shows a genotype that slows its transpiration in response to a potentially harmful VPD. It will store enough water for the plant to continue its life cycle and produce maize. The experiment was repeated a second time for all genotypes and the same results were observed. Those with similar responses to Umbelu 8930 were selected as potential genotypes that could be most useful for maize production back in Mozambique.

Chiango studying transpiration responses to soil drying at NC State.

The purpose of the second experiment was to analyze each genotype’s response to soil drying in order to determine which of those genotypes would best endure dry soil conditions. The researchers measured the plants’ transpiration every day to identify the best transpiration responses. Finding genotypes that can resist dry soil as a result of drought would be a significant success for the future of farming in Mozambique.

Transpiration responses to soil drying for CML 8923 and CML 587

The responses to soil drying for the genotypes CML 8923 and CML 587 were selected as examples of a desirable and undesirable response. On the left, CML 8923 closes its stomata around a 0.55 fraction of transpirable soil water (FTSW). This type of response means the plant will retain more water that it can use later in the growing season. In comparison, CML 587 closes at around a 0.3 FTSW depicting a response that would allow more water to escape in its delayed transpiration response. The genotypes with responses more similar to CML 8923 would be the genotypes most likely to improve yields of maize production.

Chiango is passionate about spreading the knowledge from his international research back in Mozambique. He recognizes the significance that these results could have in improving yields and fighting hunger in a part of Africa that is greatly affected by drought. Chiango is an advocate for the kind of international scientific cooperation that the Borlaug International Agriculture Science and Technology Fellowship Program promotes. This global exchange of knowledge not only benefits a fellow’s home country, but NC State University, and the United States.