College of Agriculture, Engineering
and Science (CAES)

PhD Graduates Investigate Threats to Staple Crops

Novel research investigating how to combat the threats of environmental stress and parasites on wheat and maize led to Dr Isack Mathew and Dr Admire Shayanowako receiving PhDs in Plant Breeding.

Mathew completed his research on the topic of pre-breeding of wheat (Triticum aestivum L.) for biomass allocation and drought tolerance. The production and productivity of this cereal crop, one of the most important globally after maize and rice, is affected by recurrent drought and declining soil fertility.

‘Wheat cultivars with a well-balanced biomass allocation and improved root systems have better water- and nutrient-use efficiency and, hence, increased productivity under dry-land farming systems,’ said Mathew’s supervisor, Professor Hussein Shimelis. ‘The enhanced ability of cultivars with well-balanced biomass allocation to extract and use water efficiently contributes to “climate-smart” agriculture by increasing yield potential while retaining carbon-rich residues for soil restitution. This will also have spill over benefits of carbon sequestration,’ said Shimelis.

Mathew, who set out to develop breeding populations of wheat with enhanced drought tolerance and biomass allocation under water-limited conditions, identified elite genotypes that can be used to develop high yielding wheat varieties that are drought tolerant and have enhanced capacity to sequester carbon into the soil. He was also able to identify possible candidate genetic regions responsible for controlling biomass allocation in wheat, providing important information for wheat breeding programmes.

Mathew’s research has been published in several international, peer-reviewed journals including the Journal of Agronomy and Crop ScienceEuphytica, and Agriculture, Ecosystems and Environment,increasing the reach of his work to impact the agricultural development community. He presented his research at the 2017 and 2019 Combined Congress, and the 12th Southern African Plant Breeding Symposium in 2018.

During his studies, Mathew served as a supplemental instruction tutor, providing academic support to students in high-risk modules in the School of Agricultural, Earth and Environmental Sciences (SAEES), and assisted several master’s students in Plant Breeding and Crop Science.

He acknowledged his supervisors, Shimelis and Dr Vincent Chaplot, for their guidance and mentorship which motivated him to achieve this milestone. He also thanked his family for their support.

Shayanowako’s research dealt with integrated management of Striga asiatica (L.) Kuntze in maize through resistance breeding and biocontrol.

Striga, a parasitic weed, is one of the major biotic constraints limiting production and productivity in Africa in cereal crops including maize, sorghum, pearl millet, finger millet and rice,’ said Shimelis, who was also Shayanowako’s supervisor. ‘Yield losses of 30 to 90% have been reported regularly in the semi-arid regions of sub-Saharan Africa, including South Africa.’

With several proposed cultural, chemical and host resistance measures not being taken up by affected farmers because of high costs or the ineffectiveness of the control method, an alternative was needed. Exploration of the combination of partial resistance in the host crops, together with a biological control agent, Fusarium oxysporum f.sp strigae (FOS), have provided excellent control of Striga’s hermonthicaand asiatica species in maize and sorghum crops.

In his research, Shayanowako developed maize cultivars with Striga resistance and FOS compatibility.

This work attracted international interest and collaborations. Shayanowako was invited by Montana State University in the United States to participate in three weeks of training on the biocontrol of weeds through the Toothpick Project, an initiative aimed at commercialisation of FOS throughout Africa. His research also identified quantitative trait loci (QTL) conditioning Striga resistance in maize using genomic analysis through a collaboration with the Biosciences eastern and central Africa – International Livestock Research Institute Hub in Kenya.

Shayanowako has published his research in the International Journal of Pest Management, Maydica,Cereal Research Communications and Acta Agriculturae Scandinavica. He presented his research results at the 2019 Combined Congress, the 2018 College of Agriculture, Engineering and Science Postgraduate Research and Innovation Symposium, the 12th Southern African Plant Breeding Symposium and the 26th Asian-Pacific Weed Science Society Conference in Japan.

Having completed their doctorates, both Mathew and Shayanowako have taken up postdoctoral research posts at UKZN’s African Centre for Crop Improvement to continue their Plant Breeding research.

Words: Christine Cuénod

Photograph: Gugu Mqadi