PhD research gives pigeonpea a boost in Malawi
The improvement of a lesser-known legume that could be a major contributor to continental food security. That was the focus of Dr Esnart Nyirenda Yohane when she set about tackling her PhD research project in 2017.
Pigeonpea contains high levels of protein, amino acids, minerals and vitamins. It is also drought tolerant. Nyirenda Yohane chose to work on pigeonpea [Cajanus cajan (L) Millspaugh) because “it is one of the most important legume crops in Malawi”.
Reeling off its attributes, she said it is “a good source of protein and cash income for millions of farmers. Pigeonpea crop residues form excellent animal feed. It also serves in atmospheric nitrogen fixation and biomass allocation in the soil.”
Malawi is a major pigeonpea grower in Africa, producing 403,519 tonnes on 248,400 hactares. Grain yield, however, is low compared with the potential yield of the crop (2000 kg ha-1).
“The yield gap is due to various production constraints, including Fusarium wilt disease, insect pests, and lack of early maturing and high yielding varieties that are photoperiod insensitive,” said Nyirenda Yohane. “Breeding and deployment of high yielding, early maturing, and Fusarium-wilt-resistant cultivars have the potential to enhance pigeonpea production and productivity, hence my study focus,” she said.
Nyirenda Yohane grew up in a farming community and her parents have farmed—mostly maize and legumes—her whole life.
“All along, my parents have been growing local varieties because of their unique traits, though they are low yielding. I was inspired to study plant breeding so that I could develop improved varieties that are high yielding with unique traits that they prefer.”
Before embarking on her PhD studies and research, Nyirenda Yohane obtained a diploma in agriculture from Natural Resource College, Malawi, a BSc in forestry from Mzuzu University, Malawi and a MSc Agronomy from the University of Malawi, Bunda College of Agriculture. Her research, titled “Genetic Improvement of Pigeonpea [Cajanus cajan (L.) Millspaugh] for Yield, Earliness and Resistance to Fusarium Wilt (Fusarium udum Butler) in Malawi”, was funded by Alliance for a Green Revolution in Africa and comprised four steps.
After conducting a survey in four pigeiopea-growing districts in southern Malawi, where farmers’ trait preferences and production constraints were identified, the next step was to assess the phenotypic diversity among pigeonpea accessions in selected target production environments, as a basis to select complementary and unique genotypes for breeding. Eighty-one pigeonpea genotypes were evaluated in six environments in Malawi. The morphological markers confirmed the genetic diversity among the genotypes
“My third step was to examine genetic relationships among 81 genotypes using 4122 single nucleotide polymorphism (SNP) markers. The SNP markers confirmed the genetic diversity among the genotypes,” said Nyirenda Yohane.
Finally, she determined the combining ability and gene action controlling the agronomic traits and resistance to Fusarium wilt (Fusarium udum Butler) in pigeonpea. The best and most diverse genotypes from the diversity studies with early maturity, Fusarium wilt (FW) resistance from diversity studies and farmer-preferred varieties were selected for crosses and 25 progenies were successfully developed.
The parents and progenies were evaluated at two locations. The test genotypes were evaluated for FW resistance through a root dip inoculation technique. Both the parents and hybrids showed significant genetic variation for days to 50% flowering (DTF), days to 75% maturity (DTM), plant height (PH), 100 seed weight (HSWT), FW resistance, and grain yield (GYD).
Nyirenda Yohane faced several challenges during her four years of research work, including losing precious research time due to an agronomical setback and having to water plants by hand during a dry spell. Her biggest test, however, was having to leave her three small daughters behind when she came to South Africa to do her course work. Like many of the ACCI’s women students, she found balancing her studies and family responsibilities stressful.
“I felt guilty and at times it distracted my focus. I thank God for keeping them safe and mostly I thank my dear husband for taking good care of them,” she said.
“During my study time, I have realized that determination and hardworking are key for one’s success. In my case, I had so many issues that could have prevented me from finishing my PhD study, such as doing my write-up at home where internet, electricity are not stable, and on top of that I had family to look after, but I told myself to be focused and work as a servant. I used to lock myself in my office from morning up until 10 PM, doing my write-up.”
Nyirenda Yohane is currently working as a a legume breeder with the Department of Agricultural Research Services in Malawi. “I work on three legumes; pigeonpea, soybean and cowpea.
Her research work looks set to have a lasting impact on Malawi’s pigeonpea farmers. “I can happily say I have initiated a pigeonpea breeding program in Malawi, which was not there for decades. The breeding population developed during my study will be start-up materials,” she said.
Words: Shelagh McLoughlin