School of Agricultural, Earth and Environmental Sciences

Pigeonpea Focus of Doctoral Research by Mother of Three

The improvement of a lesser-known legume that could be a major contributor to continental food security was the goal of Dr Esnart Yohane when she began her PhD research project in 2017.

The legume, Pigeonpea, contains high levels of protein, amino acids, minerals and vitamins as well as being drought tolerant. Esnart 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 and 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 400h. 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 Esnart. ‘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.

Esnart grew up in a farming community and her parents have farmed – mostly maize and legumes – for as long as she can remember.

‘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, Esnart obtained a diploma in agriculture from the Natural Resource College in Malawi, a BSc in Forestry from Mzuzu University also in Malawi, and an MSc Agronomy from the University of Malawi’s Bunda College of Agriculture.

Her PhD 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 the Alliance for a Green Revolution in Africa (AGRA).

After conducting a survey in four pigeonpea-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 4 122 single nucleotide polymorphism (SNP) markers. The SNP markers confirmed the genetic diversity among the genotypes,’ said Esnart.

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).

Esnart 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 African Centre for Crop Improvement’s (ACCI) female 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 my daughters safe and mostly I thank my dear husband for taking good care of them,’ she said.

‘During my study time, I have realised that determination and hard work 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 the internet and 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 10pm (while) doing my write-up.’

Esnart is currently working as 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 programme in Malawi which has not been there for decades. The breeding population developed during my study will be start-up materials,’ she said.

Words: Shelagh McLoughlin

Photograph: Supplied