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African Centre for Crop Improvement

“Training African Breeders on African Crops, in Africa”


Tackling rice yellow mottle virus in Tanzania

A burning desire to improve the lot of small-scale farmers like his parents inspired Dr William Suvi to pursue a career in plant breeding.

Suvi hails from Mngeta village in Kilombero district, found in the Morogoro region in Tanzania.

“My family were peasants cultivating rice, maize and other crops like sweetpotato and vegetables,” he said. “I was motivated to study plant breeding in order to improve yields for farmers. In my village, most farmers including my parents use landraces that produce low yields, and there is not enough for food and to sell as surplus.  Because of this farmers are unable to pay for basic items like clothes, school fees and health services.”

Dr William Suvi collecting data in the field

Suvi’s tertiary education includes a BSc in general agriculture and a MSc in crop science, specialised in agriculture and plant breeding, respectively, at Sokoine University of Agriculture in Tanzania.

“I selected my topic based on the research gap affecting farmers in rice production,” he said.  “The title of my study was “Breeding for resistance to rice yellow mottle virus and improved yield in rice in Tanzania,” he said.

Despite the fact that rice production and consumption have steadily climbed in Sub-Saharan Africa (SSA), rice is the largest imported commodity crop in the region, due to low productivity by domestic farmers.

Suvis’ thesis describes how this is due to a number of biotic and abiotic stresses and socio-economic constraints, with rice yellow mottle virus (RYMV) the most important biotic challenge in SSA, causing yield losses ranging from 20% to 100%. 

According to Suvi, “current RYMV disease management through generic crop protection chemicals is not economic, nor is it successful, due to the presence of a large number of vector species disseminating the virus. In addition, cultural practices are ineffective against RYMV because the virus is spread by several agents, including insect vectors”.

He said the use of RYMV-resistant cultivars remains the most effective, economic and environmentally friendly method for resource-poor farmers, but these resistant varieties have not yet been developed and deployed in SSA.

The first step in his research, which began in 2018, was to conduct a participatory rural appraisal (PRA) in order to assess farmer’s preferences, production constraints, and variety preferences of rice.

“I then screened rice germplasm based on agronomic traits and resistance to RYMV under field hotspot conditions, and after that I assessed the genetic diversity and population structure of a selected population of rice genotypes,” he said.

“Finally population development and evaluation was done to determine the combining ability and gene action for rice yellow mottle virus disease resistance and agronomic.”

Challenges faced in the course of his field work included a scarcity of rain and limited access to technology, such as a rice emasculator, to do crossing work.

Suvi, whose studies were funded by Alliance for a Green Revolution in Africa,  is currently working on cotton and rice  breeding programmes in Tanzania.

Words: Shelagh McLoughlin

Photo: Supplied

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