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Partnerships for enhanced engagement in research (PEER) SCIENCE
Cycle 2 (2012 Deadline)

Improving yam (Dioscorea spp.) seed systems through production of dormancy-controlled seed tubers in temporary immersion bioreactors

PI: Morufat Balogun (University of Ibadan)
U.S. Partner: Wayne Curtis (The Pennsylvania State University)
Project Dates: August 2013 to July 31, 2015
2-504 Building a PVC media reservoir
Dr. Balogun and team members work to create a PVC media reservoir (Photo courtesy Dr. Balogun).
The production of yams, which are food security and poverty alleviation staples in West Africa, is constrained by scarcity of planting materials and low multiplication rates, which account for up to 63% of production cost. Tuber dormancy also hampers out-of-season production, while uncontrolled sprouting after dormancy causes storage losses. Microtubers produced in test tubes (in vitro) have been proposed as alternative propagules whose dormancy can be exogenously controlled (Balogun, 2005). Although the duration of dormancy of microtubers was shown to be affected by plant growth regulators applied at different growth phases, the tuber production rate remains slow, the low yields are not amenable to farm level production, and small tuber size limits direct transplanting to the field. Use of temporary immersion bioreactors in in vitro cultures has been recognized as a means to improve plant propagation in other crops, and the idea is adaptable to hundreds of species. Temporary immersion facilitates scale-up of propagation of large masses of plant tissue, which is useful because it does not require costly agar, reduces contamination in cultures, and provides a means for sequential manipulation of the nutrient medium at different developmental stages with minimal labor input.
The goal of this project is to identify optimum conditions for production of seed tubers of white yam whose dormancy can be efficiently controlled. This research will aid the optimization of protocols for seed yam production and increase seed supply and quantities consumed at lower expenditure levels. The immediate uses of the research results will be micropropagation of disease-free plantlets, in vitro conservation of plantlets without losses associated with field collections, and in vitro evaluation of yield in transgenic yam. The potential uses of the results include out-of-season production and extension of the storage cycle. The overall development impact is that enhanced yam productivity will help Nigeria to feed her people while also empowering them through trade.
Summary of Recent Activities
The yams planted at the end of 2013 were harvested in December 2014 and the healthy tubers were positively selected from the harvest. The hormone treated tubers planted in 2014 were also harvested and the project team has reached out to the High Performance Liquid Chromatography technologists at the University of Ibadan and Pennsylvania State University to conduct residue analysis for the growth regulators in the harvested tubers. Additionally, multiple bioreactors were set up, but are currently operated manually pending the installation of automation software.

Dr. Balogun and the team are working with the Agricultural Development Program Offices from four states with the state of Oyo already facilitating access to 2,263 farmers representing different local jurisdictions and farm sizes. This is a significant milestone towards the creation of a yam seed producer network as the team can now create a social media and outreach platforms using the available database.

In the coming months, the project team plans to increase the voltage of the solar back-up power to accommodate the bioreactors and cool the culture rooms. In addition, they will plan for the residue analysis of tubers for growth regulators, construct an aphid-proof screenhouse, and visit the Agricultural Development Program Offices of the four participating states. The team will also work with the US partner to finalize the design of the remaining bioreactors to be set up in the lab and will continue to plant the harvested tubers from previous years.

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