Friday 16 April 2021
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Plant mutation breeding to enhance crop productivity

By Staff Reporter
Plant mutation breeding to enhance crop productivity and food security in drought-prone environments in Namibia is a major contributor to the Namibian economy and is highly correlated to growth and development. The country has semi-arid and arid climatic regions and is one of the driest countries in sub-Saharan Africa, consequently crop yields are severely limited by drought. Since 2013, pearl millet or mahangu – grown by subsistence farmers in many parts of northern Namibia – yields have been extremely low because of unreliable and poor rainfall patterns.
FAO/IAEA on its website attributes the low yields to the fact that most of the crops are grown under rain-fed conditions and the land is prone to severe soil degradation. Namibia has had low and erratic annual rainfall between 300-700 mm within and between years. This situation has not only affected crops but also livestock production as there is a lack of grazing land and feed. Desperate farmers have been taking grass from their thatched huts to feed their cattle and goats.
Pearl millet, followed by cowpeas, is a major staple food crop in northern Namibia. Sorghum is ranked third in economic importance. Cowpeas is a nitrogen fixer and is inter-cropped with pearl millet and sorghum, as it provides organic nitrogen fertiliser to the other crops. However, average yields of these crops are extremely low ranging from 250-350 kilogrammes/hectare for cowpeas to 800-920 kg/ha for pearl millet. Yields are particularly low when drought spells occur. Existing varieties are no longer meeting farmer’s requirements as they are prone to pests and diseases, produce poor yields and are susceptible to changing climatic conditions such as drought and extreme heat stress.
The Namibia Agricultural Research Plan (NARP) classified research projects on local and staple food crops such as cowpeas, pearl millet and sorghum as priority areas for research and development.
The project
The project: “Using Mutation Breeding and Integrated Soil Plant Management Techniques to Develop Sustainable, High Yielding and Drought Resistant Crops of Pearl Millet, Sorghum and Cowpea” was set up in 2008 as a collaboration between the Government of the Republic of Namibia through the Ministry of Agriculture, Water and Forestry and the International Atomic Energy Agency (IAEA), with the support of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture.
The objective of the project was to apply plant mutation breeding and soil management techniques to develop new mutant lines/varieties with high yield potential and enhanced tolerance to drought conditions for drought affected farms. Seed of local varieties of cowpeas, sorghum and pearl millet were treated with gamma rays at the FAO/IAEA’s laboratories, Seibersdorf, Austria.
The treated seeds were shipped back to Namibia and planted, and a mutation breeding programme was initiated by the Ministry of Agriculture, Water and Forestry. Three crop research stations have been involved in developing new improved mutant varieties, namely, Omahenene in the north-west, Mannheim in the north central and Bagani Research in the north east of Namibia.
The R&D effort in Namibia was supported by the Joint FAO/IAEA Division in 2009 in the form of a fellowship training programme in plant mutation breeding at FAO/IAEA laboratories, Seibersdorf, Austria.
In subsequent years, a number of the young scientists (eight in plant breeding and eight in soil and water management) have been trained in nuclear techniques applied in plant mutation breeding and soil and water management. The training targeted techniques that produce desired mutants and those that could be used in developing and advancing selected mutant lines for field performance trials in Namibia for drought tolerance, in cowpeas, sorghum and pearl millet.
Outputs of the project
Ten years from the initiation of the project, Namibia now has several advanced mutant lines in cowpeas (14), sorghum (11) and pearl millet (11) with better yield (10-20 percent higher than local varieties), better seed shape, large and different coloured seed, early maturity and drought tolerance. These promising lines are now being prepared for testing prior to being released to farmers.

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