Challenge Program on Biological Nitrogen Fixation

R. Serraj and J. Adu-Gyamfi

International Crops research Institute for the Semi Arid Tropics (ICRISAT)

PO Patancheru, 502324 Andhra Pradesh, INDIA

http://www.icrisat.org

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The International Crops Research Institute for the Semi Arid Tropics (ICRISAT) has recently proposed a recent Challenge Program on Biological Nitrogen Fixation (CPBNF), as part of the new global initiative taken by the CGIAR. The overall goal of CPBNF would be to harness some of the most recent breakthroughs in BNF technologies and research on legume-rhizobium symbiosis, where it is most needed, i.e., to mitigate the downward spiral of soil fertility loss, food insecurity, poverty and malnutrition in developing countries. The current plan is to build a large stakeholder consortium, to promote BNF technologies in developing countries with a major focus on most vulnerable areas, such as South Asia and Sub-Saharan Africa.

The N₂-fixing legume plants usually require more phosphorus than plants dependent on mineral N fertilizer. Nodule establishment and functioning are important sinks for P, and nodules have usually highest P content in the plant. Therefore, P deficiency conditions results in reduced BNF potential and P fertilization will usually result in enhanced nodule number and mass, as well as greater BNF Potential. Work at ICRISAT and elsewhere have shown that legume like lupine and pigeonpea have the ability to extract P from sparingly soluble P sources. Genotypic differences in the P solubilizing ability has also been reported in several legume species, thus the inclusion of selected P-efficient genotypes in cropping systems could enhance the P available pool in soils and boost the BNF potential in legumes.