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The Prospects for Increased Pigeon Pea Production in India
Reference
Vanaja, M., Reddy, P.R.R., Lakshmi, N.J., Razak, S.K.A., Vagheera, P., Archana, G., Yadav, S.K., Maheswari, M. and Venkateswarlu, B. 2010. Response of seed yield and its components of red gram (Cajanus cajan L. Millsp.) to elevated CO2. Plant, Soil and Environment 56: 458-462.

Background
The authors write that "food grain requirements of India (both human and cattle) are estimated at 300 Mt in 2020," citing Sinha et al. (1998); and in this context they note that "grain legumes are one of the mainstays of the drylands, as these crops provide much needed nutritional security in the form of proteins to the predominant vegetarian populations of India and also the world." And they further state that legumes -- of which pigeon peas are an important example -- "have the potential to maximize the benefit of elevated CO2 by matching stimulated photosynthesis with increased N2 fixation," citing Rogers et al. (2009).

What was done
Vanaja et al. grew pigeon peas (Cajanus cajan L. Millsp.) from seed to maturity out-of-doors at Hyderabad (India) within open-top chambers maintained at atmospheric CO2 concentrations of either 370 or 700 ppm (ambient or enriched, respectively), after which they harvested them and measured a number of pertinent productivity parameters.

What was learned
The team of nine Indian scientists -- from their country's Central Research Institute for Dryland Agriculture -- reports that "total biomass recorded an improvement of 91.3%, grain yield 150.1% and fodder yield 67.1%." And they state that "the major contributing components for improved grain yield under elevated CO2 were number of pods, number of seeds and test weight," which exhibited increases of 97.9%, 119.5% and 7.2%, respectively. In addition, they found there was "a significant positive increase of harvest index at elevated CO2 with an increment of 30.7% over ambient values," which they say was due to the crop's "improved pod set and seed yield under enhanced CO2 concentration."

What it means
Their several positive findings, in the words of Vanaja et al., illustrate the importance of pigeon peas for "sustained food with nutritional security under a climate change scenario," which should be good news for everyone, especially citizens of India and other Asian countries.

References
Rogers, A., Ainsworth, E.A. and Leakey A.D.B. 2009. Will elevated carbon dioxide concentration amplify the benefits of nitrogen fixation in legumes? Plant Physiology 151: 1009-1016.

Sinha, S.K., Kulshreshtha, S.M., Purohit, A.N. and Singh, A.K. 1998. Base Paper. Climate Change and Perspective for Agriculture. National Academy of Agricultural Sciences, 20.

Reviewed 9 February 2011