Paper Reviewed
Sreeharsha, R.V., Sekhar, K.M. and Reddy, A.R. 2015. Delayed flowering is associated with lack of photosynthetic acclimation in Pigeon pea (Cajanus cajan L.) grown under elevated CO2. Plant Science 231: 82-93.

In the words of Sreeharsha et al. (2015), pigeonpea [Cajanus cajan (L.)] "is an important food legume crop of equatorial and semiarid parts of the world," where they say it "is a rich source of protein (with 20-22% protein by dry seed weight) in vegetarian diets for many countries," citing in this regard the work of Bohra et al. (2011). And they therefore state that "it is highly crucial to study the responses of this potent grain legume to elevated CO2 conditions," which is what they thus did, discovering and reporting what they learned in the paper here reviewed.

Working at the high-CO2 experimental research facility of the University of Hyderabad, India, the three researchers grew pigeon pea plants from seed to maturity on a red sandy loam soil in open-top chambers maintained at either the ambient CO2 concentration of 395 ppm or at an enriched level of 550 ppm for two full growing seasons under both well watered and fertilized conditions, with the exception of nitrogen, standard dressings of which were withheld from the plants. And the results of this work?

Sreeharsha et al. determined that over the course of the two growing seasons, the 39% increase in atmospheric CO2 concentration led to (1) a 36% increase in season-long net photosynthesis, (2) a 29.3% increase in total plant dry weight, (3) a 38.6% increase in the number of nitrogen-producing nodules that led to (4) a 74.9% increase in total nodule dry weight, and last of all (5) a 29.0% increase in seed yield, all of which results led them to conclude that a "future elevated CO2 atmosphere favors pigeonpea to sequester more atmospheric CO2 and N2 resulting in better economic yields under natural habitats."

Reference
Bohra, A., Dubey, A., Saxena, R.K., Penmetsa, R.V., Poornima, K.N., Kumar, N., Farmer, A.D., Srivani, G., Upadhyaya, H.D., Gothalwal, R., Ramesh, S., Singh, D., Saxena, K., Kishor, P.B.K., Sing, N.K., Town, C.D., May, G.D., Cook, D.R. and Varshney, R.K. 2011. Analysis of BAC-end sequences (BESs) and development of BES-SSR markers for genetic mapping and hybrid purity assessment in pigeonpea (Cajanus spp.). BMC Plant Biology 11: 10.1186/1471-2229-11-56.