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Rising CO2 Enhances the Growth of Eighteen Blackgram Genotypes

Paper Reviewed
Vanaja, M., Sankar, G.R.M., Maheswari, M., Lakshmi, N.J., Yadav, S.K., Vagheera, P., Razak, S.K.A., Abraham, B., Kumar, G.V. and Venkateswarlu, B. 2015. Genotypic variation for growth and yield response at two elevated levels of CO2 and three seasons in blackgram (Vigna mungo). Indian Journal of Agricultural Sciences 85: 321-330.

Blackgram is a popular bean grown primarily in southern Asia on the Indian subcontinent. It is a fairly nutritious pulse, recommended for diabetics and shown useful in helping to lower cholesterol. In addition, it contains high levels of protein, potassium, calcium, iron, niacin, thiamine and riboflavin.

Given the importance of this crop in the diets of many people in India, Pakistan, and the surrounding region, it comes as little surprise that researchers are interested in how blackgram might respond to future changes in atmospheric CO2 and climate. Such was the case with the ten-member research team of Vanaja et al. (2015), who grew eighteen genotypes of blackgram from seeds in plastic pots inside open-top chambers at three CO2 levels (390, 550 and 700 ppm) across three distinct growing seasons (summer, rainy and winter seasons). Their purpose in doing so was to evaluate which genotypes would perform the best in each growing-season climate regime under elevated CO2. Plant performance was thus evaluated based upon analyses of five morphological (root length, root volume, shoot length, number of branches and number of pods), six dry weight (root, stem, leaf, pod, fodder and total biomass) and eight yield (filled seed number, total seed count, filled seed weight, seed yield, test weight, husk weight, percentage of shelling and harvest index) plant growth traits.

And what did these several analyses reveal?

According to the authors -- each of whom bears an association with the Central Research Institute for Dryland Agriculture in India -- "performance of the majority of traits improved with both elevated CO2 levels of 550 ppm and 700 ppm in all three seasons," with the result that seed yield and total biomass were found to be "significantly improved" by elevated CO2.

The magnitude of the various trait responses examined differed by growing season, with the lowest performance generally found in the winter season and the highest observed in the summer and rainy seasons. And by identifying these differences, Vanaja et al. hope their work will encourage policy makers and farmers to choose the best or most suitable genotype to grow, based upon whatever growing conditions the future might bring. That way, growers can be prepared to take maximum advantage of the growth benefits of rising atmospheric CO2 on blackgram, regardless of future changes in climate. And that would appear to be the wisest and most prudent plan to follow.

Posted 25 October 2016