Rising carbon dioxide levels lowering rice yields

Berlin: Rising levels of carbon dioxide are lowering the high grain yields of dwarf rice varieties, says a new research from Germany.

A dwarf variety called IR8, which has now disappeared almost completely from the market, succeeded in protecting humanity against global famine in the 1960s and was in the vanguard of Green Revolution. Declining yields from IR8 prompted Bernd Muller-Rober from the Max Planck Institute and colleagues from the University of Potsdam to explore whether it was linked to rising levels of carbon dioxide (CO2), up by 25 percent since the 1960s. Using the model plant Arabidopsis thaliana (generally known as thale cress), researchers were able to observe that a higher CO2 concentration results in freeing the capacity of dwarf plant to form gibberellic acid, according to a institute statement. The CO2 appears to have the same growth-stimulating effect as that triggered by the gibberellic acid. Thus, in the experiment, the dwarf plants gradually lost their advantage and increasingly resembled the ordinary plants. "Breeders now face the challenge of developing new plants that can continue to provide good yields under the altered climatic conditions," said Jos Schippers, study co-author. The cultivation of dwarf varieties is not only common in the case of rice, farmers also prefer short-stalked varieties of wheat; both cereals are the staple food consumed by a majority of the global population. The researchers are now looking for the mechanism through which the gaseous carbon dioxide influences the growth of the plants. IANS