Yield response of tetraploid and hexaploid wheat varieties to CO2 enrichment

Abstract

In an experiment conducted during the winter season of 1996-97 and 1997-98, two varieties (HD 4502' and 'B4409') of durum wheat (Triticum aestivum Desf.) and two ('Kalyansona' and 'Kundan') of bread wheat. (T. aestivum L. emend. Fiori & Paol.) were grown in the field at atmospheric and elevated CO2 (650 +/- 50 ppm) concentrations inside open-top chambers to examine yield components at maturity. The CO2 enrichment enhanced the grain yield mostly through an increase in the number of ear-bearing tillers. Individual ear weight was also increased in plants grown under elevated CO2 concentration. Varieties however differed in the manner, in which the individual ear weight was increased. In 'B 449' and 'Kalyansona', the increase in grain yield of the individual ear of plants grown under elevated CO2 concentration was due to an increase in individual grain weight. In 'HD 4502', an increase in grain yield of the individual ear of plants grown under elevated CO2 concentration was due to higher grain number/ear as a result of an increase in spikelets/ ear. Genotypic differences in response to elevated CO2 were observed. Varieties having greater sink capacity in terms of higher grains/ear showed a greater yield response in both tetraploid and hexaploid wheat.