Yield, growth and grain nitrogen response to elevated CO2 in six lentil (Lens culinaris) cultivars grown under Free Air CO2 Enrichment (FACE) in a semi-arid environment

Abstract

Abstract Atmospheric CO 2 concentrations ([CO 2 ]) are predicted to increase from current levels of about 400 ppm to reach 550 ppm by 2050. The direct benefits of elevated [CO 2 ] (e[CO 2 ]) to plant growth appear to be greater under low rainfall conditions, but there are few field (Free Air CO 2 Enrichment or FACE) experimental set-ups that directly address semi-arid conditions. The objectives of this study were to investigate the following research questions: 1) What are the effects of e[CO 2 ] on the growth and grain yield of lentil ( Lens culinaris ) grown under semi-arid conditions under FACE? 2) Does e[CO 2 ] decrease grain nitrogen in lentil? and 3) Is there genotypic variability in the response to e[CO 2 ] in lentil cultivars? Elevated [CO 2 ] increased yields by approximately 0.5 t ha −1 (relative increase ranging from 18 to 138%) by increasing both biomass accumulation (by 32%) and the harvest index (by up to 60%). However, the relative response of grain yield to e[CO 2 ] was not consistently greater under dry conditions and might depend on water availability post-flowering. Grain nitrogen concentration was significantly reduced by e[CO 2 ] under the conditions of this experiment. No differences were found between the cultivars selected in the response to elevated [CO 2 ] for grain yield or any other parameters observed despite well expressed genotypic variability in many traits of interest. Biomass accumulation from flowering to maturity was considerably increased by elevated [CO 2 ] (a 50% increase) which suggests that the indeterminate growth habit of lentils provides vegetative sinks in addition to reproductive sinks during the grain-filling period.