Elevated CO2 influences photosynthetic characteristics of Avena sativa L cultivars.

ABSTRACT

The impact of elevated CO2 concentration on the growth, photosynthesis and biomass production was investigated in three oat (Avena sativa L) cultivars viz. Kent, JHO-822 and JHO-851 by growing under three environmental conditions i.e. elevated CO2 at 600 ± 50 μ mol mol-1 (C600), OTC with ambient CO2 (COTC) and under open field condition (Ca). Plant height and leaf area increased in the elevated CO2 grown plants. JHO-822 attained maximum height under C600 followed by Kent and JHO-851. The specific leaf mass (SLM) and specific leaf area (SLA) were also influenced significantly when the plants were grown under C600. Kent showed highest SLM under C600 corresponding lower value of SLA. The accumulation of soluble protein in the oat leaves decreased under C600 except JHO-822 where marginal increase in soluble protein was recorded under C600. JHO-822 showed an increase in Chl orophyll a, b and total in C600 over Ca, whereas other two cultivars did not follow any specific trend in the pigment accumulation. Our results confirmed that the net phosynthetic rate (PN) increased by 37% in Kent followed by JHO 822 under elevated CO2 over the control. This strong association of PN with gs was evidenced by a positive significant correlation (r=0.885**). A clear stimulatory effect at elevated CO2 was detected in all the cultivars in term of green and dry matter production than at ambient CO2 and COTC. A large increase in PN in the present investigation was accompanied by relatively small decrease in gs, which limits the water loss through transpiration rate. The elevated CO2 induced changes in gs and reduction in transpiration.