Elevated CO 2 influences photosynthetic characteristics of Avena sativa L cultivars

The impact of elevated CO 2 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 CO 2 at 600 ± 50 μ mol mol -1 (C 600 ), OTC with ambient CO 2 (C OTC ) and under open field condition (C a ). Plant height and leaf area increased in the elevated CO 2 grown plants. JHO-822 attained maximum height under C 600 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 C 600 . Kent showed highest SLM under C 600 corresponding lower value of SLA. The accumulation of soluble protein in the oat leaves decreased under C 600 except JHO-822 where marginal increase in soluble protein was recorded under C 600 . JHO-822 showed an increase in Chl orophyll a, b and total in C 600 over C a , whereas other two cultivars did not follow any specific trend in the pigment accumulation. Our results confirmed that the net phosynthetic rate (P N ) increased by 37% in Kent followed by JHO 822 under elevated CO 2 over the control. This strong association of P N with g s was evidenced by a positive significant correlation (r=0.885**). A clear stimulatory effect at elevated CO 2 was detected in all the cultivars in term of green and dry matter production than at ambient CO 2 and C OTC . A large increase in P N in the present investigation was accompanied by relatively small decrease in g s, which limits the water loss through transpiration rate. The elevated CO 2 induced changes in g s and reduction in transpiration.