Journal of Environmental Biology

Elevated CO₂ influences photosynthetic characteristics of Avena sativa L cultivars

 

R.K. Bhatt¹, M.J. Baig*² and H.S. Tiwari¹

 

¹Indian Grassland and Fodder Research Institute, Jhansi - 284 003, India

 

²Central Rice Research Institute, Cuttuck? - 753 006, India

(Received: May 12, 2009; Revised received: February 02, 20010; Accepted: February 26, 2010)

 

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 m mol mol^-1 (C₆₀₀), OTC with ambient CO₂ (C_OTC) and under open field condition (C_a). 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 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 CO₂ 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 CO₂ was detected in all the cultivars in term of green and dry matter production than at ambient CO₂ 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 CO₂ induced changes in g_s and reduction in transpiration.

Key words: Biomass production, Oat, OTC, Specific leaf mass, Photosynthesis, Stomatal conductance

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