Effect of elevated CO2 levels in Kinnow mandarin and Kagzi Kalan lemon under controlled environment conditions

Abstract

With the countinious increment in global industrialization, productivity of horticultural crops is expected to be affected drastically by changing climate especially due to increasing of atmospheric carbon dioxide concentration. A study were carried out on one-year-old budded plants of Kinnow (Citrus nobilis × Citrus deliciosa) and Kagzi Kalan (Citrus limon) to assess the physiological and biochemical changes induced under elevated CO2 concentration (450 and 550 ppm). The per cent increase in plant height (Kinnow - 17.06 & 6.80, Kagzi Kalan- 33.38 & 25.64) and leaf number (Kinnow - 14.20 & 22.92, Kagzi Kalan- 33.94 and 19.81) were significantly higher at 450 and 550 ppm, respectively over control. Initially, the photosynthetic rate was significantly increased over control (13.9 and 12.1 μmol CO2 m-2s-1 at 550 ppm in Kinnow and Kagzi Kalan, respectively), with increasing CO2 level regardless of genotype. The total chlorophyll content in both the species (3.15 & 2.32 mg/gFW), activity of catalase (1.32 and 1.44 (μ moles H2O2 hydrolyzed min−1 mg−1 protein), proline concentration (153.80 and 252.83 μg/g FW) and peroxidase (520.12 and 669.50 A436 unit min-1 μg g-1 FLW) were significantly higher in Kinnow leaved compared to Kagzi Kalan at both the CO2 levels. Hence, Kinnow showed more tolerance as compared to Kagzi Kalan lemon for increasing CO2 challenge.