Study of physiological responses of Allium sativum to elevated CO2 and temperature

Abstract

Aim: The present investigation was undertaken to study the response of some garlic varieties of Allium sativum under different ambient and elevated CO2 and temperature conditions in order to investigate the physiological responses under changing climatic condition. Methodology: A two factorial CRD experiment was conducted for two years with four varieties of Allium sativum (Ekfutia Assam, Assam Local, Bhima Omkar and Bhima Purple) under four atmospheric regimes [T1= Ambient CO2 and temperature; T2= Carbon dioxide Temperature Gradient Tunnel-I (400 ppm CO2 + 2oC higher than ambient); T3 = Carbon dioxide Temperature Gradient Tunnel-II (550 ppm CO2 + 4oC higher than ambient); T4 = Carbon dioxide Temperature Gradient Tunnel-III (700 ppm CO2 + 6oC higher than ambient)]. Major changes in physiological parameters of the varieties were recorded in Carbon dioxide Temperature Gradient Tunnel-II as compared to ambient condition. The rate of photosynthesis was measured on fully expanded youngest leaves of each sample plant using a portable Infrared Gas Analyzer. Results: The mean photosynthetic rate of all four varieties grown over two years was 13.43% higher in Carbon dioxide Temperature Gradient Tunnel-II over varieties grown for two consecutive years under Ambient CO2 and temperature. However, high CO2 concentration and temperature stress significantly reduced the stomatal conductance approximately by 27.48%. Interpretation: The results of this study gives a comprehensive analysis of garlic varieties under four different climatic conditions of CO2 and temperature and revealed that Ekfutia Assam and Assam Local and garlic varieties Bhima Omkar and Bhima Purple were promising varieties as they responded significantly to elevated CO2 and temperature regimes. This may provide some critical inputs for optimizing the strategies in future farming and farming opportunities of this commercially and medicinally important crop under changing climatic conditions.