Journal of Environmental Biology

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

N. Rahman¹*, R. Das², B.D. Narzary³, D.B. Phookan⁴, A. Saikia⁴ and S. Alam⁴ 

¹Regional Agricultural Research Station, Assam Agricultural University, Shilongani- 782 002, India

²Department of Crop Physiology, Assam Agricultural University, Jorhat- 785 013, India

³Department of Horticulture, SCCA, Dhubri-783 376, India

⁴Department of Horticulture, Assam Agricultural University, Jorhat-785 013, India

*Corresponding Author Email : naseema.rahman@aau.ac.in

Received: 02.09.2020                                                                      Revised: 01.02.2021                                                  Accepted: 08.06.2021

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 + 2^oC higher than ambient); T³ = Carbon dioxide Temperature Gradient Tunnel-II (550 ppm CO² + 4^oC higher than ambient); T⁴ = Carbon dioxide Temperature Gradient Tunnel-III (700 ppm CO² + 6^oC 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.

Key words: Carbon-di-oxide, Garlic varieties, Photosynthesis, Stomatal conductance, Temperature

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