Journal of Environmental Biology

Response of soybean genotypes to iron limiting stress in calcareous vertisol under ambient and elevated CO₂ and temperature conditions

Kiran Karthik Raj¹, 5, R.N. Pandey¹*, Bhupinder Singh², M.C. Meena¹, A. Talukdar³ and D. Chakraborty⁴

¹Soil Science and Agricultural Chemistry, ICAR-Indian Agricultural Research Institute, New Delhi-110 012, India

²Nuclear Research Laboratory, Centre for Environment Science and Climate Resilient Agriculture, ICAR-IARI, New Delhi-110 012, India

³Genetics, ICAR-Indian Agricultural Research Institute, New Delhi-110 012, India

⁴Agricultural Physics, ICAR-Indian Agricultural Research Institute, New Delhi-110 012, India

⁵Natural Resource Management, ICAR-Central Island Agricultural Research Institute, Port Blair-744 107, India

*Corresponding Author Email : rnpandeyssaciari@rediffmail.com

Received: 11.07.2019                                                                           Revised: 20.06.2020                                             Accepted: 31.10.2020

Abstract

Aim: To compare the relative performance of two contrasting genotypes of soybean to iron limiting conditions under ambient and elevated CO₂ and temperature conditions.

Methodology: A pot culture experiment was performed using calcareous vertisol soil. The environmental factors viz. CO₂ and temperature were combined and applied as a single factor with two levels: a-[CO₂+T] (400±10 µmol mol^-1, day/night temperature 30^oC/22^oC) and e-[CO₂+T] (610±10 µmol mol^-1, day/night temperature 34^oC/26^oC). Soybean genotype that differed in iron use efficiency was used as another factor and two contrasting genotypes were used as two levels viz. iron efficient and responsive (FeER) and iron inefficient and responsive (FeIR).   

Results: The higher partial pressure of CO₂ under elevated carbon dioxide and temperature condition (Pco₂ = 61.8 Pa) dissolved the native CaCO₃ from calcareous vertisol soil and thereby resulted in higher HCO₃^- ion concentration. The antagonistic interaction between Fe²⁺ with HCO₃^- ion resulted in greater iron stress. As compared to ambient condition, seed yield was significantly reduced under more stressed e-[CO₂+T] condition and resulted in ~1.4 and ~1.9 times drop in FeER and FeIR genotypes, respectively. Iron efficient and responsive (FeER) genotype recorded an impressive performance, as compared to the iron inefficient and responsive (FeIR) genotype, in counteracting iron deficiency stress, both under ambient and elevated conditions.                         

Interpretation: The intra-specific variability between soybean genotypes and their response to elevated CO₂ and temperature can be exploited to remediate the emerging iron deficiency stress in soybean plants and suggest ways to structure the future breeding programmes to adapt to the climate change.        

Key words: Calcareous vertisol, Chlorosis, Climate change, CO₂, Soybean

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