Antioxidant Defence Response and Micronutrient Content Availability in Cyamopsis Varieties in eCO2 Concentration

Abstract

There is need for research that explores the impact of elevated carbon dioxide on the antioxidant defense system, crop nutrition and
soil micro-nutrients availability which was not investigated much in past studies.
A pot experiment was performed to analyse antioxidant defence response including Superoxide dismutase (SOD) enzyme assay, total
Ascorbate, Ascorbate peroxidase (APX) leaf data assay, Flavanoid and Total Phenolic content (TPC) in leaves samples. Micronutrients
analysis and nutritional quality were estimated including Cr, Mn, Fe, Co, Cu, Zn, As, Se, Mo and Pb elements. Micronutrients analysis
were determined in soil, leaves, pods and seeds of RGC 1002 and RGC 1066 Cyamopsis varieties fumigated under e[CO2]=550±20ppm
and a[CO2]=420±20ppm maintained at FACE setup at CSIR- NBRI, Lucknow.
Superoxide dismutase activity was found to decline in RGC 1002 [-16.63%] and RGC 1066 [-17.90%] while total ascorbate, ascorbate
peroxidise activity, total phenol and flavonoid content increased in RGC 1002 [+9.37%, +6.30%, +11.53%, +10.46%] and RGC 1066
[+66.32%, +12.17%, +76.50%, +19.82%] under elevated carbon dioxide e[CO2] concentration in both the cultivars. Micronutrient content
declined in leaves but it was enhanced in pods and seeds of both the cultivars under e[CO2] concentration. In leaves, pods and seeds
of RGC 1002 micro-nutrient contents were Fe [-56.00%, +6.00%, +9.75%], Cu[-23.16%, +7.45%, +10.46%], Zn[-30.61%,+28.30%,+7.41],
Mn[-32.29%, +23.05., +7.52] content. However in RGC 1066, there was a differential response regarding some of the metals Cu[-
52.81%,+5.58%, +6.42%], Zn[-20.29%.+9.50%.+6.50%], Mn[+31.54%, +11.18%, +9.96%], Fe[+32.99%, +4.00%, +8.71%] content was
found to increased under e[CO2] concentration.
Antioxidant response in both the cultivars was enhanced under e[CO2] concentration that leads to the scavenging of ROS particles thus
leading to declining of ROS and mitigating the plant against abiotic stress condition. This conditions leads to altogether improvement
in plant antioxidant defences system. It was observed that the interaction between e[CO2] and both plant varieties increased uptake of
micro-nutrients in pods and seeds in both the cultivars. Apart from these RGC 1066 varieties showed better uptake and translocation
of micro-nutrient content (Fe, Cu, Zn) than RGC 1002 plant variety under e[CO2] concentration. Thus, it can be concluded that RGC 1066
is better than RGC 1002 plant variety which is adapting and performing in better way under e[CO2] concentration.