Influence of elevated CO2 on growth, yield, haulm, and kernel quality of groundnut (Arachis hypogaea L.)

A study was conducted to evaluate the effect of elevated CO2 on groundnut growth, yield, kernel and haulm nutritional quality in the Open Top Chambers (OTC). Three regimes of CO2, ambient (380 ppm) and two elevated CO2 levels (550 and 700 ppm) are maintained in three different OTCs. Compared to the ambient CO2 conditions, the kernel yield per plant declined by 32.28% and 28.40% at 550 and 700 ppm, respectively, although the pod yield remained unaffected under elevated CO2. Under elevated CO2, plant height, specific leaf area, root area and root volume are reduced, while specific leaf weight increased because of leaf thickening. Root dry weight increased due to allocation of extra fixed carbon to roots for greater support to growth under CO2 enriched conditions. Haulm quality is reduced under elevated CO2, observed as reduced metabolizing energy and in-vitro organic matter digestibility at 550 ppm, and low ash and nitrogen content at 700 ppm. Kernel oil (6.54% and 2.98%) and protein content (7.07% and 4.56%) declined at 550 and 700 ppm as compared to ambient conditions, while fatty acid content remained unaffected. Among minerals, kernel iron and manganese content remained unaffected, while copper (13.93% and 26.19%) and calcium (24.33% and 8.20%) content declined at both elevated CO2 levels. The genotype by trait biplot analysis revealed ICGV 03043 as the best performing genotype with a superior trait profile alongside high kernel yield and oil content across three CO2 levels, making it a candidate for future studies to understand the insensitivity to elevated CO2.