Maize hybrids response to limited nitrogen under current and future CO2 environments

Authors: THENVEETTIL, NAFLATH - Mississippi State University; BHEEMANAHALLI, RAJU - Mississippi State University; Reddy, Krishna; REDDY, RAJA - Mississippi State University

Submitted to: Plant Physiology Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2024
Publication Date: 7/13/2024
Citation: Thenveettil, N., Bheemanahalli, R., Reddy, K.N., Reddy, R.K. 2024. Maize hybrids response to limited nitrogen under current and future CO2 environments. Plant Physiology Reports. https://doi.org/10.1007/s40502-024-00802-7.
DOI: https://doi.org/10.1007/s40502-024-00802-7

Interpretive Summary: Given the increased nitrogen fertilization, rise in fertilizer prices, and the atmospheric CO2 levels, it is crucial to understand how crop respond to these changing environmental conditions. Scientists from Mississippi State University, Mississippi Sate, Mississippi and USDA-ARS, Crop Production Systems Research Unit, Stoneville, Mississippi have investigated the responses of ten maize hybrids to elevated CO2 (eCO2, 760 ppm) and low nitrogen (20% of control, LN) conditions during early seedling stage. The study revealed significant differences in the measured morpho-physiological and biomass parameters among the hybrids under LN, except for root traits. Under eCO2 and LN conditions, the chlorophyll content and nitrogen balance index reduced by 15% and 39%, respectively, compared to the control. Across the maize hybrids, the LN and eCO2 reduced the total seedling biomass by 33% over control with major allocation to root. The treatments increased the root length and branching in all the hybrids. The N limitations majorly contributed the poor seedling performance and eCO2 did not compensate the biomass loss. The cross over response of maize under CO2 saturation might have caused the non-significant effect of eCO2. Among the ten hybrids, the cumulative eCO2 and LN response index revealed that PGY7215VT2P and Armor-1717 had high responses, indicating their potential for growing under nitrogen-limited conditions.

Technical Abstract: Given the increased nitrogen fertilization, rise in fertilizer prices, and the atmospheric CO2 levels, it is crucial to understand how crop respond to these changing environmental conditions. In this study, using sunlit growth chambers, we investigated the responses of ten maize hybrids to elevated CO2 (eCO2, 760 ppm) and low nitrogen (20% of control, LN) conditions during early seedling stage. The study revealed significant differences (p<0.5 to p<0.001) in the measured morpho-physiological and biomass parameters among the hybrids under LN, except for root traits. Under eCO2 and LN conditions, the chlorophyll content and nitrogen balance index reduced by 15% and 39%, respectively, compared to the control. Conversely, the flavonoid and anthocyanin increased by 37% and 25% under eCO2 and LN, respectively. The LN had a remarkable impact on shoot growth, leading to significant reductions in plant height (28%), leaf area (52%), and shoot dry weight (43%) under eCO2 compared to control N and aCO2. In contrast, the effect of eCO2 on shoot growth was not evident, suggesting a cross-over response of C4 plants to the eCO2 levels. Under eCO2 and LN, the plants produced longer roots (8.9%) with a reduced diameter and a high root-to-shoot ratio compared to the control. The percent changes in root length, average diameter, and root-to-shoot ratio under eCO2 and low nitrogen were 23%, -8.8%, and 96%, respectively. Among the ten hybrids, the cumulative eCO2 and LN response index revealed that PGY7215VT2P and Armor-1717 had higher responses compared to D57VP51 and REV-25BHR26, indicating their potential for growing under nitrogen-limited conditions.