Genotypic differences in photosynthetic limitations to carbon assimilation in peanut under drought at the onset of flowering

Authors: PILON, C - University Of Georgia; SNIDER, J - University Of Georgia; MORENO, L - University Of Georgia; KVIEN, C - University Of Georgia; OZIAS-AKINS, P - University Of Georgia; Holbrook Jr, C

Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2024
Publication Date: 12/9/2024
Citation: Pilon, C., Snider, J.L., Moreno, L.A., Kvien, C.K., Ozias-Akins, P., Holbrook Jr, C.C. 2024. Genotypic differences in photosynthetic limitations to carbon assimilation in peanut under drought at the onset of flowering. Peanut Science. 51(1):126-136. https://doi.org/10.3146/0095-3679-51-PS1625.
DOI: https://doi.org/10.3146/0095-3679-51-PS1625

Interpretive Summary: Drought can greatly limit carbon assimilation in plants. This study aimed to verify potential drought tolerance associated with the photosynthetic process within ten diverse peanut genotypes grown under drought as well as to determine the limitation to carbon assimilation in these genotypes and identify parameter(s) that can be used as reference indicator of photosynthesis response to drought intensity. Experiments were conducted in 2017 and 2018 using rainout shelters to impose drought for 40 days starting 34 days after planting. Ten peanut genotypes were planted in two blocks, one fully irrigated and one under drought stress during the reproductive development. The breeding line, C76-16 was identified as the most drought tolerant genotype. In addition, two photosynthetic component processes were identified that can be used as reference indicators of the photosynthetic status of peanut under varying drought intensities.

Technical Abstract: Drought can greatly limit carbon assimilation in plants. However, different species have distinct photosynthetic components governing limitations to photosynthetic response to drought is also expected. Information on underlying limitations to carbon assimilation in peanut (Arachis hypogaea L.) has been controversial. Therefore, this study aimed to verify potential drought tolerance associated with the photosynthetic process within ten diverse peanut genotypes grown under drought as well as to determine the limitation to carbon assimilation in these genotypes and identify parameter(s) that can be used as reference indicator of photosynthesis response to drought intensity. Experiments were conducted in 2017 and 2018 using rainout shelters to impose drought for 40 days starting 34 days after planting. Ten peanut genotypes were planted in two blocks, one fully irrigated and one under drought stress during the reproductive development. Photosynthetic measurements were taken at 25 and 40 days after onset of stress. C76-16 was identified as the most tolerant genotype due to improved plasticity, downregulating photosynthesis under mild drought stress and upregulating multiple photosynthetic component processes under more severe drought to sustain photosynthesis. The primary limitation to photosynthesis across all peanut genotypes was stomatal conductance whereas non-stomatal factors (photochemical reactions) were nearly unaffected by mild drought. In addition, stomatal conductance and electron flux to CO2 assimilation contributed the most to explain drought tolerance in peanut genotypes. Moreover, these two photosynthetic component processes can be jointly used as reference indicators of photosynthetic status of peanut under varying drought intensities.