Relationships among carbon isotope composition, growth, and foliar nitrogen in soybean

• Published in: Journal of crop improvement Vol. 36; no. 1; pp. 90 - 107
• Main Authors: Ingwers, Miles W., Steketee, Clinton J., Yadav, Sushil K., Li, Zenglu
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 02.01.2022; Taylor & Francis Ltd
• Subjects: Accumulation; Biomass; breeding; Carbon; carbon isotope composition; Carbon isotopes; Cultivars; drought; Drought resistance; Gas exchange; Genotypes; Glycine max; Isotope composition; Leaves; Moisture content; Moisture resistance; Moisture stress; Nitrogen; Plant breeding; Soil conditions; Soil moisture; Soil water; soybean; Soybeans; Stomata; Stomatal conductance; Transpiration; Water content; Water potential
• ISSN: 1542-7528; 1542-7536
• DOI: 10.1080/15427528.2021.1910092

Interactions between carbon isotope composition (δ 13 C), foliar nitrogen concentration (foliar N), and biomass accumulation (growth) merit further investigation in soybean (Glycine max (L.) Merr.) and other species as these metrics may be valuable for assessing moisture stress and for screening of drought-resistant varieties. To this end, we examined the response of six soybean genotypes to water-deficit stress in a greenhouse study. Two treatments were imposed: low soil moisture (5-10% volumetric water content) and high soil moisture (30-38% volumetric water content). Above-ground biomass accumulation, foliar N, and δ 13 C were measured at the end of the experiment. Leaf water potential and midday gas exchange (net assimilation, stomatal conductance, and transpiration) were measured multiple times throughout the experiment. All measurements were affected by water-deficit stress. Significant, but weak, positive relationships were found between δ 13 C and biomass accumulation in both soil moisture treatments. Foliar N was significantly, but weakly, correlated to growth in the high soil-moisture treatment, but not in the low soil-moisture treatment. The data suggest that selection for genotypes with higher δ 13 C values could result in improved biomass accumulation. The relationship between foliar N and δ 13 C was negative under high soil-moisture conditions and positive under low soil-moisture conditions. The relationships between δ 13 C and foliar N could be a highly informative metric to help understand the effects of water-deficit stress and may further indicate whether water or nitrogen acquisition is limiting in a specific environment, which should help in breeding improved soybean cultivars.