Speaker
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Introduction: Thinopyrum intermedium (Th. int.) accessions are currently under breeding for better grain productivity (Bajgain et al., 2022). Their introduction into the fields aims at diversifying cropping systems by proposing a crop enabling grain production while ensuring a range of services typically offered by perennial forages, namely fodder production and soil and nutrient conservation (Ryan et al., 2018). However, few data are available to characterize Th. int. phenotypes and plant functional traits (PFT) compared to other grass crops. Such a comparison can help to unravel the potential differences between this new crop and the well-known crops grown in temperate European cropping systems.
Materials and methods: We measured morphological, phenological and chemical traits (above-belowground) mainly linked to plant resource use strategies and reproductive efforts of 22 accessions of forage and grain crops corresponding to 14 different species. The plants were sown in autumn 2022 in individual soil columns, watered with drip irrigation, fertilized with ammo-nitrate in spring, and harvested in the summer 2023. For each treatment, 4 replicates were carried out, each being duplicated to have a plant available for analysis and destructive sampling in the spring and another for final measurements at maturity. The spring samples allowed measurements of functional traits (root and leaf morphology and nutrient content) at the vegetative stage. The summer samples were used to obtain performance traits in terms of root, above-ground, and seed biomass production.
Results: The accessions of Th. int. had lower seed mass than the other cereals (p-value < 0.001) and produced a wide range of shoot biomass, including the highest and the lowest values among cereals. Their root biomass was higher compared to other cereals (p-value < 0.001) and more like forage grasses. When examining leaf and root traits in spring, plants were mainly spread across a two-dimensional space mainly structured by gradients of tissue thinness, nutrient content in leaves (P, K, N, S), and unit mass of the seeds. The clustering separated most of the Th. int. individuals from other forage grasses and cereals. Th. int. individuals generally had lower specific leaf area (SLA) and specific root length (SRL) values compared to forage grasses, and higher root diameter (RD) values compared to forage and grain crops (p-value < 0.001). Th. int. accessions had intermediate levels of silicon (Si) between cereals and forage grasses.
Discussion: A diversification strategy with Th. int. currently requires considering much lower grain production than with annual cereals on a plant basis. Furthermore, despite shoot and root biomass production close to other forage grasses, Th. int. leaf and root traits differed. Th. int. accessions appeared to express a trait syndrome (higher RD & Si content in leaves, lower SRL & SLA) identified in the literature about plants adapted to stressful conditions (Laughlin, 2023). This syndrome may help in harsh conditions but can be detrimental to productivity, resource use efficiency in peak season, and to fodder values for animal feed. Also, a higher average root diameter is likely to influence the dynamics of carbon storage in soil, soil exploration, and the mycorrhizal symbiosis (Bergmann et al., 2020; Kim et al., 2022). Future attempts to diversify cropping systems will need to align plant growth strategies with farmers’ objectives in terms of production, soil functioning and input use.
References
Bajgain, P., Crain, J.L., Cattani, D.J., Larson, S.R., Altendorf, K.R., Anderson, J.A., Crews, T.E., Hu, Y., Poland, J.A., Turner, M.K., Westerbergh, A., DeHaan, L.R., 2022. Breeding Intermediate Wheatgrass for Grain Production, in: Plant Breeding Reviews. Wiley, pp. 119–217. https://doi.org/10.1002/9781119874157.ch3
Bergmann, J., Weigelt, A., van der Plas, F., Laughlin, D.C., Kuyper, T.W., Guerrero-Ramirez, N., Valverde-Barrantes, O.J., Bruelheide, H., Freschet, G.T., Iversen, C.M., 2020. The fungal collaboration gradient dominates the root economics space in plants. bioRxiv.
Kim, K., Daly, E.J., Gorzelak, M., Hernandez-Ramirez, G., 2022. Soil organic matter pools response to perennial grain cropping and nitrogen fertilizer. Soil Tillage Res. 220, 105376. https://doi.org/10.1016/j.still.2022.105376
Laughlin, D.C., 2023. Plant Strategies: The Demographic Consequences of Functional Traits in Changing Environments. Oxford University Press.
Ryan, M.R., Crews, T.E., Culman, S.W., DeHaan, L.R., Hayes, R.C., Jungers, J.M., Bakker, M.G., 2018. Managing for Multifunctionality in Perennial Grain Crops. BioScience 68, 294–304.
| Keywords | diversification; functional traits; phenotype; grain and forage crops; perennial grain; |
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