Seedling regeneration techniques affect root systems and the response of Quercus robur seedlings to water shortages

Authors: ZADWORNY, MARCIN - POLISH ACADEMY OF SCIENCES; MUCHA, JOANNA - POLISH ACADEMY OF SCIENCES; JAGODZINSKI, ANDRZEJ - POLISH ACADEMY OF SCIENCES; KOSCIELNIAK, PAULINA - POLISH ACADEMY OF SCIENCES; LAKOMY, PIOTR - POZNAN UNIVERSITY OF LIFE SCIENCES; MODRZEJEWSKI, MATEUSZ - POLISH ACADEMY OF SCIENCES; UFNALSKI, KRZYSZTOF - POLISH ACADEMY OF SCIENCES; ZYTKOWIAK, ROMA - POLISH ACADEMY OF SCIENCES; Comas, Louise; RODRÍGUEZ-CALCERRADA, JESÚS - UNIVERSIDAD POLITÉCNICA DE MADRID

Submitted to: Forest Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/29/2020
Publication Date: 9/18/2020
Citation: Zadworny, M., Mucha, J., Jagodzinski, A.M., Koscielniak, P., Lakomy, P., Modrzejewski, M., Ufnalski, K., Zytkowiak, R., Comas, L.H., Rodríguez-Calcerrada, J. 2020. Seedling regeneration techniques affect root systems and the response of Quercus robur seedlings to water shortages. Forest Ecology and Management. 479. Article e118552. https://doi.org/10.1016/j.foreco.2020.118552.
DOI: https://doi.org/10.1016/j.foreco.2020.118552

Interpretive Summary: Regenerating oak seedlings by different methods impacts taproot architecture, root-to-shoot partitioning and, potentially soil water use and plant growth under water limitations. In the present study, Quercus robur (L.) seedlings regenerated by four different methods were subjected to four levels of water availability. These treatments were used to test the hypotheses that root morphology, anatomy and biochemistry varied among regeneration methods, and, thus, differentially affected plant responses to water-shortages. For most traits, the response to water shortage of acorn-sown in the field and container-grown seedlings was similar, and opposite to that of shoot- and root-pruned seedlings. Water shortage altered the partitioning between absorptive and structural roots within the root system differently across the regeneration methods, leading to acorn-sown and container-grown oaks producing more pioneer roots, and shoot- and root-pruned oaks more highly-branched fine roots with a greater root length and surface area. Acorn-sown and container-grown oaks appear primed for water foraging, and shoot- and root-pruned oaks for water absorption efficiency in response to water shortage. Results generally indicated that seedling response to water limitation depended on the regeneration method, and highlighted the importance of root-to-shoot partitioning, taproot development and carbon reserves in response to water shortage. Acorn-sown and containerized oaks seedlings might be more suitable for forest regeneration in sites characterized by severe water shortage periods.

Technical Abstract: Regenerating oak seedlings by different methods impacts taproot architecture, root-to-shoot allometry and, potentially, soil water use plant growth under water limitations. In the present study, Quercus robur (L.) seedlings regenerated by four different methods – sowing (acorn-sown seedlings), sowing followed by shoot clipping (coppiced), sowing followed by root-pruning (root-pruned), and container planting with the root ball intact (containerized) – were subjected to four water-shortage regimes – regular watering and 75, 50, and 25% of regular watering. These treatments were used to test the hypotheses that root morphology, anatomy and biochemistry varied among regeneration methods, and, thus, differentially affected plant responses to water-shortages. For most traits, the response to water shortage of acorn-sown and containerized seedlings was similar, and opposite to that of coppiced and root-pruned seedlings. Water shortage did not change tree allocation to total root biomass across plants regenerated differently but altered the partitioning between absorptive and structural roots biomass within the root system. Acorn-sown and containerized oaks produced more pioneer roots, and coppiced and root pruned oaks more highly-branched fine roots with greater specific root length and specific root surface area under greater water shortage. Thus, acorn-sown and containerized oaks appear primed for water foraging, and coppiced and root-pruned oaks for water absorption efficiency in response to water shortage. Water shortage caused a reduction in nonstructural carbohydrate concentrations in fine roots of acorn-sown and containerized seedlings and in the taproot of coppiced and root-pruned seedlings. Results generally indicated that seedling response to water limitation depended on the regeneration method, highlighting the importance of root-to-shoot allometry, taproot development, and carbon reserve mobilization for plant functioning under water shortage. Acorn-sown and containerized oaks seedlings might be more suitable for forest regeneration in sites characterized by severe water shortage periods.