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Plant Sociology numero 54 (1) S1

pag. 19-27: Root adaptive management for improving plant quality and field performance under drought: experiences with native tree species from a South American Mediterranean-type ecosystem

J.F. Ovalle1, R. Ginocchio1,2, E.C. Arellano1,2 & P. Valenzuela2

1Pontificia Universidad Católica de Chile, Center of Applied Ecology & Sustainability (CAPES-UC), Avenida Libertador Bernardo O’Higgins 340, Santiago, Chile.

2Pontificia Universidad Católica de Chile, Facultad de Agronomía e Ingeniería Forestal, Departamento de Ecosistemas y Medio Ambiente, Avenida Vicuña Mackenna 4860, Santiago, Chile.

doi: 10.7338/pls2017541S1/03

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abstract

Plant quality attributes have been widely studied for numerous tree species inhabiting the Mediterranean Basin, resulting in a positive impact on restoration success in degraded forest ecosystems. However, there has been less research on root morphological attributes, especially of native tree species in South American Mediterranean-type ecosystems, which are currently subject to unprecedented drought events and degradation. We summarize experiments examining the use of root adaptive management during the nursery and field stages for improving plant quality and seedling performance under water-limited conditions in central Chile. The first experiment (E-1) evaluated the effect of controlled-drought regimens on root development and seedling performance of two tree species (Quillaja saponaria and Cryptocarya alba) with contrasting root growth strategies. The E-1 results confirmed the importance of considering the root growth strategy as a criterion in the selection of species and watering decisions. The second experiment (E-2) assessed the effect of increasing fertilization doses in the nursery on Q. saponaria root morphology 1 year after planting seedlings in the field. The results showed that, as a result of nutrient deprivation, small plants with a greater stem diameter and lower shoot:root ratio contributed to improving water-stress resistance early during a drought period. The third experiment (E-3) determined the effect of different locations of fertilizer placement into the soil profile on rhizosphere salinity and root development of Q. saponaria seedlings. The E-3 results showed that fertilization practices in dryland areas require watering because this acts to control the increase in salinity in the rhizosphere and, consequently, avoids negatively impacting the root volume growth. Our findings could be useful for identifying the major gaps present in the production and establishment stages of native tress in Chile, and could address the latter through root adaptive management.

keywords

central Chile, dryland forest, nursery fertilization, seedling quality, root architecture