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Low root reserve accumulation during drought may lead to winter mortality in poplar seedlings
Author(s) -
Galvez David A.,
Landhäusser S. M.,
Tyree M. T.
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12129
Subject(s) - dormancy , seedling , root system , biology , growing season , agronomy , drought tolerance , botany , horticulture , germination
Summary Climate models suggest that more frequent drought events of greater severity and length, associated with climate change, can be expected in the coming decades. Although drought‐induced tree mortality has been recognized as an important factor modulating forest demography at the global scale, the mechanisms underlying drought‐induced tree mortality remain contentious. Above‐ and below‐ground growth, gas exchange, water relations and carbon reserve accumulation dynamics at the organ and whole‐plant scale were quantified in P opulus tremuloides and P . balsamifera seedlings in response to severe drought. Seedlings were maintained in drought conditions over one growing and one dormant winter season. Our experiment presents a detailed description of the effect of severe drought on growth and physiological variables, leading to seedling mortality after an extended period of drought and dormancy. After re‐watering following the dormant period, drought‐exposed seedlings did not re‐flush, showing that the root system had died off. The results of this study suggest a complex series of physiological feedbacks between the measured variables in both P opulus species. Further, they reveal that reduced reserve accumulation in the root system during drought decreases the conversion of starch to soluble sugars in roots, which may contribute to the root death of drought‐exposed seedlings during the dormant season by compromising the frost tolerance of the root system.