Responses to Drought in Seedlings of European Larch (Larix decidua Mill.) from Several Carpathian Provenances

Ioana M Plesa,Monica Boscaiu,Jaime Prohens,Oscar Vicente,Radu E Sestras,Adriana F Sestras,Sara González-Orenga,Mohamad Al Hassan

doi:10.3390/f10060511

Abstract

European larch (Larix decidua Mill.) has been reported either as more tolerant or as more sensitive to drought than conifers with perennial leaves. Previous studies have revealed that Carpathian populations of European larch display a high genetic variability. A comparative study of the responses of these populations to drought stress at the seedling stage might allow the identification of drought tolerant genotypes and reliable drought stress biomarkers, which could be eventually used for the early detection of drought effects in larch, not only under control greenhouse conditions, but also in their natural stands. Growth responses were analyzed in larch seedlings from six Romanian Carpathian populations, submitted to one month of mild drought stress under controlled conditions. Levels of photosynthetic pigments (chlorophylls a and b, and carotenoids), osmolytes (proline and total soluble sugars), monovalent cations (Na+ and K+), and malondialdehyde (MDA) and non-enzymatic antioxidants (total phenolics and flavonoids) were compared with control treatments and between populations. Growth and the pattern of the biochemical responses were very similar in the six populations. Drought stress lead to stem length decrease in all population, whereas reduction of fresh weight of needles was significant only in one population (BVVC), and reduction of water content of needles in two populations (BVVC and GuHo). The optimal biochemical traits for an early detection of drought symptoms in this species is the increase—in most populations—of total soluble sugars, MDA, and total phenolic compounds, whereas K+ reduction was significant in all populations. Photosynthetic pigments remained unchanged, except for the Anin population where they were reduced under stress. Multivariate principal component and hierarchical clustering analyses confirmed the impact of drought in the growth and physiology of European larch, and revealed that the humidity of the substrate was positively correlated with the growth parameters and the levels of K+ in needles, and negatively correlated with the levels of MDA, total soluble sugars, total phenolic compounds, and flavonoids in needles.

Highlights

Drought, as a consequence of climate change, is a threat to many forest stands, which will have to cope with new adverse environmental conditions within their current natural habitats [1,2,3,4,5]
There were no significant differences between the different provenances either in the mean values of the control or of the drought treatments (Figure 2)
The results presented here indicate that the six provenances responded in a similar way to one month of lack of irrigation, and no correlation with the latitude or altitude of parental populations could be established, as neither in seedlings from the control treatment

Summary

Introduction

As a consequence of climate change, is a threat to many forest stands, which will have to cope with new adverse environmental conditions within their current natural habitats [1,2,3,4,5]. Existing forest stands may withstand these changing climate conditions for some time, but long-term responses might depend on the capability of species to adapt [6]. This capability can be determined by the variation within and between species in their physiological responses to changes such as water deficiency. A high phenotypic plasticity of forest species is essential for surviving stressful conditions [7]

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Discussion

Conclusion