Mediterranean woody plant specialized metabolites affect germination of Linum perenne at its dry and upper thermal limits

Abstract

Aims: Soil temperature and moisture impact plants not only during growth and survival but also 9 during seed germination and interaction of seeds with the chemical environment. The quantitative 10 impacts of either temperature and moisture or plant specialized metabolites (PSM) on germination 11 are widely studied. However, the combined effect of PSM and moisture or temperature on 12 germination remains poorly understood. 13 Methods: We addressed this issue by studying the effect of PSM extracted from four Mediterranean 14 woody plants on germination speed and final percentages of a subordinate herbaceous plant, Linum 15 perenne. 16 Results: By using hydro-and thermal time threshold models, we show how PSM interact with 17 temperature and moisture levels to limit germination at dry and upper thermal limits, with the 18 magnitude of effects depending on the source plant. PSM effects on germination, also observed on 19 natural soils, persisted after their removal from the seed environment. 20 Conclusions: We conclude that the impact of climate change on reproduction of herbaceous plants 21 can be modulated by effects of PSM from woody plants, which might exacerbate the negative 22 impacts of global changes on biodiversity.

Phytotoxic Activity of the Natural Compound Norharmane on Crops, Weeds and Model Plants

“…Although these tests show specificity of NOR for different species, it must be taken into account that the phytotoxicity of a natural compound can be affected by environmental conditions (light, temperature, etc.) [ 31 , 32 , 33 ]. This point must be considered when analyzing the results.…”

Chemical interaction between Quercus pubescens and its companion species is not emphasized under drought stress

“…Drought applied during the first year, or on more sensitive target species, may lead to different results. For instance, Hashoum et al (2019) showed that drought and allelopathy from Cotinus interact to decrease the germination of the herbaceous Linum perenne L. In addition, under natural conditions drought can be more pronounced that the drought treatment applied here and reach lethal levels for seedlings, particularly under the expected climate change (Giorgi and Lionello 2008). In that case, an inhibition of oak seedling root development by neighboring allelopathic species such as Cotinus and Pinus could reduce survival probability in case of more pronounced water stress.…”