Water use efficiency, growth and anatomic-physiological parameters of Mediterranean xerophytes as affected by substrate and irrigation on a green roof

Lamprini Tassoula,Georgios Liakopoulos,Maria Papafotiou,George Kargas

doi:10.15835/nbha49212283

Lamprini Tassoula, Georgios Liakopoulos + Show 2 more

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https://doi.org/10.15835/nbha49212283

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Abstract

The water use efficiency, growth and anatomic-physiological parameters of Mediterranean medicinal xerophytes on a green roof was investigated, under the effect of water stress and different types of substrate. Rooted cuttings of Convolvulus cneorum, Origanum dictamnus, Sideritis athoa, Atriplex halimus and Lomelosia cretica were planted on a roof in Athens, Greece. Two substrate types, 10 cm deep, were used, i.e. grape marc compost: perlite: soil: pumice (3:3:2:2, v/v) and a lighter one, i.e. grape marc compost: perlite: pumice (3:3:4, v/v). Two irrigation frequencies were applied during the dry period (summer), normal and sparse, when substrate moisture was 17-20% and 5-11%, respectively. Water use efficiency was increased by sparse irrigation in A. halimus and L. cretica and by soil substrate in C. cneorum. Sparse irrigation reduced dry weight in O. dictamnus, S. athoa and L. cretica and in A. halimus in combination with soilless substrate. It increased leaf thickness in all species and reduced Chlολ in all species, other than S. athoa, while in C. cneorum, O. dictamnus and L. cretica this was evident only in the presence of soil in the substrate. In summer, one d before irrigation, stomatal resistance (Rleaf) was increased and maximum quantum yield of PSII (ΦPSIIο) decreased indicating water limitation, while both parameters were restored to normal levels one d after irrigation indicating that both can serve as sensitive indicators of the onset of water stress. ΦPSIIο values, never fell to critical levels, excluding irreversible damage to the photosynthetic apparatus. Therefore, all five plant species are recommended for use on extensive green roofs in semi-arid areas.

Highlights

The indisputable fact of global warming causing constant climate change (Nila et al, 2019; IPCC, 2014; 2007) leads to vegetation changes (Sangüesa-Barreda et al, 2019) and predicts that the 30 - 90 years, there will be severe and extensive droughts due to water scarcity and increased evaporation (Dai, 2013)
Rooted cuttings of Convolvulus cneorum, Origanum dictamnus, Sideritis athoa, Atriplex halimus and Lomelosia cretica were planted on a roof in Athens, Greece
Experimental setup The experiments were performed on a second floor, fully exposed flat roof at the Agricultural University of Athens (37o 59 ́ Ν, 23o 42 ́ Ε) from July 15 2011 to October 15 2013 (Convolvulus cneorum, Origanum dictamnus. and Sideritis athoa) and from February 15 2013 to September 15 2014 (Atriplex halimus and Lomelosia cretica)

Summary

Introduction

The indisputable fact of global warming causing constant climate change (Nila et al, 2019; IPCC, 2014; 2007) leads to vegetation changes (Sangüesa-Barreda et al, 2019) and predicts that the 30 - 90 years, there will be severe and extensive droughts due to water scarcity and increased evaporation (Dai, 2013) Environmental strategies, such as "green constructions" and "green networks", will play a dynamic role in the urban environment, living standards and public health (Cameron et al, 2012; Santamouris, 2014; Kondo et al, 2018; Abass et al, 2020; Feitosa and Wilkinson, 2020; Cristiano et al, 2021). Experiments on the production of herbs and vegetables in extensive green roofs, especially in shallow substrates, have given positive results, either as a complementary source of food production (Walters and Stoelzle Midden, 2018) or helping to manage rainwater in quantity or quality (Whittinghill et al, 2013; 2015; Liu et al, 2021)

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