Anatomy, chlorophyll content and photosynthetic performance in current-year and previous-year Aleppo pine (Pinus halepensis Mill.) needles

Tomo Trstenjak,Antunovic Dunic,Marin Skoro,Vera Cesar,Selma Mlinaric,Hrvoje Lepedus,Lidija Begovic

doi:10.2298/botserb2001061t

Tomo Trstenjak, Antunovic Dunic + Show 5 more

Open Access

https://doi.org/10.2298/botserb2001061t

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Abstract

Aleppo pine (Pinus halepensis) is a widespread Mediterranean woody species. Needles usually fall off the tree after the second year, which can be the reason for substantial crown defoliation under extreme environmental stress. The aim of the present investigation was to compare the anatomy, chlorophyll content and photosynthetic performance in current-year (CY) and previous-year (PY) Aleppo pine needles. Chlorophyll concentrations were determined spectrophotometrically, while photosynthetic performance was determined by measuring the increase in chlorophyll a fluorescence (the JIP test). The obtained results revealed that concentrations of chlorophylls a and b were almost twice as great in PY needles as in CY ones. The chlorophyll a to b ratio and values of the maximum quantum yield of photosystem II (Fv/Fm) showed no statistically significant difference between CY and PY needles. However, the performance index (PIABS) was significantly higher in CY needles compared to PY ones. Analysis of PIABS components revealed that CY needles had increased electron transport beyond the primary electron acceptor, QA -, which was associated with a lower value of variable fluorescence at 2 ms (VJ) in comparison with PY needles. Also, some differences were observed in needle anatomy. Current-year needles had an increased proportion of mesophyll tissue, together with decreased proportions of vascular cylinder and resin duct areas. Also, many more starch grains were present in PY than in CY needles. Based on the presented results, it can be concluded that despite considerably lower chlorophyll content, CY needles exhibited photosynthetic performance better than that of older needles, which is an unusual phenomenon in woody species.

Highlights

IntroductionIts natural and cultivated populations can be frequently found in the coastal area of the Adriatic Sea and Dalmatian islands, where it covers about 40000 ha of the land area
Aleppo pine (Pinus halepensis Mill.) is a widespread Mediterranean woody species
Current-year needles were much brighter than PY needles, which was in accordance with measured chlorophyll concentrations

Summary

Introduction

Its natural and cultivated populations can be frequently found in the coastal area of the Adriatic Sea and Dalmatian islands, where it covers about 40000 ha of the land area It was introduced in the Dalmatia region more than 1000 years ago, it is considered to be an autochthonous species that grows successfully in semi-arid and sub-humid areas with a Mediterranean climate, independently of the soil type (Prgin 2005). The needles of Aleppo pine fall off the tree after the second year. The significance of this lies in filling of grooves and holes in the landscape, which results in generation of humus and forest soil (Jeddi et al 2009). Numerous previous investigations of Aleppo pine revealed its sensitivity to different environmental factors alone or in combinations, –e.g., air pollutants such as ozone, SO2 and NO2 (Velissariou et al 1992; Anttonen et al 1995; Elvira et al 1998; Kivimäenpää et al 2010); drought (Gerant et al 1996; Borghetti et al 1998; Alonso et al 2001; Atzmon et al 2004; Inclán et al 2005; Alexou 2013; Taibi et al 2018); temperature (Fernández et al 2003; Puértolas et al 2005); surfactants (Richard et al 1996); salt (Rocco et al 2013); cement dust (Bačić et al 1999); and other complex mixtures created by the release of various industrial pollutants (Pasqualini et al 2003; Robles et al 2003)

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