Seasonal changes in optically assessed epidermal phenolic compounds and chlorophyll contents in leaves of sessile oak (Quercus petraea): towards signatures of phenological stage

Abstract

Seasonal patterns of dry mass invested in chlorophyll and epidermal phenolic compounds (EPhen) were investigated in vivo using optical methods, in leaves of 2-year-old oaks (Quercus petraea Matt. (Liebl.)) grown under semi-controlled conditions. The plasticity of the seasonal pattern was investigated by applying stem girdling treatment. In control young expanding leaves, leaf dry mass per area, dry mass investment in chlorophyll and abaxial EPhen content increased. In late May, at leaf maturity, these variables reached a plateau, and adaxial and abaxial EPhen contents became similar. Thereafter, as leaves aged, dry mass investment in chlorophyll gradually decreased, whereas it remained steady for EPhen. Girdling treatment impacted this seasonal pattern differently depending on the phenological stage. Treatment effects and their reversion revealed in vivo EPhen turnover. Finally, optical signatures of immature and mature leaf phenological stages with contrasting nitrogen and carbon economy were proposed, based on the relationship between the chlorophyll to EPhen ratio and the leaf nitrogen to carbon ratio.

Age-Related Changes of Some Chemical Components in the Leaves of Oriental Beech (Fagus orientalis Lipsky.)

“…H 2 O 2 ratio increased in case the chlorophyll b content was high [37]. Contents of chlorophyll b and H 2 O 2 in aged trees also confirmed this result ( Table 1, 4). Since carotenoids, which protect the chloroplast membranes with their antioxidant characteristics, were more stable compounds compared to the chlorophyll molecule, they did not show a significant change among the trees [33].…”

“…In studies analysing the growth and development of trees, the balance between photosynthesis/respiratory rate [1], coordination between the above-ground and underground organs [2], metabolic processes [3] and the changes in environmental factors were found to be affecting the growth and development of trees [4,5]. Approximately, 1/3 of daily photosynthesis gain of young trees was used for respiration [6]; this consumption increased in old trees even more with the change in the ratio of photosynthetic tissue/nonphotosynthetic tissue [7][8][9]; deficiency in nutrient distribution and the respiratory activities were the determining factors that reflect the aging phenology; and when the tissues and organs completed their maturation period, the respiration slowed down, while the senescence accelerated [10].…”

Solar UV‐B effects on PSII performance in Betula nana are influenced by PAR level and reduced by EDU: results of a 3‐year experiment in the High Arctic

“…EDU remains in the leaf apoplast for more than 10 days, but the apparent protective effect of EDU is only important in the first days in relation to UV‐B (Gatta et al 1997). Potentially UV‐B‐protective pigments can accumulate over short time intervals (Barnes et al 2008), and in vivo assessment of UV transmittance measurements along with other fluorescence techniques could provide information whether this is the main mechanism for the recovery of photochemical processes (Lenk et al 2007, Gilbert et al 2009, Louis et al 2009). The detailed JIP test analysis of ozone sensitivity in Fraxinus excelsior showed EDU to prevent inactivation of PSII RCs (Contran et al 2009).…”

Rediscovering leaf optical properties: New insights into plant acclimation to solar UV radiation

“…As previously noted, the ability of leaves to adjust their UV shielding in response to UV exposure during leaf development is well established and studies, such as the one above and others [e.g., (Morales et al, 2011;Louis et al, 2009)], are providing insights into the precise time courses of these responses as they relate to UV protection under field conditions. What is less clear, however, is how pliable these UV screening properties are in leaves once they have matured and developed under one set of conditions and are then confronted with abrupt changes in these conditions.…”