Chlorophyll pigment and needle macronutrient responses and interactions to soil moisture and atmospheric CO2 treatments of eight pine and spruce species

John E Major,Alex Mosseler

doi:10.1007/s00468-021-02173-0

John E Major, Alex Mosseler

Open Access

https://doi.org/10.1007/s00468-021-02173-0

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Abstract

Key messageLarge differences were detected between genera and among species in chlorophyll pigment and macronutrient concentrations. Pines have greater variances than spruces and showed less downregulation of chlorophyll pigment concentrations than spruces in response to eCO2 and DRT. There was strong genetic control of chlorophyll pigments and most macronutrients.Chlorophyll pigment and needle macronutrient concentrations were quantified for eight tree species in two commercially important genera, Pinus and Picea grown in a 2 × 2 factorial of atmospheric CO2 (370 and 740 ppm) and soil moisture stress (− 0.1 to − 0.5 and − 0.7 to − 1.0 MPa) treatments. Four of the pines and three of the spruces are native to eastern North America, while a fourth spruce, Norway spruce (NS: Picea abies), is from Europe but has been widely used for reforestation in northeastern North America. Overall, spruces had significantly greater chlorophyll a, b, (CHLa, CHLb), and total chlorophyll concentration (TCC) and carotenoid concentration (CAR) than pines. Ambient CO2 (aCO2) had significantly greater TCC than in response to elevated CO2 (eCO2), and TCC and CAR was significantly downregulated more in spruces than in pines in response to eCO2. Pines had equal or greater TCC and CAR in response to drought treatment (DRT) than well-watered treatment, whereas spruces had significantly lower values in response to DRT. Needle N, P and Ca concentrations were greater for spruces than pines. Needle N concentrations declined in response to both eCO2 and DRT. Needle P increased in response to eCO2 but declined in response to DRT. Using total biomass as a covariate, needle N showed no response in pines; whereas spruces showed a slight positive response to increasing total biomass. Covariate analysis showed that TCC had a significant positive relationship to needle N and Mg, with greater TCC in spruces than in pines for a given needle N. Photosynthetic quantum efficiency (QE), derived from light response curves, had a significant positive relationship to TCC that was greater in pines than in spruces for a given TCC. Photosynthetic light convexity had a significant positive relationship to TCC that was also greater in pines than in spruces for a given TCC, indicating a sharper curvature compared to a more progressive curve for spruce. Pine species have greater variances than spruce species. While Pinus strobus (white pine, subgenus Strobus) stands out as having greater chlorophyll and nutrient concentrations than the other three pines (subgenus Pinus). Overall, pines showed less downregulation of chlorophyll pigment concentrations than spruces in response to eCO2 and DRT. There was strong genetic control for chlorophyll pigments and most macronutrients.

Highlights

To better understand biological responses to climate change factors we need to examine the genetic, environment, and genetic × environment interactions
Studies have shown that photosynthetic apparatus downregulation generally ranges from none to complete downregulation (when A is the same under eCO2 as it is under ambient CO2 (aCO2)), (Luomala et al 2003; Zhou et al 2011) and that this is strongly influenced by carbon sink demand (Ainsworth et al 2004; Major et al 2018)
white pine (WP) had the greatest total chlorophyll concentration (TCC) followed by jack pine (JP), and red pine (RP), which were significantly greater than pitch pine (PP) (Fig. 1c)

Summary

Introduction

To better understand biological responses to climate change factors we need to examine the genetic, environment, and genetic × environment interactions. Multiple species in response to environmental change studies can help inform reforestation plans for future climate scenarios. Chlorophyll pigment and nutrient concentrations are important underlying plant traits that vary widely among species,. Depending on the species and severity, moisture stress and elevated CO2, can reduce chlorophyll pigment content (Zhou et al 2011; Rasheed et al 2021), but by how much? Downregulation of the photosynthetic apparatus (e.g., chlorophyll and biochemical efficiency traits) can occur in response to sustained elevated CO2 (eCO2), vary among species and can result in reductions in carboxylation efficiencies and maximum assimilation, along with other related traits (Crous et al 2008; Major et al 2018). Species interactions with e CO2 and soil moisture stress are important indicators of future fitness. Elevated CO2 can mitigate some of the negative effects of water stress in mulberry (Sekhar et al 2017) and cacao (Lahive et al 2021), but was neutral or negative depending on the genotype for maritime pine (Sanchez-Gomez et al 2017)

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