Nitrogen Use Efficiency for Growth of Fagus crenata Seedlings Under Elevated Ozone and Different Soil Nutrient Conditions

Makoto Watanabe,Yoshiyuki Kinose,Takeshi Izuta,Hiroka Hiroshima,Shigeaki Okabe

doi:10.3390/f11040371

Makoto Watanabe, Yoshiyuki Kinose + Show 3 more

Open Access

https://doi.org/10.3390/f11040371

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Abstract

Ozone is a phytotoxic gaseous air pollutant and its negative effects on forest production are a major concern. To understand the effects of ozone on forest production, it is important to clarify the nitrogen use efficiency (NUE) for tree growth under elevated ozone conditions, because nitrogen is a primal limiting factor of forest production in many cool-temperate forests. Soil nutrient conditions are considered factors affecting ozone susceptibility of tree growth. Therefore, in the present study, we investigated the effects of ozone on NUE for the growth of Siebold’s beech (Fagus crenata Blume) seedlings grown under different soil nutrient conditions. Seedlings of Siebold’s beech were grown under three gas treatments (charcoal-filtered air or ozone at 1.0 or 1.5 times the ambient concentration) in combination with three soil nutrient conditions (non-fertilised, low-fertilised or high-fertilised) for two growing seasons. Based on the dry mass and nitrogen concentration in each plant organ, we calculated NUE and its components, including nitrogen productivity (NP) and the mean residence time of nitrogen (MRT) during the second growing season. Ozone did not decrease the NUE of the seedlings during the second growing season, whereas leaf level photosynthetic nitrogen use efficiency (PNUE), a component of NP, was decreased by ozone. On the other hand, the soil nutrient supply decreased the NUE of the seedlings. Reductions in both NP and MRT were attributed to the decrease in NUE because of soil nutrient supply, whereas PNUE did not respond to soil nutrient supply. There was no significant interaction of ozone and soil nutrient supply on the NUE, or its components, of the seedlings. Our results indicated that there is a difference in the response between the NUE for individual growth and that of leaf level PNUE of Siebold’s beech seedlings to ozone and soil nutrient supply.

Highlights

Ozone (O3 ) in the troposphere is recognised as a phytotoxic gaseous air pollutant
We investigated the effects of O3 on Nitrogen use efficiency (NUE) and its components for Siebold’s beech seedlings grown under different soil nutrient conditions
Seedlings in non-fertilised treatment (NF) treatment, whereas the ΔW was not decreased by the exposure to O3 in both low-fertilised treatment (LF) and treatment, whereas the ∆W was not decreased by the exposure to O3 in both LF and high-fertilised treatment (HF) treatments

Summary

Introduction

The atmospheric concentration of tropospheric O3 has been increasing since the Industrial Revolution [1,2,3]. This increasing trend will continue especially in East Asia in the near future [4,5,6]. O3 is considered one of the most critical factors in decreasing forest production [11,12]. Nitrogen use efficiency (NUE) is an important trait for tree growth because nitrogen is a primary limiting factor for forest production in many temperate climate zones [13,14,15,16].

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