Effects of atmospheric CO2 concentration, irradiance, and soil nitrogen availability on leaf photosynthetic traits of Polygonum sachalinense around natural CO2 springs in northern Japan

Abstract

Long-term exposure to elevated CO2 concentration will affect the traits of wild plants in association with other environmental factors. We investigated multiple effects of atmospheric CO2 concentration, irradiance, and soil N availability on the leaf photosynthetic traits of a herbaceous species, Polygonum sachalinense, growing around natural CO2 springs in northern Japan. Atmospheric CO2 concentration and its interaction with irradiance and soil N availability affected several leaf traits. Leaf mass per unit area increased and N per mass decreased with increasing CO2 and irradiance. Leaf N per area increased with increasing soil N availability at higher CO2 concentrations. The photosynthetic rate under growth CO2 conditions increased with increasing irradiance and CO2, and with increasing soil N at higher CO2 concentrations. The maximal velocity of ribulose 1,5-bisphosphate carboxylation (V (cmax)) was affected by the interaction of CO2 and soil N, suggesting that down-regulation of photosynthesis at elevated CO2 was more evident at lower soil N availability. The ratio of the maximum rate of electron transport to V (cmax) (J (max)/V (cmax)) increased with increasing CO2, suggesting that the plants used N efficiently for photosynthesis at high CO2 concentrations by changes in N partitioning. To what extent elevated CO2 influenced plant traits depended on other environmental factors. As wild plants are subject to a wide range of light and nutrient availability, our results highlight the importance of these environmental factors when the effects of elevated CO2 on plants are evaluated.

Polygonum sachalinense alters the balance between capacities of regeneration and carboxylation of ribulose‐1,5‐bisphosphate in response to growth CO2 increment but not the nitrogen allocation within the photosynthetic apparatus

“…Polygonum sachalinense significantly altered the balance between RuBP regeneration and carboxylation depending on growth CO 2 concentration. This result was consistent with our previous studies showing that the J max to V cmax ratio in P. sachalinense responded to growth CO 2 concentration (Onoda et al 2009, Osada et al 2010). The alteration was 5.7% on average, which was equivalent to a meta‐analysis of FACE experiments (Long et al 2004, Ainsworth and Long 2005).…”

“…In the present study, we used Polygonum sachalinense , a perennial herb. Osada et al (2010) studied P. sachalinense plants growing in a natural gradient of CO 2 concentration around CO 2 springs and found that growth CO 2 significantly affected the J max to V cmax ratio. Onoda et al (2009) raised P. sachalinense plants in open top chambers (OTC) and also found that growth CO 2 significantly alters the J max to V cmax ratio.…”

Leaf nitrogen is closely coupled to phenophases in a desert shrub ecosystem in China

“…According to Butler et al (2012), soil warming may induce an increase in available soil N, which may consequently increase leaf N and the relative growth rate. NUE may also be positively related to soil N (Osada et al, 2010). However, increasing atmospheric CO 2 concentration may decrease availability of N in the soil and decrease leaf N (Kahmen et al, 2008;Garten et al, 2011).…”

Phenotypic and genetic differences in a perennial herb across a natural gradient of CO2 concentration

“…Tube inlets for sampling air were positioned at a height of 5 cm from the ground, where P. asiatica leaves developed and air was taken 10 min for each plot. For plots L5 and L5 0 , we used CO 2 monitors (Telaire 7001; TELAIRE, Goleta, CA, USA; Osada et al 2010), in which [CO 2 ] was recorded every 5 min. Both systems were calibrated with the same standard gas.…”