Interactive Effects of Elevated Atmospheric CO2 and Waterlogging on Vegetative Growth of Soybean (Glycine max (L.) Merr.)

Abstract

Waterlogging is a major predicted agricultural problem for crop production in some areas under current climate change, but no studies are available on the interactive effects of waterlogging and elevated atmospheric CO₂ concentration (CO₂]). We hypothesized that elevated CO₂] could alleviate the damage caused by waterlogging, and tested the hypothesis using vegetative growth of soybean (Glycine max) in 10 experiments (different sowing time and different soil type) conducted at Morioka and Tsukuba for three years. The 2-week-old plants grown under elevated and ambient CO₂] were exposed to waterlogging for 2 weeks. Total dry weight at the end of the treatment was higher under elevated CO₂] than under ambient CO₂], and it was significantly reduced by waterlogging under both levels of CO₂], without significant CO₂]×waterlogging interactions, at both locations. The negative effects of the waterlogging were greater in root dry weight than in top dry weight, and the root exudation per unit root dry weight was also reduced by waterlogging, without a CO₂] ×waterlogging interaction. Therefore, the hypothesis of a CO₂]×waterlogging interaction can be rejected, and provide an important basis for predicting future damage caused by waterlogging under elevated CO₂] conditions.