Waterlogging tolerance of five soybean genotypes through different physiological and biochemical mechanisms

Waterlogging is a serious environmental threat that limits crop growth and yield in low-lying, rainfed areas in many regions across the globe. Here we investigated the effects of waterlogging and subsequent re-oxygenation on the physiology and biochemistry of three soybean [Glycine max (L.) Merrill] genotypes (PELBR10-6000, PELBR11-6028, and PELBR11-6042) and two cultivars (TEC IRGA 6070 and BMX Potencia). Plants were grown under greenhouse conditions until the V4 stage when they were subjected to waterlogging for seven days. The water was then drained and plants were allowed to recover for another seven days. Overall, all genotypes suppressed waterlogging stress with distinct mechanisms. Waterlogged PELBR10-6000 surpassed control plant levels of CO2 assimilation rate and readily responded to the energy lack induced by hypoxia by activating the fermentative enzymes and alanine aminotransferase. Similar mechanisms were observed in BMX Potencia, which restored metabolism to control levels at the end of the recovery. PELBR11-6028 and PELBR11-6042 activated the antioxidant defenses, and TEC IRGA 6070 did not delay flowering.