The Effect of Carbon Dioxide on Maize Seed Recovery after Flooding

Flooding of recently planted fields of maize (Zea mays L.) in the spring results in poor emergence of some germplasm. Previous studies have shown genetic variation for flooding tolerance of maize inbreds and hybrids. This study was conducted to identify a biochemical basis of reduced germination after flooding and determine differences between tolerant and sensitive inbreds. Seeds soaked in nonaerated water accumulated CO2. Reduction of germination after soaking was partially reversed by venting the seed with ambient air after soaking and prior to planting. Respiration was measured immediately after soaking and after venting. Respiration rates of flood tolerant inbreds increased faster and to a higher level after flooding and venting than those of sensitive inbreds. The apparent Michaelis constants for succinate oxidation by isolated intact mitochondria of flood sensitive inbreds were higher than those of tolerant inbreds. Succinate oxidation was competitively inhibited by bicarbonate. As the apparent quantitation of inhibition (Ki) bicarbonate increased, flooding sensitivity decreased. Genetic differences in flooding tolerance of maize inbred seed germination were at least in part influenced by sensitivity of respiration to CO2.