Soybean Seedling Response to Anaerobiosis1

Abstract

Death and stunting of soybean [Glycine max (L.) Merr.] seedlings in soils with excess water is generally thought to be a response to low oxygen (O2) levels in soils. To evaluate the effect of low soil O2 level on root development of selected soybean cultivars, soybean seedling roots or roots and shoots, were exposed to a nitrogen gas (99.995% N2) environment (anaerobiosis) for up to 16 hours. The resulting data indicate that soybean seedling roots can survive anaerobiosis better than anticipated. Data suggest that when the seedling shoot is in air, O2 may diffuse down the stem, providing an unaerated root with sufficient O2 to elongate at approximately 14% of the rate obtained in air. When entire seedlings were enclosed in a N2 environment taproot elongation was inhibited. Recovery from anaerobiosis (in terms of root elongation) was inversely proportional to anaerobiosis duration. Exposing the entire developing seedling to 14 hours of anaerobiosis killed the elongating taproot tip of the less‐tolerant cultivars in some experiments. There also appeared to be cultivar differences in root elongation rate after anaerobiosis. ‘Semmes’ and ‘Dowling’ cultivars recovered more rapidly than ‘Biloxi’ and ‘Bragg’. The roots of Semmes soybean seedlings recovered more quickly from 4 hours of anaerobiosis than the roots of two cotton [Gossypium hirsutum L.] cultivars (‘Deltapine 61’ and ‘Tamcot SP37H’) and two rice [Oryza sativs L.] cultivars (‘Caloro’ and ‘Labelle’).