Effect of Carbon Dioxide, Oxygen, and Soil Moisture Suction on Germination of Corn and Soybeans

Abstract

AbstractCorn and soybeans were planted in soil‐filled glass tubes which were continuously aerated with known mixtures of CO2, O2, and N2. Initial soil moisture suction was varied independently of gas composition. Various aspects of germinative growth were measured during and after various intervals of aeration.The results indicate that the kind and extent of response obtained from a given CO2 treatment was influenced in varying degrees by time, soil suction, plant species, and the growth variables measured. The importance of excessive CO2 as a causal agent of plant injury during germination has probably been overestimated. Corn and soybeans during germination tolerated, and sometimes were stimulated by, CO2 concentrations higher than those normally found in soils. When CO2 was sufficiently high to cause severe toxicity, seedlings recovered quickly upon aeration with air. Comparatively small changes in soil moisture suction often completely overshadowed the effect of different CO2 levels on root growth. In general, growth increased as soil moisture suction decreased; but excessive soil moisture, apart from the aeration treatments used, severely limited or completely stopped germinative growth. With corn the effect occurred at soil saturation and was probably due to reduced O2 diffusion rates. With soybeans the effect occurred at a lesser moisture content and was due primarily to invasion by pathogenic organisms.