Effects of Oxygen Concentration on the Respiration of Excised Root-Tip Segments of Maize and Rice, and of Germinating Grains of Rice and Buckwheat |
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Authors: | RAYMOND E GIRTON |
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Institution: | Department of Soils and Plant Nutrition, College of Natural Resources, University of California, Berkeley, California 94720 U.S.A. |
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Abstract: | In view of the known tolerance of rice (Oryza sativa) to wet soils, in contrast to maize (Zea mays), a comparison of the respiratory responses of the two plants to different O2 concen trations was made. It was found that if the O2 concentration was raised to 100%, an increase was observed of the O2 input and the CO2 output in maize root-tip segments and in germinating grains of rice and also in buckwheat (Fagopyrum sp.). In marked contrast rice root-tip segments, when treated with 100% O2, exhibited no such increase over the air controls. Increased O2 concentrations decreased RQ values ranging from 2.0 (with 5% O2) to 0.86 (with 100% O2). Air-control RQ values were lowest with maize roots (0.9) and highest with germinating rice grains (1.0). Rice grains also exhibited the highest F/R ratio (0.85), and buckwheat grains the lowest (0.45). The addition of sucrose to maize root tips tended to promote fermentation (CO2 output) rather than aerobic respiration (O2 input). |
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