Some Effects of Indoleacetic Acid and Maleic Hydrazide on the Respiration and Flowering of Wheat

Wheat seedlings were grown in sand culture in 1 qt. crocks. Maleic hydrazide (10 mg. per crock per day) prevented flowering and increased the oxygen consumption per unit dry weight of the first leaves by 20 to 50%, but did not alter the C6/C1 ratio, which was measured by incubating leaf disks with glucose-6-C14 and glucose-1-C14. Indoleacetic acid (0.5 mg. per crock per day) increased oxygen uptake by only 10 to 15%, but stimulated flowering and apparently lowered the C6/C1 ratio. The C6/C1 ratio of leaf disks was approximately halved by 2 hours pretreatment with 5.0 and 8.3 p.p.m. of indoleacetic acid, mainly because of a decrease in the recovery of C6.The results are discussed briefly in relation to the effect of obligate parasites in increasing the indoleacetic acid content and in lowering the C6/C1 ratio of susceptible cereal leaves.