REGULATION OF PREGERMINATIVE RATES OF RESPIRATION IN SEEDS OF VARIOUS WEED SPECIES BY POTASSIUM-NITRATE

The effects of potassium nitrate (KNO3) on germination and O2 uptake in seeds of various weed species [Avena fatua, Galium aparine, Chenopodium album, Stellaria media, Lactuca sativa] were compared and contrasted with water controls. When KNO3 promoted germination, rates of O2 uptake were increased, when it was inhibitory, rates were decreased, and when it had no effect there were no appreciable differences between the rates of O2 uptake of KNO3- and water-imbibed seeds. These effects were clearly the result of early metabolic events for differences in O2 uptake were detectable soon after the seeds were placed in the liquid media and for some considerable time prior to germination (i.e. the protrusion of the radicle). The results are discussed in relation to a published hypothesis of other workers concerning the mechanism of seed dormancy breakage.