PHOSFON-INHIBITION OF GERMINATION AS AFFECTED BY TEMPERATURE AND RADIATION

Inhibition of radiation-induced germination in Verbascum thapsusL. by low concentrations of the growth retardant Phosfon isincreased by maintenance temperature of 30 or higher. The germinationprocess is most sensitive to combined supraoptimal temperatureand Phosfon treatments during the time when root protrusionor processes preparatory to it occur in control seeds. At 25,inhibition of induced germination by Phosfon is relieved bycontinuous irradiation, with effective wavebands centered onwave-lengths of 430, 535, 600 and 650 mµ. The bands at485 and 735 mµ reduce germination to or below the levelof briefly red-irradiated seeds. (Received November 22, 1965; )