Thermotherapy via dry heat for the treatment of safflower seeds

The objectives of this work were to evaluate the method of thermotherapy via dry heat for the treatment of safflower (Carthamus tinctorius L.) seeds and, to verify its effect on the physiological and sanitary quality of seeds. The experiment was conducted in entirely randomized design, arranged in 5x6+1 factorial scheme, with six levels of temperature: 35, 45, 55, 65, 75 and 85 ºC and with five time periods: 24, 48, 72, 96 and 120 h, plus the additional treatment (control), with eight repetitions. The seeds were packaged in Kraft paper bags and submitted to the forced circulation greenhouse according to the factorial mentioned above. We evaluated the physiological and sanitary qualities by the standard tests of germination, length and mass of seedlings, emergence at field and sanity. We observed that the thermotherapy can be used as treatment of safflower seeds, and it is efficient in the control of phytopathogens, without damage to the physiological quality up to 45 ºC, and the combination of 45 ºC 24 h-1 provided better phytosanitary quality for these seeds, increasing their germinative potential and emergence at field.