Thermotherapy via Humid Heat for the Treatment of Safflower Seeds

The objectives of this work were to evaluate and adequate the method of thermotherapy via humid heat for the treatment of safflower seeds (Carthamus tinctorius L.) and, to verify its effect on the physiological and sanitary quality of seeds. The experiment was performed in the period from September to November, 2016 and from May to July, 2017, in entirely randomized design, arranged in 5 × 6 + 1 factorial scheme, with five temperatures: 25, 35, 45, 55 and 65 ºC and with six time periods: 5, 10, 15, 30, 45 and 60 min, plus the additional treatment (control), with eight repetitions. The seeds were packaged in glass of 500 mL and disposed in thermodigital water bath device with heated water according to the abovementioned factorial. We evaluated the degree of humidity of the seeds after thermotherapic treatments, the germination of normal seedlings, the emergence at field, the speed indexes of germination and emergence, the length and dry mass of seedlings and the sanity test. We observed that the treatment of seeds via humid heat thermotherapy was efficient in the control of phytopathogens, without damage to the physiological quality until 45 ºC. The treatment of 45 ºC for 15 min provided the greater reduction of the pathogens on the safflower seeds, incrementing its germinative potential and emergence at field.