ABSTRACT
The aim of this study was to evaluate the thermotherapy method (dry-heat and hot water) in the germination and control of microorganisms associated to castor bean seeds. Using the dry-heat treatment, the seeds were exposed for 6 different times [0 (control); 3; 6; 9; 12; 15 days] at temperatures of 70º C and 75º C. In a second treatment, three different temperatures (42º C, 46º C and 50º C) were used for 15 and 30 minutes in hot water. Another set of seeds were treated with carbendazim + thiram (60 g + 140 g/ 100 kg seed), as a control. The incidence of fungi was evaluated by means of the seed health test. Seed germination was evaluated through the paper towel method. The control of microorganisms was satisfactory for both thermal treatments, compared with the control. The higher exposure times to dry-heat treatment presented a contamination index of 0.59, compared to 2.58 for the control. Using hot water, at higher temperaturas, the contamination index was 0.9, compared to 2.92 for the control. However, the seed germination was compromised when using dry-heat treatment at these temperatures. For its part the hot water treatment did not affect the seed germination percentage.
KEY WORDS
seed pathology; thermotherapy; fungicide;
Ricinus communis
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