Thermotherapy on physiological and health quality of stored Jatropha seeds

Abstract

Among the many species that can be used to obtain vegetable oil for energy, Jatropha is considered one of the best options. Therefore, it is necessary to have seeds with good physiological and health quality in order to have a good establishment of plants in the field. This study aimed to evaluate the efficiency of heat treatment to the control of seed-borne pathogens in stored Jatropha seeds. The experimental design was completely randomized with a factorial 5x4 (five periods of storage x four treatment temperatures). The seeds of Jatropha were collected in Dourados - MS, and were subjected to processing and sun drying, and then stored in a dry chamber in glass flaskswith a screw cap and a capacity of 500 mL, for periods of 0, 90, 180, 270, and 360 days. After each storage period, seeds were subjected to thermotherapy by immersion in hot water at temperatures of 45°C, 50°C, and 55°C for 15 minutes; the control treatment was immersed in water at room temperature (25±2°C) for 15 minutes. The parameters evaluated were: moisture content, germinations, germination speed index, electrical conductivity and health. Heat treatment at temperatures of 45°C, 50°C and 55°C don’t affect germination and the cell membrane integrity of the seed. After 180 days the use of thermotherapy contributed to the conservation of seed vigor. The fungus Penicillium sp. and Acremonium sp. are eliminated by thermotherapy at temperatures of 45°C, 50°C and 55°C, and Aspergillus sp. is controlled at a temperature of 55°C in periods of storage of 180 and 270 days.