Tecnologia para sementes de Bertholletia excelsa bonpl. (Lecythidaceae) para fins de propagação

Abstract

Bertholletia excelsa Bonpl. is a tree native to the Amazon region that is economically important for the use of seeds in human food and for the extraction of oil used in cosmetics. The optimization of production with the implementation of more rational plantations for the extraction of seeds requires quality seedlings obtained with the use of viable seeds. The objective of this study was to evaluate the viability of the seeds when submitted to storage under refrigeration and submersion in water, in addition to determining a methodology to determine the water content of the seeds. In Chapter 1, the methods for determining the water content used for B. excelsa seeds were tested. It was verified that 24 hours in an oven at 105 ºC were enough to determine the water content of this seed. A proposal was also made to determine the water content of B. excelsa seeds with the use of the embryo only, since the determination with the use of whole seed ends up overestimating the value of the water content of the embryo. In Chapter 2 the seeds were stored, with different water contents, under refrigeration at 15 ºC in waterproof, semipermeable packaging and double bags. The viability evaluation was done by the tetrazolium test and the water content of the embryos was determined. The results showed that the containers maintained the water content throughout the storage. The viability of the seeds was maintained for 2 months using semipermeable packaging, with seed water content of 19%. Seeds with a water content of 7% died before storage. The loss of viability increased with the prolongation of the independent storage of the packaging, being able to be related to temperature of 15 ºC. The appearance of white spots in the central part of the embryo was not related to the reduction of water content, indicating the need for more detailed studies to understand the physiology of the seeds. In the third chapter the seed submersion was tested for tegument removal without loss of viability. The seeds were submerged in water (25 ºC), for 9 periods, between 1 and 15 days of submersion. By the tetrazolium test it was verified that the submersion did not affect the viability and that the longer submersed the smaller the time for the tegument removal. It was observed that submersion after 2, 5, 9 and 13 days had no effect on germination when sown with tegument, with a high percentage of normal seedlings formed when sown without tegument.Being indicated as a pre-germinative treatment the immersion in water for 13 days.