Germination of tucumã (Astrocaryum aculeatum G. Mey.) as a function of thermal pretreatment and stratification temperature

Sidney Alberto Do Nascimento Ferreira,Nelson Felipe De Albuquerque Lins Neto,Daniel Felipe De Oliveira Gentil

doi:10.1590/2317-1545v43230606

Abstract

Abstract: Germination of tucumã (Astrocaryum aculeatum G. Mey.) seeds is slow and although the removal of the endocarp favors the speed of the process, the time is still considered long. Thus, this study aimed to investigate the effects of different pretreatment and stratification temperatures on the germination of tucumã seeds. Two experiments were set up. The first experiment was conducted using a completely randomized design in a factorial scheme and seedling emergence was evaluated as a function of the pretreatment of diaspores at different temperatures (27, 30, 35, and 40 °C) during different periods (20, 40, and 60 days). The second experiment was also conducted in a completely randomized design and seed germination was evaluated as a function of seed stratification at constant (25, 30, 35, and 40 °C) and alternating temperatures (26 - 30, 26 - 35, and 26 - 40 °C). Germination decreased progressively in all tested periods as the pretreatment temperature increased. Seed stratification at different constant and alternating temperatures showed different results. The pretreatment of diaspores at different temperatures for different periods was not effective in overcoming the dormancy of tucumã seeds. Seed stratification at alternating temperatures, with the highest thermal amplitude (26 - 40 °C), favored the overcoming of dormancy and the germination of tucumã seeds.

Highlights

According to Baskin and Baskin (2014), seed dormancy can be classified as endogenous when related to the embryo, exogenous when related to other diaspore structures, and combinatorial. These authors observed that water impermeability is the cause of physical dormancy, while the mechanical limitation is due to physiological dormancy, as embryo growth is sufficient to overcome the restrictive structures of the diaspore after overcoming the physiological dormancy
The diaspores used in this study came from ripe fruits obtained in Manaus, State of Amazonas, Brasil, being characterized as a mixture of half-sibling progenies derived from fruits of various racemes and plants
Cleaning was carried out to remove the rest of the pulp adhering to the endocarp through the initial immersion in water for three days, followed by rubbing with sand and washing in running water, according to the procedure adopted by Ferreira and Gentil (2006)

Summary

Introduction

The demand for fruits is mostly supplied by the semi-extractive activity due to the small number of commercial plantations. According to Baskin and Baskin (2014), seed dormancy can be classified as endogenous (morphological, physiological, or morphophysiological) when related to the embryo, exogenous (physical) when related to other diaspore structures, and combinatorial (physical and physiological). These authors observed that water impermeability is the cause of physical dormancy, while the mechanical limitation is due to physiological dormancy, as embryo growth is sufficient to overcome the restrictive structures of the diaspore after overcoming the physiological dormancy

Objectives

Methods

Results