Abstract
Abstract The aim of this work was to verify the effect of size classification on the physical and physiological quality of Eucalyptus spp. seeds to optimize the selection for covering. The seeds were separated in sieves with six size classes: 850, 710, 600, 500, 425 µm, and a non-perforated bottom (< 425 µm). Were evaluated the sieve retention, purity, weight of a thousand seeds, germination, and first count of germination. Sieve classification is effective for the separation of materials according to the best physical and physiological qualities. E. grandis seeds from the 710 µm sieve, E. robusta from the 850 µm sieve, and E. urophylla from the 710 and 850 µm sieves can be selected for covering, as they present maximum physical and physiological quality. For the three species, the smallest materials, retained in the 500, 425, and bottom <425µm sieves, must be discarded due to low purity and germination potential.
Highlights
AND OBJECTIVESMarketed eucalyptus seed lots are a mixture of pure seeds with inert material, such as unfertilized eggs and crop remains (Affonso et al, 2018; Brasil, 2013)
E. grandis seeds from the 710 μm sieve, E. robusta from the 850 μm sieve, and E. urophylla from the 710 and 850 μm sieves can be selected for covering, as they present maximum physical and physiological quality
For E. grandis and E. robusta, there was a higher concentration of material in the 500 and 425 μm sieves
Summary
AND OBJECTIVESMarketed eucalyptus seed lots are a mixture of pure seeds with inert material, such as unfertilized eggs and crop remains (Affonso et al, 2018; Brasil, 2013). Due to the small size and similar physical characteristics of these materials, it is difficult to obtain seed lots with high purity by processing only (Santos, 2016) Those lots have a different seeds size, it can vary according to the nutritional and water supply, as well as the seasonality of production, mainly in forest species such as eucalyptus and by the point of physiological maturity (Hoppe & Brun, 2004). There are reports that the size of E. grandis seeds might affect seedling germination and survival in nurseries, as was found by Naidu & Jones (2007) These studies show us only the physiological aspects, without analyzing the physical aspects of the seed lots, namely size class
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