Abstract
Abstract: The exudate coloring test has been promising in order to quickly evaluate the quality of coffee seeds. The objective of the research was to adjust the coloring exudate test for coffee seeds and to evaluate the influence of the water content of seeds and of the imbibition period on the test results. Seeds from five lots of 'Catuaí 44' were used, with the following water contents: 30%, 20% and 12%. For the exudate coloring test, the parchment and silver skin (spermoderm) from the seeds were removed. Then, the seeds were distributed on a paper towel, moistened with water, and kept in a germinator at 25 °C for 24, 48, 72, 96 and 120 h. Four classes of coloring intensity were established: absence of color (A), light (L), medium (M) and strong (S) intensities, assigning the values 0, 3, 5 and 10 for each class, respectively. The Viability Index (VI) was calculated by the equation VI=100-(0xA)-(3xL)-(5xM)-(10xS). The exudate coloring test may be recommended to estimate the viability of coffee seeds, providing results correlated to the germination test. The best results were obtained for the seeds with 12% moisture content imbibed for 72, 96 and 120 h and seeds with 30% moisture content after 72 and 120 h of imbibition.
Highlights
Coffee seeds have a slow and irregular germination, even under favorable conditions
The quality of the seeds from each lot were evaluated by the following tests: Seed moisture content: the oven method was used at 105 ± 3 °C, with two subsamples of 30 seeds per treatment, after the removal of the parchment (Brasil, 2009)
For coffee seeds with 12% of water content (Figure 2A), it was observed that the germination of lots 1 and 4 was higher than the one for lots 3 and 5
Summary
Even by removing the endocarp or parchment, the germination of these seeds, under ideal conditions in the laboratory, demands a period of at least 30 days (Brasil, 2009). It is fundamental to use quick tests in order to evaluate the physiological quality of these seeds, in order to support the decision-making process related to the postharvest management and the commercialization of lots. The tests that demand less time to be conducted are related to enzymatic and respiratory activities of the seeds or to the integrity of the cellular membranes (Marcos-Filho, 2015b). The loss of the selective permeability of the cellular membranes has been reported as one of the initial events of the deterioration process of seeds, which culminates with the loss of the germination power (Marcos-Filho, 2015a)
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