Potencial de extratos produzidos por microrganismos na degradação do endocarpo da semente e no desenvolvimento da plântula de café

Abstract

The production of arabica coffee seedlings is predominantly carried out through sexual propagation. However, seed germination is slow and uneven, with the presence of the endocarp (parchment) being one of the main limiting factors in this process. In several studies, methods for parchment removal have been investigated, whether chemical, mechanical, or manual yet no consolidated, safe, and effective technique has been established. In this context, the use of fungal extracts with cellulolytic activity emerges as a promising alternative, given that microorganisms exhibit high efficiency in producing lignocellulolytic enzymes. The objective in this study was to evaluate the potential of extracts produced by microorganisms in degrading the parchment of coffee seeds, aiming to reduce both germination time and seedling emergence. The study was conducted in three stages: (i) production of enzymatic extracts from two microorganisms (Trichoderma stromaticum, obtained from the commercial product Tricovab® – Ceplac, Brazil accession #Ts3550 – and Colletotrichum fructicola, strain 8F3F_AC), cultured in semi-solid medium containing three substrates—wheat bran, orange peel, and coffee seed parchment; in the extracts, as well as in isolated commercial enzymes, cellulase, xylanase, and laccase activities were quantified; (ii) evaluation of the degradation of coffee seed parchment at different moisture contents by quantifying reducing sugars through the DNS method, using the selected extracts and commercial enzymes; (iii) efficiency test of the extracts in degrading the parchment on coffee seeds, conducted through the evaluation of seedling emergence in trays.Among the substrates evaluated, wheat bran is the most appropriate for inducing the production of cellulase and xylanase, especially by the T. stromaticum isolate. The C. fructicola extract in wheat bran and in coffee seed parchment stands out in laccase production. The enzymatic extracts evaluated, especially the ones produced by Trichoderma stromaticum, are capable of degrading Coffea arabica seed parchment, with this degradation being dependent on the moisture content of the seeds. The use of microorganism extracts does not surpass the increase in the emergence speed of coffee seedlings provided by the manual removal of the parchment. Thus, it is concluded that the microbial extracts promote parchment degradation, but further studies are still needed to make their use viable as a strategy to reduce the emergence time of seedlings and accelerate the production of coffee seedlings.