Beneficiamento de sementes de café (Coffea arabica L.) em máquinas de ar e peneiras e mesa gravitacional
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Data
2001
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Resumo
Apesar da importância da cultura do cafeeiro para o Brasil, praticamente inexistem informações sobre o uso da máquina de ar e peneiras e da mesa gravitacional no beneficiamento de sementes de café. Geralmente o termo "beneficiamento" é utilizado para discriminar as operações de "descascamento" de grãos de café com destino à indústria e não diz respeito ao "beneficiamento de sementes", do ponto de vista da Tecnologia de Sementes. Assim, o presente trabalho foi realizado com o
objetivo de avaliar a eficiência da máquina de ar e peneiras e da mesa gravitacional no beneficiamento de sementes de café (Coffea arabica L.). Um lote de sementes de café Catuaí Amarelo, linhagem IAC-H2077- 2-5-62, foi submetido inicialmente à ação da máquina de ar e peneiras e em seguida classificado em mesa gravitacional, onde as sementes foram separadas, respectivamente, em três classes de tamanho e quatro classes de peso específico. Todas as frações obtidas no beneficiamento foram avaliadas quanto a teor de água, rendimento e perda de sementes, tipo de semente (chatas e mocas), germinação e vigor (primeira contagem da germinação, porcentagem e velocidade de emergência e massa de matéria seca de
plântulas). O delineamento experimental utilizado foi o inteiramente casualizado, com quatro repetições, e a comparação de médias foi feita pelo teste de Tukey a 5% de probabilidade. Os resultados obtidos permitiram concluir que: a) o uso conjugado de peneiras com perfurações oblongas e peneiras com perfurações circulares, na máquina de ar e peneiras, proporcionou separação eficiente de sementes mocas; b) a mesa gravitacional pode ser regulada com três bicas de descarga sem que haja perda de eficiência do equipamento ou ocorra prejuízo para a qualidade fisiológica das sementes; c) as sementes pequenas que
atravessaram a peneira 18" (7,14 mm), e as leves, descarregadas na parte mais baixa da mesa gravitacional, apresentaram baixa qualidade fisiológica, com germinação inferior a 60%, e devem ser descartadas para que haja melhoria da qualidade fisiológica do lote; d) o beneficiamento em máquina de ar e peneiras e mesa gravitacional melhorou a qualidade fisiológica das sementes, aumentando a germinação em oito pontos percentuais; e) as sementes mocas, retidas na peneira com perfurações oblongas 13 x ¾" (5,16 x 19,05mm), apresentaram qualidade fisiológica compatível com a das sementes chatas, não havendo razão para serem descartadas do lote; f) a realização exclusiva do teste de germinação não foi suficiente para a avaliação da qualidade fisiológica das sementes, devendo ser complementada por um teste de vigor (porcentagem ou velocidade de emergência de plântulas em campo).
Despite of the significance of the coffee crop in Brazil, little is known about seed quality improvement attainable through the common seed processing procedure (cleaning, sizing and weight grading). Usually coffee processing is more related to conditioning the grain for industry purposes than to reach the aims of the seed technologists. This experiment was carried out to evaluate the efficiency of the air-screen machine and the gravity table to improve the quality of a coffee seed lot. The seeds of yellow Catuaí IAC-2077-2-5-62 cultivar were conditioned through an air-screen machine with two screens and an upper air aspiration where three size classes of seeds were obtained. Subsequently the seeds were graded on a gravity table to four weight classes. Seed samples were collected on each step of the processing for several characteristics determinations: seed water content, seed losses, seed shapes, seed germination and vigor (first count of the germination test, field emergence index, field emergence speed and seedling dry matter weight). The statistical analysis was made through a completely randomized design with four replications and the means were compared by Tukey test with 5% of probability. The results showed that: a) the selection of screen with oblong openings for the first screen (top) and a second screen with round openings was efficient to separate the seeds by their shape and size; b) the gravity table can be adjusted to three discharge zones without loss of efficiency or negative effects on the seeds physiological quality; c) both the small seeds that drop through 18/64 inch (7,14 mm) screen openings and the light seeds discharged from the lower side of the gravity table deck showed low physiological quality (less than 60% germination) and should be discarded from the lot; d) the processing increased 8 percent point on seed germination; e) the oval seeds (moca) retained over the screen with 13 x ¾ inch (5,16 x 19,05 mm) oblong openings presented physiological quality as good as the normal seeds (flat), so that there is no reason to be eliminated from the seed lot; f) the physiological quality of the seeds was better evaluated when the germination test was complemented with a vigor test (percentage of field emergence or field emergence speed).
Despite of the significance of the coffee crop in Brazil, little is known about seed quality improvement attainable through the common seed processing procedure (cleaning, sizing and weight grading). Usually coffee processing is more related to conditioning the grain for industry purposes than to reach the aims of the seed technologists. This experiment was carried out to evaluate the efficiency of the air-screen machine and the gravity table to improve the quality of a coffee seed lot. The seeds of yellow Catuaí IAC-2077-2-5-62 cultivar were conditioned through an air-screen machine with two screens and an upper air aspiration where three size classes of seeds were obtained. Subsequently the seeds were graded on a gravity table to four weight classes. Seed samples were collected on each step of the processing for several characteristics determinations: seed water content, seed losses, seed shapes, seed germination and vigor (first count of the germination test, field emergence index, field emergence speed and seedling dry matter weight). The statistical analysis was made through a completely randomized design with four replications and the means were compared by Tukey test with 5% of probability. The results showed that: a) the selection of screen with oblong openings for the first screen (top) and a second screen with round openings was efficient to separate the seeds by their shape and size; b) the gravity table can be adjusted to three discharge zones without loss of efficiency or negative effects on the seeds physiological quality; c) both the small seeds that drop through 18/64 inch (7,14 mm) screen openings and the light seeds discharged from the lower side of the gravity table deck showed low physiological quality (less than 60% germination) and should be discarded from the lot; d) the processing increased 8 percent point on seed germination; e) the oval seeds (moca) retained over the screen with 13 x ¾ inch (5,16 x 19,05 mm) oblong openings presented physiological quality as good as the normal seeds (flat), so that there is no reason to be eliminated from the seed lot; f) the physiological quality of the seeds was better evaluated when the germination test was complemented with a vigor test (percentage of field emergence or field emergence speed).
Descrição
Trabalho apresentado no Simpósio de Pesquisa dos Cafés do Brasil (2. : 2001 : Vitória, ES). Resumos. Brasília, D.F. : Embrapa Café, 2001. 181p. : il.
Palavras-chave
Café Sementes beneficiamento, Coffea arabica Seeds Processing Physiological quality.
Citação
Giomo, Gerson Silva; Razera, Luiz Fernandes; Gallo, Paulo Boller. Beneficiamento de sementes de café (Coffea arabica L.) em máquinas de ar e peneiras e mesa gravitacional. In: Simpósio Brasileiro de Pesquisa dos Cafés do Brasil (2. : 2001 : Vitória, ES). Anais. Brasília, D.F. : Embrapa Café, 2001. (CD-ROM), p. 1648-1658