Pesquisa Agropecuária Tropical
URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/13103
Navegar
5 resultados
Resultados da Pesquisa
Item Effect of fruit load of the first coffee harvests on leaf gas exchange(Escola de Agronomia - UFG, 2021-01-14) Muñoz, Carlos Andres Unigarro; Bejarano, Lina Marcela Díaz; Acuña, José RicardoCoffee production between the first and second harvest presents a difference in the fruit load with the plant age that could affect the leaf gas exchange. This research aimed to evaluate the effect of the increase in fruit load that occurs between the first and second harvest of the Coffea arabica L. production cycle on the measured gas exchange, at the two phenological stages of the fruit. The accessions E057, E318, E338 and E554 were used, as well as a completely randomized design, with three replications, using the accessions as treatments and the harvest measurements during the production cycle as the repeated measures. The variables yield per tree, number of fruits, absolute growth rates for height and stem, leaf area, leaf-to-fruit ratio and leaf gas exchange were measured across the phenological stages of fruit filling and ripening. The increase in the fruit load that occurs with age in the second harvest, if compared to the first harvest, showed a positive and significant effect on the net assimilation rate that was not expected for the obtained leaf-to-fruit ratios. Likewise, the differences in the assimilation rates were higher during the fruit-filling stage. This result suggests that the source-sink relationship may vary with the crop age and fruit phenological stage, and is not entirely depend on the leaf-to-fruit ratio.Item Early selection of drought-tolerant Coffea arabica genotypes at the seedling stage using functional divergence(Escola de Agronomia - UFG, 2022-08-15) Reis, André Moraes; Mendes, Antônio Nazareno Guimarães; Abrahão, Juliana Costa de Rezende; Santos, Meline de Oliveira; Silva, Vânia AparecidaThe development of more drought-tolerant cultivars is essential for the maintenance of global agricultural production. This study aimed to perform an early selection of drought-tolerant Coffea arabica genotypes by evaluating their functional divergence using morphological, anatomical and physiological analyses. Seedlings of 14 genotypes were subjected to the drought stress imposed by irrigation for 18 days. Growth and anatomical parameters, leaf water potential and gas exchanges were measured. Under irrigated conditions and prolonged drought (18 days), the divergence among the genotypes was determined mainly by morphological traits, such as leaf area, stem diameter and, consequently, shoot dry mass. Under moderate drought (14 days), parameters such as water potential, cuticle thickness, stomatal density, number of xylem vessels and water-use efficiency were important for the divergence of the group with the highest ability to maintain its water status. The genotypes 1, 2, 4, 11 and 12 have characteristics that contributed to the maintenance of water status, such as greater cuticle thickness, stomatal density, smaller number of xylem vessels and phloem thickness, bigger root length and greater water-use efficiency. The functional divergence combining morphological, anatomical and physiological analyses in response to the moderate drought indicated the early selection of the genotypes 1, 2,4, 11 and 12 as more drought tolerant during the seedling stage.Item Adaptations to the drought season and impacts on the yield of ‘Híbrido de Timor’ coffee tree in the Minas Gerais State Cerrado (Brazilian Savanna)(Escola de Agronomia - UFG, 2022-09-02) Santos, Cyntia Stephânia dos; Freitas, Ana Flávia de; Silva, Glauber Henrique Barbosa da; Carvalho, Milene Alves de Figueiredo; Santos, Meline de Oliveira; Carvalho, Gladyston Rodrigues; Silva, Vânia AparecidaClimate change threatens the survival of commercial crops due to their narrow genetic base. One of the alternatives is the identification of plants with potential for abiotic stress tolerance. This study aimed to verify the physiological and anatomical adaptations to the drought period and the impacts on the yield of ‘Híbrido de Timor’ coffee tree accessions. The experimental design was randomized blocks, in a 7 x 2 factorial arrangement, being seven genotypes (UFV 377-21, UFV 377-21, UFV 442-42, BE 5 Wush-Wush x UFV 366-08, UFV 428-02, UFV 376-31 and UFV 427-55) and two seasonal periods (dry and rainy), with two replications. The stomatal conductance; predawn water potential; levels of hydrogen peroxide and malondialdehyde; activity of the enzymes catalase, superoxide dismutase and ascorbate oxidase; ascorbate content; cuticle thickness of the adaxial surface and leaf lamina; stomatal density; ratio between polar and equatorial diameter; phloem area; area, diameter and frequency of xylem vessels; relative hydraulic conductivity; vulnerability index; and yield were evaluated. The results showed acclimatization of the accessions to the dry period, with some of them maintaining higher water potential values in the predawn; induction of the antioxidant system with the increase in the activity of the superoxide dismutase enzyme and ascorbate levels; increase in the cuticle and leaf lamina thickness; and a higher ratio between polar and equatorial diameters. Most of the evaluated accessions showed a good productive performance, especially the ‘UFV 377-21’, ‘UFV 442-42’ and ‘UFV 376-31’, with adaptations to the dry period and yield potential.Item Adsorption isotherms and isosteric heat in Coffea arabica beans(Escola de Agronomia - UFG, 2020) Santos, Samuel Gonçalves Ferreira dos; Silva, Daniel Pereira da; Sarti, Jefferson Kran; Almeida, Vinícius Gonçalves; Rodovalho, Renato SouzaO conhecimento do equilíbrio higroscópio de adsorção em café é pertinente para a adequação de seu armazenamento, garantindo a qualidade do produto até o consumidor final. Objetivouse determinar as isotermas de adsorção de grãos de café Arábica (cultivar Acauã Novo) nas temperaturas de 30 ºC, 40 ºC, 50 ºC e 60 ºC, bem como o calor isostérico integral de adsorção. Os teores de água de equilíbrio foram obtidos pelo método estático gravimétrico, com atividades de água entre 0,10 e 0,83 (decimal). A partir dos dados obtidos, foram ajustados diversos modelos matemáticos para representar as isotermas de adsorção. Os critérios estatísticos para a seleção do melhor modelo foram o coeficiente de determinação, erro médio estimado, erro médio relativo e a distribuição de resíduos. O modelo de Peleg foi o que melhor representou as isotermas de adsorção dos grãos de café Arábica nas condições estudadas. As isotermas apresentaram formato sigmoidal tipo II. Sob atividade de água constante, o aumento da temperatura promove diminuição no equilíbrio do teor de umidade em grãos de café Arábica. Os valores de calor isostérico com teor de água entre 0,0191 e 0,2534 (base seca) variaram de 4.042,19 kJ kg-1 a 2.395,48 kJ kg-1.Item Agroclimatic zoning for coffee crop in Angola(Escola de Agronomia - UFG, 2018) Ngolo, Aristides Osvaldo; Fernandes Filho, Elpídio Inácio; Ferreira, Williams Pinto Marques; Fernandes, Raphael Bragança AlvesO Governo de Angola tem a intenção de recuperar sua alta produção de café da década de 1970, por meio de programas de financiamento agrícola direcionados especialmente aos agricultores familiares. Objetivou-se realizar o zoneamento agroclimático para a cultura do cafeeiro em território angolano. Dados ou estimativas de temperatura anual, precipitação efetiva e total, balanço hídrico climático e déficit de água anual foram avaliados para todos os 163 municípios angolanos. Os dados de precipitação efetiva e total foram utilizados para o zoneamento agroclimático da cultura do cafeeiro no país. Com o uso da precipitação efetiva, 1 %, 20 % e 79 % do território de Angola foram considerados adequado, marginal e inapto para o café Arábica, respectivamente, enquanto, para o café Robusta, esses mesmos percentuais foram de 1 %, 8 % e 91 %. Com a utilização da precipitação total, esses mesmos valores foram de 2 %, 27,5 % e 70,5 % para o café Arábica e 1 %, 11,8 % e 87,2 % para o Robusta. As áreas marginais e inaptas para a produção de café em Angola estão associadas às condições de déficit hídrico, principalmente na região sudoeste do país e ao longo da faixa costeira. Os resultados obtidos a partir do balanço hídrico climático indicam que a maior parte do território angolano é marginal ou inapta para a cultura do cafeeiro.