Quality of Arabica coffee grown in Brazilian Savannah and impact of potassium sources.

Located in Brazil's Central Plateau, the Cerrado Savannah is an emerging coffee-growing region with significant potential for the national coffee market. This study investigated the impact of potassium fertilization on Arabica coffee quality in the Cerrado, using three potassium sources (K2SO4, KCl, and KNO3) and five cultivars (Arara, Aranãs, IPR103, Catiguá and Topázio) across two consecutive harvests. We focused on productivity, granulometry, chemical composition, and sensory characteristics. No significant difference in productivity across the cultivars studied or potassium sources as isolated factors were observed. Regarding chemical parameters, potassium sources only affected NO3- and SO42- levels in the grains. Cultivar-specific differences were noted in caffeine (CAF), citric acid (CA), and sucrose (SUC), highlighting a strong genetic influence. K2SO4 improved productivity in Arara (15 %) and IPR103 (11 %), while KNO3 reduced flat grain percentage to 70 % in Catiguá. Sensory evaluation showed that all potassium sources and cultivars produced specialty coffees, with the Arara cultivar treated with K2SO4 achieving the highest SCA score (83.3) while IPR 103 treated with KCl scored the lowest at 78. Only three treatments were below but very close to the threshold (80). Multivariate analysis indicated a trend where specific treatments correlated with higher productivity and quality. Despite the subtle differences in productivity and quality among potassium sources, a cost-benefit analysis may favor KCl due to its affordability, suggesting its viability as a potassium fertilization option in coffee cultivation. Future research is needed to confirm these trends and optimize potassium source selection to enhance coffee quality in the Cerrado.

Physiological Changes of Arabica Coffee under Different Intensities and Durations of Water Stress in the Brazilian Cerrado.

Coffee farmers have faced problems due to drought periods, with irrigation being necessary. In this sense, this study aimed to evaluate the responses to different levels and durations of water deficit in arabica coffee genotypes in the Cerrado region. The experiment consisted of three Coffea arabica genotypes and five water regimes: full irrigation (FI 100 and FI 50-full irrigation with 100% and 50% replacement of evapotranspiration, respectively), water deficit (WD 100 and WD 50-water deficit from June to September, with 100% and 50% replacement of evapotranspiration, respectively) and rainfed (without irrigation). The variables evaluated were gas exchange, relative water content (RWC) and productivity. The results showed that during stress, plants under the FI water regime showed higher gas exchange and RWC, differently from what occurred in the WD and rainfed treatments; however, after irrigation, coffee plants under WDs regained their photosynthetic potential. Rainfed and WD 50 plants had more than 50% reduction in RWC compared to FIs. The Iapar 59 cultivar was the most productive genotype and the E237 the lowest. Most importantly, under rainfed conditions, the plants showed lower physiological and productive potential, indicating the importance of irrigation in Coffea arabica in the Brazilian Cerrado.

Influência do potássio e da calagem na composição química, qualidade fisiológica e na atividade enzimática de sementes de soja / Influence of potassium and liming on chemical composition, physiological quality and enzyme activities of soybean seeds

A composição química das sementes pode ser influenciada por fatores genéticos, ambientais e pela disponibilidade de nutrientes no solo durante a produção e, como consequência, terem o seu vigor afetado. O potássio pode influenciar a atividade de várias enzimas presentes nas plantas, necessárias em várias reações envolvidas na utilização de energia, síntese de amido, metabolismo do nitrogênio e respiração. Avaliou-se o efeito da adubação potássica e da calagem na composição química, qualidade fisiológica e na atividade de enzimas de sementes de soja. A pesquisa foi desenvolvida nos laboratórios de análises e biotecnologia de sementes do Departamento de Agricultura e no Laboratório de Produção Vegetal do Departamento de Ciências dos Alimentos da Universidade Federal de Lavras (UFLA). Em sementes de soja do cultivar Msoy 8001, produzidas sob 2 níveis de saturação por base (48 por cento e 85 por cento) e quatro doses de K2O por hectare (0, 50, 100 e 200 kg), foram avaliados teores de óleo e proteína, germinação, envelhecimento acelerado e atividade das enzimas envolvidas nos processos de germinação e deterioração de sementes. A adubação potássica não afeta a germinação e o vigor das sementes, enquanto a elevação da saturação por base, proporciona maior vigor de sementes de soja. Há aumento no teor de óleo e redução no teor de proteína em sementes de soja à medida que a dose de K2O é aumentada. Ocorre aumento de teor de proteínas em sementes de soja, produzidas sob maiores níveis de saturação por base. A atividade das enzimas piruvato quinase, esterase e álcool desidrogenase em sementes de soja é afetada pela concentração de potássio e saturação por base no solo.

The chemical composition of seeds can be influenced by genetical and environmental factors and by the availability of nutrients in the soil during production, which consequently affect their vigor. Potassium can influence the activity of several enzymes present in plants. These enzymes are necessary in a number of reactions involved in the utilization of energy, starch synthesis, nitrogen metabolism and respiration. The effects of potassium fertilization and liming on the chemical composition, physiological quality and enzymes activities of soybean seeds were evaluated. The research was developed in the Seed Analysis Laboratory of the Agriculture Department and in the Plant Production Laboratory in the Food Science Department of the Federal University of Lavras, Lavras (UFLA). In soybean seeds of cultivar Msoy 8001 produced under two levels of base saturation (48 percent and 85 percent) and four doses. ha-1 of K2O, 0, 50, 100 and 200, oil and protein contents, seed germination, aging test and the activity of some enzymes involved in the seed germination and deterioration processes were evaluated. Seed germination and vigor are not influenced by fertilization with potassium. However, base saturation increases the vigor of soybean seeds. Highert doses of potassium increase oil content and reduce protein in soybean seeds. High base saturation level increases the protein content. The activities of the enzymes piruvate kinase, esterase and alcohol dehydrogenase are altered by the doses of potassium and levels of soil base saturation.

Tolerância de sementes de soja à dessecação / Desiccation tolerance of soybean seeds

A colheita antecipada de sementes, após a maturidade fisiológica, permite a obtenção da melhor qualidade fisiológica e sanitária, rotação de culturas e otimização das estruturas de processamento. Sementes não toleram a secagem durante todos estádios e adquirem tolerância em estádios específicos. Durante a maturação, esta aquisição da tolerância à dessecação pode coincidir com a maturidade fisiológica e, em sementes de soja, ocorre no estádio R7, com umidade ao redor de 45 por cento a 50 por cento. Assim, a presente pesquisa teve como objetivo avaliar a tolerância à dessecação de sementes de soja. As sementes foram colhidas em três estádios fenológicos, R6, R6/R7 e R7 e foram submetidas à secagem artificial a 35°C até 20 por cento de teor de água e a 42°C até 13 por cento. Uma quarta colheita foi realizada com sementes secadas no campo, sendo estas utilizadas como testemunha. A qualidade das sementes foi avaliada pelos testes de germinação, de condutividade elétrica, de frio, de peso seco de plântulas e eletroforese de proteínas lea. O delineamento experimental foi inteiramente casualizado em esquema fatorial com quatro repetições. A testemunha foi comparada individualmente com cada tratamento. Com os resultados, concluiu-se que a germinabilidade e a tolerância à dessecação de sementes de soja aumentam com a perda natural de água no campo; sementes colhidas no estádio R7 apresentam maior qualidade fisiológica, padrão diferenciado de proteínas lea e maior tolerância à dessecação do que nos estádios R6 e R6/R7; secagem de sementes colhidas próximo à maturidade induz a síntese de lea proteínas; e sementes colhidas no estádio R7 apresentam qualidade fisiológica e padrão de proteína lea similares aos de sementes secadas no campo até 14 por cento de teor de água.

The anticipated harvest of seeds after physiological maturity allows the obtaining of the better quality physiological, crop rotation and optimization of the processing structures. Seeds do not tolerate dissection over all the stages and acquire tolerance in particular stages During maturation, this acquisition of dissection tolerance may coincide with physiological maturity and in soybean seeds, it take place at R7 stage with moisture close from 45 percent to 50 percent. So, the present research was intended to evaluate dissection tolerance of soybean seeds. The seeds were harvested at three phenologic stages, R6, R6/R7 and R7 and were submitted to artificial drying at 35°C to 20 percent of water content and at 42°C to 13 percent. A fourth harvest was accomplished with field dried seeds, these being utilized as a control. The quality of seeds was evaluated by tests of germination, electric conductivity and of cold, of dry weight of seedlings and lea protein electrophoresis.The experimental design was completely randomized in factorial scheme with four replicates. The control was compared singly with each treatment. From the results, it follows that both germinability and dissection tolerance of soybean seeds increase with the natural water loss in the field; seeds harvest at R7stage show increased physiologic quality, distinct pattern of lea proteins and greater dissection tolerance than at R6 and R6/R7stages; seeds drying harvested close to maturity induces the synthesis of lea proteins; and seeds harvested at R7 stage present physiological quality and lea protein pattern similar to the ones of filed dried seeds up to 14 percent of water content.