Bioactive compounds and physical-chemical characteristics of two genotypes of peach trees submitted to nitrogen fertilization

Nitrogen, which is the primary nutrient peach trees need, may affect their fruit quality. Thus, this study aimed at evaluating the effect of nitrogen fertilization on two genotypes of peach trees, regarding their fruit quality, in three consecutive crops. The experiment was carried out in the experimental area that belongs to the Embrapa Clima Temperado, located in Pelotas, Rio Grande do Sul (RS), Brazil, from 2016, 2016, 2017 and 2018. Four doses of nitrogen (0, 60, 120 and 180 Kg ha-1) and two peach tree genotypes ('Cascata 1513' and 'Cascata 1067') were used. For the fruit, we evaluated epidermis color, pulp firmness, epidermis firmness, soluble solids concentration, titratable acidity, concentration of total phenolic compounds, anthocyanins and antioxidant activity. Fruit underwent physical, chemical and bioactive compound analyses. Results showed that the highest dose of nitrogen (180 Kg ha-1) applied to the soil retards fruit ripening, while no application of nitrogen fertilization brings fruit maturation forward. Nitrogen fertilization via soil does not favor anthocyanins in fruit. Doses of 60 and 120 Kg ha-1 of nitrogen are recommended because they lead to improvement in peach color, epidermis firmness and acidity. Peach tree genotypes influence soluble solids, juice pH, phenolic compounds and antioxidant activity of their fruit.

Bioactive content of six passion fruit genotypes cultivated in southern Brazil

Passion fruit production in Brazil is concentrated in tropical regions, however, recently production has expanded to regions with temperate climate. Cultivar performance in different climate and soil can lead to variation in the contents of bioactive compounds in the juice and rind of the fruit. This study characterized the bioactive content of passion fruit rind and juice of six passion fruit genotypes ('Catarina Roxo', 'Catarina', 'Urussanga', 'BRS Gigante Amarelo', 'BRS Rubi do Cerrado', and 'BRS Sol do Cerrado') cultivated in southern Brazil. Phenolic, flavonoid, anthocyanin, carotenoid, and ascorbic acid contents and the antioxidant potential of each fruit portion from each genotype were evaluated. Fruit composition varied with genotype and evaluated tissue. Bioactive compound contents were greatest in the rind of 'Urussanga' and 'Catarina', whereas the juice of 'BRS Sol do Cerrado' and 'Catarina Roxo' had the greatest bioactive content. Given cultivar and tissue variability for bioactive content, postharvest use of passion fruit will determine the choice of cultivar to obtain a product with maximum bioactive compounds. Passion fruit genotypes evaluated in this study have shown to be potential sources of bioactive compounds. Fruit rind has the potential to be explored in the scientific and technological scope, due to its high amounts of phenolic compounds and antioxidant activity.

Comparison among chemical thinners applied to Maciel and Sensação peach trees / Comparação entre realentes químicos em pessegueiros 'Maciel' e 'Sensação'

Peach tree thinning, whichaims at reducing plant load so as to ensure productivity and fruit quality, has been manually carried out within a short period of time in the stage of fruit development. Due to the need and shortage of qualified man power, chemical thinning is one of the alternatives that can solve these difficulties found in manual thinning. This study aimed at evaluating the effect of different products which have been applied ­ either alone or in combination ­ to fruit thinning of peach tree cultivars 'Sensação' and 'Maciel' in Pelotas, Rio Grande do Sul (RS) state, Brazil. The experiment was conducted in the 2015/2016 crop in a commercial peach orchard located in Morro Redondo, RS, Brazil. The following seven treatments were carried out 40 days after full bloom (DAFB): plants with no thinning, manual thinning, metamitron, benzyladenine, benzyladenine + metamitron, ethephon, ethephon + metamitron. Fruit abscission, effective fructification, number of fruits and production per plant, mean mass and fruit classification into caliber classes, epidermis color, pulp firmness and soluble solids were evaluated. Production and number of fruits per plant decreased excessively, whereas fruits placed in categories of higher caliber increased when ethephon was either used alone or in combination with metamitron. When both metamitron and benzyladenine were applied, either alone or in combination, they led to fruit abscission and resulted in mean fruit size and weight, at harvest time, similar to those found in manual thinning. Application of chemical products ­ either alone or in combination ­ may be an alternative of peach tree thinning in orchard management.

O raleio em pessegueiro visa reduzir a carga da planta para assegurar a produtividade e a qualidade dos frutos, sendo realizado manualmente em um curto período durante a etapa de desenvolvimento dos frutos. Devido à exigência e falta de mão de obra qualificada, o raleio químico é uma das alternativas para suprir essa demanda encontrada no raleio manual. O objetivo deste trabalho foi avaliar o efeito de diferentes produtos aplicados de forma isolada ou combinada no raleio de frutos de pessegueiros das cultivares Sensação e Maciel na região de Pelotas. O experimento foi conduzido na safra 2015/2016, em pomar comercial de pessegueiro localizado no município de Morro Redondo, RS. Foram realizados sete tratamentos aos 40 dias após a plena floração, consistindo em plantas sem raleio, raleio manual, metamitron, benziladenina, benziladenina + metamitron, ethephon, ethephon + metamitron. Avaliou-se a abscisão dos frutos, frutificação efetiva, número de frutos e produção por planta, massa média e classificação dos frutos em classes de calibre, coloração da epiderme, firmeza de polpa e sólidos solúveis. A produção e o número de frutos por planta reduziram excessivamente, enquanto a alocação dos frutos em categorias de maior calibre aumentou, quando utilizado o ethephon isolado ou em combinação com o metamitron. O metamitron e a benziladenina aplicados isolados ou em combinação promoveram a abscisão dos frutos e resultaram em tamanho e peso médio dos frutos na colheita semelhantes aos provenientes do raleio manual. Aplicação de produtos químicos isolados ou em combinação pode ser uma alternativa de manejo dos pomares para o raleio de pessegueiros.

Nitrogen fertilization associated with cold storage and its impacts on the maintenance of peach quality / Adubação nitrogenada associada ao armazenamento refrigerado e seus impactos na manutenção da qualidade do pêssego

Nitrogen, which is considered the most important nutrient for peach trees, may interfere in both quantitative production characteristics and quality of fruits. This study aimed at evaluating the effect of the combination of doses of N fertilization and different periods of cold storage on physico-chemical and phytochemical characteristics of peaches in post-harvest. The experiment had a randomized complete block design in a 4x3 factorial scheme, i. e., four doses of fertilization (0, 60, 120 and 180 Kg N ha-1) and three periods of storage (on the harvest day, on both the 15th and the 30th storage days at 1±1ºC, each followed by a day of simulated commercialization at 20±1ºC). The following aspects were evaluated in fruits yielded by peach trees of the genotype Cascata 1067: fruit color, soluble solid content, titratable acidity, pulp firmness, mass loss, total phenolic compounds and antioxidant activity. Different periods of cold storage and doses of N fertilization were found to affect epidermis luminosity, pulp firmness and titratable acidity of fruits. Peaches may be stored at low temperatures for 15+1 days. After that, loss of fruit firmness increases. N fertilization affects neither the soluble solid content nor the epidermis color of peaches, but both parameters are influenced by storage. Values of phenolic compounds and antioxidant activity decrease when there is N increment in the soil and when longer storage is carried out. Results suggest that peach composition may be affected by cultural practices, such as N fertilization, in harvest and after storage.

O nitrogênio é o nutriente considerado de maior importância para o pessegueiro, podendo interferir nas características quantitativas da produção, bem como na qualidade dos frutos. O objetivo do trabalho foi avaliar o efeito da combinação de doses de adubação nitrogenada e de diferentes períodos de armazenamento refrigerado nas características físico-químicas e fitoquímicas de pêssegos na pós-colheita. O delineamento experimental foi o de blocos casualizados em esquema fatorial 4x2, quatro doses de adubação (0, 60, 120 e 180 Kg N ha-1) e três períodos de armazenamento (dia da colheita, aos 15 e 30 dias armazenamento refrigerado a 1±1ºC, seguido de um dia de simulação de comercialização a 20±1ºC). Avaliou-se, nos frutos de pessegueiro do genótipo Cascata 1067, a coloração dos frutos, o teor de sólidos solúveis, acidez titulável, firmeza da polpa, perda de massa, compostos fenólicos totais e a atividade antioxidante. Verificou-se que diferentes períodos de armazenamento refrigerado e doses de adubação nitrogenada afetam a luminosidade da epiderme, a firmeza de polpa e a acidez titulável dos frutos. Os pêssegos podem ser armazenados em baixa temperatura até 15+1 dias, após esse período, a perda de firmeza nos frutos é elevada. A adubação nitrogenada não altera o teor de sólidos solúveis e a coloração da epiderme dos pêssegos, mas esses parâmetros são influenciados durante o armazenamento. Os compostos fenólicos e atividade antioxidante decrescem com o incremento de nitrogênio no solo, bem como durante o avanço dos dias de armazenamento. Os resultados sugerem que a composição dos pêssegos pode ser afetada com práticas culturais como a adubação de nitrogênio na colheita e após o armazenamento.