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.

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.