‘Esmeralda’ is an orange fleshed peach cultivar primarily used for juice extraction and secondarily used for the fresh fruit market. Fruit yield and quality depend on several local environmental and managerial factors, mainly on nitrogen, which must be balanced with other nutrients. Similar to other perennial crops, peach trees show carryover effects of carbohydrates and nutrients and of nutrients stored in their tissues. The aims of the present study are (i) to identify the major sources of seasonal variability in fruit yield and qu Fruit Tree Department of Federal University of Pelotas (UFPEL), Pelotas 96010610ality; and (ii) to establish the N dose and the internal nutrient balance to reach high fruit yield and quality. The experiment was conducted from 2014 to 2017 in Southern Brazil and it followed five N treatments (0, 40, 80, 120 and 160 kg N ha⁻¹ year⁻¹). Foliar compositions were centered log-ratio (clr) transformed in order to account for multiple nutrient interactions and allow computing distances between compositions. Based on the feature ranking, chilling hours, degree-days and rainfall were the most influential features. Machine learning models k-nearest neighbors (KNN) and stochastic gradient decent (SGD) performed well on yield and quality indices, and reached accuracy from 0.75 to 1.00. In 2014, fruit production did not respond to added N, and it indicated the carryover effects of previously stored carbohydrates and nutrients. The plant had a quadratic response (p < 0.05) to N addition in 2015 and 2016, which reached maximum yield of 80 kg N ha⁻¹. In 2017, harvest was a failure due to the chilling hours (198 h) and the relatively small number of fruits per tree. Fruit yield and antioxidant content increased abruptly when foliar clr_Cu was >−5.410. The higher foliar P linearly decreased total titratable acidity and increased pulp firmness when clr_P > 0.556. Foliar N concentration range was narrow at high fruit yield and quality. The present results have emphasized the need of accounting for carryover effects, nutrient interactions and local factors in order to predict peach yield and nutrient dosage.

The objective of this research was to evaluate the technical feasibility of SPAD index in the diagnosis of N status in ‘Esmeralda’ peach. The field trial, with five N rates applied to the soil (0, 40, 80, 120 and 160 kg ha-1 of N as urea form) was conducted in a randomized block design with four replications. During the years 2014, 2015, 2016 and 2017, SPAD readings were carried out with a Minolta SPAD-502 chlorophyll meter, in the leaf middle part, in 40 leaves per plot. The leaf N content determination was performed in CHN-S Elemental Analyzer. SPAD index and leaf N content increased in a linear way in response to increasing N rates applied in soil. There was a positive linear correlation between SPAD index and N concentration in leaves (0.652; 0.756; 0.762 and 0.767, p<0.05). SPAD index can be used for nutritional N diagnosis purpose in peach when readings are taken between the 13th and 15th weeks after full bloom. In the range between 39 and 49, the SPAD index indicates the leaf N content is included in “normal” class (33 – 45 g kg-1) of agronomic interpretation for the States of Rio Grande do Sul and Santa Catarina, Brazil.

Among the factors that affect peach productivity is the proper nutrition of plants, being nitrogen (N) one of the main nutrients for the crop. Thus, the objective of the current study was to evaluate the effect of nitrogen fertilization on macronutrient leaf contents, plant development and production of different genotypes of peach trees cultivated at high planting density, seeking to recommend the most appropriate concentration. The experiment was conducted between 2016 and 2018 using peach selections ‘Cascata 1513’ and ‘Cascata 1067’ and with nitrogen fertilization concentrations (0, 60, 120 and 180 kg ha-1 of N). Pruning mass, trunk diameter, number of fruits per plant, average fruit mass, yield per plant, yield per hectare and leaf macronutrients were evaluated. The increase of N concentration increases the N content in leaves. For the conditions of this experiment the maximum production per plant was obtained for the highest dose of 180 Kg ha of N.

O cultivo do morangueiro sem solo apresenta inúmeras vantagens, como facilidade de manejo, redução de doenças radiculares, redução dos custos da lavoura, fornecimento adequado de água e nutrientes, entre outros. Entretanto, há poucas informações sobre pós-colheita de morangos produzidos fora do solo. Assim, o objetivo do presente trabalho foi comparar a qualidade de frutas de diferentes cultivares de dias neutros de morangueiro, em cultivo sem solo recirculante. O experimento foi realizado na Embrapa Clima Temperado, em Pelotas, RS, entre 2015 e 2016. Avaliou-se teor de sólidos solúveis, acidez titulável, relação sólidos solúveis acidez titulável, potencial hidrogeniônico, firmeza da polpa, tamanho das frutas e coloração. Estudou-se quatro cultivares de morangueiro de dias de neutros: Albion, Aromas, Monterey e San Andreas. A qualidade das frutas foi influenciada pelo fator cultivar, bem como pelo clima. Em sistema de cultivo sem solo recirculante, a qualidade dos morangos varia de acordo com a cultivar utilizada.

Fast ripening of fruits is one of the main hindrances to peach preservation. Even though the use of cold storage has extended commercialization periods, fruit quality is affected during storage. This study aimed at evaluating the influence of application of salicylic acid (SA) during cold storage, followed by commercialization simulation, regarding physical and chemical characteristics of ‘BRS Kampai’ peaches, which were harvested in the 2017 crop. The experiment was conducted in a completely randomized factorial design (4×3: SA concentrations × storage days), with four replications of ten fruits each. SA was applied at the following concentrations: 0, 2, 4 and 6 mM. Afterwards, fruits were submitted to cold storage at 1±0.5ºC and 80-85% relative humidity. Analyses were carried out on harvest day, on the 10th cold storage day, followed by a day at room temperature (20ºC) and on the 20th cold storage day, followed by a day at room temperature. Fruits were evaluated in terms of their mass loss, epidermis color, chromatic hue, pulp firmness, soluble solids (SS), pH and titratable acidity (TA). Both application of SA and cold storage contributed to decrease mass loss and TA, besides increasing the SS/TA relation. Fruits which were stored for 20 days and kept at room temperature for a day exhibited the highest values of SS and the lowest values of both brightness and pulp firmness. SA was efficient to maintain the quality of ‘BRS Kampai’ peaches submitted to cold storage for 10 and 20 days and an extra day of commercialization simulation.

In cultivation of peaches, thinning is conventionally performed on fruits by hand, and needs to be done in a short time and with specialized labor, which increases the operational costs of this practice. Mechanical thinning can be an alternative to manual fruit thinning. Thus, the objective of this study was to evaluate the effect of mechanical flower thinning with different equipment in advanced peach orchard. The experiment was conducted in 2016 and 2017, combining advanced selections of peach trees and thinning methods. The evaluated variables were percentage of flowers thinning, thinning time, fruit number per plant, plant production, estimated yield, average fruit mass and fruit diameter class. Flower mechanic thinning alters the yield index of peach trees. Mechanical thinning on peach trees was efficient in flower thinning and reduced the practice execution time. Therefore, mechanical thinning is an alternative to the manual fruit thinning of peach trees.