First report of Calosphaeria pulchella causing cankers in peach (Prunus persica) in Chile.

Peach (Prunus persica) is an important stone fruit crop in Chile, with 7,665 h in 2022. Trunk diseases symptoms, including shoot dieback, longitudinal cankers and internal dark-brown to purple discolorations in cross sections were observed in a commercial orchard, in March of 2021. In severe cases, mostly in old trees, periderm sections were detached from the cankers, showing circinate groups of black long necked perithecia. To isolate the causal agent, wood samples were collected from March 2021 to October 2022, from symptomatic trees (n=23) of commercial orchards (n=12) (34°12'36.47"S 70°46'3.43"O to 34°34'26.48"S 70°58'17.97"O), located in O'Higgins Region, in the center of Chile. Isolations were performed cutting wood sections (0.5 cm) from the necrosis progress area, disinfecting them in sodium hypochlorite (10%), plating on a quarter-strength potato dextrose agar amended with 1 mg/L tetracycline (aPDA-tet) and incubating at 25°C, until mycelial development. Cultures were purified on PDA and identified by morphological means. Colonies on PDA were dark-pink and purple to orange-red, with regular margins, usually white, and produced abundant hyaline ellipsoidal to allantoid conidia (3.8-5.7 × 1.3 µm). In some cases, perithecia developed on disinfected wood on culture media, showing clavate unitunicate asci with hyaline allantoid ascospores 4.5-6.2 × 0.7 µm. The morphological characteristics of anamorph and teleomorph structures of field and culture isolates accorded to those described for Calosphaeria pulchella (1,2). DNA from representative isolates was extracted and the ITS region was amplified by PCR using ITS1/ITS4 primers (3), sequenced and BLAST analyzed. BLAST results revealed that ITS sequences identity of the representative isolates HMDu263 and HMDu271, shared 99 and 100% similarity, respectively, when compared to isolate CBS115999 (EU367451) (1,2,4). Sequences were accessioned to GenBank (OP216663 and OP216664 [ITS]). To determine the pathogenicity of C. pulchella, 17 representative isolates were inoculated on peach canes (25 cm) (n=7 per isolate), that were previously rooted on tap water amended with 500 ppm of indole-butyric acid, for 30 d. Mycelial plugs (0.5 cm) from actively growing colonies on PDA were placed on circular injuries made in the upper third of the shoots using a sterile corkborer and covered with plastic film. Sterile agar was used for controls. After 60 d of incubation in aerated tap water, at 23 +/-3 °C, bark was removed, and the necrosis length was measured and compared. Mean length values of lesions went from 9.5 to 27 cm. The most virulent isolates (n=7) were inoculated on fresh cuts of main shoots of nursery plants (n=3 per isolate) cv. Royal Glory, with 200 µL conidial suspensions (1x105 conidia/mL), on March 18th, 2022. Plants were incubated at shadehouse for 102 d and after the incubation period, shoots were cut (30 cm), bark was removed, and discoloration length was measured. All the isolates were pathogenic, with differences among their virulence (ANOVA, LSD, P < 0.05) from 5.2 cm (HMDu246) to 24.3 cm (HMDu266). Fungus was successfully reisolated from symptomatic canes (100%) and trees (98.7%), but not from the controls in both pathogenicity tests, fulfilling Koch's postulates. Calosphaeria pulchella was recently reported causing trunk disease in sweet cherry in Chile (4) and these results contribute to the knowledge of trunk diseases of fruit crops in Chile and to the understanding of the pathogen worldwide.

Metabolite Profiling Reveals the Effect of Cold Storage on Primary Metabolism in Nectarine Varieties with Contrasting Mealiness.

Chilling injury is a physiological disorder caused by cold storage in peaches and nectarines. The main symptom of chilling injury is mealiness/wooliness, described as a lack of juice in fruit flesh. In this work, we studied two nectarine varieties (Andes Nec-2 and Andes Nec-3) with contrasting susceptibility to mealiness after cold storage. A non-targeted metabolomic analysis was conducted by GC-MS to understand if changes in metabolite abundance are associated with nectarine mealiness induced by cold storage. Multivariate analyses indicated that in unripe nectarines, cold storage promoted a higher accumulation of amino acids in both varieties. Interestingly, for ripe nectarines, cold storage induced an accumulation of fewer amino acids in both varieties and showed an increased abundance of sugars and organic acids. A pathway reconstruction of primary metabolism revealed that in ripe nectarines, cold storage disrupted metabolite abundance in sugar metabolism and the TCA cycle, leading to a differential accumulation of amino acids, organic acids, and sugars in mealy and juicy nectarines.

Kinetic parameters related to nitrogen uptake in 'Okinawa' peach rootstocks are altered by 'Chimarrita' scion Nitrogen uptake in 'Okinawa' peach rootstock.

BACKGROUND: The kinetic parameters of peach rootstock are a major factor contributing to its nitrogen (N) uptake efficiency, which directly affects the yield and quality parameters. However, the impact of grafting on N kinetic parameters is not sufficiently known as rootstocks are grafted with other scion cultivars before being transplanted to the field. The objective of this study was therefore to evaluate whether the grafting of 'Okinawa' rootstock with the scion cultivar 'Chimarrita' can alter the kinetic parameters related to N uptake. RESULTS: The plants were acclimatized in Hoagland solution for 21 days and, sequentially, were tested to assess the depletion of the internal reserves at 15 and 30 days in CaSO4 solution. Morphological and physiological parameters were evaluated, and kinetic parameters were calculated. The depletion period for to reach the minimum concentration (Cmin ) of NO3 - and NH4 + in the plant was 62 h and 56 h, respectively. The optimal time for internal reserve depletion for 'Okinawa' rootstock with and without the 'Chimarrita' scion was 30 days. CONCLUSION: 'Okinawa' rootstock grafted with 'Chimarrita' scion cultivar was more efficient in NO3 - and NH4 + uptake. © 2022 Society of Chemical Industry.

Leaf mineral concentration of peach after the use of resistance inducers / Concentração mineral da folha do pessegueiro após o uso de indutores de resistência

This research studied the effect of the inducers acibenzolar-S-Methyl, potassium phosphite, and potassium silicate on the leaf mineral concentration of peach. The experiment was carried out in Tezontepec, Puebla, in the years 2017 and 2018. The treatments consisted of the foliar application of the resistance inducers acibenzolar-S-Methyl, potassium phosphite, and potassium silicate. Inducers were applied at commercially recommended dose. The experimental design was in randomized blocks with four replicates. Foliar quantification of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, copper and silicon was carried out. The use of resistance inducers increases the leaf concentrations of calcium. The interaction of resistance inducers and years of application modified the foliar concentration of magnesium, phosphorus and sulfur in peaches.

O objetivo desta pesquisa foi estudar o efeito dos indutores acibenzolar-S-Metil, fosfito de potássio e silicato de potássio sobre o teor de minerais foliares do pessegueiro. O experimento foi realizado em Tezontepec, Puebla, nos anos de 2017 e 2018. Os tratamentos consistiram na aplicação foliar dos indutores acibenzolar-S-Metil, fosfito de potássio e silicato de potássio. Os indutores foram aplicados na dose comercialmente recomendada. O delineamento experimental foi em blocos casualizados com quatro repetições. Foi realizada a quantificação foliar de nitrogênio, fósforo, potássio, cálcio, magnésio, enxofre, cobre e silício. A interação de indutores de resistência e anos de aplicação modificou a concentração foliar de magnésio, fósforo e enxofre nas folhas de pessegueiro.

Leaf mineral concentration of peach after the use of resistance inducers / Concentração mineral da folha do pessegueiro após o uso de indutores de resistência

ABSTRACT: This research studied the effect of the inducers acibenzolar-S-Methyl, potassium phosphite, and potassium silicate on the leaf mineral concentration of peach. The experiment was carried out in Tezontepec, Puebla, in the years 2017 and 2018. The treatments consisted of the foliar application of the resistance inducers acibenzolar-S-Methyl, potassium phosphite, and potassium silicate. Inducers were applied at commercially recommended dose. The experimental design was in randomized blocks with four replicates. Foliar quantification of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, copper and silicon was carried out. The use of resistance inducers increases the leaf concentrations of calcium. The interaction of resistance inducers and years of application modified the foliar concentration of magnesium, phosphorus and sulfur in peaches.

RESUMO: O objetivo desta pesquisa foi estudar o efeito dos indutores acibenzolar-S-Metil, fosfito de potássio e silicato de potássio sobre o teor de minerais foliares do pessegueiro. O experimento foi realizado em Tezontepec, Puebla, nos anos de 2017 e 2018. Os tratamentos consistiram na aplicação foliar dos indutores acibenzolar-S-Metil, fosfito de potássio e silicato de potássio. Os indutores foram aplicados na dose comercialmente recomendada. O delineamento experimental foi em blocos casualizados com quatro repetições. Foi realizada a quantificação foliar de nitrogênio, fósforo, potássio, cálcio, magnésio, enxofre, cobre e silício. A interação de indutores de resistência e anos de aplicação modificou a concentração foliar de magnésio, fósforo e enxofre nas folhas de pessegueiro.

Phenological and physicochemical changes during fruit development in two peach cultivars in the high tropics / Cambios fenológicos y fisicoquímicos durante el desarrollo del fruto en dos cultivares de duraznero en trópico alto

ABSTRACT Several aspects of the development of the peach fruit under tropical conditions are unknown, this information allows agronomic practices to be carried out with technical criteria. Therefore, the objective was to determine the different changes and phenological changes of peach fruit depending on the Growing Degree Days (GDD) in the varieties 'Dorado' and 'Rubidoux', grown in the Colombian high tropics. This study randomly selected 51 trees and 100 flowers per plant that were in full flowering for sampling every 15 days until harvest to determine physical variables such as firmness, color index of the epidermis and pulp, and chemical properties such as soluble solids, titratable acidity, and respiratory rate. From full bloom to harvest, the Dorado and Rubidoux varieties took 1081.8 GDD (153 days) and 1667.1 GDD (205 days) respectively. The firmness increased in the two cultivars during phase 1 of development, then decreased until harvest. The color index of the epidermis and pulp increased during ripening, indicating yellow tones in the two varieties. The soluble solids increased continuously, with final values of 15.9 ± 0.9 and 15.5 ± 0.3 °Brix. The acidity increased during phase 2 and then decreased during ripening. The respiratory rate decreased between phase 1 and 3, with an increase in phase 2, which is related to the lignification of the endocarp in the two cultivars. These results contribute to the understanding of the development of the two peach cultivars under tropical conditions.

RESUMEN Se desconocen varios aspectos del desarrollo del fruto de duraznero en condiciones tropicales, información que permite realizar labores agronómicas con criterio técnico, por tanto, el objetivo fue determinar los diferentes cambios fisicoquímicos y fenológicos del fruto de durazno, en función del tiempo térmico, de las variedades 'Dorado' y 'Rubidoux', cultivados en zonas de trópico alto colombiano. Se seleccionaron al azar 51 árboles y 100 flores/planta, en estado de plena floración. Cada 15 días y hasta la cosecha, se hicieron mediciones de la firmeza, el índice de color de epidermis y pulpa, los sólidos solubles, la acidez titulable y la tasa respiratoria. De plena floración a cosecha, las variedades Dorado y Rubidoux tardaron 1081,8 GDC (153 días) y 1667,1 GDC (205 días), respectivamente. La firmeza presentó un incremento en los dos cultivares durante la fase 1 de desarrollo, luego disminuyó hasta la cosecha. El índice de color de epidermis y pulpa aumentó durante la maduración, con tonalidades amarillas, en las dos variedades. Los sólidos solubles incrementaron de forma continua y en los dos cultivares, con valores finales de 15,9 ± 0,9 y 15,5 ± 0,3 °Brix. La acidez mostró un incremento durante la fase 2 y luego disminuyó durante la maduración. La tasa respiratoria decreció entre la fase 1 y 3, con un incremento en la fase 2, relacionado con la lignificación del endocarpio, en los dos cultivares. Estos resultados contribuyen al entendimiento del desarrollo de los dos cultivares de durazno, bajo condiciones tropicales.

Structural Determinants of Sugar Alcohol Biosynthesis in Plants: The Crystal Structures of Mannose-6-Phosphate and Aldose-6-Phosphate Reductases.

Sugar alcohols are major photosynthetic products in plant species from the Apiaceae and Plantaginaceae families. Mannose-6-phosphate reductase (Man6PRase) and aldose-6-phosphate reductase (Ald6PRase) are key enzymes for synthesizing mannitol and glucitol in celery (Apium graveolens) and peach (Prunus persica), respectively. In this work, we report the first crystal structures of dimeric plant aldo/keto reductases (AKRs), celery Man6PRase (solved in the presence of mannonic acid and NADP+) and peach Ald6PRase (obtained in the apo form). Both structures displayed the typical TIM barrel folding commonly observed in proteins from the AKR superfamily. Analysis of the Man6PRase holo form showed that residues putatively involved in the catalytic mechanism are located close to the nicotinamide ring of NADP+, where the hydride transfer to the sugar phosphate should take place. Additionally, we found that Lys48 is important for the binding of the sugar phosphate. Interestingly, the Man6PRase K48A mutant had a lower catalytic efficiency with mannose-6-phosphate but a higher catalytic efficiency with mannose than the wild type. Overall, our work sheds light on the structure-function relationships of important enzymes to synthesize sugar alcohols in plants.

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.

Evaluating chemicals for inducing budburst in peach orchard grown in subtropical conditions / Avaliação de produtos químicos para indução de brotação em pomar de pessegueiro cultivado em condições subtropicais

The availability of chill hours influences the break dormancy, sprouting and production of temperate fruit trees in different regions. During the winter, the chilling requirements for growing peaches in subtropical locations are restricted, and certain chemicals are required to overcome dormancy and induce budburst. As a result, further information concerning the use of these compounds on stimulating sprouting in peach trees is required. The purpose of this study was to evaluate the ability of hydrogen cyanamide, nitrogen fertilizer, and calcium nitrate to trigger budburst in the 'Douradão' peach orchard, which is in the subtropical area of São Paulo state, Brazil. The following tree chemicals were tested: 0.6 % hydrogen cyanamide, 2.5 % nitrogen fertilizer with 4 % calcium nitrate, 4 % calcium nitrate, and control. The hydrogen cyanamide accelerated, predicted, and focused blooming on plants, along with improving fruit set and output. Furthermore, combining nitrogen fertilizer with calcium nitrate accelerated budburst, which boosted flowering, output per tree, and yield. The spraying of the peach plants with just calcium nitrate produced results like those obtained in the control. The results allow for the use of hydrogen cyanamide or nitrogen fertilizer + calcium nitrate as an option for triggering budburst in Douradão cultivar peach trees under subtropical circumstances, depending on the orchards system management used.(AU)

A disponibilidade de horas de frio influencia a quebra da dormência, brotação e produção de árvores frutíferas de clima temperado em diferentes regiões. Os requerimentos de frio para o cultivo de pessegueiros em regiões subtropicais são limitados durante o inverno e alguns produtos químicos são necessários para superar a dormência e induzir a brotação. Portanto, são necessárias mais informações sobre o uso desses compostos na promoção da brotação em pessegueiros. Este trabalho teve como objetivo avaliar a cianamida hidrogenada, o fertilizante nitrogenado e o nitrato de cálcio para brotação, num pomar de pessegueiro 'Douradão', localizado em região subtropical do estado de São Paulo, Brasil. Para isso, três produtos químicos foram avaliados: 0,6% de cianamida hidrogenada; 2,5% de fertilizante nitrogenado + 4% de nitrato de cálcio; 4% de nitrato de cálcio e o controle. A cianamida hidrogenada aumentou o florescimento das plantas, além de aumentar a frutificação e a produção. Além disso, fertilizante nitrogenado + nitrato de cálcio também proveram a brotação, potencializando o florescimento e a produção das plantas. A pulverização dos pessegueiros somente com nitrato de cálcio apresentou desempenho semelhante ao observado na testemunha. Os resultados permitiram indicar a utilização da cianamida hidrogenada ou fertilizante nitrogenado + nitrato de cálcio, como alternativa para indução de brotação em pessegueiros cultivar Douradão, em condições subtropicais, dependendo do sistema de cultivo adotado nos pomares.(AU)

Preservation of cv. Jubileu peaches in a conventional cold storage system under a dynamic controlled atmosphere / Conservação de pêssegos cv. Jubileu em sistema refrigerado convencional, atmosfera controlada e dinâmica

The peach tree (Prunus persica) has a considerable global economic impact because its fruits are consumed worldwide. As climacteric fruits, peaches ripen after harvest and are also highly perishable postharvest. The aim of this study was to investigate alternatives for extending storage time and preventing a decline in quality in peaches using conventional cold storage (CS) compared with controlled atmosphere (CA) and ultralow oxygen (ULO) systems. A completely randomized design was used, with a 3 x 6 factorial scheme (3 storage systems x 6 storage times), thirteen parameters assessed by analysis of variances and significance by Tukey's test and regression. Total soluble solids (TSS) varied from 12.72 to 16.07ºBrix, titratable acidity (TA) declined during storage and pH varied significantly among the systems used from 40 days of storage onwards. The best TSS/TA ratio was obtained under ULO after 40 days, while firmness and weight loss declined in CA and ULO, contrasting with the brightly colored pulp. Reducing and non-reducing sugars decreased under CA and ULO at 30 and 40 days of storage, whereas phenolic compounds and antioxidant activity remained similar in these systems at 30, 40 and 50 days. Carotenoids remained stable for up to 40 days in ULO.CA and ULO maintained the best physical and chemical quality parameters, both systems being the most recommended. The phytochemical compounds analyzed in this study changed little during storage in the systems analyzed.(AU)

O pessegueiro (Prunus persica) apresenta grande impacto econômico global, por produzirem frutos apreciados em todo o mundo. Seus frutos climatérios amadurecem após a colheita, além disso, possuem alta perecibilidade pós-colheita. O objetivo deste trabalho foi buscar alternativas que ampliem ainda mais o tempo de armazenamento evitando-se o decaimento da qualidade dos pêssegos, utilizando o sistema refrigerado convencional (SAR) em contraponto com a atmosfera controlada (SAC) e dinâmica com ultrabaixo oxigênio (SAUO). O delineamento experimental foi inteiramente casualizado em um esquema fatorial 3 x 6 (3 sistemas x 6 períodos) de armazenamento, e treze parâmetros analisados pelo teste análise de variância, significância pelo teste Tukey e regressão. Os valores de sólidos solúveis variaram de 12,72ºBrix a 16,07ºBrix, a acidez titulável reduziu ao longo do armazenamento, já o pH apresentou variação significativa a partir de 40 dias entre os sistemas utilizados. A relação SS/AT alcançou os melhores índices no SAUO até 40 dias, já a firmeza de polpa e a perda de massa apresentaram redução nos SAC e SAUO, contrastando com elevada coloração da polpa. Açúcares redutores e não redutores apresentaram redução no SAC e SAUO aos 30 e 40 dias de armazenamento, já para os compostos fenólicos e atividade antioxidante, nestes sistemas, com 30, 40 e 50 dias os valores mantiveram-se semelhantes. Os carotenóides foram mantidos até 40 dias no SAUO. O SAC manteve os melhores parâmetros de qualidade físico-químicos analisados, juntamente com SAUO, sendo ambos os mais indicados. Os compostos fitoquímicos analisados neste estudo apresentaram poucas alterações durante os dias de armazenamento nos sistemas analisados.(AU)

First report of Anthracnose on Peach Fruit Caused by Colletotrichum siamense in Uruguay.

Peach (Prunus persica L.) is an economically important deciduous fruit crop in Uruguay. Anthracnose caused by species of the genus Colletotrichum is one of the major diseases in peach production, originating significant yield losses in United States (Hu et al. 2015), China (Du et al. 2017), Korea (Lee et al. 2018) and Brazil (Moreira et al. 2020). In February 2017, mature peach fruits cv. Pavia Canario with symptoms resembling anthracnose disease were collected from a commercial orchard located in Rincon del Colorado, Canelones, in the Southern region of Uruguay. Symptoms on peach fruit surface were characterized as circular, sunken, brown to dark-brown lesions ranging from 1 to 5 cm in diameter. Lesions were firm to touch with wrinkled concentric rings. All lesions progressed to the fruit core in a V-shaped pattern. The centers of the lesions were covered by orange conidial masses. Monosporic isolates obtained from the advancing margin of anthracnose lesions were grown on PDA at 25ºC and 12h photoperiod under fluorescent light. The representative isolates DzC1, DzC2 and DzC6 were morphologically and molecularly characterized. Upper surface of colonies varied from white or pale-gray to gray and on the reverse dark-gray with white to pale-gray margins. Conidia were cylindrical, with both ends predominantly rounded or one slightly acute, hyaline and aseptate. The length and width of conidia ranged from 9.5 to 18.9 µm (x ̅=14.1) and from 3.8 to 5.8 µm (x ̅=4.6), respectively. The ACT, ßTUB2, GAPDH, APN2, APN2/MAT-IGS, and GAP2-IGS gene regions were amplified and sequenced with primers ACT-512F/ACT-783R (Carbone and Kohn, 1999), BT2Fd/BT4R (Woudenberg et al. 2009), GDF1/GDR1 (Guerber et al. 2003), CgDLR1/ColDLF3, CgDLF6/CgMAT1F2 (Rojas et al. 2010) and GAP1041/GAP-IGS2044 (Vieira et al. 2017) respectively and deposited in the GenBank database (MZ097888 to MZ097905). Multilocus phylogenetic analysis revealed that Uruguayan isolates clustered in a separate and well supported clade with sequences of the ex-type (isolate ICMP 18578) and other C. siamense strains (isolates Coll6, 1092, LF139 and CMM 4248). To confirm pathogenicity, mature and apparently healthy peach fruit cv. Pavia Canario were inoculated with the three representative isolates of C. siamense (six fruit per isolate). Fruit were surface disinfested with 70% ethanol and wounded with a sterile needle at two equidistant points (1 mm diameter x 1 mm deep). Then, fruit were inoculated with 5 µl of a spore suspension (1×106 conidia mL-1) in four inoculation points per fruit (two wounded and two unwounded). Six fruit mock-inoculated with 5 µl sterile water were used as controls. Inoculated fruit were placed in moist chamber and incubated at 25°C during 10 days. Anthracnose lesions appeared at 2 and 4 days after inoculation in wounded and unwounded points, respectively. After 7 days, disease incidence was 100% and 67% for wounded and unwounded fruit, respectively. The control treatment remained symptomless. The pathogens were re-isolated from all lesions and re-identified as C. siamense. C. siamense was previously reported in South Carolina causing anthracnose on peach (Hu et al. 2015). To our knowledge, this is the first report of anthracnose disease on peach caused by C. siamense in Uruguay. Effective management strategies should be implemented to control anthracnose and prevent the spread of this disease to other commercial peach orchards.

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.

Generation of fruit postharvest gene datasets and a novel motif analysis tool for functional studies: uncovering links between peach fruit heat treatment and cold storage responses.

MAIN CONCLUSION: A survey of developed fruit gene-specific datasets and the implementation of a novel cis-element analysis tool indicate specific transcription factors as novel regulatory actors under HT response and CI protection. Heat treatment (HT) prior to cold storage (CS) has been successfully applied to ameliorate fruit chilling injury (CI) disorders. Molecular studies have identified several HT-driven benefits and putative CI-protective molecules and mechanisms. However, bioinformatic tools and analyses able to integrate fruit-specific information are necessary to begin functional studies and breeding projects. In this work, a HT-responsive gene dataset (HTds) and four fruit expression datasets (FEds), containing gene-specific information from several species and postharvest conditions, were developed and characterized. FEds provided information about HT-responsive genes, not only validating their sensitivity to HT in different systems but also revealing most of them as CS-responsive. A special focus was given to peach heat treatment-sensitive transcriptional regulation by the development of a novel Perl motif analysis software (cisAnalyzer) and a curated plant cis-elements dataset (PASPds). cisAnalyzer is able to assess sequence motifs presence, localization, enrichment and discovery on biological sequences. Its implementation for the enrichment analysis of PASPds motifs on the promoters of HTds genes rendered particular cis-elements that indicate certain transcription factor (TF) families as responsible of fruit HT-sensitive transcription regulation. Phylogenetic and postharvest expression data of these TFs showed a functional diversity of TF families, with members able to fulfil roles under HT, CS and/or both treatments. All integrated datasets and cisAnalyzer tool were deposited in FruitGeneDB (https://www.cefobi-conicet.gov.ar/FruitGeneDB/search1.php), a new available database with a great potential for fruit gene functional studies, including the markers of HT and CS responses whose study will contribute to unravel HT-driven CI-protection and select tolerant cultivars.

Metabolite Fruit Profile Is Altered in Response to Source-Sink Imbalance and Can Be Used as an Early Predictor of Fruit Quality in Nectarine.

Peaches and nectarines [Prunus persica (L.) Batsch] are among the most exported fresh fruit from Chile to the Northern Hemisphere. Fruit acceptance by final consumers is defined by quality parameters such as the size, weight, taste, aroma, color, and juiciness of the fruit. In peaches and nectarines, the balance between soluble sugars present in the mesocarp and the predominant organic acids determines the taste. Biomass production and metabolite accumulation by fruits occur during the different developmental stages and depend on photosynthesis and carbon export by source leaves. Carbon supply to fruit can be potentiated through the field practice of thinning (removal of flowers and young fruit), leading to a change in the source-sink balance favoring fruit development. Thinning leads to fruit with increased size, but it is not known how this practice could influence fruit quality in terms of individual metabolite composition. In this work, we analyzed soluble metabolite profiles of nectarine fruit cv "Magique" at different developmental stages and from trees subjected to different thinning treatments. Mesocarp metabolites were analyzed throughout fruit development until harvest during two consecutive harvest seasons. Major polar compounds such as soluble sugars, amino acids, organic acids, and some secondary metabolites were measured by quantitative 1H-NMR profiling in the first season and GC-MS profiling in the second season. In addition, harvest and ripening quality parameters such as fruit weight, firmness, and acidity were determined. Our results indicated that thinning (i.e., source-sink imbalance) mainly affects fruit metabolic composition at early developmental stages. Metabolomic data revealed that sugar, organic acid, and phenylpropanoid pathway intermediates at early stages of development can be used to segregate fruits impacted by the change in source-sink balance. In conclusion, we suggest that the metabolite profile at early stages of development could be a metabolic predictor of final fruit quality in nectarines.

Harvest season, productivity and physicochemical quality of peach fruits grown in Dois Vizinhos, Paraná State, Brazil / Época de colheita, produtividade e qualidade físico-química de frutos de pessegueiros cultivados em Dois Vizinhos, PR

The objective of this study was to determine the harvest time, main components of yield and the physicochemical quality attributes of peach cultivars produced in a subtropical climate. The study was carried out in the Fruit Growing sector of the Federal Technological University of Paraná, Campus Dois Vizinhos, Paraná State, Brazil. The main components of yield and estimated productivity, background color of the epidermis, pulp firmness, soluble solids (SS), titratable acidity (TA) and the SS/TA ratio of 17 peach cultivars were determined for two crop cycles: 2016 and 2017. The experimental design was a randomized block with four replicates of one tree per experimental unit, in a 17 x 2 bifactorial scheme (cultivars x years). Fruits of the cultivars: Aurora-1, Bonão, Douradão, Leonense, Ouromel, Rubimel and Zilli matured early, whereas those of Eldorado and BR-1 were last to mature. The cultivars Bonão, Charme and Eldorado were the most productive. Eldorado produced the highest caliber of fruits and Bonão produced the highest number of fruits per tree. The cultivars BR-1 and Eldorado produced the sweetest fruits and Leonense, the most acidic. The 2016 crop season provided greater productivity, with fruits of greater caliber and firmness of pulp.(AU)

O objetivo do trabalho foi determinar a época de colheita, os principais componentes de rendimento e atributos de qualidade físico-química de cultivares de pessegueiro produzidos em Dois Vizinhos, PR. O trabalho foi realizado no setor de Fruticultura da Universidade Tecnológica Federal do Paraná, Campus Dois Vizinhos. Obteve-se em duas safras agrícolas, 2016 e 2017, as datas de início de colheita, os principais componentes de rendimento e a produtividade estimada, cor de fundo da epiderme, firmeza de polpa, teores de sólidos solúveis (SS) e acidez titulável (AT), bem como a relação SS/AT (ratio) de 17 cultivares de pessegueiros. O delineamento experimental foi de blocos ao acaso com quatro repetições de uma planta por unidade experimental, num esquema bifatorial 17 x 2 (cultivares x anos de cultivo). Os frutos das cultivares Aurora-1, Bonão, Douradão, Leonense, Ouromel, Rubimel e Zilliam adureceram mais cedo, enquanto os de Eldorado e BR-1 foram os últimos a amadurecer. As cultivares Bonão, Charme e Eldorado foram as mais produtivas. Eldorado produziu o maior calibre de frutos e Bonão produziu o maior número de frutos por planta. As cultivares BR-1 e Eldorado produziram os frutos mais doces e Leonense, os mais ácidos. A safra de 2016 proporcionou maior produtividade, com frutos de maior calibre e firmeza da polpa.(AU)

Estimates of genetic parameters, genetic variability, and selection in the S1 generation of peach / Estimativas de parâmetros genéticos, variabilidade genética e seleção em geração S1 de pessegueiros

The growing of peach in mild winter regions is made viable through the use of genotypes that have low need for cold conditions, and this is one of the main aims of breeding for these regions. Thus, the aims of this study were to estimate genetic parameters, evaluate genetic variability, and select families adapted to mild winter regions in the S1 generation of peach through mixed model methodology (REML/BLUP). For that purpose, 22 populations, 84 families, and 2090 individuals were evaluated for the following traits: bud burst rate (BR), node density (ND), plant height (PH), and trunk diameter (TD). Genetic variability was found for all the traits. Individual heritability in the broad sense was of low and medium magnitudes. The PH trait had positive genotypic correlation of high magnitude with TD. The ND trait had moderate negative genotypic correlation with PH and TD. Clustering by the Tocher method resulted in the formation of six mutually exclusive groups. Considering selection intensity of 25%, simultaneous selection for BR, ND, and TD led to predicted gains of 11.3% for BR, 9.7% for ND, -14.2% for PH, and -14.3% for TD, showing the great potential of the germplasm evaluated.(AU)

O cultivo do pessegueiro em regiões de inverno ameno é viabilizado pela utilização de genótipos que apresentam baixa necessidade de frio, sendo este um dos principais objetivos do melhoramento para essas regiões. Assim, os objetivos deste estudo foram estimar parâmetros genéticos, avaliar a variabilidade genética e selecionar famílias adaptadas a regiões de inverno ameno em geração S1 de pessegueiros via metodologia de modelos mistos (REML/BLUP). Para isso, 22 populações, 84 famílias e 2090 indivíduos foram avaliados quanto as características: taxa de brotação (TB), densidade de nós (DN), altura da planta (AP) e diâmetro do tronco (DT). Verificou-se variabilidade genética para todas as características. As herdabilidades individuais no sentido amplo foram de baixa e média magnitudes. A característica AP apresentou correlação genética positiva de magnitude elevada com DT. A característica DN apresentou correlação genética negativa moderada com AP e DT. O agrupamento pelo método de Tocher resultou na formação de seis grupos mutuamente excludentes. Considerando intensidade de seleção de 25%, a seleção simultânea para TB, DN e DT propiciou ganhos preditos de 11.3% para TB, 9.7% para DN, -14.2% para AP e -14.3% para DT, evidenciando o grande potencial do germoplasma avaliado.(AU)

Raleio mecânico de frutos e flores em pessegueiros / Mechanical thinning of fruits and flowers in peach trees

Técnicas que melhorem a eficiência do processo e reduzam o custo de operação são importantes ferramentas na redução dos custos. Dois dispositivos mecânicos foram utilizados para testar a eficiência no raleio de frutos e flores em pessegueiros e a influencia nas características produtivas e qualitativas dos frutos. O estudo foi realizado na cultivar Maciel em pomar comercial no município de Pelotas, Rio Grande do Sul, Brasil. Os tratamentos foram: raleio mecânico de flores com o equipamento Carpa Electro® e derriçadeira, raleio mecânico de frutos com o equipamento derriçadeira e raleio manual de frutos. O raleio mecânico associado ao repasse manual em pessegueiros pode ser uma alternativa viável ao raleio manual, pois reduz o tempo de execução desta prática. Os dois equipamentos podem ser utilizados para o raleio mecânico, pois não alteraram a produção por planta, o número de frutos por planta, a massa dos frutos, diâmetro dos frutos, as características físico-químicas e os compostos bioativos dos frutos.(AU)

Techniques that improve process efficiency are important to reduce the operational cost of orchards. Two mechanical devices were tested to verify the efficiency of peach tree thinning and the influence on fruit production and quality characteristics. The experiment was conducted using the Maciel cultivar in a commercial orchard in Pelotas, Rio Grande do Sul, Brazil. The treatments consisted of mechanical flower blossom thinning using the Carpa ElectroTM and trimming equipment; mechanical fruit thinning using the trimming equipment; and manual fruit thinning. The mechanical thinning associated with manual thinning of peach trees may be a viable alternative to manual thinning since it reduces the execution time. Both equipment can be used for mechanical thinning since they didn't change the production per plant, number of fruits per plant, fruit mass, fruit diameter, physicochemical characteristics, and bioactive compounds of the fruits.(AU)

Potassium fertilization in peach fruit quality / Adubação potássica na qualidade de frutos de pessegueiro

For peach trees produced in southern Brazil, information about the influence of potassium fertilization on fruit quality remains scarce. This study set out to determine the physicochemical properties and bioactive compounds of peaches treated with different doses of potassium applied to the soil for three consecutive crop years. The experiment examined the Sensação cultivar in a commercial orchard in the municipality of Morro Redondo, Rio Grande do Sul, Brazil, during the 2016, 2017, and 2018 crop years. Peach trees of the Sensação cultivar were fertilized with potassium (K); doses of 0, 40, 80, 120, and 160 kg ha-1 of K2O in the form of potassium chloride were applied to the soil surface. After harvest, an assessment was made of the soluble solids (SS) content, titratable acid (TA) content, SS/TA ratio, pH levels, flesh color, skin and flesh firmness, total carotenoid content, total phenolic content, and antioxidant activity. The peaches skin firmness, SS/TA ratio, and concentration of carotenoids responded to potassium fertilization, but only in some production cycles. Their color, flesh firmness, soluble solids, juice pH levels, total phenols, and antioxidant activity did not change with the application of potassium in the soil.(AU)

Para pessegueiros produzidos na região sul do Brasil ainda são escassas as informações sobre a influência da adubação potássica sobre a qualidade dos frutos. Deste modo, o presente trabalho teve como objetivo avaliar os atributos físico-químicos e compostos bioativos dos frutos de pessegueiros submetidos a diferentes doses de potássio aplicadas no solo por três safras consecutivas. O experimento foi realizado estudando a cultivar Sensação em um pomar comercial no município de Morro Redondo, RS Brasil, durante as safras de 2016, 2017 e 2018. Os pessegueiros da cultivar Sensação foram adubados com potássio (K) nas doses de 0, 40, 80, 120 e 160 kg ha-1 de K2O na forma de cloreto de potássio, aplicadas na superfície do solo. Após a colheita foram determinados os teores de sólidos solúveis (SS), acidez titulável (AT), relação SS/AT, pH, coloração da polpa, firmeza da epiderme e da polpa, teor de carotenoides totais, compostos fenólicos totais e atividade antioxidante. A firmeza da epiderme, a relação SS/AT e a concentração de carotenoides dos pêssegos responderam à adubação potássica, mas apenas em alguns ciclos de produção. Os parâmetros de coloração, firmeza da polpa, sólidos solúveis, pH do suco, fenóis totais e atividade antioxidante dos pêssegos não alteraram em decorrência da aplicação de potássio ao solo.(AU)

Nutritional status of peach trees in Brazils main commercial peach-growing region / Estado nutricional do pessegueiro na principal região produtora de pêssego para indústria no Brasil

O presente trabalho teve como objetivo caracterizar nutricionalmente plantas de pessegueiro na região produtora de Pelotas, RS. Foram amostrados 65 pomares de pessegueiros das cultivares Maciel, Granada, Esmeralda e Sensação nos municípios de Pelotas, Canguçu e Morro Redondo no ciclo produtivo de 2018. As amostras foliares, após secas e moídas, foram analisadas quanto aos seus teores de nitrogênio (N), fósforo (P), potássio (K), cálcio (Ca), magnésio (Mg), boro (B), cobre (Cu), ferro (Fe), manganês (Mn) e zinco (Zn) e os resultados foram apresentados em distribuições de frequência nas classes de suficiência indicadas para a cultura na região além da correlação entre os nutrientes. Observou-se maiores deficiências nos teores de nitrogênio, cobre, ferro e zinco. Entretanto, para a maioria das amostras, os teores de potássio encontraram-se na classe acima do normal, encontrou-se correlações entre P/Ca, P/Cu, Ca/P, Ca/Mg e Ca/B. É possível constatar a carência do uso de ferramentas para avaliar o estado nutricional dos pomares, principalmente a diagnose foliar, o que levou ao uso inadequado de fertilizantes e consequentemente um desbalanço nutricional das plantas.(AU)

This study set out to assess the nutritional status of peach trees in the commercial peach-growing region of Pelotas, Rio Grande do Sul. The sample includes 65 peach orchards of the Maciel, Granada, Esmeralda, and Sensação cultivars in the municipalities of Pelotas, Canguçu, and Morro Redondo during the 2018 agricultural cycle. After drying and grinding the leaf samples for an analysis of their nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) content, the results were presented in frequency distributions divided into classes based on the nutrient requirements indicated for the crop in the region, in addition to the correlations between the nutrients. Greater deficiencies were observed in nitrogen, copper, iron, and zinc content. However, potassium content was found in the above normal class for most of the samples, and there were correlations between P/Ca, P/Cu, Ca/P, Ca/Mg, and Ca/B. An insufficient use of the tools to assess the nutritional status of the orchards was observed, especially the leaf diagnosis, which led to the inappropriate use of fertilizers and the consequent nutrient imbalance in the plants.(AU)