DURATION OF THE PHENOLOGICAL STAGES OF PEACH TREES AT TROPICSDuration of the phenological stages of peach trees at tropics

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DURATION OF THE PHENOLOGICAL STAGES OF PEACH TREES AT TROPICSDuration of the phenological stages of peach trees at tropics Maraisa Helen Tadeua, Rafael Pioa, Gabi Nunes Silvab, Mercy Olmsteadc, Cosme Damião Cruzd, Filipe Bittencourt Machado de Souzae,*, Rayane Barcelos Bisia, Guilherme Locatellia a

Departamento de Agricultura, Universidade Federal de Lavras, Campus Universitário, Lavras, 37200-000, Brazil Departamento de Matemática, Campus Ji-Paraná, Fundação Universidade Federal de Rondônia Rua Rio Amazonas, 351, Jardim dos Migrantes, Ji-Paraná 76900-726, Brazil c California Strawberry Commission, 180 Westridge Drive, Suite 101, Watsonville, CA 95076, USA d Departamento de Biologia Geral, Universidade Federal de Viçosa, Av. Peter Henry Rolfs s/n, Campus Universitário, Viçosa 36570-900, Brazil e Av. Filadélfia, 568 - St. Oeste, Centro Universitário Tocantinense Presidente Antônio Carlos (UNITPAC), Araguaína 77816-540, Brazil b

A R T I C LE I N FO

A B S T R A C T

Keywords: Prunus persica Chill hours accumulation Precociousness Growing degree days Adaptability

This study aims to evaluate the duration of the phenological stages and determine the adaptability and stability of reproductive and vegetative phases of peach trees under tropics with the purpose of optimizing the production system. The experiment was set up in a randomized plot design with 23 cultivars (‘Aurora-1′, ‘Biuti’, ‘Bonão’, ‘Centenário’, ‘Charme’, ‘Delicioso Precoce’, ‘Diamante’, ‘Douçura-2′, ‘Douradão’, ‘Dourado-2′, ‘Eldorado’, ‘Flordaprince’, ‘Jóia-3′, ‘Kampai’, ‘Libra’, ‘Maciel’, ‘Maravilha’, ‘Marli’, ‘Okinawa’, ‘Ouromel-4′, ‘Premier’, ‘Régis’, and ‘Tropical’) in 2014-2016. The average duration (in days) for the three years, between pruning day and each phenological stage (OS - sprouted buds had opened, onset of flowering – OF, full bloom – FB, end of flowering – EF, beginning of fruit harvest - BH, and end of harvest - EH) in each plot, was evaluated through visual observations including the chill hours accumulation(CA) of each cultivar for accumulated number of hours with temperatures (≤7.2 °C), (≤12 °C) and (≥25℃), the thermal demand, expressed in degree-days of development (GDD) and the adaptability and stability of OS and EH.

1. Introduction The spread of commercial farming of temperate fruit crops in subtropical and tropical regions has increased rapidly in recent years. Peach production in tropic has expanded as the plant is well adapted to these areas and has an extended harvest period, which contributes to the diversification and improvement of fruit quality and yield (Souza et al., 2013). This increase is especially noticeable regarding peaches in Brazil, where the climatic conditions are highly variable. Subtropical humid zones, as those located in Southern Brazil, have hot, humid, rainy summers, which favor disease development (Scariotto et al., 2013). The study of phenology is one approach to observe the effects of climate change (Schwartz, 1999). The impact of possible changes in winter chilling accumulation or increased frost risks can then be assessed for trees in temperate climates under the different climate change scenarios (Rea and Eccel, 2006). Knowledge and awareness of flower bud phenological stages and fruit growth development are

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important requirements for many facets of crop management. Phenological models can inform farmers of crop growth and developmental stages during the growing season and may be useful tools for improving the efficacy and management of fruit production (Chmielewski, 2003). The precocious maturation of fruit should be considered the main factor of economic success for the farmer, due to the low supply in the market (Araújo et al., 2008). Peach trees must meet a chilling requirement in order to break dormancy and a heat requirement in order to bloom (Campoy et al., 2012). The chilling requirement may be different for different species, varieties, or growing regions (Wang et al., 2012). Chilling requirements are the major factor that determines the bloom date and the overcoming of dormancy (Alburquerque et al., 2008) These parameters are cultivar-specific and are useful for predicting the probability of the successful adaptation of a cultivar to a particular environment. The determination of chilling requirements and heat requirements are also important within a breeding program, to choose the correct parents for selection of early or late blooming cultivars (Campoy et al., 2011).

Corresponding author. E-mail address: fi[email protected] (F.B.M. de Souza).

https://doi.org/10.1016/j.scienta.2019.108976 Received 19 July 2019; Received in revised form 22 October 2019; Accepted 24 October 2019 0304-4238/ © 2019 Elsevier B.V. All rights reserved.

Please cite this article as: Maraisa Helen Tadeu, et al., Scientia Horticulturae, https://doi.org/10.1016/j.scienta.2019.108976

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‘Okinawa’ rootstock and trees of the ‘Okinawa’ cultivar also were grafted onto ‘Okinawa’ rootstock. ‘Okinawa’ rootstock is the most commonly used rootstock in southeastern Brazil because it provides a robust tree canopy and resists nemotodes of the genus Meloidogyne (Fachinello et al., 2000; Souza et al., 2013). Moreover, this rootstock is well adapted to the study region. Were planted in the field in July 2011, with 5.0 m between rows and 1.5 m between plants (population density of 1333 plants per ha), trained to a “Y’ system. The orchard received standard fungicide and insecticide sprays and fertilization, similar to the treatments used in commercial orchards. Pruning was performed on June 2nd, 2014; June 13 th, 2015 and May 31 st, 2016 and the degree of peach pruning depended on the vigor of the trees, as proposed by Borba et al. (2005). The pruning was followed by an application of 0.25 % hydrogen cyanamide (a.i.). The difference in the effect of cyanamide among the varieties was low because were selected cultivars adapted to the tropical climate according to the recommendations of Souza et al. (2013) and Matias et al. (2016), and hydrogen cyanamide was applied according to the method described by Tadeu et al. (2019) and Souza et al. (2019). The average duration (in days) for the three years, between pruning day and each phenological stage in each plot, was evaluated through visual observations as which the ones that follows: onset of bud sprouting (OS - when more than 5 % of sprouted buds had opened), onset of flowering (OF - when more than 5 % of flowers had opened), full bloom (FB - when more than 50 % of flowers had opened), end of flowering (EF - when 90 % of flowers had opened), beginning of fruit harvest (BH), and end of harvest (EH) as shown in Fig. 2. Air temperature data was collected at a frequency of one hour by Lavras Main Weather Station (UFLA/INMET) at UFLA (University of Lavras), a km from the experimental area to calculate the number of hours when temperatures were (≤7.2 °C), (≤12 °C) and (≥25℃) from April to September in 2014, 2015 and 2016. The chill hours accumulation (CA) of each cultivar for accumulated number of hours with temperatures (≤7.2 °C), (≤12 °C) and (≥25℃) from April 1 until the onset of budding, onset of flowering and full bloom for each cultivar in 2014, 2015 and 2016. The thermal demand, expressed in growing degree days (GDD), was calculated by using the sum of degree days accumulated from the day of pruning to the phenological stages of onset of bud sprouting, onset of

Mild winter conditions are highly variable for peach tree production and are primarily related to temperatures during the dormancy period of the plants. The cultivars that are best adapted to the tropics have reduced chilling requirements (between 70 and 200 h at temperatures below 7.2 °C) during their bud endodormancy period (Barbosa et al., 2010). It is believed that temperatures as high as 12 °C are effective in overcoming endodormancy in these cultivars, as verified by Citadin et al. (2014). The variability in chilling requirements, associated with the year-toyear variation and a diverse cultivar response conditioned by the contrasting dormancy intensity for different each cultivars (Saure, 1985). The lack of adaptation of peach tree cultivars to mild winter conditions can cause both blooming and flowering to be insufficient and sporadic, thus limiting subsequent fruit yields (Scariotto et al., 2013). The cultivars with low chilling requirement and with good production stability are important for success in tropics. The precocious cultivars need lower chilling requirement to begin flowering and usually present a lower heat requirement (Citadin et al., 2003). Given these considerations, the objective was to evaluate the duration of the phenological stages and determine the adaptability and stability of reproductive and vegetative phases of peach trees under tropics with the goal of optimizing the production system. 2. Materials and methods The experiment was conducted at an experimental orchard in Southern Minas Gerais State, municipality of Lavras, Brazil, between 2014 and 2016. The city is located at 21°14’ south latitude and 45°00’ west longitude, at an average altitude of 918 m. The climate is described as tropical, with dry winters and rainy summers (Souza et al., 2013). The average precipitation during the three years of experimental period was 99.28 mm monthly, whereas the average normal climatic rainfall was 1530 mm as shown in Fig. 1. The experiment was set up in a randomized plot design with 23 cultivars (‘Aurora-1’, ‘Biuti’, ‘Bonão’, ‘Centenário’, ‘Charme’, ‘Delicioso Precoce’, ‘Diamante’, ‘Douçura-2’, ‘Douradão’, ‘Dourado-2’, ‘Eldorado’, ‘Flordaprince’, ‘Jóia-3’, ‘Kampai’, ‘Libra’, ‘Maciel’, ‘Maravilha’, ‘Marli’, ‘Okinawa’, ‘Ouromel-4’, ‘Premier’, ‘Régis’, and ‘Tropical’), and three replicates, two trees per plot. The peach cultivars were grafted on

Fig. 1. Climate data from January 2014 to December 2016 in Lavras, MG, Brazil. Source: Lavras Main Climatological Station – UFLA/INMET. 2

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Fig. 2. Number of accumulated chill hours: (≤7.2 °C), (≤12 °C), and (≥25 °C) between the months of April and September for 2014 and 2016 in Lavras, Minas Gerais, Brazil.

OF and BF, with the exception of the ‘Premier’, which was precocious only when considering FB, were ‘Eldorado’ and ‘Marli’, which presented a full bloom later and it was the last considering EF. The first cultivars when considering EF were ‘Aurora-1′, ‘Bonão’, ‘Centenário’, ‘Flordaprince’, ‘Kampai’, ‘Libra’, ‘Régis’. The cultivar ‘Eldorado’ was sooner considering BH and EH, but it has high standard deviation, that is, a high variation between the years. The latest, when considering BH and EH, was the cultivar ‘Biuti’ (Table 1). The year 2016 was the latest considering OS. In 2014 there was no difference for OS of the cultivars. In 2015 and 2016 the cultivar ‘Eldorado’ had the latest OS. In 2015 the cultivars that presented a precocious development of OS were ‘Bonão’, ‘Eldorado’, ‘Flordaprince’, ‘Kampai’, ‘Libra’, ‘Okinawa’, ‘Régis’ and ‘Tropical’. In 2016, the cultivars ‘Aurora-1′, ‘Flordaprince’, ‘Jóia-3′, ‘Marli’, ‘Okinawa’, ‘Premier’ and ‘Régis’ were precocious considering OS (Table 2). In 2014 and 2015, there was no difference between cultivars considering CA (≤7.2 ℃) for OS. In 2016 the cultivars that showed higher CA (≤7.2℃) for OS were ‘Douradão’, ‘Eldorado’ and ‘Maciel’, and the lowest ones were ‘Aurora-1′, ‘Delicioso Precoce’, ‘Douçura-2′, ‘Flordaprince’, ‘Maravilha’, ‘Okinawa’ and ‘Régis’ (Table 3). In 2014, there was no difference between cultivars considering CA (≤12 ℃) for OS. In 2015, ‘Eldorado’ showed higher CA (≤12 ℃), and the lower values were found for the cultivars ‘Bonão’, ‘Flordaprince’, ‘Jóia-3′, ‘Kampai’, ‘Libra’, ‘Okinawa’, ‘Régis’ and ‘Tropical’. In 2016, ‘Eldorado’ and ‘Maciel’ had higher CA (≤12℃) for OS and the lower were ‘Biuti’, ‘Centenário’, ‘Douçura-2′, ‘Jóia-3′, ‘Kampai’, ‘Maravilha’, ‘Ouromel-4′, ‘Premier’ and ‘Tropical’. In 2016, all cultivars showed higher CA (≤7.2 ℃ and ≤12 ℃). Regarding the accumulation of hours at warm temperatures (≥25 ℃) in OS, the warm temperature is important for grow the branches. In 2014 there was no difference between cultivars. In 2015 and 2016, the cultivar with the highest accumulation was ‘Eldorado’. In 2015 the lowest accumulation was presented by the cultivars ‘Aurora-1′, ‘Biuti’, ‘Bonão’, ‘Centenário’, ‘Douçura-2′, ‘Douradão’, ‘Dourado-2′, ‘Flordaprince’, ‘Kampai’, ‘Libra’, ‘Maravilha’, ‘Okinawa’ and ‘Régis’. In 2016, the same results were found, except for ‘Bonão’ and ‘Douradão’, and the ‘Delicioso Precoce’ in this group, only in 2016. The onset of flowering was latest in 2016, compared to the other

flowering, full bloom and beginning of fruit harvest: ⅀GDD = ⅀ (Ta–Tb), where Ta = daily average temperature, and Tb = base temperature (7℃). The Tb adopted for the peach tree was 7 °C, according to Dejong (2005). The GDD average was calculated in the years 2014, 2015 and 2016. The interaction between the years and the cultivars was presented through the method proposed by Eberhart and Russell (1966). This method was used for the variables OS and EH. Their model is based on computations of linear regression (βi) for each genotype compared to environmental conditions and deviation from regression (S2di). By using regression coefficient and deviation from regression, the authors have established a method that provides estimates for stability and adaptability parameters of genotypes grown under various conditions. Genotypes in which βi > 1 respond better to more favorable conditions, whereas genotypes in which βi < 1 respond better to adverse environmental conditions. A stable cultivar is considered to be the one that has regression coefficient approximately at 1 and standard error of regression as low as possible. All statistical analyses were performed using GENES software (Cruz, 2013). 3. Results In 2015 there were no hours recorded below average minimum temperature below 7.2 °C, but in the year 2014, 11 h of cold temperature, below 7.2 °C, were recorded, and concentrated in the month of August, and in 2016, 23 h of cold temperature, below 7.2 °C and these were concentrated in the months between June and August. The accumulation of chill hours below 12 °C, which may also have an impact on dormancy was 382, 103 and 303 h for 2014, 2015 and 2016, respectively (Figs. 1 and 2). ‘Eldorado’ was the latest cultivar when considering OS, OF, FB and EF. The precocious cultivars when considering OS were ‘Aurora-1′, ‘Centenário’, ‘Flordaprince’, ‘Jóia-3′, ‘Kampai’, ‘Okinawa’, ‘Régis’ and ‘Tropical’. Considering OF, the precocious ones were ‘Aurora-1′, ‘Biuti’, ‘Bonão’, ‘Centenário’, ‘Delicioso Precoce’, ‘Douçura-2′, ‘Dourado-2′, Flordaprince, ‘Jóia-3′, ‘Kampai’, ‘Libra’, ‘Maravilha’, ‘Okinawa’, ‘Ouromel-4′, ‘Régis’ and ‘Tropical’. The precocious cultivars considering 3

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Table 1 The duration (in days) between pruning day and each phenological stage in each plot, was evaluated through visual observations as which the ones that follows: onset of bud sprouting (OS - when more than 5 % of sprouted buds had opened), onset of flowering (OF - when more than 5 % of flowers had opened), full bloom (FBwhen more than 50 % of flowers had opened), end of flowering (EF - when 90 % of flowers had opened), beginning of fruit harvest (BH), and end of harvest (EH) for average of 2014, 2015 and 2016 at the experimental peach orchard with 23 cultivars in Lavras, Minas Gerais, Brazil. Cultivars

OSz

Aurora-1 Biuti Bonão Centenário Charme Delicioso Precoce Diamante Douçura-2 Douradão Dourado-2 Eldorado Flordaprince Jóia-3 Kampai Libra Maciel Maravilha Marli Okinawa Ouromel-4 Premier Régis Tropical General Average CV (%) Accuracy (%)

23.17 27.33 30.25 25.25 35.33 30.00 34.58 27.25 29.75 29.17 53.92 21.50 25.75 23.25 26.58 38.75 29.50 36.75 23.50 31.08 27.83 22.50 24.67 29.46 7.79 98.23

OFy ± 4.13t d* ± 4.68 c ± 7.26 c ± 4.88 d ± 6.50 b ± 4.92 c ± 6.85 b ± 5.58 c ± 8.29 c ± 6.20 c ± 9.52 a ± 4.47 d ± 5.38 d ± 5.34 d ± 6.03 c ± 7.58 b ± 5.97 c ± 7.02 b ± 3.70 d ± 5.38 c ± 4.38 c ± 4.32 d ± 4.92 d

25.33 31.67 29.75 26.17 35.00 30.17 37.67 29.75 35.08 30.42 48.83 27.67 26.00 26.58 29.50 38.00 27.83 42.17 30.92 29.00 33.67 22.58 26.17 31.30 10.85 94.57

FBx ± 2.64 ± 3.52 ± 6.19 ± 3.71 ± 5.18 ± 3.76 ± 5.30 ± 3.55 ± 7.39 ± 5.05 ± 6.61 ± 3.34 ± 4.00 ± 4.64 ± 4.72 ± 7.45 ± 4.33 ± 5.29 ± 3.45 ± 3.26 ± 3.20 ± 2.63 ± 4.09

d d d d c d c d c d a d d d d c d b d d c d d

38.83 43.17 48.58 42.17 63.67 47.33 64.92 45.17 55.67 47.50 76.25 44.08 40.33 43.33 48.00 62.17 39.67 69.92 42.25 45.42 39.50 35.50 50.17 49.29 10.46 96.20

EFw ± 2.87 ± 3.34 ± 9.47 ± 4.23 ± 7.14 ± 3.36 ± 9.99 ± 4.87 ± 9.27 ± 6.37 ± 7.86 ± 3.74 ± 4.04 ± 7.66 ± 7.53 ± 9.11 ± 2.97 ± 6.41 ± 3.06 ± 2.58 ± 6.75 ± 2.95 ± 5.65

c c c c b c b c b c a c c c c b c a c c c c c

78.50 96.75 79.67 79.08 105.83 84.58 103.42 91.33 90.08 87.25 119.50 80.33 84.75 81.92 76.83 97.33 86.33 118.33 90.92 89.67 90.00 73.50 83.42 89.97 4.37 98.26

BHv ± 11.99 ± 17.94 ± 13.51 ± 11.45 ± 12.05 ± 11.93 ± 12.53 ± 12.30 ± 13.40 ± 13.88 ± 15.69 ± 10.78 ± 10.94 ± 12.73 ± 11.07 ± 18.45 ± 10.02 ± 13.23 ± 14.42 ± 13.17 ± 16.26 ± 11.59 ± 10.10

e e e e b d b d d d a e d e e c d a d d d e e

126.00 173.00 117.92 123.75 118.42 134.42 149.33 137.17 133.17 140.17 75.83 118.92 129.75 133.58 117.00 138.42 122.50 120.42 151.08 146.33 128.17 117.17 121.17 129.29 10.90 89.22

EHu ± 3.33 c ± 3.28 a ± 12.37 c ± 2.40 c ± 18.52 c ± 2.83 b ± 4.60 b ± 4.31 b ± 4.66 b ± 5.13 b ± 29.95 d ± 3.55 c ± 3.36 c ± 5.05 b ± 3.12 c ± 21.51 b ± 1.92 c ± 23.30 c ± 3.66 b ± 2.66 b ± 19.26 c ± 3.15 c ± 3.46 c

151.92 198.75 135.83 153.67 137.00 158.08 174.50 166.25 167.42 169.08 81.00 144.75 159.67 163.83 141.83 156.42 143.33 145.42 172.75 175.00 143.00 145.33 140.33 153.27 8.99 93.25

± 5.50 c ± 6.08 a ± 14.05 c ± 4.45 c ± 21.38 c ± 4.75 c ± 6.46 b ± 4.10 b ± 8.32 b ± 5.21 b ± 32.08 d ± 6.92 c ± 4.26 b ± 7.86 b ± 6.40 c ± 24.24 c ± 3.80 c ± 28.99 c ± 3.62 b ± 4.15 b ± 21.68 c ± 5.59 c ± 3.82 c

OS = The duration (in days) between pruning day and onset of bud sprouting. y OF = The duration (in days) between pruning day and onset of flowering. x FB = The duration (in days) between pruning day and full bloom. w EF = The duration (in days) between pruning day and end of flowering. v BH = The duration (in days) between pruning day and beginning of fruit harvest. u EH = The duration (in days) between pruning day and end of harvest. t Represent the average ± standard error. *Average values followed by the same letter belong to the same group according to the Scott-Knott test (P ≤ 0.05). z

they were ‘Aurora-1′, ‘Biuti’, ‘Centenário’, ‘Delicioso Precoce’, ‘Douçura-2′, ‘Dourado-2′, ‘Flordaprince’, ‘Jóia-3′, ‘Maravilha’, ‘Okinawa’, ‘Ouromel-4′, ‘Premier’, ‘Régis’ and ‘Tropical’. In 2014, the cultivars that needed higher CA (≤7.2℃) for FB were ‘Charme’, ‘Diamante’, ‘Eldorado’, ‘Maciel’ and ‘Marli’. In 2015 there was no difference between the cultivars for CA (≤7.2 ℃). In 2016 ‘Bonão’, ‘Charme’, ‘Diamante’, ‘Douradão’, ‘Eldorado’, ‘Libra’, ‘Maciel’ and ‘Marli’ needed a higher CA (≤7.2℃) to reach full bloom. The cultivars that needed the lowest CA (≤7.2 ℃) were ‘Biuti’, ‘Okinawa’ and ‘Premier’. ‘Eldorado’ had the highest CA (≤12℃) for FB in 2014 and the cultivars that needed the lowest were ‘Aurora-1′, ‘Biuti’, ‘Bonão’, Joía-3, ‘Kampai’, ‘Libra’, ‘Maravilha’, ‘Okinawa’, ‘Régis’ and ‘Tropical’. In 2015 ‘Charme’ and ‘Eldorado’ needed the highest CA (≤12℃) to reach FB. The cultivars ‘Bonão’, ‘Diamante’, ‘Douradão’, ‘Eldorado’, ‘Libra’, ‘Maciel’ and ‘Marli’ presented the highest CA (≤12℃) to reach FB in 2016. ‘Eldorado’ accumulated more hours at warm temperatures (≥25℃) in the 3 years, although without significant difference between ‘Charme’ in 2015 and the cultivars ‘Bonão’, ‘Diamante’, ‘Douradão’, ‘Libra’, ‘Maciel’ and ‘Marli’ in 2016 (Table 7). Overall, 2016 had the highest CA (≤7.2 ℃ and ≤12 ℃) with more hours under warm temperatures (≥25 ℃) for OS, OF and FB. Regarding GDD until OS, the cultivar with the highest GDD was ‘Eldorado’ and the lowest ones were ‘Aurora-1′, ‘Centenário’, ‘Flordaprince’, ‘Jóia-3′, ‘Kampai’, ‘Okinawa’, ‘Régis’ and ‘Tropical’ (Table 5). Regarding OF and FB, ‘Eldorado’ was the cultivar with the highest GDD, but ‘Marli’ showed only the highest GDD for FB. The cultivars that had the lowest GDD for OF and for FB were ‘Aurora-1′, ‘Biuti’, ‘Bonão’, ‘Centenário’, ‘Delicioso Precoce’, ‘Douçura-2′, ‘Dourado2′, ‘Flordaprince’, ‘Jóia-3′, ‘Kampai’, ‘Libra’, ‘Maravilha’, ‘Okinawa’, ‘Ouromel-4′, ‘Premier’, ‘Régis’ and ‘Tropical’, and ‘Premier’ presented the lowest GDD only for FB. ‘Biuti’ was the cultivar that presented the highest GDD for BH and the lowest one was ‘Eldorado’ (Table 8).

years (Table 4). The cultivar with the latest OF in 2014 was ‘Eldorado’. In 2015, the cultivars showed the latest OF were ‘Biuti’, ‘Charme’, ‘Delicioso Precoce’, ‘Diamante’, ‘Eldorado’, ‘Maciel’, ‘Marli’ and ‘Premier’. In 2016, the latest ones were ‘Bonão’, ‘Diamante’, ‘Douradão’, ‘Eldorado’, ‘Maciel’ and ‘Marli’. In 2016, the cultivars that presented higher CA (≤7.2℃) for OF were ‘Bonão’, ‘Diamante’, ‘Douradão’, ‘Eldorado’, ‘Kampai’, ‘Maciel’, ‘Maravilha’ and ‘Marli’. There was no difference between cultivars in 2014 and 2015 considering CA (≤7.2℃) for OF (Table 5). ‘Eldorado’ was the cultivar which had higher CA (≤12℃) for OF in all three years. In 2015, there was no difference among the cultivars considering CA (≤12℃). In 2016, the cultivars that needed the highest CA (≤12℃) for OF were ‘Biuti’, ‘Diamante’, ‘Douradão’, ‘Eldorado’, ‘Maciel’ and ‘Marli’. During 2016, the greatest accumulation of chill hours (≤7.2℃) or (≤12℃) for OF. For the accumulation of hours at warm temperatures (≥25℃) in the OF, the cultivar ‘Eldorado’ was the one that accumulated the most hours during the 3 years period, not differing from the ones that had a higher accumulation only in 2015, which were ‘Biuti’, ‘Charme’, ‘Delicioso Precoce’ and ‘Premier’, and only in 2016, which were ‘Bonão’ and ‘Douradão’. The cultivars that did not differ amongst themselves, with the highest accumulation in 2015 and 2016 were ‘Diamante’, ‘Maciel’ and ‘Marli’. The cultivars vs. years in FB (Table 6). In 2014 and 2015 ‘Eldorado’ was the latest cultivar considering FB. The precocious cultivars, in 2014, were ‘Aurora-1′, ‘Biuti’, ‘Bonão’, ‘Jóia-3′, ‘Kampai’, ‘Maravilha’, ‘Okinawa’, and ‘Régis’. In 2015, the precocious cultivars were ‘Aurora1′, ‘Biuti’, ‘Bonão’, ‘Centenário’, ‘Delicioso Precoce’, ‘Diamante’, ‘Douçura-2′, ‘Douradão’, ‘Dourado-2′, ‘Flordaprince’, ‘Jóia-3′, ‘Kampai’, ‘Libra’, ‘Maciel’, ‘Maravilha’, ‘Okinawa’, ‘Ouromel-4′, ‘Premier’, ‘Régis’ and ‘Tropical’. The latest cultivars considering FB in 2016 were ‘Bonão’, ‘Diamante’, ‘Douradão’, ‘Maciel’ and ‘Marli’. As for the most precocious, 4

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bud sprouting and onset of flowering. According to Citadin et al. (2003) when studying the heritage of the heat requirement for anthesis and budding, observed that individuals requiring a large number of heat units resulted in a delay of flowering, but did not display delayed vegetative bud burst with the same intensity. The genetic control for heat requirement is different from floral and vegetative buds (Citadin et al., 2003). Therefore, there is a possibility that the genes related to the chilling and heat requirement exert a very similar degree of influence in the dormancy process in peach. However, in the floral buds, the genetic control of chilling requirement is greater in the vegetative buds. ‘Biuti’ showed the latest beginning of fruit harvest (173 days). This cultivar, when evaluated for the tropics, concluded the average between full bloom and beginning of fruit harvest at 151–180 days and beginning of fruit harvest in Dec.–Jan. (Barbosa et al., 2010). ‘Eldorado’ showed later onset of flowering, full bloom and end of flowering, but early beginning of fruit harvest and end of harvest, this may be possible due to the high variation between the plots and years without harvest. These results disagree to the ones by Alves et al. (2012) in which the ‘Eldorado’ cultivar presented the latest maturation and highest productivity, however in this study had chill hour accumulation average of 295 to 7.2℃. The highest CA was recorded in 2016, which delay of onset of bud sprouting and onset of flowering. The CA varies according to the cultivar, besides the type of bud and its location in the plant (Wagner Júnior et al., 2009). Herter et al. (2001) reported that cold affects the base of dormancy in the spring season, decreasing and increasing rapidly, with the increase in the accumulation of cold, respectively. The cultivars that were most precocious were the ones with the highest CA under warm temperatures, above 25 ℃. According to Putti et al. (2003), a variation in budbreak among cultivars may be related not only to the CA but also to the heat requirement, because this requirement is necessary for the occurrence of budbreak. There was a variation for onset of flowering and full bloom among the years for the cultivars ‘Charme’, ‘Diamante’, ‘Eldorado’, ‘Maciel’, ‘Marli’ and ‘Premier’, this may be due to a variation of temperatures. According to Scariotto et al. (2013), the flowering may be staggered due to a lack of adequate accumulation of cold hours during the endodormancy period or to some problem during the leaf fall period. Alves et al. (2012) observed that the ‘Marli’ cultivar increased the cycle between years, possibly due to the increase in temperature and the decrease in the number of cold hours recorded in August. The results in this study showed that the variation in the phenology was observed in all the cultivars with increase CA when warm temperatures increase (≥25 ℃.). According to Pedro Júnior et al. (2007), when evaluating the CA below 7.2 and 13℃ for full bloom, ‘Régis’ presented a CA (≤7.2℃) lower than 40 h, as for (≤13℃), it was less than 500 h, and full bloom took place before July/10th. ‘Centenário’, ‘Aurora-1’; ‘Doçura-2’, ‘Flordaprince’, and ‘Douradão’ had CA (≤7.2℃) from 41 to 50 h, and for CA (≤13℃), it was between 501–560 hours and full bloom from July 11th until the 20th. ‘Premier’ and ‘Biuti’ had CA (≤7.2 ℃) for 51–70 h, as for CA (≤13℃), it was less than 561–650 h and full bloom took place from July 21st to 31st. The cultivars ‘Eldorado’, ‘Diamante’ and ‘Marli’ had CA (≤7.2℃) and (≤13 ℃) for 70 and 650 h, respectively and FB after the beginning August. The results showed that the CA observed in this study was lower than those observed in the literature. The cultivars with the highest CA (≤7.2℃) in all the assessed years were ‘Charme’, 'Diamante', 'Eldorado', ‘Maciel’ and ‘Marli’, with maximum 16 h. For CA (≤12℃) the highest values were found for ‘Eldorado’ (358 h), and the lowest was ‘Régis’ (107.33 h). The most precocious cultivars, with lower CA for onset of bud sprouting, onset of flowering and full bloom were ‘Aurora-1’, ‘Biuti’, ‘Jóia-3’, ‘Kampai’, ‘Maravilha’, ‘Okinawa’, ‘Régis’ and ‘Tropical’. The effect of temperature, however, is ambiguous. The cultivar CA is determined genetically, and it must be met as the temperature is decisive for flowering. Variations in flowering time may be due to the

Table 2 The duration (in days) between pruning day and onset of bud sprouting (OS when more than 5 % of sprouted buds had opened), for each cultivar in 2014, 2015 and 2016 at the experimental peach orchard in Lavras, Minas Gerais, Brazil. Cultivars

OSz 2014

Aurora-1 Biuti Bonão Centenário Charme Delicioso Precoce Diamante Douçura-2 Douradão Dourado-2 Eldorado Flordaprince Jóia-3 Kampai Libra Maciel Maravilha Marli Okinawa Ouromel-4 Premier Régis Tropical General Average CV1 CV2

15.00 15.00 19.67 15.00 18.67 16.33 18.33 15.00 16.00 20.00 26.33 15.00 16.00 15.00 16.00 22.00 16.00 20.33 16.00 19.00 17.67 15.00 15.00 17.32 15.57 33.98

2015 C C B C C C C C C B B B C B B C C C B C C B B

a* a a a a a a a a a a a a a a a a a a a a a a

26.67 27.67 18.00 26.00 40.00 34.33 35.33 26.33 25.00 26.00 83.67 17.67 27.33 19.33 21.00 44.33 29.00 36.00 17.00 39.00 31.67 19.00 17.00 29.88

2016 Bc Bc Bd Bc Bb Bb Bb Bc Bc Bc Aa Bd Bc Bd Bd Bb Bc Bb Bd Bb Bb Bd Bd

41.00 50.00 67.33 48.33 64.00 51.67 67.33 53.33 70.33 58.67 80.33 43.33 47.00 50.00 57.00 72.33 58.67 70.00 42.33 52.33 47.00 44.00 50.00 55.93

A A A A A A A A A A A A A A A A A A A A A A A

d c b d b c b c b c a d d c c b c b d c d d c

z OS = the duration (in days) between pruning day and onset of bud sprouting. *Average values followed by the same capital letter in the row and small letter in the column belong to the same group according to the Scott-Knott test (P ≤ 0.05).

Regarding adaptability and stability standards by Eberhart and Russell for the period between pruning and onset of bud sprouting (OS), the cultivars ‘Biuti’, ‘Centenário’, ‘Charme’, ‘Delicioso Precoce’, ‘Douçura-2’, ‘Dourado-2’, ‘Kampai’, ‘Libra’, ‘Maravilha’, ‘Ouromel-4’ and ‘Tropical’ were considered as generally adaptable. They did not show differences between the climate during the period (Table 9). The cultivars with adaptability to favorable environments were ‘Bonão’, ‘Diamante’, ‘Eldorado’, ‘Douradão’, ‘Maciel’ and ‘Marli’. The cultivars ‘Aurora-1’, ‘Flordaprince’, ‘Jóia-3’, ‘Okinawa’, ‘Premier’ and ‘Régis’ showed adaptability to unfavorable environments. The highest stability or predictability was presented by ‘Aurora-1’ and ‘Premier’. The other cultivars showed low stability or predictability. As for the adaptability and stability standards by Eberhart and Russell for the period between pruning and the end of harvest (EH), the cultivars considered to have general adaptability were ‘Aurora-1’, ‘Biuti’, ‘Bonão’, ‘Charme’, ‘Centenário’, ‘Delicioso Precoce’, ‘Diamante’, ‘Douçura-2’, ‘Dourado-2’, ‘Douradão’, ‘Flordaprince’, ‘Jóia-3’, ‘Kampai’, ‘Libra’, ‘Maravilha’, ‘Marli’, ‘Okinawa’, ‘Ouromel-4’, ‘Tropical’ and ‘Régis’. The cultivars with adaptability to favorable environments were ‘Eldorado’, ‘Maciel’ and ‘Premier’. All of the cultivars showed low stability or predictability.

4. Discussion The occurrence of thermal fluctuation during winter and temperatures above 20 °C is undesirable in overcoming the endodormancy of Prunus persica (Erez et al., 1979). The cultivars ‘Bonão’, ‘Eldorado’, ‘Maravilha’ and ‘Ouromel-4’ presented onset of bud sprouting before onset of flowering, as for ‘Charme’, ‘Delicioso Precoce’ and ‘Maciel’ had almost the same day for onset of 5

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Table 3 The chill hours accumulation (CA) of each peach cultivar for accumulated number of hours with temperatures (≤7.2 °C), (≤12 °C) and (≥25℃) from April 1 until the onset of budding (OS - when more than 5 % of sprouted buds had opened), for each cultivar in 2014, 2015 and 2016 at the experimental orchard in Lavras, Minas Gerais, Brazil. Cultivars

Aurora-1 Biuti Bonão Centenário Charme Delicioso Precoce Diamante Douçura-2 Douradão Dourado-2 Eldorado Flordaprince Jóia-3 Kampai Libra Maciel Maravilha Marli Okinawa Ouromel-4 Premier Régis Tropical General Average CV1 CV2

CA (≤7.2℃) of OSz

CA (≤12℃) of OS

2014

2015

2016

2014

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32.72

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

7.00 d* 12.00 b 12.00 b 10.33 c 13.33 b 8.67 d 13.33 b 8.67 d 14.67 a 12.00 b 16.00 a 8.67 d 10.33 c 12.00 b 12.00 b 14.67 a 8.67 d 13.33 b 7.00 d 10.33 c 10.33 c 8.67 d 12.00 b 11.13

110.00 110.00 119.33 110.00 117.00 110.00 110.67 110.00 110.00 118.33 128.67 110.00 110.00 110.00 110.00 126.33 110.00 121.67 110.00 118.33 117.00 110.00 110.00 113.80 8.01 18.34

B B B B B B B B B B C B B B B B B B B B B B B

a a a a a a a a a a a a a a a a a a a a a a a

Temp. (≥25℃) of OS 2015

2016

105.33 B b 106.33 B b 90.67 C c 105.33 B b 121.00 B b 115.33 B b 117.00 B b 104.00 B b 103.00 B b 103.00 B b 201.00 B a 88.33 C c 96.00 B c 94.00 B c 96.33 B c 126.33 B b 107.67 B b 118.00 B b 81.00 C c 124.33 B b 111.00 B b 94.00 B c 81.00 C c 108.26

171.00 205.00 224.67 197.00 227.67 191.00 231.33 192.67 238.33 217.00 256.00 181.00 195.67 205.00 216.33 238.67 194.00 231.33 178.33 197.00 195.67 186.33 205.00 207.65

2014 A A A A A A A A A A A A A A A A A A A A A A A

d c b c b c b c a b a d c c b a c b d c c d c

190.00 190.00 192.33 190.00 190.00 190.00 190.00 190.00 190.00 190.00 198.67 190.00 190.00 190.00 190.00 191.33 190.00 191.33 190.00 190.00 190.00 190.00 190.00 190.59 4.53 8.97

2015 B B B B B B B B B B C B B B B B B B B B B B B

a a a a a a a a a a a a a a a a a a a a a a a

169.33 172.33 163.00 170.67 196.00 191.67 193.33 174.00 170.67 172.67 331.00 163.00 183.33 163.00 163.00 206.67 178.33 187.33 163.00 195.00 186.67 163.00 163.00 183.48

2016 C B C C B B B B C B B C B C C B B B C B B C C

c c c c b b b c c c a c b c c b c b c b b c c

286.33 304.00 337.33 301.67 325.33 299.33 335.67 298.00 345.33 320.67 372.00 288.67 295.00 304.00 314.67 350.00 304.67 350.33 283.67 301.67 295.00 286.00 304.00 313.19

A A A A A A A A A A A A A A A A A A A A A A A

c c b c b c b c b c a c c c c b c b c c c c c

z

CA = chill hours accumulation; OS = onset of budding. *Average values followed by the same capital letter in the row and small letter in the column belong to the same group according to the Scott-Knott test (P ≤ 0.05).

combination of the depth of dormancy and rate of temperature increase (Szabó and Nyéki, 2000). The CA and warm temperatures (≥25℃) observed in this study, show that the increase of both cause delays in the phenological cycle. This is in agreement with Nava (2007), who stated that peach trees that showed full flowering under diurnal temperatures above 25℃ (under greenhouse) anticipated in 10 days in comparison to the outdoor plants, under diurnal temperatures below 25℃. The cultivars observed in this study that were most precocious had lower CA and warm temperatures for onset of bud sprouting, onset of flowering and full bloom were ‘Aurora-1’, ‘Biuti’, ‘Jóia-3’, ‘Kampai’, ‘Maravilha’, ‘Okinawa’, ‘Régis’ and ‘Tropical’. The interaction between the cultivar and the chilling requirement was significant in the GDD, which is the accumulation necessary to reach 10 % of budbreak, after 800 h of chilling. ‘Eldorado’ had the highest GDD (10,434) among all cultivars (Citadin et al., 2001). The result agrees with the ones observed for ‘Eldorado’, which presented high GDD for onset of bud sprouting, onset of flowering and full bloom; however, higher GDD were observed in a previous study than the ones observed in this study (Citadin et al., 2001). The selected cultivars with higher GDD for flowering tend to delay flowering, however, they slow, with the same intensity, the budding time (Citadin et al., 2003). As it was observed in this study, the cultivar with the lowest GDD for onset of bud sprouting, onset of flowering and full bloom behaves as precocious, and these cultivars were ‘Aurora-1’, ‘Centenário’, ‘Flordaprince’, ‘Jóia-3’, ‘Régis’ and ‘Tropical’. Mounzer et al. (2008) observed different phenological growth stages for the cultivar ‘Flordastar’ peach trees, in Murcia, Spain. The requirements were presented by accumulated GDD since dormancy breaking until leafing and the formation of buds, as 225 chilling hours were needed to break dormancy and start swelling of buds. As temperature increased, the following phenological stages for BBCH - Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (flower bud swell/stage BBCH 51, perceptible flower petals/stage BBCH

Table 4 The duration (in days) between pruning day and the onset of flowering (OF when more than 5 % of flowers had opened), for each peach cultivar in 2014, 2015 and 2016 at the experimental orchard in Lavras, Minas Gerais, Brazil. Cultivars

OFz 2014

Aurora-1 Biuti Bonão Centenário Charme Delicioso Precoce Diamante Douçura-2 Douradão Dourado-2 Eldorado Flordaprince Jóia-3 Kampai Libra Maciel Maravilha Marli Okinawa Ouromel-4 Premier Régis Tropical General Average CV1 CV2

19.00 22.00 19.67 17.00 18.67 21.33 29.67 22.33 22.00 25.33 64.33 23.00 16.00 15.00 23.67 20.67 18.33 35.00 26.00 21.67 23.00 15.00 16.00 23.25 21.70 34.64

2015 B b* Bb Bb Bb Bb Bb Bb Bb Bb Bb Aa Bb Bb Bb Bb Bb Bb Bb Bb Bb Bb Bb Bb

27.00 38.00 21.00 25.00 45.00 31.67 30.67 27.33 26.33 25.33 37.67 25.33 24.00 24.00 24.33 31.33 23.67 32.00 27.33 29.33 32.33 22.67 22.00 28.41

2016 Bb Aa Bb Bb Aa Ba Ba Bb Bb Bb Ba Bb Bb Bb Bb Ba Bb Ba Bb Bb Aa Bb Bb

37.00 44.00 59.33 44.00 50.67 47.00 63.67 47.00 70.00 54.33 64.33 44.00 44.00 50.00 52.00 70.67 50.00 66.33 48.33 44.00 44.00 35.00 45.00 51.07

A A A A A A A A A A A A A A A A A A A A A A A

b b a b b b a b a b a b b b b a b a b b b b b

z OF = the duration (in days) between pruning day and the onset of flowering. *Average values followed by the same capital letter in the row and small letter in the column belong to the same group according to the Scott-Knott test (P ≤ 0.05).

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Table 5 The chill hours accumulation (CA) of each peach cultivar for accumulated number of hours with temperatures (≤12 °C) and (≥25℃) from April 1 until the onset of flowering (OF - when more than 5 % of flowers had opened), for each cultivar in 2014, 2015 and 2016 at the experimental orchard in Lavras, Minas Gerais, Brazil. Cultivars

Aurora-1 Biuti Bonão Centenário Charme Delicioso Precoce Diamante Douçura-2 Douradão Dourado-2 Eldorado Flordaprince Jóia-3 Kampai Libra Maciel Maravilha Marli Okinawa Ouromel-4 Premier Régis Tropical General Average CV1 CV2

CA (≤7.2℃) of OFz

CA (≤12℃) of OF

2014

2015

2016

2014

0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0.09 46.29

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

7.00 c* 8.67 c 13.33 a 8.67 c 10.33 b 10.33 b 13.33 a 10.33 b 13.33 a 10.33 b 12.00 a 8.67 c 8.67 c 12.00 a 10.33 b 13.00 a 12.00 a 13.00 a 10.33 b 8.67 c 8.67 c 7.00 c 10.33 b 10.45

117.00 124.67 117.67 112.33 117.00 127.67 140.67 126.33 124.00 135.67 243.67 131.00 110.00 110.00 131.00 119.33 110.00 144.00 138.00 124.00 126.33 110.00 110.00 128.28 12.61 22.88

Bb Bb Bb Bb Bb Bb Bb Bb Bb Bb Aa Bb Bb Bb Bb Bb Bb Bb Bb Bb Bb Bb Bb

Temp. (≥25℃) of OF 2015

2016

105.33 B a 120.00 B a 97.33 B a 100.67 B a 130.67 B a 113.00 B a 110.00 C a 106.33 B a 104.00 B a 104.00 C a 119.33 B a 103.00 B a 91.00 B a 103.00 B a 101.67 B a 110.00 B a 103.00 B a 111.00 C a 106.00 C a 107.67 B a 114.33 B a 100.67 B a 88.67 B a 106.55

163.67 183.33 219.33 186.33 197.33 195.67 224.00 195.67 237.00 204.33 221.67 186.33 184.67 205.00 204.00 235.67 205.00 225.67 197.00 186.33 186.33 157.00 189.00 199.58

2014 A A A A A A A A A A A A A A A A A A A A A A A

b b a b b b a b a b a b b b b a b a b b b b b

190.00 190.00 190.00 190.00 190.00 191.33 203.33 190.00 192.33 194.33 253.67 190.00 190.00 190.00 192.67 190.00 190.00 215.33 197.00 190.00 193.00 190.00 190.00 195.35 7.93 11.35

2015 B B B B B B B B B B B B B B B B B B B B B B B

b b b b b b b b b b a b b b b b b b b b b b b

169.33 195.33 163.00 166.00 213.67 182.33 184.67 173.33 166.00 164.33 194.33 163.00 173.33 163.00 167.33 187.33 163.00 188.00 168.67 178.33 185.67 164.33 164.33 175.59

2016 B B B B B B B B B C C B B B B B B B B B B B B

b a b b a a a b b b a b b b b a b a b b a b b

269.00 288.00 325.33 286.00 298.00 295.00 327.67 295.00 352.00 311.33 332.00 286.00 283.00 304.00 300.33 356.33 304.00 342.33 301.67 286.00 286.00 265.00 291.00 303.7

A A A A A A A A A A A A A A A A A A A A A A A

b b a b b b a b ab b a b b b b a b a b b b b b

CA = chill hours accumulation; OF = onset of flowering. *Average values followed by the same capital letter in the row and small letter in the column belong to the same group according to the Scott-Knott test (P ≤ 0.05).

z

57, and flowers forming a hollow ball/stage BBCH 59) were reached as more than 50 % of opened flowers were ‘Régis’ for full bloom and after accumulating an average of 329 GDD. Beginning of fruit harvest required 1246 GDD. This result agrees with the ones observed for full bloom that varies between the lower GDD of ‘Régis’ (422.67) and the greater for ‘Eldorado’ (927.13). In beginning of fruit harvest, GDD ranged among the ones found for ‘Eldorado’ (1083.84) and the ones found for ‘Biuti’ (2378.02). The period from full bloom to fruit maturity for cultivars of peach is influenced by daily temperatures between the start of full bloom and 30 days after full bloom. Typically, warm temperature and GDD accelerate fruit development. The temperatures in the first 90 days after full bloom are the primary factor in influencing the maturity time of peach cultivars in California (Tombesi et al., 2010). Lopez and Dejong (2007) also observed that excessively high Spring temperatures can reduce fruit size. However, as it was observed for the cultivars ‘Aurora-1’, ‘Bonão’, ‘Centenário’, ‘Charme’, ‘Flordaprince’, ‘Jóia-3’, ‘Libra’, ‘Maravilha’, ‘Marli’, ‘Premier’, ‘Regís’ and ‘Tropical’, they were precocious and required fewer GDD to initiate budbreak and flowering. According to Souza et al. (2017a, 2017b) the cultivars ‘Biuti’, ‘Centenário’, Douçura and ‘Maravilha’ were considered to have general adaptability and good predictability for the time between pruning and onset of bud sprouting, as these cultivars didn’t behave differently under different climate for onset of bud sprouting. The cultivars ‘Douçura-2’, ‘Douradão’, ‘Kampai’ and ‘Okinawa’ were considered to have general adaptability and good predictability for the time between pruning and end of harvest, as these cultivars didn’t present significantly time of production. The results found in this study were different. The cultivars ‘Biuti’, ‘Centenário’, ‘Douçura-2’, ‘Maravilha’ showed general adaptability for onset of bud sprouting and for the entire production cycle, that is, days between pruning and end od harvest, the cultivars with general adaptability were ‘Douçura-2’, ‘Douradão’, ‘Kampai’, and ‘Okinawa’.

Table 6 The duration (in days) between pruning day and full bloom (FB - when more than 50 % of flowers had opened), for each cultivar in 2014, 2015 and 2016 at the experimental peach orchard in Lavras, Minas Gerais, Brazil. Cultivars

Aurora-1 Biuti Bonão Centenário Charme Delicioso Precoce Diamante Douçura-2 Douradão Dourado-2 Eldorado Flordaprince Jóia-3 Kampai Libra Maciel Maravilha Marli Okinawa Ouromel-4 Premier Régis Tropical General Average CV1 CV2

FBz 2014

2015

32.33 A d* 39.00 B d 36.33 B d 49.33 A c 80.33 A b 55.67 A c 84.33 A b 50.33 A c 50.67 B c 56.67 A c 105.00 A a 52.00 A c 37.33 B d 24.00 B d 45.67 B c 72.00 B b 37.33 B d 84.67 A b 39.67 B d 52.33 A c 52.33 A c 33.00 B d 45.00 B c 52.84 20.93 34.86

38.67 45.33 32.00 32.33 60.67 41.67 42.67 34.00 36.00 30.33 77.00 32.33 34.33 34.33 31.67 37.33 35.33 52.33 37.67 41.67 40.00 28.00 34.00 39.55

2016 Ac Bc Bc Bc Bb Bc Bc Bc Bc Bd Ba Bc Bc Bc Bc Cc Bc Bb Bc Ac Ac Bc Bc

50.67 A c 57.33 A c 93.67 A a 57.33 A c 75.67 A b 56.67 A c 98.00 A a 63.67 A c 100.67 A a 71.00 A c 80.67 B b 54.67 A c 58.00 A c 79.00 A b 80.00 A b 102.00 A a 53.33 A c 91.67 A a 56.33 A c 51.33 A c 52.67 A c 50.00 A c 65.00 A c 69.54

z

FB = the duration (in days) between pruning day and full bloom. *Average values followed by the same capital letter in the row and small letter in the column belong to the same group according to the Scott-Knott test (P ≤ 0.05).

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Table 7 The chill hours accumulation (CA) of each peach cultivar for accumulated number of hours with temperatures (≤7.2 °C), (≤12 °C) and (≥25℃) from April 1 until the full bloom (FB - when more than 50 % of flowers had opened), for each cultivar in 2014, 2015 and 2016 at the experimental orchard in Lavras, Minas Gerais, Brazil. Cultivars

Aurora-1 Biuti Bonão Centenário Charme Delicioso Precoce Diamante Douçura-2 Douradão Dourado-2 Eldorado Flordaprince Jóia-3 Kampai Libra Maciel Maravilha Marli Okinawa Ouromel-4 Premier Régis Tropical General Average CV1 CV2

CA (≤7.2℃) of FBz

CA (≤12℃) of FB

2014

2015

2016

0 B b* 0Bb 0Bb 0Bb 2.67 B 0.67 B 4.00 B 0Bb 1.33 B 0Bb 4.00 B 0.67 B 0Bb 0Bb 0Bb 3.33 B 0Bb 4.00 B 0Bb 0Bb 1.33 B 0Bb 0Bb 0.96 28.18 43.67

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

12.00 10.33 14.67 12.00 14.67 12.00 14.67 13.33 16.00 13.33 14.67 12.00 13.33 13.00 14.67 16.00 12.00 16.00 10.33 12.00 10.33 12.00 13.33 13.16

a b a b a b

a a

b

B B B B C B C B B B C B B B B C B C B B B B B

a a a a a a a a a a a a a a a a a a a a a a a

2014 A A A A A A A A A A A A A A A A A A A A A A A

b c a b a b a b a b a b b b a a b a c b c b b

143.67 153.33 156.33 205.00 291.33 229.67 318.67 208.67 213.67 229.00 358.00 215.33 152.00 134.67 181.67 292.67 152.33 319.00 155.00 218.00 215.00 143.33 183.67 211.74 14.35 19.34

Temp. (≥25℃) of FB 2015

Bd Bd Bd Ac Ab Ac Ab Ac Bc Ac Aa Ac Bd Bd Bd Ab Bd Ab Bd Ac Ac Bd Bd

120.67 125.00 110.00 111.00 171.33 125.00 126.33 115.00 117.00 109.67 197.67 111.67 116.00 115.33 109.67 123.67 116.00 137.67 117.33 124.33 125.00 107.33 113.00 123.72

2016 B B C B C B C B C B C B B B C B B B B B B B C

b b b b a b b b b b a b b b b b b b b b b b b

207.00 206.33 264.67 213.00 241.00 215.33 264.33 224.33 282.00 239.00 261.67 212.00 219.33 237.00 256.33 282.00 210.00 282.00 205.00 207.33 197.33 205.00 231.00 233.17

2014 Ab Ab Aa Ab Bb Ab Ba Ab Aa Ab Ba Ab Ab Ab Aa Aa Ab Aa Ab Ab Ab Ab Ab

208.00 216.00 215.33 216.67 297.33 222.67 286.33 217.00 223.67 217.00 374.00 222.33 216.00 191.33 216.33 247.00 214.00 288.67 216.00 217.00 228.00 208.67 216.33 233.72 12.81 24.20

2015 Bc Bc Bc Bc Bb Bc Bb Bc Bc Bc Aa Bc Bc Bc Bc Bc Bc Bb Bc Bc Bc Bc Bc

199.67 204.00 190.00 189.33 251.67 200.00 202.67 188.00 192.67 180.33 309.67 187.00 190.00 191.67 186.33 194.00 192.67 222.67 199.33 199.00 196.00 172.00 192.00 201.33

2016 B B B B B B C B B B B B B B B B B C B B B B B

b b b b a b b b b b a b b b b b b b b b b b b

304.00 309.67 436.67 318.00 360.67 310.67 490.33 333.00 450.67 352.00 375.33 309.33 318.67 358.00 391.67 431.00 309.33 416.67 307.00 304.00 301.67 304.00 345.67 353.83

A A A A A A A A A A A A A A A A A A A A A A A

b b a b b b a b a b b b b b a a b a b b b b b

z

CA = chill hours accumulation; FB = full bloom. *Average values followed by the same capital letter in the row and a small letter in the column belong to the same group according to the Scott-Knott test (P ≤ 0.05).

Table 8 The necessary number of growing degree days [GDD (base 7 °C)] to reach the specific phenological stages of the average duration (in days) for the three years (2014, 2015 and 2016), between pruning day and each phenological stage in each plot, was evaluated through visual observations as which the ones that follows: onset of bud sprouting (OS - when more than 5 % of sprouted buds had opened), onset of flowering (OF - when more than 5 % of flowers had opened), full bloom (FB - when more than 50 % of flowers had opened) and beginning of fruit harvest (BH) at the experimental orchard in Lavras, Minas Gerais, Brazil. Cultivars

GDD of OSz

Aurora-1 Biuti Bonão Centenário Charme Delicioso Precoce Diamante Douçura-2 Douradão Dourado-2 Eldorado Flordaprince Jóia-3 Kampai Libra Maciel Maravilha Marli Okinawa Ouromel-4 Premier Régis Tropical General Average CV (%) Accuracy(%)

278.42 324.55 362.28 302.00 422.56 347.34 410.72 313.41 357.27 348.25 662.18 258.75 309.14 278.35 317.60 466.99 328.94 441.49 281.89 360.95 331.78 268.75 294.28 350.78 7.91 98.32

GDD of OF ± 44.19y d* ± 49.77 c ± 82.46 c ± 52.27 d ± 72.87 b ± 47.46 c ± 77.83 b ± 55.68 c ± 94.77 c ± 69.06 c ± 115.70 a ± 47.91 d ± 59.26 d ± 57.26 d ± 66.14 c ± 86.52 b ± 55.46 c ± 80.67 b ± 39.12 d ± 53.51 c ± 46.71 c ± 45.88 d ± 52.71 d

301.94 378.45 355.15 311.34 419.55 358.63 450.52 353.35 420.01 361.74 581.64 327.73 310.93 315.53 350.12 459.09 330.53 508.24 366.92 345.14 402.21 270.01 309.26 373.39 11.12 94.46

GDD of FB ± 26.62* d ± 37.90 d ± 70.15 d ± 38.71 d ± 58.22 d ± 39.49 d ± 58.77 d ± 37.10 d ± 86.31 c ± 55.78 d ± 75.95 a ± 34.82 d ± 42.31 d ± 49.35 d ± 51.51 d ± 87.64 c ± 45.83 d ± 60.23 b ± 36.07 d ± 33.73 d ± 34.90 c ± 26.42 d ± 43.99 d

465.60 500.91 581.18 500.73 766.24 560.88 790.44 536.51 662.61 563.00 927.13 521.70 482.74 498.92 578.45 719.63 474.90 833.22 494.61 538.19 454.40 422.66 599.96 585.85 11.34 95.85

GDD of BH ± 29.36* c ± 30.60 c ± 111.69 c ± 47.12 c ± 84.19 b ± 35.55 c ± 126.71 b ± 55.45 c ± 107.10 b ± 74.66 c ± 95.62 a ± 40.93 c ± 44.33 c ± 78.03 c ± 90.58 c ± 98.53 b ± 30.43 c ± 76.90 a ± 28.21 c ± 26.60 c ± 75.77 c ± 30.69 c ± 68.01 c

1627.50 2378.02 1518.51 1585.33 1563.87 1763.83 2002.98 1814.07 1743.94 1865.97 1083.84 1657.30 1691.13 1708.49 1629.43 1865.71 1566.69 1635.55 2036.87 1961.56 1760.83 1491.93 1555.85 1717.79 11.62 88.48

± 68.75 c ± 84.78 a ± 167.36 c ± 50.61 c ± 253.63 c ± 64.15 c ± 79.11 b ± 88.96 b ± 89.33 c ± 100.30 b ± 428.34 d ± 106.88 c ± 80.07 c ± 87.02 c ± 108.81 c ± 300.63 b ± 45.46 c ± 321.02 c ± 81.93 b ± 61.79 b ± 270.82 c ± 58.16 c ± 68.10 c

z GDD = growing degree days; OS = onset of bud sprouting; FB = full bloom; BH = beginning of fruit harvest. yRepresent the average ± standard error. *Average values followed by the same capital letter in the row and the small letter in the column belong to the same group according to the Scott-Knott test (P ≤ 0.05).

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Table 9 Estimate parameters of adaptability and phenotypic stability, [17], for 22 peach cultivars evaluated for the onset of bud sprouting (OS - when more than 5 % of sprouted buds had opened) and the end of harvest (EH) in days for average of three years (2014, 2015 and 2016) at the experimental orchard in Lavras, Minas Gerais, Brazil. Cultivars

Onset of bud sprouting ß0

Aurora-1 Biuti Bonão Centenário Charme Delicioso Precoce Diamante Douçura-2 Douradão Dourado-2 Eldorado Flordaprince Jóia-3 Kampai Libra Maciel Maravilha Marli Okinawa Ouromel-4 Premier Régis Tropical General Average V(ß0): V(ßi): r(ß0,ßi):

z

23.17 27.33 30.25 25.25 35.33 30.00 34.58 27.25 29.75 29.17 53.92 21.50 25.75 23.25 26.58 38.75 29.50 36.75 23.50 31.08 27.83 22.50 24.67 29.46 2.16 0.01 0.73

ßi

y

0.72** 0.85ns 1.23** 0.88ns 1.13ns 0.87ns 1.24* 0.97ns 1.47* 1.07ns 1.38** 0.77* 0.82* 0.96ns 1.07ns 1.34** 1.09ns 1.23** 0.62** 0.90ns 0.77ns 0.76** 0.85ns

End of harvest S²d

x

R²(%) ns

0.65 −4.87ns 100.13′’ −8.26ns 5.23ns 5.07ns −7.37ns −6.62ns 15.69ns 6.90ns 560.39′’ 5.13ns −7.25ns 7.50ns 15.83ns 9.39ns −7.69ns −4.42ns 26.42′ 31.01′ −0.31 ns 1.36ns 38.05′’

96.74 99.03 88.18 99.91 98.02 96.68 99.85 99.60 97.93 97.53 63.99 95.86 99.61 96.81 96.15 98.14 99.85 99.48 85.29 91.67 97.44 96.88 89.12

w

ß0 151.92 198.75 135.83 153.67 137.00 158.08 174.50 166.25 167.42 169.08 81.00 144.75 159.67 163.83 141.83 156.42 143.33 145.42 172.75 175.00 143.00 145.33 140.33 153.27 52.36 0.17 −0.59

ßi

R²

S²d ns

0.79 0.91ns 0.72ns 0.63ns 1.24ns 0.63ns 0.89ns 0.61ns 1.32ns 0.72ns 3.83** 0.61ns 0.54ns 1.24ns 0.91ns 1.86* 0.39ns 0.98ns 0.51ns 0.54ns 2.28** 0.61ns 0.24ns

−64.20 −45.89ns 760.02′ −127.02ns 1238.87′’ −149.20ns −45.89ns −185.04ns −50.54ns −98.30ns 5918.93′’ 294.87ns −115.95ns −44.65ns −55.69ns 4669.68′’ −109.40ns 14,304.10′’ −170.53ns −97.46ns 2749.42′’ −74.98ns −19.03ns ns

(%)

71.94 75.42 24.45 74.43 38.86 79.72 74.63 90.26 86.84 73.87 58.99 31.04 65.10 84.86 76.46 29.90 47.80 3.86 80.09 60.81 51.42 62.33 15.33

*and ** significantly different from 1, by the t test, at P ≤ 0.05 and 0.01, respectively.’ and’ ’ significantly different from 0, by the F test, at P ≤ 0.05 and 0.01, respectively. NS Nonsignificant. zß0: observed average of the cultivars. yßi: linear regression coefficient (Cultivars in which βi > 1 respond better to more favorable conditions, βi < 1 respond better to adverse environmental conditions and βi = 1 considered to have general adaptability). xS²d: deviation from regression (Cultivars in which S²d = 0 high stability or predictability). wR2: coefficient of determination.

5. Conclusion

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