Figures (2)  Tables (7)

    • Figure 1. 

      Histogram representing distribution of dry matter data for: (a) Sweetheart (SH) cherries over the 2018, 2019, and 2021 growing years; (b) Staccato (SC) cherries over the 2018, 2019, and 2021 growing years; and (c) Sentennial (SL) cherries over the 2019 and 2021 growing years. For all parts, the 3-4 colour level is solid black, the 4-5 level is black stripes, and the 5-6 level is solid grey. On the horizontal axis different dry matter value (DM) ranges are shown via bins and on the vertical axis the frequency or proportion (%) of cherries within the DM bins/ranges are shown. Data was generated from two replicates of samples of 25 cherries (i.e. 50 cherries) from all available growing years.

    • Figure 2. 

      Principal component analysis (PCA) plot for: Sweetheart (SH) cherries with data from 2018 and 2019 growing years at the 3-4, 4-5, and 5-6 colours levels (SH34-2018, SH45-2018, SH56-2018, SH34-2019, SH45-2019, and SH56-2019; Staccato (SC) cherries with data from 2018, 2019 and 2021 growing years at the 3-4, 4-5, and 5-6 colour levels (SC34-2018, SC45-2018, SC56-2018, SC34-2019, SC45-2019, SC56-2019, SC34-2021, SC45-2021, and SC56-2021); and Sentennial (SL) cherries with data from 2019 growing year (SL34-2019, SL45-2019, and SL56-2019). PC1 and PC2 accounted for 84.75% variation. The variables include: average temperature (AT), average high temperature (AHT), average low temperature (ALT), average relative humidity (ARH), colour at harvest (ColourH), SS at harvest (SSH), SS after 28 d of storage at 0.5 °C (SS05), titratable acidity at harvest (TAH), titratable acidity after 28 d of storage at 0.5 °C (TA05) and dry matter of cherry fruit at harvest (DMH). Orchard growing factors, flavour quality attributes (loading factors), along with sweet cherry cultivars from each growing season (component scores) were presented as lines with arrows, lines with circles, and squares, respectively. Variables close to each other with small angles between them are strongly positively correlated; variables at right angles are likely not correlated; variables at large angles (close to 180°) are strongly negatively correlated.

    • Cultivar Colour level Soluble solids (SS, °Brix)
      2018 2019 2021
      Harvest Storage (0.5 °C) Harvest Storage (0.5 °C) Harvest Storage (0.5 °C) [3 °C]
      Sweetheart 3-4 18.1aA1 17.7aA1 18.1aA1 18.2aA1 − −
      4-5 20.0bA1 19.8bA1 19.4bA1 18.8bA1 − −
      5-6 21.9cA1* 21.1cA1* 19.9bA1* 19.6cA1* − −
      Staccato 3-4 17.2aA2 17.2aA1 17.1aA2 17.2aA1 18.8aA* 18.9aA*
      18.4a
      4-5 17.8aA2 17.9aA2 18.3bA23 18.1bA1 19.9bA* 18.6aB
      18.9ab
      5-6 20.2bA2 17.9aB2* 20.2cA1 20.3cA13 20.1bA 19.5aA
      19.7b
      Sentennial 3-4 − − 18.1aA1 18.1aA1 − −
      4-5 − − 18.9bA13 18.5aA1 − −
      5-6 − − 20.8cA2 20.6bA23 − −
      Main effects Significance F-value Degrees of freedom
      Cultivar p < 0.0001 36.90 2
      Colour level p < 0.0001 125.76 2
      Year p < 0.0001 9.26 2
      Time (harvest or storage at 0.5 °C) p = 0.0002 13.68 1
      Colour differences: within common time and cultivar, values followed by different lower case letters indicate significant differences (p ≤ 0.05); Cultivar differences: within common colour level and time, values followed by different numbers indicate significant differences (p ≤ 0.05); Growing year differences: within common time, colour level and cultivar, values followed by * indicate significant differences (p ≤ 0.05); Storage differences (Harvest versus 0.5 °C storage): within common cultivar, colour level and growing year, values followed by different uppercase letter indicate significant differences (p ≤ 0.05); Temperature differences: within Staccato cultivar at 28 d storage and at common colour level, bolded values indicate significant differences (p ≤ 0.05) between storage temperatures (0.5 °C vs 3 °C). (N.B. no bolded values appear in this table).

      Table 1. 

      Soluble solids values as affected by cultivar, growing year, storage, and colour level at harvest.

    • Cultivar Colour level Titratable acidity (TA, g·L−1 malic acid)
      2018 2019 2021
      Harvest Storage (0.5 °C) Harvest Storage (0.5 °C) Harvest Storage (0.5 °C) [3 °C]
      Sweetheart 3-4 8.99aA1* 7.11aB1* 7.31aA1* 6.31aB1* − −
      4-5 9.55bA1* 7.57bB1* 7.14aA1* 6.13aB1* − −
      5-6 10.56cA1* 8.57cB1* 7.56aA1* 6.50aB1* − −
      Staccato 3-4 8.53aA2* 6.65aB2* 6.96aA1* 5.51aB2* 12.0aA* 10.5aB*
      9.7a
      4-5 8.87abA2* 7.04bB2* 7.30aA1* 6.21bB1* 12.8aA* 10.2aB*
      9.3a
      5-6 8.91bA2* 6.91abB2 7.18aA1* 6.46bB1 10.6bA* 9.5b*
      8.5b
      Sentennial 3-4 − − 9.21acA2 7.60aB3 − −
      4-5 − − 9.33aA2 7.89aB2 − −
      5-6 − − 8.79bcA2 7.66aB2 − −
      Main effects Significance F-value Degrees of freedom
      Cultivar p < 0.0001 193.58 2
      Colour level p = 0.0023 5.49 2
      Year p < 0.0001 1,007.20 2
      Time (harvest or storage at 0.5 °C) p < 0.0001 474.18 1
      Colour differences: within common time and cultivar, values followed by different lower case letters indicate significant differences (p ≤ 0.05); Cultivar differences: within common colour level and time, values followed by different numbers indicate significant differences (p ≤ 0.05); Growing year differences: within common time, colour level and cultivar, values followed by * indicate significant differences (p ≤ 0.05); Storage differences (Harvest versus 0.5 °C storage): within common cultivar, colour level and growing year, values followed by different uppercase letter indicate significant differences (p ≤ 0.05); Temperature differences: within Staccato cultivar at 28 d storage and at common colour level, bolded values indicate significant differences (p ≤ 0.05) between storage temperatures (0.5 °C vs 3 °C).

      Table 2. 

      Titratable acidity values as affected by cultivar, growing year, storage and colour level at harvest.

    • Cultivar Colour level Soluble solids to titratable acidity ratio (SS/TA)
      2018 2019 2021
      Harvest Storage (0.5 °C) Harvest Storage (0.5 °C) Harvest Storage (0.5 °C) [3 °C]
      Sweetheart 3-4 2.02a1A* 2.49a1B* 2.49a1A* 2.78a1B* − −
      4-5 2.09a1A* 2.61a1B* 2.71b1A* 3.06b1B* − −
      5-6 2.07a1A* 2.46a1B* 2.63b1A* 3.02b1B* − −
      Staccato 3-4 2.01a1A* 2.58a1B* 2.46a1A* 3.11a2B* 1.57aA* 1.79aB*
      1.89a
      4-5 2.0a1A* 2.54a1B* 2.51a2A* 2.91b1B* 1.55aA* 1.83aB*
      2.04a
      5-6 2.27b2A* 2.58a1B* 2.81b1A* 3.14a1B* 1.89bA* 2.06bB*
      2.32b
      Sentennial 3-4 − − 1.97a2A 2.38a3B − −
      4-5 − − 2.02a3A 2.34a2B − −
      5-6 − − 2.37b2A 2.69b2B − −
      Main effects Significance F-value Degrees of freedom
      Cultivar p < 0.0001 94.79 2
      Colour level p < 0.0001 22.04 2
      Year p < 0.0001 361.13 2
      Time (harvest or storage at 0.5 °C) p < 0.0001 134.15 1
      Colour differences: within common time and cultivar, values followed by different lower case letters indicate significant differences (p ≤ 0.05); Cultivar differences: within common colour level and time, values followed by different numbers indicate significant differences (p ≤ 0.05); Growing year differences: within common time, colour level and cultivar, values followed by * indicate significant differences (p ≤ 0.05); Storage differences (Harvest versus 0.5 °C storage): within common cultivar, colour level and growing year, values followed by different uppercase letter indicate significant differences (p ≤ 0.05); Temperature differences: within Staccato cultivar at 28 d storage and at common colour level, bolded values indicate significant differences (p ≤ 0.05) between storage temperatures (0.5 °C vs 3 °C).

      Table 3. 

      Soluble solids to titratable acidity ratio values as affected by cultivar, growing year, storage and colour level at harvest.

    • Cultivar Colour level Dry matter (DM, %)
      2018 2019 2021
      Harvest Storage (0.5 °C) Harvest Storage (0.5 °C) Harvest Storage (0.5 °C) [3 °C]
      Sweetheart 3-4 20.9aA1* 20.6aA1* 18.6aA1* 18.6aA1* 22.1aA1* −
      4-5 21.9bA1 22.0bA1* 19.9bA1* 19.8acA1* 22.5bA1 −
      5-6 25.2cA1* 23.5cB1* 21.1cA1* 20.6bcA1* 23.6cA1* −
      Staccato 3-4 20.2aA1* 19.5aA2* 18.4aA2* 18.1aA23* 21.0aA2* 20.6aA*
      19.8a
      4-5 20.4aA2* 20.8bA2* 19.1aA1* 18.8aA2* 22.0bA2* 21.6bA*
      21.9b
      5-6 22.4bA2 22.3cA2 22.9bA2* 21.6bA23 23.0cA2 22.2bA
      22.4b
      Sentennial 3-4 − − 18.2aA2 18.4aA13 20.5aA2* −
      4-5 − − 19.3bA1 18.8bA2 22.6bA12* −
      5-6 − − 22.9cA2 20.9bA13 23.5cA12 −
      Main effects Significance F-value Degrees of freedom
      Cultivar p < 0.0001 11.36 2
      Colour level p < 0.0001 130.99 2
      Year p < 0.0001 56.64 2
      Time (harvest or storage at 0.5 °C) Not significant, p = 0.0922 2.97 1
      Colour differences: within common time and cultivar, values followed by different lower case letters indicate significant differences (p ≤ 0.05); Cultivar differences: within common colour level and time, values followed by different numbers indicate significant differences (p ≤ 0.05); Growing year differences: within common time, colour level and cultivar, values followed by * indicate significant differences (p ≤ 0.05); Storage differences (Harvest versus 0.5 °C storage): within common cultivar, colour level and growing year, values followed by different uppercase letter indicate significant differences (p ≤ 0.05); Temperature differences: within Staccato cultivar at 28 d storage and at common colour level, bolded values indicate significant differences (p ≤ 0.05) between storage temperatures (0.5 °C vs 3 °C). (N.B. no bolded values appear in this table).

      Table 4. 

      Dry matter values as affected by cultivar, growing year, storage and colour level at harvest.

    • Growing year Colour level Harvest date Average
      temperature
      (AT) (°C)      		 Average relative humidity (ARH) Average low temperature (ALT) (°C) Average high temperature (AHT) (°C)
      2018 Sweetheart 3-4 July 16 18.96 61.5% 7.17 32.14
      4-5 July 23 18.85 59.8% 7.17 32.13
      5-6 July 30 20.45 56.85% 7.49 32.05
      Staccato 3-4 July 30 19.74 59.17% 7.42 32.04
      4-5 August 9 21.14 54.46% 7.42 32.77
      5-6 August 9 21.14 54.49% 7.42 32.77
      2018 overall average 20.05 57.71% 7.35 32.32
      2019 Sweetheart 3-4 July 18 17.86 66.04% 7.22 28.79
      4-5 July 24 18.39 66.1% 7.22 28.59
      5-6 July 24 18.39 66.1% 7.22 28.59
      Staccato 3-4 July 22 18.03 66.16% 7.22 28.59
      4-5 July 29 19.19 62.92% 8.67 29.39
      5-6 July 31 19.19 62.92% 8.67 29.39
      Sentennial 3-4 July 22 18.03 66.16% 7.22 28.59
      4-5 July 29 18.99 63.77% 8.67 29.39
      5-6 August 6 19.79 59.94% 8.67 29.39
      2019 overall average 18.87 63.65% 8.19 28.96
      2021 Sweetheart 3-4 July 5 24.01 40.68% 8.51 50.68
      4-5 July 12 24.28 40.68% 10.68 49.23
      5-6 July 20 24.10 40.68% 9.66 47.47
      Staccato 3-4 July 13 24.01 40.68% 8.51 50.68
      4-5 July 21 24.28 40.68% 10.68 49.23
      5-6 July 27 24.10 40.68% 9.66 47.47
      Sentennial 3-4 July 12 24.01 40.68% 8.51 50.68
      4-5 July 19 24.28 40.68% 10.68 49.23
      5-6 July 26 24.10 40.68% 9.66 47.47
      2021 overall average 24.12 40.68% 9.62 49.13

      Table 5. 

      Temperature and relative humidity environmental data for 2018, 2019, and 2021 growing years.

    • Growing year Colour
      level      		 Average colour measured at harvest
      [average dry matter at harvest]      		 Dry matter bin (%), highest
      proportions of cherries      		 Respiration rate (mg CO2 kg−1·h−1)
      assessed at 0.5, 5 or 10 °C
      0.5 °C 5 °C 10 °C
      2018 Sweetheart 3-4 3.74a1 [20.9%] 21, 38% 2.87a1 * 5.99a1* 9.75a1*
      4-5 4.66b1 [21.9%] 22.5, 38% 3.57b1* 5.53b1* 9.06a1*
      5-6 5.54c1 [25.2%] 25.5, 26% 3.50b1* 5.18b1* 9.58a1*
      Staccato 3-4 3.58a1 [20.2%] 19.5, 44% 4.43a2* 7.08a2* 9.90a1*
      4-5 4.62b1 [20.4%] 21, 36% 4.58a2* 8.05b2* 11.22b2*
      5-6 5.64c1 [22.4%] 22.5, 50% 4.12b2* 6.43c2* 9.78a1*
      2019 Sweetheart 3-4 3.76a1 [18.6%] 18, 26%; 19.5, 26% Nd 6.04 13.7
      4-5 4.42b1 [19.9%] 21, 32% Nd Nd 8.3
      5-6 5.42c1 [21.1%] 22.5, 28% Nd 6.95 13.5
      Staccato 3-4 3.46a1 [18.4%] 19.5, 32% Nd 5.8 12.47
      4-5 4.40b12 [19.1%] 19.5, 40% Nd 6.14 Nd
      5-6 5.40c1 [22.9%] 22.5, 26% Nd Nd Nd
      Sentennial 3-4 3.62a1 [18.2%] 18, 28% Nd 6.5 12.80
      4-5 4.22b2 [19.3%] 21, 40% Nd 3.76 Nd
      5-6 5.20c2 [22.9%] 22.5, 24% Nd Nd Nd
      2021 Sweetheart 3-4 Nd [22.1%] 22.5, 40% 3.18a1* 5.86a1* 8.8a1*
      4-5 Nd [22.5%] 22.5, 28% 2.78a1* 5.08b1* 8.1a1*
      5-6 Nd [23.6%] 24, 30% 2.65a1* 4.32c1* 9.19a1*
      Staccato 3-4 3.50a1 [21.0%] 19.5, 28% 2.72a1 4.65ab2 10.94a2*
      4-5 4.80b1 [22.0%] 21, 24%; 22.5, 20% 3.27a1* 4.38a2* 8.22b1*
      5-6 5.60c1 [23.0%] 24, 30% 3.05a1* 5.07b2* 9.57ab1*
      Sentennial 3-4 Nd [20.5%] 21, 48% 2.71a1* 4.77a2* 7.84a1*
      4-5 Nd [22.6%] 22.5, 28%; 24, 24% 2.78a1* 4.81a12* 8.28ab1*
      5-6 Nd [23.5%] 22.5, 28%; 24, 24% 4.23b2 4.47a12 9.88b1*
      Within common cultivar and growing year, values followed by different letters indicate significant differences (p ≤ 0.05)-shows colour differences; Within common colour level and growing year, values followed by different numbers indicate significant differences (p ≤ 0.05)-shows cultivar differences; Within common cultivar, growing year and colour level, values followed by * indicate significant differences (p ≤ 0.05)-shows respiration rate differences at the different temperatures. Due to incomplete data, statistical analysis was not performed on 2019 data. Nd = Actual colour was not calculated for Sweetheart and Sentennial cherries in 2021 although cherries were collected 3-4, 4-5, 5-6 colour levels as in previous years and can be considered to have colour levels of approximately 3.5, 4.5, and 5.5, respectively.

      Table 6. 

      Average colour level and respiration rate of sweet cherries at harvest.

    • Relationship assessed for Sweetheart*,
      Staccato, and Sentennial**
      cultivars over 2018, 2019,
      and 2021 growing seasons      		 Pearson's
      correlation
      coefficient      		 Significance
      level
      (p value)
      Colour correlated with
      Soluble solids at harvest r = +0.845 p ≤ 0.0005
      Soluble solids at 28-d storage r = +0.684 p ≤ 0.005
      Dry matter at harvest r = +0.768 p ≤ 0.0005
      Dry matter correlated with
      Soluble solids at harvest r = +0.871 p ≤ 0.0005
      Soluble solids at 28-d storage r = +0.776 p ≤ 0.0005
      Colour at harvest r = +0.769 p ≤ 0.0005
      Titratable acidity at harvest r = +0.439 p ≤ 0.05
      Titratable acidity at 28 d storage r = +0.398 p ≤ 0.10
      Respiration rate at 5 °C r = −0.514 p ≤ 0.025
      Insignificant correlations
      Colour and titratable acidity at harvest r = +0.099 p = 0.696
      Colour and titratable acidity at 28 d storage r = +0.100 p = 0.692
      Colour and soluble solids to titratable
      acidity ratio at harvest      		 r = +0.218 p = 0.383
      Colour and soluble solids to titratable
      acidity ratio at 28 d storage      		 r = +0.073 p = 0.774
      Colour and respiration rate at 0.5 °C r = +0.252 p = 0.364
      Colour and respiration rate at 5 °C r = −0.206 p = 0.462
      Colour and respiration rate at 10 °C r = +0.084 p = 0.766
      Dry matter and soluble solids to titratable
      acidity ratio at harvest      		 r = −0.135 p = 0.595
      Dry matter and soluble solids to titratable
      acidity ratio at 28 d storage      		 r = −0.227 p = 0.365
      Dry matter and respiration rate at 0.5 °C r =−0.125 p = 0.657
      Dry matter and respiration rate at 10 °C r = −0.181 p = 0.519
      *Only 2018 and 2019 growing season data available; **only 2019 growing season data available.

      Table 7. 

      Correlations between colour and dry matter at harvest with sweet cherry flavour quality attributes and respiration rate.