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Heliyon 9 (2023) e17260
Available online 17 June 2023
2405-8440/© 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Deciphering the response of thirteen apple cultivars for growth,
fruit morphology and fruit physico-chemical attributes during
different years
Mohammed Tauseef Ali
a
,
*
, Sheikh Mehraj
a
, Mohammad Saleem Mir
a
,
Immad Ahmad Shah
b
, Zahoor Ahmad Shah
c
,
**
, Hamed A. El-Serehy
d
,
Eajaz Ahmad Dar
e
, Arif Hussain Bhat
f
, Sartaj Ahmad Wani
g
, Uzma Fayaz
f
,
Fahad A. Al-Misned
d
, Hesham M. Shak
h
a
Division of Fruit Science, Sher-e-Kashmir University of Agricultural Sciences & Technology of Kashmir, Shalimar, 190025, India
b
ICMR- National Institute of Occupational Health, Ahmedabad, Gujarat, 380016, India
c
Division of Agricultural Extension and Communication, Sher-e-Kashmir University of Agricultural Sciences & Technology of Kashmir, Shalimar,
190025, India
d
Department of Zoology, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
e
Krishi Vigyan Kendra, Ganderbal, Sher-e-Kashmir University of Agricultural Sciences & Technology of Kashmir Shalimar, Jammu and Kashmir,
190025, India
f
Division of Plant Pathology, Sher-e-Kashmir University of Agricultural Sciences & Technology of Kashmir, Shalimar, 190025, India
g
Division of Soil Science, Sher-e-Kashmir University of Agricultural Sciences & Technology of Kashmir, Shalimar, 190025, India
h
Hungarian Academy of Sciences, Limnoecology Research Group, University of Pannonia, Gyetem u. 10, H-8200, Veszprem, Hungary
ARTICLE INFO
Keywords:
Malus ×domestica
Kashmir
Length
Weight
Sugars
Colour
Yield
ABSTRACT
Apple cultivation is one of the most signicant means of subsistence in the Kashmir region of the
northwestern Himalayas. It is considered as the backbone of the region’s economy. Apple culti-
vation in the region is dominated by a late maturing cultivar “Red Delicious” which usually on
maturity causes glut in the market. In order to bring new cultivars in the cultivation, and to
expand the maturity season, it is necessary to evaluate the new cultivars on fruit physico-chemical
attributes which ultimately decide the market rates before recommending to farmers for cultivars
adoption. Therefore, the current study was carried out to evaluate thirteen apple cultivars on
physico-chemical attributes over two years, 2017 and 2018 under agro-climatic conditions of
Kashmir region The results revealed that cultivars differed signicantly in terms of physico-
chemical properties. Cultivars with the highest and lowest values for initial fruit set, fruit drop,
nal fruit retention, and fruit rmness in 2017 did not follow the same trend in 2018. During
2017 and 2018, cultivar Mollie’s Delicious possessed the highest fruit length (72.39 mm and
81.45 mm), fruit diameter (81.18 mm and 84.14 mm), and fruit weight (205.85 g and 247.16 g),
whereas cultivar Baleman’s Cider had the lowest values (50.76 mm and 52.83 mm, 60.10 mm and
62.08 mm, and 71.46 g and 86.94 g), respectively. The harvesting dates were quite spread out
during both years of study. Cultivar Mollie’s Delicious was harvested the earliest in both years, on
August 5th, 2017 and August 8th, 2018. Cultivar Fuji Zehn Aztec was the last cultivar harvested
in 2017 on October 2 and in 2018 on October 5. The maximum number of seeds per fruit was
* Corresponding author.
** Corresponding author.
E-mail addresses: tauseefwani500@gmail.com (M.T. Ali), zahoor37@gmail.com (Z.A. Shah).
Contents lists available at ScienceDirect
Heliyon
journal homepage: www.cell.com/heliyon
https://doi.org/10.1016/j.heliyon.2023.e17260
Received 18 February 2023; Received in revised form 1 June 2023; Accepted 12 June 2023
Heliyon 9 (2023) e17260
2
noticed in the cultivar Mollie’s Delicious (8.34 and 8.71) during both 2017 and 2018, respec-
tively. Cultivar Starkrimson had the fewest seeds per fruit in 2017 (7.11) and 2018 (7.42).
Cultivar Baleman’s Cider had the highest acidity in 2017 (0.63%) and 2018 (0.52%). In both
2017 (0.25%) and 2018 (0.23%), the Adam’s Pearmain cultivar was the least acidic. Cultivar
Allington Pippin (16.13 ◦Brix) and Red Gold (16.73 ◦Brix) had the highest TSS in 2017 and 2018,
respectively, whereas Vance Delicious (12.30 ◦Brix) and Top Red (10.78 ◦Brix) had the lowest TSS
in 2017 and 2018, respectively. The cultivars Mollie’s Delicious and Red Gold had the highest
total sugars (11.33 and 11.40%) in 2017 and 2018, respectively. Cultivar Baleman’s Cider had the
lowest total sugars (9.82%) in 2017 while Top Red (9.78%) in 2018. The cultivar Vance Delicious
had the highest ratio of leaves to fruits in 2017 (55.44) and for Shalimar Apple-2 in 2018 (49.65).
In 2017, cultivars Fuji Zehn Aztec (29.26) and Silver Spur (24.51), had the fewest leaves per fruit.
The highest leaf chlorophyll content was recorded in cultivar Shireen (3.50 and 3.57 mg g
−1
fresh
weight) during the years 2017 and 2018, respectively. Cultivar Baleman’s Cider had the lowest
leaf chlorophyll content (2.15 mg g
−1
fresh weight) during 2017, while cultivar Allington Pippin
(2.09 mg g
−1
fresh weight) had the lowest leaf chlorophyll content in 2018. The cultivars Fuji
Zehn Aztec, with a yield efciency of 0.78 kg/cm
2
and Silver Spur with a yield efciency of 1.14
kg/cm
2
were the most yield efcient during the years 2017 and 2018, respectively. Cultivar
Shalimar Apple-2 was least performing with yield efciencies of 0.05 and 0.07 kg/cm
2
during
2017 and 2018, respectively.The ndings suggest that cultivar Mollie’s Delicious commercially
matures rst and has the highest fruit length, diameter, and weight; hence, it can be a good option
for cultivation so as to fetch the maximum price in the market when other cultivars are still
maturing. Shalimar Apple-2 is precluded for cultivation due to least yield efciency, whereas
cultivars Fuji Zehn Aztec and Silver Spur are recommended to farmers for their higher yield
efciency.
1. Introduction
Apple (Malus domestica Borkh.) is a major fruit crop and is traded internationally [1]. Apple is thought to have its roots in Central
Asia’s Tien Shan Mountains and moved via trade routes to Asia and Europe [2]. It is a temperate region-grown deciduous fruit that is
quite lucrative. With 86.44 metric tonnes of output in 2020, apples are the second-most produced fruit tree crop on this planet, after
bananas (119.83 metric tonnes) [3]. Apples are a crucial part of the food and are utilized in the food industry to make drinks and other
food items. Apples contain vitamins (Vitamin C) [4], organic acids (malic acid), sugars [5,6], macronutrients (Ca, Na, K, Mg, and P),
trace elements (zinc, copper, manganese and iron) [7], and brous materials [8]. Despite the availability of more than 20 000 cultivars,
only a few are currently farmed commercially across the globe [9]. The wide range of qualitative features determines variability among
apple cultivars [10]. On rst sight, the colour, gloss, and size of the apple are considered to determine its quality. Next, the texture,
total soluble solids (TSS) content, and titrable acidity are considered to help customers identify a fruit that is higher in quality [11].
Fruit quality identication is vital since pome fruit varieties are diverse. Fruit quality encompasses a diverse range of internal and
exterior characteristics which determines the food’s suitability for eating. One of the important components in determining a fruit’s
appearance is its colour, which is a component of external fruit quality [12]. The product is rst evaluated by the consumer based on its
look (colour, size, and shape), followed by its eating quality, however the latter may inuence the customer’s decision to repurchase
the item [13]. Fruit colour control has a signicant impact on sales, but it is typically done visually, trusting on the correctness of a
person’s eyes to analyse and decide colour, however, colour is seen differently by each person. Additionally, since each individual will
perceive a colour slightly differently, it is quite challenging to adequately express colour in words [14]. Cultivars had disseminated
across the globe to regions with unique environments, where their inherit characteristics are not always expressed. Typically, growers
choose a cultivar based on commercial rather than scientic information, causing low fruit quality that is frequently unsuitable for
international markets [15]. Weather inuences crop yield quantity and quality, and is thus a driving force behind farm income
volatility [16]. Regardless of the maturity index used for harvest date, both acid concentration and fruit rmness decreased, while
soluble-solids content increased in certain cases; all of these changes may have come from earlier owering and greater temperatures
during the maturation period [17]. While yield quantity risks and their factors are typically well documented, yield quality risks are
frequently overlooked [18].
The Kashmir region comprises mainly continental temperate climate [19]. In the Kashmir region, apples have the largest acreage
and yield among temperate fruits. The majority of the population in Kashmir is dependent on the apple industry for their livelihood.
Most apple studies that aimed to compare physico-chemical attributes focused on a small number of apple cultivars, and probably no
attempts have been made to demonstrate the major horticultural attributes of thirteen apple cultivars grown under identical orchard
conditions and that too with two years of consecutive data in the Kashmir region of the northwestern Himalayas. Hence, scarce in-
formation is available on the physico-chemical characteristics of apple cultivars cultivated in Kashmir. Therefore, in 2017 and 2018, a
two-year research trial was started in order to evaluate thirteen cultivars on physico-chemical parameters under the ecological con-
ditions of the Kashmir region.
M.T. Ali et al.
Heliyon 9 (2023) e17260
3
2. Materials and methods
2.1. Location and plant material
Kashmir region is located between 33◦20′and 34◦54′N latitude and 73◦55′and 75◦35′E longitude (Fig. 1), with an elevation
range of 1300 to 4500 m above mean sea level, and is a biogeographic area of the North-Western Himalaya in India [20–22]. Thirteen
apple cultivars (Fig. 2) were studied namely “Adam’s Pearmain”, “Allington Pippin”, “Baleman’s Cider”, “Fuji Zehn Aztec”, “Mollie’s
Delicious”, “Red Gold”, “Red Velox”, “Shalimar Apple-2”, “Shireen”, “Silver Spur”, “Starkrimson”, “Top Red” and “Vance Delicious”
grafted on MM-106 rootstock located at the University “SKUAST-Kashmir” at the experimental eld of Pomology, Srinagar, J&K, India.
The trial location is situated at a latitude and longitude of 34.1467◦and 74.8791◦, respectively, and is 1588 m above mean sea level.
The samples were taken from uniform, healthy trees and horticultural practices were performed as per university recommendations.
Fruits harvested were quickly brought to the lab for examination.
2.2. Characteristics studied
2.2.1. Initial fruit set (%)
It was calculated on marked branches measuring 1 m in length with three replications (plants) for each cultivar:
Initial fruit set (%) =[Number (No.) of fruitlets at pea stage/Number of flowers] ×100
2.2.2. Final fruit retention (%)
The fruits retained on earlier marked branches of 1 m length in all the cultivars (three replications each) were recorded at the time
of harvesting.
Final fruit retention (%) =[No. of fruits at harvest/No. of fruitlets at pea stage] ×100
Fig. 1. Experimental eld location on map (a. world map highlighting country India b. India c. Kashmir region d. Srinagar).
M.T. Ali et al.
Heliyon 9 (2023) e17260
4
(caption on next page)
M.T. Ali et al.
Heliyon 9 (2023) e17260
5
2.2.3. Fruit drop (%)
By dividing the total number of fruits dropped by the total number of fruits set at the beginning, the fruit drop percentage was
calculated on three replications of each cultivar.
Fruit drop =[No. of fruitlets at pea stage - No. of fruits at harvest/No. of fruitlets at pea stage] ×100
2.2.4. Fruits per cluster
Fruits per cluster number of each cultivar replication was calculated at the time of harvesting on whole tree basis.
Fruits per cluster (No.) =No. of fruits in clusters/No. of clusters
2.2.5. Commercial maturity date
The commercial maturity date of each cultivar was determined on three replications by assessing multiple indicators like fruit size,
weight, colour, seed colour turning into a dark colour and ease of separation of fruit from plant.
2.2.6. Fruit colour (h◦)
The colour of fruit samples was determined using Hunter colour lab (A60-1014 593) equipment using fruits of fruit weight samples.
2.2.7. Fruit length (mm)
On each of the tree’s four sides, ten fruits were collected. With the aid of a vernier calliper, the length of ten randomly chosen fruits
from each replication of the cultivar was measured and expressed in millimetres (mm).
2.2.8. Fruit diameter (mm)
From each of the tree’s four sides, ten fruits were collected and combined. With the aid of a vernier calliper, the diameter of ten
randomly chosen fruits from each replication of the cultivar was measured and expressed in millimetres (mm).
2.2.9. Fruit weight (g)
Ten fruits each were collected from the four sides of the tree at random and mixed together. A sensitive monopan balance was used
to weight each of the ten randomly chosen fruits from each replication of the cultivar and the weight was recorded in gram.
2.2.10. Fruit shape
Shape of the fruit cultivars was determined by following apple descriptor [23].
2.2.11. Fruit rmness (kg/cm
2
)
Ten fruits each were collected from the four sides of the tree at random and mixed together. From these randomly ten selected fruits
from each replication of cultivar was used to determine fruit rmness with the use of Effegi Penetrometer (Model-Ft-3-27). At two
different fruit surface, each fruit was punched after removing peel of about one square inch and rmness was recorded as kg cm
−2
as an
average.
2.2.12. Seeds per fruit (no.)
Ten fruits each were collected from the four sides of the tree at random and mixed together. From these ten randomly selected fruits
from each replicate were cut and seeds were removed from the core. Chaffy and shriveled seeds were discarded. The number of seeds in
each case were recorded and averaged per replication.
2.2.13. Leaf: fruit ratio
The total number of fruits and leaves of each cultivar replication at harvest were counted and averaged; ratio was obtained by
dividing total number of leaves at harvest to the total number of fruits retained at harvest.
2.2.14. Leaf area (cm
2
)
Leaf samples comprising of twenty leaves per replication was collected on July 17, 2017 and 2018 at random from diverse di-
rections of each cultivar replication and measured with the help of a leaf area meter (221 systronics) and expressed in square
centimetres.
Fig. 2. Thirteen Apple cultivars pictures with their names (a: Adam’s Pearmain b: Allington Pippin c: Baleman’s Cider d: Fuji Zehn Aztec e: Mollie’s
Delicious f: Red Gold g: Red Velox h: Shalimar Apple-2 i: Shireen j: Silver Spur k: Starkrimson l: Top Red m: Vance Delicious. (For interpretation of
the references to colour in this gure legend, the reader is referred to the Web version of this article.)
M.T. Ali et al.
Heliyon 9 (2023) e17260
6
2.2.15. Leaf chlorophyll content (mg/g fresh weight)
To prevent deterioration of chlorophyll pigment, 10 representative leaf samples were taken in the morning on May 28, 2017 and
2018 [24] and immediately placed in an ice box and stored at 0 ◦C. Under dim lighting, leaves were washed and nely chopped, and
100 mg of chopped leaf samples were inserted in vials containing 7 ml of Dimethyl Sulphoxide (DMSO). The contents of the vials were
incubated at 65 ◦C for 30 min, after which the extracts were transferred to graduated test tubes and the nal volume was adjusted to 10
ml with DMSO as per [25]. Estimation: The aforementioned extract’s optical density (OD) was measured on a Spectronic-21 at 645 nm
and 663 nm against a DMSO blank, and the total chlorophyll content was computed using the following formula:
Total chlorophyll (mg/g) =[20.2 A
645
+8.02 A
663
/a x 1000 ×w] ×V
where,
V =Volume of the extract made
a =Length of the light path in cell (usually 1 cm)
w =Sample (g) weight
A
645
=645 nm wave length absorbance
A
663
=663 nm wave length absorbance
The values so calculated were expressed as mg/g fresh weight of leaves.
2.2.16. Yield efciency (kg/cm
2
)
Yield efciency of the tree was calculated as per [26].
Yield efficiency =Yield (kg)/Cross sectional area (cm
2
) of tree trunk
For calculating tree trunk cross sectional area (TCSA), trees girth of each cultivar replication was measured fteen cm above graft
union as per following formula.
TCSA =(Girth)
2
/4
π
2.2.17. TSS (◦Brix)
The total soluble solids concentration of ten fruits collected from the four sides of the tree of each tree were determined with an
Erma Hand Refractometer (0–32◦Brix) by putting few drops of juice (obtained by squeezing apple pulp) on the prism and then
recording the reading. Calibration of refractometer with distilled water was done for precision.
2.2.18. Acidity (%)
Fruit samples (10 g) were crushed, weighed, and then added to 100 ml of distilled water before being ltered through Whatman’s
No. 1 lter paper to test acidity. The phenolphthalein indicator was used and 10 ml of aliquot was titrated against N/10 NaOH, and the
end point was established when the solution turned pink. On the basis of 1 ml of 0.1 N NaOH solution, which is equivalent to 0.0067 of
malic acid, the total titrable acidity was computed in terms of malic acid and reported in terms of percent acidity [27]. The following
formula was used to compute acidity as malic acid:
Acidity (%) =[Normality of alkali ×titre value ×volume made ×67/Volume of aliquot taken ×weight of sample ×1000] ×100
2.2.19. Total sugars (%)
A 25-g sample of fruit was crushed, mixed with 250 mL of distilled water, then neutralised with 1 N sodium hydroxide to calculate
the total sugar content. Two millilitres of lead acetate (at a concentration of 45%) were added to the initial volume of 250 mL. Extra
lead acetate was precipitated after 5–10 min after adding 2 ml of 42% potassium oxalate, which was then ltered. Fifty millilitres of
ltrate were hydrolyzed by adding 10 mL of hydrochloric acid (1:1) and letting the mixture sit at room temperature overnight. The
following day, a saturated solution of NaOH was used to neutralise the excess hydrochloric acid. An aliquot of the hydrolyzed sample
was transferred to a burette, and titration with a boiling solution of 5 ml of Fehling A and B, with methylene blue as an indicator, was
performed [27]. Cutoff point was denoted by the development of a brick red colour.
Total sugar (%) =[Fehling’s factor ×volume made up/Titre value ×sample weight] ×100
2.2.20. Reducing sugars (%)
5 ml of Fehling’s solution A and B reagent in a ask which is in boiling condition were titrated against the remaining unhydrolysed
deleaded and claried pulp solution/extract in a burette using methylene blue as an indicator to brick red end point [27].
Reducing sugar (%) =[0.05 ×Stock solution/Weight of sample ×solution used] ×100
M.T. Ali et al.
Heliyon 9 (2023) e17260
7
2.2.21. Non-reducing sugars (%)
Non-reducing sugars were computed by removing reducing sugars from total sugars, multiplying by 0.95, and expressing as a
percentage of non-reducing sugars [27].
2.2.22. Statistical analysis
Single factor analysis was performed in this experiment, which included thirteen cultivars (thirteen treatments) with three rep-
lications each (three plants) involving randomized completely block design. Utilizing statistical analysis software (R Software), data
were subjected to analysis of variance (ANOVA). The Tukey honest multiple comparison test was used to identify differences between
cultivars that were signicant at p <0.05.
3. Results
3.1. Initial fruit set
The initial fruit set varied from year to year. Signicant difference in initial fruit set of cultivars during both the years was noted as
is evident from Table-1 and Fig. 4. It reveals that the highest initial fruit set was in cultivar Mollie’s Delicious (89.12%) during 2017,
while in 2018 highest initial fruit set was in Red Gold (77.93%). Cultivar Silver Spur recorded lowest initial fruit set (25.92%) during
2017, and in 2018 Shalimar Apple-2 had lowest initial fruit set of 52.29%. The cultivars mean showed fruit set in 2017 was 60.78%,
whereas in 2018 it was 66.24%.
3.2. Final fruit retention
The highest nal fruit retention was observed in cultivar Silver Spur and Starkrimson (85.13% and 56.14%) during the years 2017
and 2018, respectively. Cultivar Top Red (11.97%) recorded lowest nal fruit retention during 2017 while Mollie’s Delicious (15.80%)
registered least nal fruit retention in 2018 (Table-1 and Fig. 4). The overall nal fruit retention mean in 2017 was 37.24%, while in
2018 it was 36.00%.
3.3. Fruit drop
Maximum fruit drop (90.05%) was noticed in cultivar Top Red during 2017, while in 2018 Mollie’s Delicious (86.22%) recorded
highest fruit drop. Minimum fruit drop was found in cultivar Silver Spur and Starkrimson (16.89% and 45.88%) during the years 2017
and 2018, respectively (Table-1 and Fig. 4). In 2017, the cultivars fruit drop percent was 64.78, while it was 66.02 in 2018.
3.4. Fruits per cluster
Cultivar Baleman’s Cider (3.16) recorded highest number of fruits per cluster in 2017 while Fuji Zehn Aztec (3.08) had highest
number of fruits per cluster in 2018. The lowest number of fruits per cluster was found in cultivar Shalimar Apple-2 (1.34 and 1.70)
during both the years (Table-2 and Fig. 4). The mean number of fruits per cluster in 2017 was 2.05, whereas in 2018, 2.21 was
recorded.
Table 1
Effect of the growing season and cultivars on the initial fruit set, nal fruit retention and fruit drop characteristics.
C.No. Cultivars (C) Initial fruit set (%) Final fruit retention (%) Fruit drop (%)
2017 2018 2017 2018 2017 2018
1 Adam’s Pearmain 28.29 ±0.47
g
59.83 ±1.95
i
42.87 ±1.06
e
30.17 ±1.79
j
59.15 ±1.18
i
71.85 ±1.28
c
2 Allington Pippin 58.55 ±0.58
d
58.62 ±2.24
i
40.75 ±0.56
f
33.15 ±2.81
h
61.27 ±1.17
h
68.87 ±2.13
e
3 Baleman’s Cider 46.48 ±0.57
f
66.36 ±2.63
f
60.99 ±0.34
b
50.86 ±1.87
b
41.03 ±1.15
l
51.16 ±1.76
k
4 Fuji Zehn Aztec 88.20 ±0.58
a
75.72 ±3.16
b
29.88 ±0.12
h
46.72 ±1.30
c
72.14 ±2.87
f
55.3 ±2.34
j
5 Mollie’s Delicious 89.12 ±1.13
a
71.03 ±1.65
d
24.65 ±0.09
i
15.80 ±1.06
l
77.37 ±1.15
e
86.22 ±1.47
a
6 Red Gold 65.40 ±1.41
c
77.93 ±1.97
a
34.32 ±1.31
g
40.07 ±1.26
e
67.7 ±1.91
g
61.95 ±1.35
h
7 Red Velox 88.08 ±1.53
a
68.09 ±0.58
e
22.17 ±1.18
j
36.6 ±0.61
f
79.85 ±1.22
d
65.42 ±1.15
g
8 Shalimar Apple-2 65.17 ±1.19
c
52.29 ±0.56
j
44.36 ±2.87
d
35.16 ±0.63
g
57.66 ±1.50
j
66.86 ±1.20
f
9 Shireen 70.29 ±0.29
b
65.2 ±0.57
fg
21.15 ±1.56
k
41.75 ±0.66
d
80.87 ±1.60
c
60.27 ±1.23
i
10 Silver Spur 25.92 ±1.98
h
74.34 ±1.24
c
85.13 ±1.70
a
19.19 ±0.58
k
16.89 ±1.44
m
82.83 ±1.24
b
11 Starkrimson 88.15 ±1.73
a
63.9 ±1.86
gh
44.92 ±1.73
c
56.14 ±2.13
a
57.1 ±1.70
k
45.88 ±1.28
l
12 Top Red 49.37 ±1.25
e
64.54 ±1.69
gh
11.97 ±1.78
l
32.26 ±1.15
i
90.05 ±1.80
a
69.76 ±1.78
d
13 Vance Delicious 27.16 ±1.49
gh
63.25 ±1.45
h
20.94 ±1.21
k
30.17 ±1.66
j
81.08 ±1.38
b
71.85 ±1.26
c
Mean 60.78 66.24 37.24 ±1.19 36.00 64.78 66.02
SE(m) ±0.07 ±0.19 ±0.08 ±0.18 ±0.01 ±0.02
Means in columns followed by different letters are signicantly different at p ≤0.05 based on Tukey’s multiple range test.
M.T. Ali et al.
Heliyon 9 (2023) e17260
8
3.5. Commercial maturity date
The commercial maturity date was quite spread during both the years of study. In both the years, cultivar Mollie’s Delicious was
earliest harvested on August 5, 2017, while in 2018 on 8th August. Fuji Zehn Aztec was the last cultivar harvested in 2017 on 2nd
October and in 2018 on 5th October (Table-2 and Fig. 5).
3.6. Fruit colour
Fruit colour of cultivars under investigation differed signicantly. Perusal of the Table-2 and Fig. 4 shows that the maximum hue
angle was observed in cultivar Adam’s Pearmain during both the years; 2017 (65.40 h◦), 2018 (56.53 h◦). Cultivar Red Velox recorded
least hue angle (25.47 h◦) during 2017 and in 2018 (18.94 h◦). The mean hue angle (h◦) of cultivars in 2017 was recorded 41.94 while
in 2018 it was 32.42.
3.7. Fruit length
The largest fruit length (Table-3 and Fig. 4) was observed in cultivar Mollie’s Delicious during 2017 (72.39 mm) and 2018 (81.45
mm). Cultivar Baleman’s Cider had smallest fruit length during both the years i.e. 2017 (50.76 mm) and 2018 (52.83 mm). In the years
2017 and 2018, mean fruit length was noted 65.30 mm and 68.45 mm, respectively.
3.8. Fruit diameter
Cultivar Mollie’s Delicious (Table-3 and Fig. 4) presented maximum fruit diameter (81.18 and 84.14 mm) during both the years of
study (2017 and 2018). Smallest fruit diameter was observed in cultivar Baleman’s Cider in the year 2017 (60.10 mm) and 2018
(62.08 mm). The mean fruit diameter was 70.86 mm in 2017, while in 2018, it was 74.71 mm.
3.9. Fruit weight
The maximum fruit weight recorded was for cultivar Mollie’s Delicious (205.85 g and 247.16 g) during the two years of study (2017
and 2018). The minimum fruit weight was recorded in cultivar Baleman’s Cider (71.46 g and 86.94 g) during both the years (2017 and
2018), respectively (Table-3 and Fig. 4). The mean fruit weight was lower in 2017 (153.58g) as compared to 2018 (178.63g).
3.10. Fruit rmness
Cultivar Vance Delicious recorded highest fruit rmness (8.76 kg/cm
2
) during 2017, whereas Top Red (10.59 kg/cm
2
) registered
maximum fruit rmness in 2018. The lowest fruit rmness was noticed in cultivar Allington Pippin (6.12 kg/cm
2
) during 2017, while
Mollie’s Delicious had least fruit rmness (6.33 kg/cm
2
) during 2018 (Table-4 and Fig. 6). The mean fruit rmness in 2017 was 7.55
kg/cm
2
, while in 2018 it was 7.82 kg/cm
2
.
3.11. Seeds per fruit
The maximum number of seeds per fruit (Table-4 and Fig. 6) was noticed in cultivar Mollie’s Delicious (8.34 and 8.71) during both
the years 2017 and 2018. Cultivar Starkrimson recorded minimum number of seeds per fruit during 2017 (7.11) and 2018 (7.42). The
mean number of seeds per fruit in 2017 was 7.77, whereas it was 8.03 in 2018.
3.12. Fruit shape
The information in Table-4 pertaining to fruit shape reveals that cultivars differed and displayed various shapes as provided in
Fig. 3. Surface air maximum and minimum temperatures (
◦C) during 2017 and 2018 at trial.
M.T. Ali et al.
Heliyon 9 (2023) e17260
9
descriptor UPOV, 2005. Adam’s Pearmain, Mollie’s Delicious, Shalimar Apple-2, Shireen and Top Red displayed conic shape while
Allington Pippin, Baleman’s Cider, Fuji Zehn Aztec, Red Velox and Silver Spur presented Globose shape. Starkrimson and Vance
Delicious had cylindrical waisted shape. Red Gold presented obloid shape (Table-4).
3.13. Leaf: fruit ratio
The highest leaf: fruit ratio value was present in cultivar Vance Delicious during 2017 (55.44) while in 2018 was cultivar Red Velox
Fig. 4. Effect of the growing season and cultivars on initial fruit set (IFS), nal fruit retention (FFS), fruit drop (FD), fruits per cluster (FPC), fruit
length (FLen), fruit diameter (FDIA), fruit weight (FWEI) and Fruit colour (FC). (For interpretation of the references to colour in this gure legend,
the reader is referred to the Web version of this article.)
M.T. Ali et al.
Heliyon 9 (2023) e17260
10
(49.65). Least leaf: fruit ratio was noticed in cultivars Fuji Zehn Aztec (29.26) during 2017 and Silver Spur (24.51) in 2018 (Table-5
and Fig. 6). In 2017, cultivars had a leaf: fruit ratio of 44.16%, while in 2018, the leaf: fruit ratio was 33.76.
3.14. Leaf area
It is evident from the data that the maximum leaf area was recorded in cultivar Baleman’s Cider 43.44 cm
2
and 41.52 cm
2
during
2017 and 2018, respectively. Smallest leaf area was found in cultivar Red Velox (22.79 cm
2
) during 2017 and Top Red (23.16 cm
2
) in
2018 (Table-5 and Fig. 6). The mean leaf area (cm
2
) of cultivars in 2017 was recorded 32.64 while in 2018 it was 32.01.
3.15. Leaf chlorophyll content
The highest leaf chlorophyll content was recorded in cultivar Shireen (3.50 and 3.57 mg g-
1
fresh weight) during the years 2017 and
2018, respectively. Cultivar Baleman’s Cider had least leaf chlorophyll content (2.15 mg g
−1
fresh weight) during 2017 while cultivar
Table-2
Effect of the growing season and cultivars on the fruits per cluster, commercial maturity date and fruit colour characteristics.
C.No. Cultivars (C) Fruits per cluster (No.) Commercial maturity date Fruit colour (h◦)
2017 2018 2017 2018 2017 2018
1 Adam’s Pearmain 1.63 ±0.15
gh
1.72 ±0.11
f
28-Sep 29-Sep 65.40 ±4.28
a
56.53 ±1.35
a
2 Allington Pippin 2.36 ±0.12
d
1.81 ±0.12
ef
16-Aug 19-Aug 53.52 ±5.74
d
25.08 ±1.45
i
3 Baleman’s Cider 3.16 ±0.13
a
2.84 ±0.27
b
30-Aug 26-Aug 51.39 ±6.60
e
35.28 ±1.95
d
4 Fuji Zehn Aztec 2.73 ±0.14
c
3.08 ±0.15
a
02-Oct 05-Oct 34.26 ±1.76
h
24.02 ±1.07
j
5 Mollie’s Delicious 1.99 ±0.16
e
1.93 ±0.11
de
05-Aug 08-Aug 29.06 ±1.75
ij
39.92 ±1.22
c
6 Red Gold 2.99 ±0.25
b
2.95 ±0.41
b
12-Aug 17-Aug 30.63 ±4.19
i
33.33 ±3.24
f
7 Red Velox 1.71 ±0.22
g
1.79 ±0.12
f
10-Sep 15-Sep 25.47 ±3.76
k
18.94 ±2.56
k
8 Shalimar Apple-2 1.34 ±0.29
j
1.70 ±0.13
f
19-Aug 16-Aug 44.28 ±3.93
f
43.41 ±1.56
b
9 Shireen 1.85 ±0.30
f
2.23 ±0.14
c
11-Sep 15-Sep 37.54 ±3.34
g
33.95 ±3.17
e
10 Silver Spur 1.96 ±0.25
ef
2.18 ±0.18
c
03-Sep 03-Sep 56.99 ±4.09
c
25.15 ±2.54
i
11 Starkrimson 1.92 ±0.36
ef
2.89 ±0.57
b
26-Aug 27-Aug 27.06 ±3.67
jk
24.14 ±2.05
j
12 Top Red 1.51 ±0.40
hi
1.96 ±0.43
d
07-Sep 08-Sep 29.40 ±1.73
i
32.44 ±1.73
g
13 Vance Delicious 1.43 ±0.49
ij
1.75 ±0.11
f
19-Sep 11-Sep 60.21 ±1.74
b
29.27 ±1.75
h
Mean 2.05 2.21 41.94 32.42
SE(m) ±0.02 ±0.05 ±0.02 ±0.04
Means in columns followed by different letters are signicantly different at p ≤0.05 based on Tukey’s multiple range test.
Fig. 5. Commercial maturity time of thirteen apple cultivars.
M.T. Ali et al.
Heliyon 9 (2023) e17260
11
Allington Pippin (2.09 mg g
−1
fresh weight) had lowest leaf chlorophyll content in 2018 (Table-5 and Fig. 6). The overall nal leaf
chlorophyll content (mg g
−1
fresh weight mean) in 2017 was 2.75, while in 2018 it was 2.74.
3.16. Yield efciency
The cultivars Fuji Zehn Aztec with yield efciency of 0.78 kg/cm
2
and Silver Spur with yield efciency of 1.14 kg/cm
2
were most
yield efcient during the years 2017 and 2018, respectively. Cultivar Shalimar Apple-2 had least yield efciency of 0.05 and 0.07 kg/
cm
2
during 2017 and 2018, respectively (Table-5 and Fig. 6). In 2017, cultivars had a mean yield efciency (kg cm-
2
) of 0.28, while in
2018, yield efciency was 0.51.
3.17. TSS
The highest TSS was observed in cultivar Allington Pippin (16.13 ◦Brix) in 2017 and Red Gold (16.73 ◦Brix) during 2018, whereas
least TSS was noticed in cultivar Vance Delicious (12.30 ◦Brix) during 2017 and Top Red (10.78 ◦Brix) in 2018 (Table-6 and Fig. 7).
During 2017 and 2018, the mean TSS (◦Brix) was recorded 13.69 and 13.37, respectively.
3.18. Acidity
The maximum acidity was recorded in cultivar Baleman’s Cider (0.63 and 0.52%) during both the years (2017 and 2018),
respectively. Minimum acidity was noticed in cultivar Adam’s Pearmain (0.25%) during 2017 and (0.23%) in 2018 (Table-6 and
Fig. 7). In 2017, cultivars had a mean acidity of 0.35%, while in 2018, the acidity was 0.34%.
Table-3
Effect of the growing season and cultivars on the fruit length, fruit diameter and fruit weight characteristics.
C.No. Cultivars (C) Fruit length (mm) Fruit diameter (mm) Fruit weight (g)
2017 2018 2017 2018 2017 2018
1 Adam’s Pearmain 56.49 ±1.64
i
58.26 ±1.06
l
60.29 ±0.89
k
62.36 ±0.48
k
105.50 ±1.59
l
120.59 ±1.17
l
2 Allington Pippin 62.35 ±0.58
h
63.10 ±2.46
j
75.12 ±0.53
c
78.99 ±2.06
d
130.93 ±1.98
k
173.20 ±1.24
h
3 Baleman’s Cider 50.76 ±1.37
j
52.83 ±1.89
m
60.10 ±0.98
l
62.08 ±1.99
l
71.46 ±1.67
m
86.94 ±1.35
m
4 Fuji Zehn Aztec 68.08 ±1.40
d
66.18 ±1.34
h
78.77 ±0.57
b
75.86 ±0.49
g
192.39 ±1.54
b
187.58 ±1.18
g
5 Mollie’s Delicious 72.39 ±1.42
a
81.45 ±2.48
a
81.18 ±0.58
a
84.14 ±1.66
a
205.85 ±2.01
a
247.16 ±1.56
a
6 Red Gold 62.62 ±1.14
g
63.86 ±1.77
i
71.02 ±1.87
g
72.94 ±1.72
i
149.87 ±1.45
i
155.79 ±1.62
k
7 Red Velox 62.61 ±1.47
g
70.48 ±0.58
g
67.12 ±0.58
i
77.58 ±0.61
e
132.65 ±1.39
j
191.44 ±1.47
f
8 Shalimar Apple-2 63.00 ±1.42
f
62.53 ±0.59
k
62.63 ±0.59
j
63.75 ±0.65
j
152.14 ±1.40
h
156.20 ±1.38
j
9 Shireen 71.39 ±1.68
b
72.48 ±0.60
e
70.55 ±0.62
h
73.06 ±0.76
h
160.25 ±1.20
g
170.79 ±1.23
i
10 Silver Spur 71.24 ±0.59
b
77.65 ±1.78
b
72.64 ±0.66
f
83.80 ±0.73
b
184.82 ±1.39
c
225.33 ±1.67
b
11 Starkrimson 69.36 ±1.05
c
71.53 ±1.92
f
74.32 ±0.71
d
77.32 ±0.78
f
164.76 ±1.37
f
202.55 ±1.73
d
12 Top Red 72.18 ±1.31
a
74.00 ±3.76
d
73.16 ±0.78
e
79.63 ±0.77
c
177.49 ±1.43
d
198.47 ±1.52
e
13 Vance Delicious 66.48±1
e
75.54 ±0.51
c
74.29 ±1.59
d
79.66 ±0.81
c
168.37 ±1.28
e
206.14 ±1.31
c
Mean 65.30 68.45 70.86 74.71 153.58 178.63
SE(m) ±0.04 ±0.09 ±0.01 ±0.02 ±0.01 ±0.02
Means in columns followed by different letters are signicantly different at p ≤0.05 based on Tukey’s multiple range test.
Table-4
Effect of the growing season and cultivars on the fruit rmness, fruit seeds and fruit shape characteristics.
C.No. Cultivars (C) Fruit rmness (kg/cm
2
) Seeds per fruit (No.) Fruit shape
2017 2018 2017 2018 2017/2018
1 Adam’s Pearmain 8.06 ±0.63
b
7.87 ±0.47
b
7.33 ±0.50
e
7.60 ±0.51
h
Conic
2 Allington Pippin 6.12 ±0.55
f
7.90 ±0.51
b
8.27 ±0.48
ab
8.58 ±0.49
b
Globose
3 Baleman’s Cider 6.60 ±0.47
e
7.79 ±0.63
b
7.88 ±0.49
c
8.21 ±0.52
de
Globose
4 Fuji Zehn Aztec 7.07 ±0.48
d
7.26 ±0.47
d
7.93 ±0.47
c
8.06 ±0.47
f
Globose
5 Mollie’s Delicious 6.61 ±0.54
e
6.33 ±0.67
e
8.34 ±0.55
a
8.71 ±0.57
a
Conic
6 Red Gold 7.15 ±0.65
d
7.45 ±0.48
cd
7.97 ±0.49
c
8.17 ±0.49
ef
Obloid
7 Red Velox 7.49 ±0.52
c
7.96 ±0.47
b
7.39 ±0.52
e
7.58 ±0.53
h
Globose
8 Shalimar Apple-2 8.70 ±0.58
a
7.70 ±0.49
bc
7.66 ±0.54
d
7.84 ±0.55
g
Conic
9 Shireen 8.26 ±0.50
b
7.82 ±0.51
b
7.72 ±0.50
d
7.83 ±0.58
g
Conic
10 Silver Spur 7.55 ±0.51
c
7.27 ±0.81
d
7.36 ±0.56
e
7.73 ±0.49
g
Globose
11 Starkrimson 7.64 ±0.55
c
7.86 ±0.47
b
7.11 ±0.47
f
7.42 ±0.59
i
Cylindrical waisted
12 Top Red 8.11 ±0.53
b
10.59 ±0.58
a
8.16 ±0.48
b
8.35 ±0.56
c
Conic
13 Vance Delicious 8.76 ±0.58
a
7.92 ±0.61
b
7.95 ±0.51
c
8.31 ±0.54
cd
Cylindrical waisted
Mean 7.55 7.82 7.77 8.03
SE(m) ±0.01 ±0.01 ±0.04 ±0.09
Means in columns followed by different letters are signicantly different at p ≤0.05 based on Tukey’s multiple range test.
M.T. Ali et al.
Heliyon 9 (2023) e17260
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3.19. Total sugars
Maximum total sugars was recorded in cultivar Mollie’s Delicious and Red Gold (11.33 and 11.40%) during both the years (2017
and 2018), respectively. Least total sugars during 2017 (9.82%) was recorded in Baleman’s Cider and in Top Red (9.78%) in 2018
Fig. 6. Effect of the growing season and cultivars on fruit rmness (FFIRM), seeds per fruit (SPF), leaf: fruit ratio, leaf area, leaf chlorophyll and
yield efciency.
M.T. Ali et al.
Heliyon 9 (2023) e17260
13
(Table-6 and Fig. 7). The mean total sugars was 10.74% in 2017, while in 2018, it was 10.73%.
3.20. Reducing sugars
Mollies’s Delicious was signicantly higher in reducing sugars during 2017 (8.05%) and in 2018 was cultivar Shireen (8.01%).
Least reducing sugars were found in cultivar Allington Pippin (5.32 and 5.16%) during both the years (Table-7 and Fig. 7). During 2017
and 2018, the mean reducing sugars (%) was recorded 6.79% and 6.74%, respectively (see Table 8).
Table-5
Effect of the growing season and cultivars on the Leaf: fruit ratio, leaf area, leaf chlorophyll content and yield efciency characteristics.
C.
No.
Cultivars (C) Leaf: fruit ratio Leaf area (cm
2
) Leaf chlorophyll content (mg/
g fresh weight)
Yield efciency (kg/cm
2
)
2017 2018 2017 2018 2017 2018 2017 2018
1 Adam’s
Pearmain
49.66 ±
4.71
d
43.25 ±
2.06
c
38.13 ±
4.21
d
39.93 ±
2.39
bc
2.78 ±0.10
ef
2.85 ±
0.21
d
0.08 ±
0.01
gh
0.12 ±
0.11
ij
2 Allington Pippin 46.87 ±
1.92
e
28.90 ±
2.23
h
42.47 ±
2.34
b
40.20 ±
3.02
b
2.18 ±0.05
i
2.09 ±0.28
f
0.15 ±
0.04
fg
0.37 ±
0.06
g
3 Baleman’s Cider 31.79 ±
4.47
j
44.18 ±
4.01
b
43.44 ±
3.68
a
41.52 ±
4.49
a
2.15 ±0.36
i
2.10 ±0.23
f
0.24 ±
0.01
e
0.17 ±0.17
i
4 Fuji Zehn Aztec 29.26 ±
4.19
k
40.37 ±
4.45
d
34.13 ±
3.34
e
33.26 ±
3.78
d
2.19 ±0.24
i
2.13 ±0.12
f
0.78 ±
0.15
a
0.49 ±0.06
f
5 Mollie’s
Delicious
38.34 ±
4.23
g
32.93 ±
5.18
f
32.83 ±
2.80
f
30.95 ±
2.88
e
3.09 ±
0.05
cd
3.04 ±
0.19
cd
0.44 ±
0.06
c
0.58 ±
0.15
de
6 Red Gold 35.63 ±
2.31
i
31.94 ±
2.10
g
28.84 ±
2.19
g
26.77 ±
2.84
g
2.92 ±
0.18
de
2.87 ±
0.21
d
0.58 ±
0.08
b
0.77 ±
0.14
bc
7 Red Velox 51.32 ±
2.34
c
26.42 ±
1.96
j
22.79 ±
1.53
j
24.58 ±
2.35
h
2.58 ±0.20
fg
2.52 ±
0.16
e
0.13 ±
0.01
gh
0.69 ±
0.13
c
8 Shalimar Apple-
2
52.24 ±
2.37
b
49.65 ±
4.78
a
39.03 ±
1.73
c
39.44 ±
1.43
c
2.34 ±0.06
hi
2.41 ±
0.24
e
0.05 ±
0.02
h
0.07 ±0.15
j
9 Shireen 37.29 ±
2.48
h
35.15 ±
3.28
e
34.67 ±
1.75
e
33.26 ±
3.29
d
3.50 ±0.07
a
3.57 ±
0.32
a
0.23 ±
0.03
ef
0.27 ±
0.16
h
10 Silver Spur 50.20 ±
4.15
d
24.51 ±
2.03
k
26.66 ±
1.77
i
25.19 ±
3.24
h
3.10 ±
0.21
cd
3.05 ±
0.09
cd
0.28 ±
0.04
de
1.14 ±
0.18
a
11 Starkrimson 49.84 ±
3.54
d
28.54 ±
2.31
h
27.44 ±
1.61
h
29.14 ±
1.75
f
3.180.15
bc
3.24 ±
0.11
bc
0.27 ±
0.05
de
0.59 ±
0.01
d
12 Top Red 46.22 ±
2.52
f
25.86 ±
2.34
j
26.07 ±
3.71
i
23.16 ±
1.73
i
2.43 ±
0.19
gh
2.46 ±
0.21
e
0.33 ±
0.02
d
0.84 ±
0.02
b
13 Vance Delicious 55.44 ±
4.15
a
27.12 ±
1.02
i
27.79 ±
4.15
h
28.75 ±
1.81
f
3.37 ±
0.23
ab
3.30 ±
0.13
b
0.12 ±
0.03
gh
0.50 ±
0.03
ef
Mean 44.16 33.76 32.64 32.01 2.75 2.74 0.28 0.51
SE(m) ±0.02 ±0.05 ±0.02 ±0.04 ±0.02 ±0.05 ±0.01 ±0.01
Table-6
Effect of the growing season and cultivars on the TSS, acidity and total sugars characteristics.
C.No. Cultivars (C) TSS (◦Brix) Acidity (%) Total sugars (%)
2017 2018 2017 2018 2017 2018
1 Adam’s Pearmain 12.32 ±0.58
h
12.78 ±0.47
g
0.25 ±0.06
e
0.23 ±0.04
d
10.25 ±0.61
e
9.93 ±0.48
f
2 Allington Pippin 16.13 ±0.61
a
13.85 ±0.53
c
0.36 ±0.08
bcde
0.40 ±0.03
ab
9.85 ±0.68
f
10.23 ±0.68
e
3 Baleman’s Cider 14.16 ±0.57
c
13.98 ±0.56
b
0.63 ±0.09
a
0.52 ±0.04
a
9.82 ±0.71
f
10.33 ±0.65
e
4 Fuji Zehn Aztec 13.18 ±0.62
e
12.42 ±0.60
h
0.29 ±0.02
cde
0.27 ±0.02
cd
10.4 ±0.75
e
9.87 ±0.75
f
5 Mollie’s Delicious 12.93 ±0.58
f
13.76 ±0.47
c
0.35 ±0.03
bcde
0.33 ±0.03
bcd
11.33 ±0.65
a
11.06 ±0.71
cd
6 Red Gold 13.42 ±0.59
d
16.73 ±0.48
a
0.27 ±0.01
cde
0.29 ±0.04
bcd
11.05 ±0.58
b
11.4 ±0.60
a
7 Red Velox 15.95 ±0.61
b
13.86 ±0.47
bc
0.39 ±0.02
bc
0.36 ±0.03
bc
10.71 ±0.56
d
11.17 ±0.53
c
8 Shalimar Apple-2 13.19 ±0.63
e
12.34 ±0.48
h
0.38 ±0.03
bcd
0.40 ±0.02
ab
10.73 ±0.69
cd
10.91 ±0.66
d
9 Shireen 14.23 ±0.64
c
13.83 ±0.60
c
0.26 ±0.02
de
0.28 ±0.05
bcd
11.32 ±0.54
a
11.09 ±0.89
c
10 Silver Spur 12.57 ±0.82
g
13.11 ±0.47
e
0.28 ±0.04
cde
0.31 ±0.04
bcd
10.97 ±0.56
b
11.23 ±0.79
abc
11 Starkrimson 14.15 ±0.58
c
12.97 ±0.58
f
0.42 ±0.02
b
0.38 ±0.03
bc
10.9b ±0.72
c
11.19 ±0.71
bc
12 Top Red 13.43 ±0.82
d
10.78 ±0.61
i
0.32 ±0.03
bcde
0.35 ±0.04
bcd
11.02 ±0.67
b
9.78 ±0.65
f
13 Vance Delicious 12.30 ±0.58
h
13.36 ±0.65
d
0.29 ±0.02
cde
0.28 ±0.03
bcd
11.3 ±0.64
a
11.35 ±0.63
ab
Mean 13.69 13.37 0.35 0.34 10.74 10.73
SE(m) ±0.01 ±0.02 ±0.01 ±0.01 ±0.04 ±0.09
Means in columns followed by different letters are signicantly different at p ≤0.05 based on Tukey’s multiple range test.
M.T. Ali et al.
Heliyon 9 (2023) e17260
14
3.21. Non-reducing sugars
Maximum non-reducing sugars were found in cultivar Red Velox (4.87 and 5.50%) during both the years of study i.e. 2017 and
2018, respectively. Minimum non-reducing sugars were noticed in cultivars Mollie’s Delicious (3.12%) during 2017 and Top Red
(2.18%) in 2018 (Table 7 and Fig. 7). The mean non-reducing sugars (%) in 2017 was 3.76, whereas it was 3.80 in 2018.
4. Discussion
The present investigation reects signicant differences for initial fruit set, fruit drop and nal fruit retention. The variations in
Fig. 7. Effect of the growing season and cultivars on TSS (TSS), acidity (ACID), total sugars (TSUG), reducing sugars and non-reducing sugars.
M.T. Ali et al.
Heliyon 9 (2023) e17260
15
initial fruit set and nal fruit retention amid dissimilar cultivars may be because of their genomic differences and year to year variation
might be due to environmental effect. Further, partial or lack of bloom synchronisation with compatible cultivar may be another
reason for variation in initial fruit set among cultivars. The initial fruit set under open pollination is also inuenced by the closeness
from the compatible pollen source. In temperate fruits, fruit set depends on the prevailing weather during blooming and the envi-
ronment after fruit set. According to Ref. [28] pollination is essential for fruit formation. Pollen germination is very temperature
sensitive. Cross-pollination is the most common method of apple pollination; however, certain varieties have been observed to be
self-pollinating [29]. claimed that the impact of the previous temperature has a substantial inuence in the June apple drop. High
temperature during fruit growth period results in more transpiration (water loss) from leaves and fruits, and consequently such fruits
are unable to withstand the moisture stress and are then shed easily. According to Ref. [30] when fruit set was plentiful, apple fruit
with fewer than 3 seeds were shed rst. Fruit species (apple, pear, and quince) that produce fruits preferentially drop fruits with fewer
seeds. Such fruits are really more vulnerable to environmental challenges, such as water stress, nutritional inadequacy, and so on, and
are thus more likely to fruit drop [31]. Therefore, the larger seed content of the fruit is the most crucial need for it to remain on the tree.
Fruit drop on fruit trees at key growth phases is a problem for growers. According to Ref. [32] fruit drop severity is specic to cultivar.
Apple production is challenged by pre-harvest fruit drop, which occurs when fruit falls off the tree before it reaches horticultural
maturity. By the start of harvest, yield losses of up to thirty percent are typical, and they get worse with any harvest delay, depending
on the growing season and cultivar. Developmental and environmental cues have an impact on this apple fruit’s abscission. Cellulase
and polygalacturonase enzymes are involved in degradation of cell wall when metabolic changes are detected. While other plant
hormones may also play a role in abscission promotion, however ethylene has proven to be affecting this phenomenon. Fruit drop
varies between orchards under varying meteorological and agrological circumstances throughout the same year, and it also varies
between years within orchard [33,34]. Temperature, wind, nutrition, sunshine, water and disease pressure are all variables that differ
across years and locales. When resources are limited, growth and development of the plant changes so as to adapt to prevailing
Table-7
Effect of the growing season and cultivars on the reducing sugars and non-reducing sugars characteristics.
C.No. Cultivars (C) Reducing sugars (%) Non-reducing sugars (%)
2017 2018 2017 2018
1 Adam’s Pearmain 6.67 ±0.27
e
6.90 ±0.48
d
3.40 ±0.41
gh
2.88 ±0.37
h
2 Allington Pippin 5.32 ±0.32
h
5.16 ±0.91
h
4.28 ±0.35
c
4.82 ±0.39
c
3 Baleman’s Cider 5.72 ±0.51
g
5.63 ±0.49
f
3.92 ±0.33
d
4.47 ±0.41
d
4 Fuji Zehn Aztec 6.87 ±0.49
d
7.15 ±0.70
c
3.35 ±0.32
hi
2.58 ±0.51
i
5 Mollie’s Delicious 8.05 ±0.34
a
7.91 ±0.58
a
3.12 ±0.38
j
2.99 ±0.53
h
6 Red Gold 6.31 ±0.38
f
6.07 ±0.73
e
4.50 ±0.31
b
5.06 ±0.28
b
7 Red Velox 5.58 ±0.65
g
5.38 ±0.65
g
4.87 ±0.28
a
5.50 ±0.42
a
8 Shalimar Apple-2 6.89 ±0.43
d
6.76 ±0.47
d
3.65 ±0.41
ef
3.94 ±0.46
f
9 Shireen 7.93 ±0.33
a
8.01 ±0.49
a
3.22 ±0.29
ij
2.93 ±0.47
h
10 Silver Spur 7.03 ±0.34
d
6.92 ±0.50
d
3.74 ±0.37
e
4.09 ±0.34
ef
11 Starkrimson 6.88 ±0.38
d
6.75 ±0.54
d
3.82 ±0.40
de
4.22 ±0.38
e
12 Top Red 7.28 ±0.40
c
7.49 ±0.58
b
3.55 ±0.43
fg
2.18 ±0.46
j
13 Vance Delicious 7.69 ±0.81
b
7.43 ±0.60
b
3.43 ±0.51
gh
3.72 ±0.39
g
Mean 6.79 6.74 3.76 3.80
SE(m) ±0.01 ±0.02 ±0.02 ±0.05
Means in columns followed by different letters are signicantly different at p ≤0.05 based on Tukey’s multiple range test.
Table-8
Climatic data of two years (2017 and 2018) at the experimental site.
Month Year
2017 2018 2017 2018
Temperature (
o
C)
Maximum Minimum
January 3.94 10.73 −2.44 −4.87
February 10.61 12.3 0.10 −0.91
March 14.82 18.45 3.12 3.32
April 19.90 21.41 6.54 6.82
May 25.35 24.65 10.16 9.00
June 26.82 28.33 13.19 13.45
July 30.24 28.84 17.54 17.16
August 30.05 30.74 15.85 16.58
September 28.60 27.98 10.97 11.93
October 25.35 21.74 3.55 2.89
November 16.08 12.07 −0.78 0.22
December 10.18 9.37 −2.68 −4.56
M.T. Ali et al.
Heliyon 9 (2023) e17260
16
conditions [35]. As a result, these variables may cause early abscission in reaction to stress [36,37]. The variation in fruits per cluster
among cultivars may be an inherent character and also effected by environmental factors. The exact mechanism causing the
year-to-year variance is yet unclear. The number of fruits per cluster at harvest were 1.06–1.49 despite applying ower removing
techniques in Apple cultivar Golden Delicious [38]. Cultivar characteristic may be the reason for the variation of commercial maturity
dates among cultivars. The fruit maturity time is specic to cultivar in particular agro-climatic conditions with a minor shift depending
on climatic conditions. These ndings are corroborated by Ref. [39] conclusions that harvest timing is affected by location, cultivar,
rootstock, year and ecological factors. The variation in commercial maturity dates may also be due to difference in bloom dates,
prevailing temperature (Fig. 3), sunshine durations, overcast days and rainfall conditions during fruit growth period. Apple maturity
also gets delayed if cooler temperature prevails during summer. Variation in maturity enables the grower to select plant cultivars for
increasing the varietal spectrum, spreading harvest time to avoid glut in the market in order to fetch remunerative price of the produce.
Fruit weight showed huge variation among cultivars. The heaviest fruits were observed in cultivar Mollie’s Delicious while lightest
fruits in Baleman’s Cider. Larger fruit weight in case of Mollie’s Delicious can be explained from the related fact that the fruits of this
cultivar were signicantly longer and had signicantly larger diameter than other cultivars, as such had heavier fruits. In case of
Baleman’s Cider with lowest fruit weight, the data shows that the fruit diameter in this case was signicantly smaller than all other
cultivars and fruit length lower than the mean fruit length of cultivars. Thus it can be said that fruit length and diameter inuence the
fruit weight. The differential behavior of cultivars to fruit length, diameter and weight can be attributed to the fact that fruit size is
typical to each cultivar and is a varietal characteristic. Variations in fruit size may also be induced by environmental factors, crop load,
vigour of the tree and difference in both number and size of cells. Our ndings are in consonance with [40] who stated that the ge-
notypes of apple showed a range of fruit length 38.29–81.42 (mm), 46.00–94.99 (mm) for fruit diameter and 43.04–310.99g for fruit
weight. Similar studies reported that fruit diameters varied signicantly among apple genotypes [41–45]. Fruit rmness affects the
quality of fruit and storability of a cultivar. Fruit rmness (textural property) is mostly employed at the marketable level to identify the
ideal harvesting period; it is a damaging measurement and used in combination with other metrics to dene the stage of ripeness [46,
47]. The variation in fruit rmness among cultivars is an inherent feature as reported by Ref. [48]. Our results are in agreement with
[40] who reported fruit rmness among apple genotypes ranged from 3.99 to 14.05 kg/cm
2
. Further our ndings are also supported by
the results of [49] who observed that fruit rmness varied among cultivars and reported that in Well Spur, Silver Spur, Oregon Spur
and Vance Delicious it ranged from 7.5 to 9.6 kg/cm
2
. Further, supported by Ref. [50] who studied fteen cultivars and found rmness
ranging from 5.53 to 10.30 kg/cm
2
. Colour is one of the most important characters in organoleptic rating of a fruit. It is the visible
colour of the fruit that attracts or repels a consumer in the rst instance, though colour preference may differ among consumers. The
apple skin colour plays a profound role in determining maturity and identication as well as consumer demand because customers tend
to prefer mostly red coloured apples while some people are having a liking for green apples. Fruit skin colour is determined by ca-
rotenoids, chlorophyll and anthocyanin present in the skin [51]. Cultivar Adam’s Pearmain recorded poor fruit colour due to highest
hue angle whereas best fruit colour was noted in cultivar Red Velox due to lowest hue angle during both years. Lower the value of hue
angle corresponds to better red colour and vice versa. The variation in fruit colour of cultivars is mainly a varietal characteristic and
also inuenced by weather conditions, leaf to fruit ratio, altitude and management practices to some extent. Thus, there can be some
variation in fruit colour in a cultivar from year to year and place to place. Our ndings are in agreement with [52] who reported fruit
colour variation among apple cultivars: Gala Red Lum, Super Chief Sandidge, and Golden Clone B at maturity and found their fruit
colour (hue angle) of 34.86 h◦, 29.16 h◦and 79.46 h◦, respectively. Consumers may often identify specic fruit cultivars by their shape
[10]. Fruit shape showed wide variation with highest frequency for conic (38.46%) and globose (38.46%) followed by cylindrical
waisted (15.38%) and obloid (7.69%). The variances in fruit shape among cultivars may be due to their genetic makeup. Round,
conical, and oblate fruit shapes were prevalent in twenty two genotypes of apple [53]. Among fteen apple varieties, apple fruit form
ranged from conical to globose to oblate to cylindrical waisted [50]. Apple form and weight are inuenced by the quantity and
dispersion of seeds inside the fruit [54]. Variation in seed number per fruit among cultivars may be both due to genetic differences and
pollination factors. The effect of seeds on fruit growth is obvious in fruits with a very uneven shape associated with the presence of
seeds in locules on one side of the fruit [55]. Our results are supported by Ref. [56] who stated that the seeds number per fruit varied
from 6.50 in Galaxy Gala to 9.3 in Granny Smith. Auxin, cytokinine, and gibberellic acid are abundantly generated in the seed and
consequently has a good impact on fruit growth by boosting cell quantity and expansion. Additionally, these hormones are reported to
facilitate the transfer of plant nutrients into fruit [10]. The cultivars under trial exhibited signicant variations for leaf: fruit ratio, leaf
area, leaf chlorophyll content and yield efciency traits. Leaf: fruit ratio is the average number of leaves per fruit in a plant. According
to Ref. [57] most apple cultivars require 30 to 40 leaves per fruit for the formation of a high quality fruit. Variation obtained among
cultivars for leaf: fruit ratio may be due to factors such as genetic, environmental adaptability, alternate bearing tendency etc. and their
interaction with each other. Differences noticed in leaf area among cultivars may be due to genetic makeup of cultivars, environmental
effect, biotic and abiotic factors around cultivars. Chlorophyll is the pigment that gives leaves their characteristic green colour, and the
amount of chlorophyll per unit area is a measure of a plant’s photosynthetic ability [58]. The variations in the chlorophyll concen-
tration of the cultivars are in agreement with the ndings of [59], who discovered that cultivar Starkspur Golden Delicious had higher
leaf chlorophyll contents all season long than conventional Golden Delicious cultivar. The variation obtained among cultivars in leaf
chlorophyll content may be due to their genetic character as well as biotic and abiotic factors inuencing this trait. The yield efciency
of a tree is an essential indicator of its production [60]. Higher the yield efciency of a cultivar better will be its production, pro-
ductivity and prot. The variation obtained among cultivars in yield efciency may be due to factors such as genetic, bearing habit,
spur density, pollination, alternate bearing, hormonal uctuations, environmental adaptability etc. and their interaction with each
other. Fruit biochemical characteristics varied signicantly among cultivars. The components of total soluble solids (TSS) are organic
acids, sugars, and inorganic salts [46,61]. According to Ref. [47] a sensory panel’s perception of sweetness was best predicted by the
M.T. Ali et al.
Heliyon 9 (2023) e17260
17
amount of total soluble solids present. For a fruit to be accepted by consumers, internal qualities like sweetness are crucial. Since
evaluating sweetness through the senses is not always easy, the total sugar content can be measured to evaluate it [47,62]. Apples
contain soluble sugars, and organic acids, both of which affect apples tastes. Sucrose, glucose and fructose were the main soluble sugars
and main sugar alcohol was sorbitol in the mature Starkrimson apples [63]. Reducing sugars are those that have free aldehyde or
ketone groups. e.g. glucose, fructose, lactose etc. Reducing sugars consists monosaccharides. The sugar is non-reducing when two or
more monosaccharides are joined by their aldehyde or ketone groups, preventing these reducing groups from being free. An example of
this is sucrose [64]. The cultivars under study exhibited signicant differences in fruit chemical characteristics. Our outcomes are in
concurrence with results of [65] who stated that TSS content in apple germplasm varied from 12.55 to 19.24 ◦Brix. Our ndings for
total sugars are in range with ndings of [66] who reported that total sugars among cultivars varied from 9.76% in Braeburn to 14.50%
in Gala Must. Our results for reducing sugars are in tune to ndings of [67] who reported variation in reducing sugars among cultivars
which varied between 6.28% in Starkrimson to 8.81% in Early Red One. Our results for non-reducing sugars are in close range with
[68] who stated that non-reducing sugars ranged from 2.74% in Granny Smith to 3.71% in Gibson Golden among cultivars studied.
According to Ref. [69], apple cultivars sugar content can vary from orchard to orchard, year by year and between harvesting dates. As a
result, a minimal to maximal range values can be a guide, but there is no single value that can be used to distinguish each cultivar. The
sensory strength of the total organic acid content (tartaric acid, malic acid and citric acid) is the fundamental fruit quality charac-
teristic known as acidity (or sourness) [70]. Organic acids give apples their distinctively sour avour, inuencing how sweet things are
perceived as well as the intensity of the avor [46,71]. Cultivar Starkrimson; main organic acid was malic acid and other organic acids
were oxalic acid, succinic acid, acetic acid and citric acid were in minor amounts [62]. Our outcomes are in accordance with [64] who
reported titratable acidity in apple germplasm to range between 0.10% and 0.82%. Apple taste is primarily related to the amount of
sugar and acid in the fruit tissues and the balance between these. There is no single desirable level of sugar, acid, or sugar/acid ratio
that applies to all cultivars [55]. Fruit requires sugars to make it edible, but it also needs acids to improve the avour and keep the
sugars from tasting sickly or insipid [72]. Further, balance of TSS and acid has important role in consumer acceptance and contributes
towards giving many fruits their characteristic taste. The genetic variations across apple cultivars may account for the noticeable
variations in TSS, total sugars, acidity, reducing and non-reducing sugars. These genetic variations then inuence the synthesis of
photosynthates and their subsequent breakdown into simple metabolites. Our ndings of fruit chemical characteristics are within the
range. These chemical parameters may vary from region to region, year to year due to climate, weather, soil and management factors.
5. Conclusion
This investigation was the rst effort to explore the physico-chemical attributes of thirteen apple cultivars during two consecutive
years in the Kashmir region of Indian Himalaya. The results in this study demonstrate the signicant effect that cultivars and year can
have on the physico-chemical attributes on apples. Microclimates as well as management practices have a profound effect on fruit
physico-chemical qualities. The research data generated can be applicable to any part of world having similar agro-climatic conditions.
The knowledge produced here would serve an important document for scientists, farmers and all stakeholders. The apple cultivars
inspected in this study have a wide fruit characteristics diversity and, therefore can be used in breeding purpose for developing new
cultivars. Further, farmers gets wide choice of selection of cultivars for apple fruit production.
Funding
This research was funded by King Saud University Researchers Supporting Project Number (RSP2023R19), King Saud University,
Riyadh, Saudi Arabia.
Declaration of competing interest
The authors declare that they have no known competing nancial interests or personal relationships that could have appeared to
inuence the work reported in this paper.
Acknowledgements
The authors also extend their sincere appreciation to the Researchers Supporting Project Number (RSP2023R24), King Saud
University, Riyadh, Saudi Arabia.
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