ISRN Agronomy

Volume 2012 (2012), Article ID 326461, 9 pages

doi:10.5402/2012/326461

Research Article

Morphological and Pomological Diversity of Fig (Ficus carica L.) Cultivars in Northwest of Tunisia

Badii Gaaliche,¹ Olfa Saddoud,² and Messaoud Mars¹

¹U.R. Agrobiodiversity, High Agronomic Institute, IRESA, University of Sousse, Chott Mariem 4042, Tunisia

²National Gene Bank, Boulevard Yesser Arafet, Charguia 1, Tunis 1080, Tunisia

Received 2 April 2012; Accepted 29 May 2012

Academic Editors: K. Aitken, T. Koba, and X. Xu

Copyright © 2012 Badii Gaaliche et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract.

The fig (Ficus carica L.) is one of the oldest fruit trees cultivated in Tunisia. Djebba region is located in the northwest of Tunisia. It is very famous by fig culture. Many specific fig genotypes are very appreciated locally and nationally. Taking into account these considerations, Djebba fig cultivars are subject of label products, namely, “Djebba figs.” This study was focused on fig germplasm characterization of 17 cultivars in Djebba region based on morphological and pomological traits. Results revealed a large variability within the local fig germplasms. The comprehensive analyses of all the data permitted to distinguish some particular genotypes as distinct cultivars, and groups of cultivars as polyclone varieties. It was possible to discriminate six distinct cultivars and two groups of multiclone varieties (Soltani and Thgagli) with different degrees of polymorphism. Hypotheses of homonymy and synonymy were suggested for some cultivars. The diversity is currently threatened by genetic erosion. Measure of conservation is necessary to be undertaken.

1. Introduction

The common fig (Ficus carica L., 2n = 26) belongs to the family Moraceae, with over 1400 species classified into about 40 genera. The genus Ficus contains about 700 species, mainly found in the tropics and currently classified into six subgenera [1]. Nowadays, the common fig grows wild in the Mediterranean Basin where it has been cultivated for its edible fruits for millennia in close association with olive and grapevine [2]. Three types of figs are grown commercially [3]: the common type that develops fruit parthenocarpically, the Smyrna type that requires pollination with pollen from caprifigs (caprification), and the San Pedro type that produces a first crop parthenocarpically and a second crop only after pollination. Total world fig production is over 1 million tons and 70% is produced in Turkey, Egypt, Greece, Iran, Morocco, Spain, and USA. Turkey produces nearly 25% of the total production [4].

In Tunisia, fig biodiversity is very high, and many niches are well suited for fig production. Despite its socioeconomic and historical importance, fig tree was considered as a secondary crop. Fig trees are grown all over the country, with more than 2,500,000 trees occupying about 33800 ha. The total annual production is about 27.000 mile tons [5]. Figs are mainly consumed as fresh fruits. A small portion is sun dried and little quantities are used for jam and alcoholic beverage production [6]. Tunisian fig cultivars are numerous and well adapted to local agroecological conditions [7]. Some are of the common type. Many others are of Smyrna type [8]. It should be stressed that several studies have reported the use of pomological traits in a number of Tunisian ecotypes collected from different zones [9]. Thus, 65 cultivars were described by Minangoin [10], 22 cultivars by Valdeyron and Crossa-Raynaud [11], and 28 by Lahbib [12]. It is noteworthy that a number of these cultivars have been destroyed as a consequence of the intensive urbanization in recent decades. Moreover, severe genetic erosion is also threatening the remaining germplasm. Thus, available information about the ancient landraces is very limited [6].

In order to preserve fig genetic resources, several prospections and alternative strategies for genetic resources management were considered. Pomological and morphological traits as well as molecular markers were used to analyse genetic diversity and characterize local cultivars [8, 13–19]. Recently, various studies on fig genetic resources are continuing across the country. But no research results have been reported so far on northwest fig germplasm. This study is part of a project of the “Union Tunisienne de l’Agriculture et de la Pêche” aiming to establish a label to Djebba’s fig. The objectives are (i) identification of different fig cultivars grown in Djebba area and (ii) analysis of genetic diversity within the germplasm.

2. Materials and Methods

2.1. Plant Material and Study Area

This study concerned the region of Djebba (altitude, 700 m; latitude, 36° 40′N; longitude 9°0′E) located at the northwest of Tunisia. The climate is subhumid with mild winter and hot summer. Annual average temperature is around 20°C. Thermal amplitude is about 16.5°C in summer and 8°C in winter. Average annual rainfall is about 600 mm. The morphological and pomological variability was studied on adult fig trees of 17 local cultivars (one tree per cultivar) grown in this region (Table 1).

Table 1: Studied fig cultivars.

N°
Cultivar
Code
Type

1
Zidi
ZD1
Smyrna

2
Zidi Artab
ZD2
Smyrna

3
Soltani Abiadh
SAB
Smyrna

4
Soltani Ahmar
SAH
Smyrna

5
Thgagli Abiadh
TAB
Smyrna

6
Thgagli Akhdher
TAK
Smyrna

7
Nemri
NMR
Smyrna

8
Hemri
HMR
Smyrna

9
Bouhouli
BHL
San Pedro

10
Wahchi
WAH
San Pedro

11
Garaï
GRI
San Pedro

12
Khenziri
KNZ
San Pedro

13
Khartoumi
KRT
Smyrna

14
Boukhobza
BKB
Smyrna

15
Zergui
ZRG
Smyrna

16
Bouharrag
BHR
Smyrna

17
Fawari
FAW
Smyrna

San Pedro produces first and second crops and Smyrna produces only second crop.

2.2. Morphological and Pomological Traits

Morphological and pomological parameters were chosen according to the fig descriptors [20]. On branches, 13 parameters related to the dimensions of shoots and internodes were measured (Table 2). For each cultivar, measurements were made after fall of leaves on six shoots per tree. For leaves, 16 parameters related to the lamina and petiole were measured on 20 mature leaves per tree and cultivar (Table 2).

Table 2: Morphological and pomological traits used for fig cultivar characterization.

Traits
Code

Branch

    Terminal bud length (mm)
TBL

    Terminal bud diameter (mm)
TBD

    TBL/TBD ratio
TBL/TBD

    1-year-old shoot length (mm)
S1Y

    Length of the 1st internode on S1Y (mm)
L1N1Y

    Diameter of the 1st internode on S1Y (mm)
D1N1Y

    Length of the 2nd internode on S1Y (mm)
L2N1Y

    Diameter of the 2nd internode on S1Y (mm)
D2N1Y

    2-year-old shoot length (mm)
S2Y

    Length of the 1st internode on S2Y (mm)
L1N2Y

    Diameter of the 1st internode on S2Y (mm)
D1N2Y

    Length of the 2nd internode on S2Y (mm)
L2N2Y

    Diameter of the 2nd internode on S2Y (mm)
D2N2Y

Leaf

    Leaf shape (1: calcarate; 14: cordate)
LS

    Shape of lobes (1: lyrate; 4: spatulate)
SL

    Leaf color (1: light green; 12: dark green)
LC

    Leaf margin dentation (1: undulate; 5: crenate)
LMD

    Apex shape (1: truncate; 3: acute)
AS

    Density of hairs (1: none; 7: pubescent/dense)
DH

    Petiole color (1: light green; 6: pinkish)
PC

    Leaf length (cm)
LL

    Leaf width (cm)
LW

    Petiole length (mm)
PL

    Petiole diameter (mm)
PD

    Depth of basal sinus (mm)
DBS

    Depth of lateral sinus 1 (mm)
DLS1

    Depth of lateral sinus 2 (mm)
DLS2

    Depth of lateral sinus 3 (mm)
DLS3

    Depth of lateral sinus 4 (mm)
DLS4

Fruit

    Fruit weight (g)
FW

    Fruit length (mm)
FL

    Fruit diameter (mm)
FD

    Neck length (mm)
NL

    Neck diameter (mm)
ND

    Ostiole diameter (mm)
OD

    Fruit shape (1: spheroid; 10: pyriform)
FS

    External color (1: violet black; 13: yellowish green)
EC

    Skin cracks (1: cracked skin; 4: not cracked skin)
SC

    Internal color (1: greenish white; 11: red)
IC

    Fruit cavity (3: very small; 9: large)
FC

    Skin thickness (mm)
ST

    Flesh thickness (mm)
FT

    pH
pH

    Total soluble solids (°Brix)
TSS

    Titratable acidity (%)
TA

On fruits (second crop), 16 parameters related to the size, external and internal appearance, and juice quality were taken into account (Table 2). During the harvesting period, pomological measurements and chemical analysis carried out on samples of 20 mature fruits per tree and cultivar were randomly collected. Total soluble solids (°Brix) were determined with a digital refractometer, PR-101 ATAGO, and Norfolk, and titratable acidity (citric acid %) was determined by titrating fig juice with 0.1 M NaOH.

2.3. Statistical Analysis

For all parameters, analysis of variance (one-way ANOVA) was used to determine differences between cultivars. Comparison of the mean values was made using the Duncan’s multiple range test (). Multivariate relationships among cultivars were revealed through a principal component analysis (PCA) using a correlation matrix derived from the significant characters. The squared Euclidean distance was used to perform cluster analysis. Statistical analyses were computed using SPSS 13.0 statistical software.

3. Results

3.1. One-Way ANOVA

The average values of parameters measured on branches are shown in Table 3. Analysis of variance showed highly significant differences between cultivars for all parameters except terminal bud diameter (TBD). The study of morphological characteristics of fig tree shoots allowed the differentiation in biology of some cultivars such as Zidi (ZD1), Zidi Artab (ZD2), and Nemri (NMR). Moreover, the most discriminating variables were terminal bud length (TBL), 1-year-old shoot length (S1Y), and 2-year-old shoot length (S2Y).

Table 3: Mean values and significance degree of differences between fig cultivars for branch characteristics.

Cultivar
TBL (mm)
TBD (mm)
TBL/TBD
S1Y (mm)
L1N1Y (mm)
D1N1Y (mm)
L2N1Y (mm)
D2N1Y (mm)
S2Y (mm)
L1N2Y (mm)
D1N2Y (mm)
L2N2Y (mm)
D2N2Y (mm)

ZD1
9.70def
5.27
1.82bcde
240.30a
38.13a
11.17bc
39.59a
10.33abc
264.90a
36.05
14.38ab
39.06b
13.74ab

ZD2
7.73f
5.33
1.46e
166.65cd
24.27cde
13.61ab
21.67defgh
12.08a
164.42bcd
30.28
15.62a
24.79bcd
15.41a

SAB
8.57ef
4.69
1.82bcde
125.29d
15.19e
7.69d
16.33fgh
6.51d
131.00bcd
23.12
8. 27h
18.52d
8.55fg

SAH
8.30ef
5.31
1.58de
135.36cd
18.18cde
9.68cd
15.32gh
9.23bcd
144.83bcd
20.17
11.43cde
20.58bcd
11.29cde

TAB
11.29bcde
4.86
2.32a
157.08cd
22.76cde
8.32cd
19.01efgh
7.36de
152.32bcd
22.00
10.11efgh
17.05d
10.47def

TAK
10.77cdef
5.15
2.12abc
169.80cd
18.64cde
9.03cd
19.94defgh
9.04bcd
122.24cd
18.61
10.50efg
18.55d
10.22defg

NMR
11.82bcd
5.92
1.98abcd
234.74ab
35.19ab
14.63a
35.99ab
10.76ab
192.88b
27.08
13.45bc
30.70abc
13.17bc

HMR
13.07abc
5.95
2.29ab
164.16cd
23.68cde
9.13cd
23.65defgh
9.13bcd
172.96bc
24.20
10.96def
27.44bcd
10.30defg

BHL
15.15a
6.48
2.33a
181.04cd
20.44cde
10.44cd
25.70cdef
9.86bc
162.56bcd
28.07
12.11cde
31.11abc
12.07bcd

WAH
9.19def
5.09
1.80cde
155.29cd
25.03cde
8.75cd
26.73bcde
8.45cd
138.06bcd
30.07
8.99fgh
32.02ab
8.77fg

GRI
11.15cde
5.18
2.14abc
169.08cd
24.32cde
9.82cd
24.28cdefg
9.90bc
145.97bcd
20.15
10.14efgh
23.69bcd
10.37def

KNZ
9.40def
5.25
1.80cde
187.30bc
26.62bcd
8.63cd
29.87bcd
9.12bcd
157.47bcd
26.47
8.38h
41.50a
9.37efg

KRT
9.72def
5.94
1.67cde
133.84cd
22.42cde
11.52bc
28.63bcde
10.41abc
127.76bcd
27.67
12.65bcd
27.40bcd
11.86bcd

BKB
10.03def
5.89
1.89abcde
147.82cd
17.46de
11.11bc
13. 81h
10.03bc
122.07cd
22.61
13.30bc
19.82cd
13.08bc

ZRG
14.08ab
6.13
2.33a
154.10cd
25.23cde
11.11bc
25.71cdef
10.72ab
147.05bcd
23.23
13.07bcd
23.64bcd
13.04bc

BHR
8.30ef
5.31
1.58de
161.59cd
18.18cde
9.68cd
15.32gh
9.23bcd
144.83bcd
20.70
12.67bcd
19.64cd
11.94bcd

FAW
9.51def
4.54
2.10abc
151.43cd
27.78bc
7.73d
33.77abc
6.62d
104.72d
22.59
8.52gh
21.21bcd
8. 08g

F-value
5.04**
1.22NS
3.93**
3.12**
4.03**
3.82**
6.15**
5.76**
3.42**
1.72NS
11.09**
4.26**
8.40**

Means in each column followed by the same letters are not significantly different at according to Duncan’s multiple range test.

ignificant at ; ignificant at ; NS: nonsignificant; TBL: terminal bud length; TBD: terminal bud diameter; TBL/TBD: TBL/TBD ratio; S1Y: 1-year-old shoot length; L1N1Y: length of the 1st internode on S1Y; D1N1Y: diameter of the 1st internode on S1Y; L2N1Y: length of the 2nd internode on S1Y; D2N1Y: diameter of the 2nd internode on S1Y; S2Y: 2-year-old shoot length; L1N2Y: length of the 1st internode on S2Y; D1N2Y: diameter of the 1st internode on S2Y; L2N2Y: length of the 2nd internode on S2Y; D2N2Y: diameter of the 2nd internode on S1Y.

The averages of characters related to leaf are shown in Table 4. Analysis of variance showed highly significant differences between cultivars for all parameters. The variability of leaf characteristics was very important and allowed the distinction between some cultivars for several parameters such as leaf shape, leaf margin dentation, and leaf dimensions (LS, LMD, LL, and LW), petiole color (PC), and the depth of basal and lateral sinus (DBS and DLS1, DLS2, DLS3, DLS4).

Table 4: Mean values and significance degree of differences between fig cultivars for leaf characteristics.

Cultivar
LS
SL
LC
LMD
AS
DH
PC
LL (cm)
LW (cm)
PL (mm)
PD (mm)
DBS (mm)
DLS1 (mm)
DLS2 (mm)
DLS3 (mm)
DLS4 (mm)

ZD1
12.84a
2.53e
6.63de
5.00a
2.79abc
4.79cdef
3.00fg
29.45a
25.42a
99.05ab
7.67a
46.37a
88.25ab
89.43a
- -
- -

ZD2
12.76ab
3.86a
6.43def
4.05b
2.74abc
3.86ghi
3.48cdef
30.05a
26.10a
94.58abcd
7.20ab
53.18a
77.72bc
76.64b
- -
- -

SAB
11.85c
3.45abc
3.05h
2.20d
2.95a
2.60k
3.95bcd
22.57cd
19.60cd
75.12fg
6.15c
11.00gh
70.07cd
71.10bc
- -
- -

SAH
8.00d
3.00cde
3.30h
2.95cd
2.65abcd
4.70cdefg
5.05a
21.97cde
19.33cde
86.95bcdef
5.75cd
17.28fgh
86.23ab
88.36a
35.95bc
37.65bc

TAB
7.25ef
3.25bcd
9.05ab
2.95cd
2.60bcd
4.60defg
3.85bcd
21.06cdef
19.23cdef
102.78 a
5.63cd
25.24cdef
78.02bc
73.44bc
34.16bc
31.92cd

TAK
12.25bc
3.85a
7.60bcd
2.70cd
2.65abcd
5.90ab
4.10bc
16. 71h
16. 10g
61. 32h
5.08de
13.34gh
38.41 e
39.97f
- -
- -

NMR
7.70de
3.20bcd
7.30cd
3.25bc
2.95a
3.60hij
2. 25h
25.71b
22.34b
76.30fg
7.00b
22.78cdef
90.46a
93.01a
40.54ab
41.02ab

HMR
12.35abc
2.90cde
2. 60h
2.45cd
2.85ab
5.30bcd
3.70bcde
20.08efg
18.07def
93.57abcde
5.64cd
11.10gh
69.87cd
67.80bcd
- -
- -

BHL
12.85a
2.95cde
2.95h
3.05cd
2.85ab
3.20ijk
3.50cdef
20.34defg
17.53efg
82.76def
5.57cd
18.88efg
59.02d
57.73de
- -
- -

WAH
7.55def
2.90cde
2.90h
2.85cd
2.90ab
5.50abc
4.10bc
21.21cde
19.52cde
85.44cdef
5.65cd
9. 49h
70.30cd
71.89bc
28.58cd
28.58de

GRI
7.30ef
2.80de
3.55gh
2.35cd
2.85ab
3.00ijk
2.50gh
21.36cde
19.04cdef
84.70def
5.46cd
23.57cdef
67.44cd
68.47bcd
28.61cd
27.12de

KNZ
11.90c
3.10cde
4.85fg
2.85cd
2.95a
5.10bcde
3.95bcd
18.93fg
17.29fg
81.21ef
4.68e
—
48.17e
47.94ef
- -
- -

KRT
6.40g
2.70de
8.85bc
2.10d
2.40d
3.20ijk
2.60gh
21.58cde
19.82cd
102.05a
5.86c
21.06def
92.12a
88.76a
46.41a
45.92a

BKB
2. 95h
2.95cde
5.65ef
2.25cd
2.80abc
6.30a
3.20ef
20.63def
18.86cdef
89.26bcde
6.12c
29.80bc
70.11cd
76.51b
38.81b
37.73bc

ZRG
7.55def
3.75ab
5.15ef
3.00cd
2.60bcd
4.20fgh
3.35def
23.23c
20.03cd
65.44gh
5.93c
26.31bcde
65.03d
63.47cd
23.81d
21.82e

BHR
7.10f
3.70ab
8.65bc
5.00a
2.50cd
4.30efgh
4.20b
18.20gh
17.26fg
80.92ef
5.81c
28.12bcd
71.07cd
70.33bc
31.13cd
31.04cd

FAW
7.35ef
3.05cde
10.45a
5.00a
2.70abc
2.90jk
5.20a
26.18b
20.89bc
97.32abc
7.43ab
33.57b
95.03a
91.55a
38.94b
40.49ab

F-value
267.18**
5.16**
23.52**
10.62**
3.12**
16.00**
16.24**
25.79**
18.64**
9.34**
14.60**
24.76**
16.58**
14.23**
7.43**
10.33**

Means in each column followed by the same letters are not significantly different at according to Duncan’s multiple range test.

ignificant at ; ignificant at ; NS: nonsignificant; —: absence of basal sinus; - -: absence of lateral sinus 3 and 4.

LS: leaf shape; SL: shape of lobes; LC: leaf color; LMD: leaf margin dentation; AS: apex shape; DH: density of hairs; PC: petiole color; LL: leaf length; LW: leaf width; PL: petiole length; PD: petiole diameter; DBS: depth of basal sinus; DLS1: depth of lateral sinus 1; DLS2: depth of lateral sinus 2; DLS3: depth of lateral sinus 3; DLS4: depth of lateral sinus 4.

The averages of characters related to fruit are given in Table 5. Analysis of variance showed highly significant differences between cultivars for all parameters. The most discriminating variables were fruit weight (FW) and fruit dimensions (FL, FD).

Table 5: Means values and significance degree of differences between fig cultivars for fruit characteristics.

Cultivar
FW (g)
FL (mm)
FD (mm)
NL (mm)
ND (mm)
OD (mm)
FS
EC
SC
IC
FC
ST (mm)
FT (mm)
pH
TSS (°Brix)
TA (%)

ZD1
96.45a
60.27a
60.52a
5.31cd
14.70a
12.74a
3.79cdef
1.79hi
4.00a
8.84abc
4.37bcdef
1.18de
12.13g
4.65ef
13.23g
0.21fg

ZD2
51.83ef g
47.03de
43.90gh
7.71bc
11.80bc
5.81defg
3.90cde
1.86h
1.76f
9.95a
3.10efgh
1.25cd
17.56abc
4.88cd
15.95ef
0.17h

SAB
59.10cde
61.50a
45.82fgh
14.43a
12.06bc
6.45cdef
4.50bc
11.95a
1.55f
9.00abc
1.90h
1.53ab
18.31ab
4.52gh
15.46f
0.25a

SAH
44.45ghi
51.09bc
39.93i
14.89a
13.54ab
5.50efg
5.65a
3.25f
3.45bcd
9.35ab
3.70defg
1.05e
16.01cde
5.10a
15.58f
0.18h

TAB
62.20cd
42.75ef
53.65c
—
—
8.22b
2.70g
12.00a
3.75abc
7.85c
6.40a
1.26cd
9.05h
4.89cd
15.56f
0.20fg

TAK
51.95efg
42.17f
50.26de
5.95cd
9.66cde
5.18fg
3.15efg
10.95c
2.90e
8.95abc
6.00ab
1.56ab
14.86de
4.45h
15.96ef
0.22bcdef

NMR
82.36b
46.57def
58.62ab
—
—
7.34bc
3.00fg
4.50d
3.75abc
8.25bc
4.60bcde
1.48b
19.07a
4.82d
16.48de
0.23abcde

HMR
57.83cde
58.12a
44.95fgh
10.90b
11.45bc
4.84g
5.00ab
3.70e
3.45bcd
8.80abc
2.20gh
1.43bc
18.90ab
4.59fg
17.56c
0.25a

BHL
64.53c
48.38cd
56.03bc
3.44d
10.58cd
5.08fg
3.15efg
2.65g
3.90ab
4.65e
5.70abc
1.05e
16.00cde
4.91bcd
15.36f
0.21cdef

WAH
41.67hij
43.50ef
44.27gh
5.92cd
10.97bcd
6.36cdef
3.40efg
11.40b
3.70abc
6.30d
2.80fgh
1.16de
17.85abc
4.95bc
19.02a
0.23abc

GRI
54.23def
45.86def
49.99de
3.91cd
7.55e
7.12bcd
2.70g
10.00c
3.60abc
3.05f
4.70abcde
1.05e
19.24a
4.29i
16.32de
0.21defg

KNZ
44.27ghi
44.31def
47.34efg
5.21cd
10.42cd
5.78defg
2.85g
11.30bc
3.35cd
8.50bc
5.00abcd
1.54ab
12.13g
4.97bc
18.32b
0.23abcd

KRT
52.77defg
46.36def
47.99ef
5.71cd
11.31bc
5.81defg
4.25bcd
10.35c
3.80abc
8.55bc
4.20cdef
1.19de
14.24ef
4.46h
17.20c
0.24ab

BKB
34.54j
35.20g
43.81h
4.26cd
8.34de
5.59efg
3.55defg
11.90a
3.70abc
9.00abc
3.10efgh
1.72a
11.34g
4.71e
15.48f
0.22bcdef

ZRG
37.38ij
43.06ef
45.49fgh
—
—
6.85cde
2.70g
1.85h
3.10de
6.65d
5.20abcd
1.63ab
15.45de
5.00ab
16.84cd
0.19gh

BHR
46.87fgh
42.76ef
43.98gh
—
—
6.44cdef
3.15efg
1.40i
3.80abc
2.00f
2.70fgh
1.55ab
12.40fg
4.91bcd
17.00cd
0.21efg

FAW
53.58defg
53.64b
52.99cd
6.34cd
11.78bc
6.41cdef
3.85cdef
2.15h
3.60abc
5.45de
4.10cdef
1.58ab
16.89bcd
4.55fgh
17.26c
0.25a

F-value
26.00**
26.30**
28.16**
21.32**
5.50**
23.00**
10.46**
977.45**
23.24**
29.54**
6.12**
13.13**
21.22**
46.17**
31.75**
10.00**

Means in each column followed by the same letters are not significantly different at P < 0.05 according to Duncan’s multiple range test.

ignificant at P < 0.05; ignificant at P < 0.01; NS: nonsignificant; —: neck less fruit.

FW: fruit weight; FL: fruit length; FD: fruit diameter; NL: neck length; ND: neck diameter; OD: ostiole diameter; FS: fruit shape; EC: external color; SC: skin cracks; IC: internal color; FC: fruit cavity; ST: skin thickness; FT: flesh thickness; TSS: total soluble solids; TA: titratable acidity.

3.2. Principal Component Analysis

Principal component analysis(PCA) was performed taking into account shoots, leaves, and fruits. The eigenvalues obtained by PCA indicate that the first three components provide a good summary of the data. They explained 51.91% of the total variability. The first component, PC1, had large positive loading for shoot length of the two years (S1Y and S2Y), lengths of the 1st, and 2nd internode on S1Y (L1N1Y and L2N1Y), diameters of the 1st, and 2nd internode on SY2 (D1N2Y and D2N2Y), depths of basal and lateral sinus (DBS, DLS1 and DLS2), leaf dimensions (LL and LW), fruit weight and diameter (FW and FD), and ostiole diameter (OD) and negative loadings for petiole color (PC), fruit external color (EC), and total soluble solids (TSS). It represented 26.46% of the total variation (Table 6). This component separated the cultivars Zidi (ZD1) and Nemri (NMR) from Soltani Abiadh (SAB), Thgagli Akhder (TAK), and Khenziri (KNZ) based on shoot length, fruit size, depth of sinus, and ostiole diameter. It allowed the distinction of cultivars Bouharrag (BHR) and Wahchi (WAH) from ZD1 based on petiole color, fruit size, and total soluble solids (Figure 1). The second component, PC2, explained 13.67% of the variability observed. It is positively correlated with fruit length and shape (FL and FS), fruit neck dimensions (NL and ND) and negatively correlated with terminal bud length (TBL), 1-year-old shoot length (S1Y), and fruit cavity (FC). This component allowed the distinction of cultivars Zergui (ZRG), Bouhouli (BHL), Garaï (GRI), KNZ, and TAK from SAB, Soltani Ahmar (SAH), and Hemri (HMR) on the basis of fruit shape, fruit neck, and cavity (Figure 1). The third component, PC3, accounted for 11.78% of the total variability estimated from shoots, leaf, and fruit traits. It is positively correlated to the apex shape (AS), fruit length (FL), and titratable acidity (TA), and negatively correlated to the internode diameter of shoots of the two years (D1N1Y, D2N1Y and D1N2Y, D2N2Y), shape of lobes (SL), depth of basal sinus (DBS), and pH. This component allowed the differentiation of cultivars Fawari (FAW), SAB, and HMR with thin shoots and acid fruits from cultivars Boukhobza (BKB), BHR, ZRG, and SAH presenting thick shoots and low acid fruits (Figure 1). The projection of cultivars in the 1–3 plot exhibited the distinction of some cultivars with particular traits such as ZD1 and Zidi Artab (ZD2) and others which are grouped together and having similar characters such as (SAB, WAH, and KNZ) and (BKB, BHR, and ZRG) (Figure 1).

Table 6: Definition the first three components of ACP made on the basis of morphological and pomological traits of fig cultivars.

Principal components
PC1
PC2
PC3

Cumulative, %
26.46
40.13
51.91

Proportion, %
26.46
13.67
11.78

Character*
Eigenvalue

TBL
0.01

0.23

SY1

0.28

L1N1Y

−0.22
0.34

D1N1Y
0.61
−0.24

L2N1Y

−0.19
0.53

D2N1Y
0.47
−0.38

SY2

−0.16
0.20

D1N2Y

−0.16

L2N2Y
0.45
−0.28
0.48

D2N2Y
0.61
−0.24

SL
−0.29
−0.08

AS
0.02
−0.05

PC

0.50
0.00

LL

0.32
−0.11

LW

0.27
−0.19

PD

0.38
−0.12

DBS

0.06

DLS1

0.55
−0.05

DLS2

0.54
−0.07

FW

−0.04
0.43

FL
0.35

FD

−0.40
0.48

NL
−0.18

−0.09

ND
0.41

0.18

OD

−0.09
0.20

FS
−0.01

0.00

EC

−0.19
0.25

FC
0.10

0.07

pH
0.04
−0.05

TA
−0.28
0.17

TSS

−0.02
0.16

ee Table 2.

Figure 1: Plot of the first and third principal components resulting from a PCA of the fig cultivars using morphological and pomological characters.

3.3. Cluster Analysis

Morphological and pomological analysis based on different characters showed high polymorphism with 17 fig cultivars. The dendrogram based on squared Euclidian distance clustered cultivars into five major groups (Figure 2). The first cluster was constituted with three cultivars: Zidi, Zidi Artab (ZD2), and Nemri (NMR). ZD2 was the most divergent from the other cultivars (). It is characterized by long internodes, spatulate, and large leaves, deep sinus, and acid fruit juice. The cultivars ZD1 and NMR meet at d = 15.9. They shared the long shoots, large fruits size, and leaves with serrate margin dentation. The cultivar Soltani Abiadh (SAB) formed the second cluster at d = 16.9. This cultivar had the shortest shoots, flattened buds, and cordate leaves with apex acute. The fruits were very long, crackled with high acid juice. The third group, detached at d = 15.9, was constituted with the unique cultivar Fawari (FAW). It is distinguishable, particularly, by short vegetative shoots and internodes, flattened buds, and dark green, large and crenate leaves, with deep sinus and yellow petiole. Fruit shape was oblate producing high acid juice. The cultivar Soltani Ahmar (SAH) formed the fourth cluster at d = 12.85 of the remaining genotypes. It has short and thin shoots with flattened buds. The fruits were relatively small, purple with very thin skin, and give low acid juice with high pH. The leaves were pubescent, serrate with widened lobes and rounded apex. The fifth group consisted of 11 cultivars with a maximum internal dissimilarity level of 10. This cluster was divided into three subgroups. The first subgroup, detached at d = 10, comprised the cultivar Thgagli Akhder (TAK). It is distinguished essentially from the remaining genotypes by small leaves with spatulate lobes, shallow sinus, and short petioles. The second subgroup contained the cultivar Bouharrag (BHR) associated with a level d = 7.85 to the three cultivars Thgagli Abiadh (TAB), Boukhobza (BKB), and Khartoumi (KRT). They are characterized particularly by green leaves with widened lobes, fruits oblate, and sweetened juice. The third subgroup consisted of six cultivars with a maximum internal dissimilarity level of 7.61. Two subsets were identified in this third subgroup. Subset 1 composed of cultivars Garaï (GRI) and Bouhouli (BHL) which associated between them at high level of similarity (d = 2.37) and rejoined the cultivar Zergui (ZRG) at d = 7.61. These cultivars presented conical buds, light green cordate leaves, and oblate fruits without neck. Subset 2 composed of cultivars Khenziri (KNZ), Wahchi (WAH), and Hemri (HMR) having cordate leaves with widened lobes and serrate margin dentation, acute apex, and yellowish green petiole. The fruits give a sweetened juice. WAH and KNZ have the highest level of similarity observed (d = 0.71). The averages values of their main characteristics were similar.

Figure 2: UPGMA dendrogram (based on squared Euclidian distance) of fig cultivars performed using morphological and pomological characters.

4. Discussion and Conclusions

Morphological and pomological traits considered in this study showed a large variability for Djebba figs. Among the 45 variables analyzed, those of high discriminating level were leaf dimensions, shoot dimensions, petiole color and dimensions, depth of sinus, fruit shape and color, fruit weight and dimensions, ostiole diameter, and juice acidity. Results of the PCA based on shoots, leaf, and fruits traits showed that 51.91% of the total variability is accounted by the three PCs. Studies based on morphological and pomological traits conducted for pomegranate and peach founded, respectively, 49.29% [21] and 63% [22] of the total variability. Characters related to shoots, leaf, and fruits were powerful for studying the genetic diversity of domestic fig in Djebba. Results showed that, among these characters, some were good criteria for discriminating between cultivars. Similar results were reported by Salah et al. [9] in fig collection in the oasis of Nefzaoua and by Chatti et al. [13] in fig collection in Chott Mariem. In addition, morphological study based on the characteristics of fig trees has shown that the first three axes of the PCA amounted to 71.7% and 81.9% of the total variability, respectively, for leaves and fruit traits [15].

The cluster analysis showed high degree of diversity in the germplasm of Djebba fig. Among the cultivars with the same names, there is a similarity between Soltani Abiadh (SAB) and Soltani Ahmar (SAH) and between Thgagli Abiadh (TAB) and Thgagli Akhder (TAK). However, the levels of similarity observed were not always high enough to believe that they are synonymous. Both cultivars Soltani have almost the same characteristics of shoots and leaf and differed mainly by the fruit external color. Both cultivars Thgagli have a significant similarity in terms of shoots and fruit, while they have a divergence in leaf and petiole. Thus, for Soltani and Thgagli, it seems to be “polyclones cultivars” or “multiclones cultivars.” Both cultivars Zidi and Zidi Artab have many differences that were focused on shoots strength developed during the two years. Also, differences were noted for leaves and fruits. The hypothesis of homonymy between these two cultivars could be proposed.

Significant similarities were observed among the cultivars Wahchi (WAH), Khenziri (KNZ), and Hemri (HMR) and between Garaï (GRI) and Bouhouli (BHL) for all morphological and pomological traits. Thus, it seems to be a case of synonymy between these cultivars.

The characters adopted in this study could be used to establish a catalog of local fig cultivars. The concordance between the results of PCA and cluster analysis showed that morphological and pomological analysis can provide reliable information on the variability in fig tree. The overall analysis of all traits brings out a wide diversity in plant material that may have important implications for genetic resources management. This diversity could be due to the antiquity of the culture in this mountainous region and particular cultural practices [7]. More interest has been focused on the diversity since it was known that the domestication of fig tree occurred independently in different areas especially around the edge of the Mediterranean. Thus, it is very interesting to conduct the proper management of these genetic resources. This can be addressed by different tools such as the establishment of ex situ collections. The on-farm conservation can ensure the sustainability of these resources. It is also possible to explore the techniques of tissue culture as an alternative as future protocols for in vitro micropropagation and even cell-cultured fig are already developed [23–26]. Further studies are needed involving chemical, biochemical, and molecular markers [14, 16, 17, 19]. They would clarify the genetic variation at the molecular level in these cultivars.

Acknowledgments

This study is part of research program of the Research Unit on Agrobiodiversity (UR03AGR04) financed by the Ministry of Higher Education, Scientific Research and Technology (Tunisia). Authors would like to thank Mrs. W. Brini for data analysis and technicians and farmers for their efficient collaboration.

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