Selection of the promising accessions of jamun (Syzygium cumini (L.) skeels) based on pomological characterizations

Abstract Jamun (Syzygium cumini [L.] Skeels) is one of the most potential underutilized fruit crops. Here, phenotypic and pomological variability among 61 accessions of this species was investigated. Analysis of variance (p < .01) revealed significant differences among the accessions studied based on the traits recorded. Ripening date ranged from late June to mid‐July. Fruit color was purple in 13, dark purple in 30, and black in 18 accessions. Fruit weight ranged from 2.12 to 8.95 g, and fruit flesh thickness varied from 1.25 to 6.78 mm. Principal component analysis showed that fruit‐related characters are very important in differentiating among selections. The studied accessions were divided into two groups and several subgroups based on cluster analysis, which showed the phenotypic variations among them. Beside the significant differences among the accessions of different regions, significant variation was observed between the accessions of each region. The obtained results are useful for designing conservation strategies for the germplasm as well as implementing breeding programs, such as introducing cultivars with different goals, including early or late ripening and seedless, nonastringent, large, and deeper color‐fruits. Based on the fruit quality attributes, such as fruit weight, color, and taste; eight accessions, including Pirdan‐3, Soldan‐1, Pirdan‐6, Soldan‐5, Nasirabad‐3, Soldan‐3, Nasirabad‐8, and Ganjabad‐11, were selected which can be cultivated directly in orchards or used as parents in breeding programs.

. Violet oil extracted from jamun seeds can be used as an effective agent against diabetes and heart and liver troubles (Sagrawat et al., 2006). The antioxidant activity of jamun fruits is due to their total phenolic compounds, which include anthocyanins.
The main sugars in the ripe fruits of jamun are glucose and fructose with no trace of sucrose. Due to the fact that the medicinal properties of jamun fruits, especially their antidiabetic properties, have been determined, so in recent years, this fruit has been considered popular.
The presence of malic acid, oxalic acid, gallic acid, and tannins has increased the medicinal value of the fruit. Also, the nutritional value of the jamun fruit is high. The fully ripe fruits with the taste of subacid spice flavor are eaten fresh and can also be used and processed into jam, jelly, squash, wine, vinegar, and pickle. Its foliage is used as feed for cattle. Its wood can be used in buildings, agricultural implements, and railway sleepers (Agarwala et al., 2019). Tree growth habit -Weeping (1) Spreading (3) Open (16) Semierect (25) Erect (16) Tree growth vigor -Low (6) Moderate (26) High (29) , 2017). Characterizing the available germplasm to identify the elite genotypes of higher yield, better fruit quality, and adaptability is of utmost importance in jamun crop improvement programs. In addition to these fruit quality attributes, genotypes with dwarf tree stature, less vigorous types, and off season bearing need to be explored in view of area expansion and productivity in jamun (Khan, & Vaishali, Sharma, 2010). Thus, the present study was taken up to know the extent of variability existing among the accessions available in Sistan-va-Baluchestan province, Iran.

| Plant material
In the present study, phenotypic and pomological variability among 61 accessions of jamun (S. cumini) selected from six natural habitats in Sistan-va-Baluchestan province, Iran was investigated. The natural habitats studied included Soldan, Ganjabad, Rask, Nasirabad, Pirdan, and Shardar. Geographical coordinates and altitude corresponding to each surveyed area are presented in Table 1. To avoid the possibility of sampling and collecting clones of the selected accessions, the appropriate distance was considered between the accessions in each site.

| The characters evaluated
Forty-two morphological and pomological characters were used to determine phenotypic variability of the studied accessions (Table 2).
A total of 50 leaves and 50 fruits per accession were randomly selected to evaluate the morphological and pomological traits. The traits, including leaf length, leaf width, petiole length, petiole width, fruit length, fruit width, fruit stalk length, fruit stalk diameter, seed length, and seed diameter, were measured using a digital caliper.
Fruit and seed weight was measured using an electronic balance with 0.01 g precision. The remaining characters were qualitatively measured based on rating and coding (Table 3).

| Statistical analysis
Analysis of variance (ANOVA) was performed to evaluate the variation among accessions based on the traits measured using SAS software (SAS® Procedures, 1990). Simple correlations between traits were determined using Pearson correlation coefficients (SPSS Inc., Chicago, IL, USA, Norusis, 1998). Principal component analysis (PCA) was used to investigate the relationship between accessions and determine the main traits effective in genotype segregation using SPSS software. The PCA is the simplest of the true eigenvector-based multivariate analyses.
Often, its operation can be thought of as revealing the internal structure of the data in a way that best explains the variance in the data (Iezzoni & Pritts, 1991). Hierarchical cluster analysis (HCA) was performed using Ward's method and Euclidean coefficient using PAST (Paleontological Statistics) software (Hammer et al., 2001). The first and second principal components (PC1/ PC2) were used to create a scatter plot with PAST software.

| RE SULTS AND D ISCUSS I ON
The ANOVA (p < .01) revealed significant differences among the accessions studied based on the traits recorded. Leaf serration and F I G U R E 1 The pictures of leaves and fruits of Syzygium cumini accessions studied leaf serration depth showed the highest coefficient of variation (CV) (128.68% for both characters). Also, the CV was higher than 50.00% for trunk type, leaf lower surface color, the tendency to form suckers, leaf serration shape, fruit shape, and leaf shape (68.64%, 59.36%, 57.81%, 55.83%, 52.13%, and 51.64%, respectively). In contrast, seed length showed the lowest CV (9.52%), followed by petiole width (10.45%), fruit length (10.97%), seed diameter (11.00%), leaf length (12.59%), leaf width (14.86%), and petiole length (15.93%) (  from India. Din et al. (2020)  The pictures of leaves and fruits of S. cumini accessions studied are shown in Figure 1.
The positive and negative correlations were observed between the recorded characteristics (Table 4) that have significant and high correlations with that desired trait can be indirectly used to measure it (Forde, 1975).
For the PCA, components with eigenvalues of more than 1.00 were retained to uphold reliability of the final output. Thus, 13 principal components (PCs) were observed which contributed 84.69% of total variance (Table 5). The values above 0.56 were considered to be significant for the studied traits. The PC1 explained 15.40% of total variance and was represented by fruit length (0.93), fruit diameter (0.93), fruit weight (0.90), flesh thickness (0.81), seed length (0.87), seed diameter (0.73), and seed weight (0.87) with positive correlations. Din et al. (2020) reported that fruit weight, fruit diameter, seed length, and seed weight were positively correlated with PC1 in a S. cumini germplasm from Pakistan, and suggested that these descriptors are very important in differentiating among selections.
Fruit quality and yield-related characters (fruit to pulp ratio, fruit size, etc.) have high economic concern (Andres- Agustin et al., 2006) and can be used as target characters by plant breeders and growers (Mehmood et al., 2014). The PC2 explained 9.64% of total variance and was constituted by leaf serration (0.96), leaf serration shape

TA B L E 5 (Continued)
analyzing breeding materials dealing with the morphological characterization of S. cumini (Anushma & Sane, 2018;Devi et al., 2016;Devi et al., 2019;Din et al., 2020;Ningot et al., 2017;Singh & Kaur, 2016;Swamy et al., 2017). Besides, the association between the natural habitats studied was visualized in greater detail according to the morphological characters. Based on the biplot created using PCA of the population analysis, the studied six natural habitats formed four groups ( Figure 4). Soldan area was placed in the first group, and Shardar area was placed in the second group. Also, Nasirabad formed the third group, while the fourth group consisted of rest of the areas, including Ganjabad, Rask, and Pirdan.
Broad phenotypic diversity existed among the studied S. cumini accessions. Beside significant variations among the accessions of different collection areas, great variability was found within the same varietal group. The considerable phenotypic variation observed here indicated that such germplasm is valuable genetic resource for S. cumini improvement. Therefore, it has become imperative to establish strategies for preserving wild S. cumini germplasm and conserving these genetic resources. Variation evident in case of qualitative and quantitative characteristics among accessions collected from same geographical area might be due to different genetic makeup (Karadeniz & Ekşi, 2002;Singh et al., 2015).
These characters can be used as a tool for cultivar identification (Sharif et al., 2019). Fruit color and shape are best indicators of ripening and have been extensively used for cultivar identification in researches (Agrawal et al., 2017). Most dependent traits for fruit characterization are fruit apex, base, and shape (Sharif et al., 2019).
Diversity in such traits was also observed as an important character for selection of plants by Bal et al. (1992) and Rodrigues et al. (2008). Several studies from other countries have been reported on morphological characterization of S. cumini collections (Devi et al., 2016;Ningot et al., 2017;Singh & Kaur, 2016;Swamy et al., 2017). While identifying the elite ones with better yield and fruit quality, emphasis needs to be given for dwarf types with compact canopy for effective utilization of limited land available (Anushma & Sane, 2018). Modern trend of selection and breeding for important cultivars has narrowed the diversity of several fruits (Mehmood et al., 2014;Sharif et al., 2019), and there is a prerequisite for exploration and evaluation of new sources of natural diversity in jamun with specific implication for improvement and germplasm management.

| CON CLUS ION
In the perennial fruit crops like jamun (S. cumini), elite clonal selection is mostly adopted for conventional crop improvement. The present data may help in the development of strategies for S. cumini Soldan-5, Nasirabad-3, Soldan-3, Nasirabad-8, and Ganjabad-11, could be selected for direct cultivation in the orchards and used in breeding programs.

ACK N OWLED G EM ENT
None.

CO N FLI C T O F I NTE R E S T
The authors declare no conflict of interest.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.