Identification of the promising accessions of spistan (Cordia myxa Roxb.) using morphological and fruit‐related traits

Abstract Spistan (Cordia myxa Roxb.) is a potentially underutilized fruit plant in arid and semi‐arid regions. It has long been associated with health and nutrition. Morphological diversity of 75 accessions of this species was evaluated. The accessions studied showed significant differences in terms of the characters measured. Ripening date varied from late May to mid‐July. Fruit color was yellow‐cream in 54, light orange in 8, and orange in 13 accessions. The range of fruit weight was 0.71–11.83 g with an average of 3.12, while fruit flesh thickness ranged from 0.63 to 7.86 mm with an average of 2.55, and fruit jelly part thickness varied between 1.34 and 6.40 mm with an average of 2.75. Principal component analysis could describe the evaluated traits as the nine main components that were able to justify 79.04% of total variance. Hierarchical clustering showed that the accessions were placed into two main clusters using the measured traits data, exhibiting a wide range of variability. Based on the traits related to selection of the ideal genotype, such as big fruit size, high fruit flesh thickness with high yield, and longer harvesting period, 11 accessions, including Jangal‐4, Jangal‐9, Rask‐7, Jangal‐5, Jangal‐6, Jangal‐11, Rask‐1, Jangal‐1, Rask‐4, Rask‐5, and Rask‐2, were superior. It is recommended to use the best accessions selected in breeding programs. The commercial orchards of those best accessions should be extensively constructed to take advantage of the high yield of C. myxa as a crop and its medicinal properties.

Cordia myxa is a fruit tree with high medicinal and nutritional value that grows well in arid and semi-arid regions. Because it is a multipurpose plant, its value in nutrition and health is of interest (Chandra and Pareek, 1992). Its fresh unripe fruits have a very unpleasant odor and are used for vegetables and pickles when conventional vegetables are not available. This plant plays an important role in the rural economy of arid regions because it can provide food (pickles and vegetables) and fuel wood (Chandra et al., 1994). Its fruits have a high medicinal value and are used for diseases of the chest and urinary passage. Its fruit flesh is used as birdlime, and its kernel is used to cure ringworm (McCann, 1985). Its fruits are rich in carbohydrates and phosphorus and contain 40 mg/100 g of ascorbic acid (Pareek and Sharma, 1993).
The first step in any breeding program is to evaluate and be aware of the variation available. The breeding programs are dependent on the diversity in the nature of the plant in different climatic conditions. Vavilov (1951) was the first to state that high diversity in each plant increases the chances of better selection for the desired traits. Most of the successful tree breeding programs are those that use the right provenance (Zobel and Talbert, 1984). Genetic diversity within and between plant populations can be significantly revealed through morphological assessments. There are very few studies on phenotypic diversity of C. myxa in the world (Sivalingam et al., 2012;Meghwal et al., 2014), while there is no information about diversity of this species in Iran. Therefore, the aim of the present study was to determine the phenotypic diversity of this species using the important morphological traits and to select the best plant materials to be used in future breeding or cultivation programs.

| Plant material
Morphological diversity of 75 accessions of C. myxa was evaluated from three areas of Sistan-va-Baluchestan and one area of Khuzestan provinces, Iran. Geographical coordinates and altitude corresponding to collection sites are shown in Table 1. The appropriate distances were considered between the accessions in each collection site to avoid the possibility of sampling and collecting clones of the selected trees.

| The characteristics evaluated
A total of 48 quantitative and qualitative morphological and pomological traits (Table 2) were used for phenotypic evaluations. The traits related to dimensions of different organs were measured using a digital caliper. Bunch weight, fruit weight, and fruit stone weight were measured using an electronic balance with 0.01 g precision.
Also, the remaining characteristics were qualitatively estimated based on rating and coding (Table 3).

| Statistical analysis
Analysis of variance (ANOVA) was performed to evaluate the variation among the accessions based on the traits measured using SAS software (SAS Institute, 1990). Simple correlations between traits were determined using Pearson correlation coefficients (SPSS Inc., Norusis, 1998). Principal component analysis (PCA) was used to investigate the relationship among the accessions and determine the main traits effective in accession segregation using SPSS software.
Hierarchical cluster analysis (HCA) was performed using Ward's method and Euclidean coefficient using PAST software (Hammer et al., 2001). The first and second principal components (PC1/PC2) were used to create a scatter plot with PAST software.

II-B
PCA could describe the evaluated traits as the nine main components that were able to justify 79.04% of total variance ( Scatter plot analysis was performed using PC1 and PC2, which accounted for 50.70% of total variance ( Figure 2). The accessions that were in close proximity were more similar in terms of effective traits in PC1 and PC2 and were placed in the same group. Also, hierarchical clustering was performed based on the dissimilarity of the accessions. The accessions were clustered into two main clusters using the measured traits data (Figure 3). The first cluster con- Hence, information on variability among the desirable characteristics and their correlation is vital for any breeding program (Johnson et al., 1955). Therefore, a species exhibiting a wide range of variability (in terms of a characteristic's value and high standard deviation) offers ample scope for undertaking screening for the desired traits (Nagar et al., 2013).
The observed variation in a characteristic is partly composed of genetic (heritable) variation and partly of nonheritable. The proportion of total variation, which is due to genetic differences, is termed as heritability in a broad sense (Nagar et al., 2013). that the improvement in these traits can be made through direct selection (Nagar et al., 2013). The C. myxa has high potential to be exploited at the industrial or commercial level (Chandra and Pareek 1992) which requires an ideal genotype having big fruit size (9.00-12.00 g), high fruit flesh thickness with high yield, and a long harvesting period (Samadia 2005).

| CON CLUS ION
Since there are no known commercial cultivars in C. myxa, improvement work for developing new cultivars should be F I G U R E 4 Bi-plot for the studied populations of C. myxa based on the morphological characters undertaken. Based on the traits related to the selection of the ideal genotype, such as big fruit size (9.00-12.00 g), high fruit flesh thickness with high yield, and longer harvesting period, 11 accessions, including Jangal-4, Jangal-9, Rask-7, Jangal-5, Jangal-6, Jangal-11, Rask-1, Jangal-1, Rask-4, Rask-5, and Rask-2, were superior. It is recommended to use the best accessions selected in breeding programs. The commercial orchards of those best accessions should be extensively constructed to take advantage of the high yield of C. myxa as a crop.

ACK N OWLED G M ENT
None.

FU N D I N G I N FO R M ATI O N
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.

R E S E A RCH I N VO LV I N G H U M A N PA RTI CI PA NTS A N D/ O R A N I M A L S
None.

I N FO R M E D CO N S E NT
None.