Evaluation of Quantitative and Qualitative Traits of Some Apricot Cultivars Grown in Zanjan Region

Introduction Apricot (Prunus armeniaca L.) has special position in Iran fruit culture industry. In terms of cultivation and producing, Iran is one of the major countries in the world but in terms of export Iran is ranked 23. For this reason, research on necessities of fruit culture industries and access to new cultivars by breeding project is required. Obviously, paying attention to quality and quantity of products and using of local germplasm that known completely, played a significant role in this project. Apricot with genomic feature 2n=16, has extensive diversity due to sexual propagation and cultivation in different areas. Central Asia and Caucasian groups of apricot that involving Iranian and Turkish cultivars, have greatest phenotypic variations, while European group including cultivars that cultivated in North America, Australia and South Africa have the lowest diversity. Climate adaptation, increasing of fruits quality, self-compatibility and resistance to diseases are the most important goals of apricot breeding. Of course, the quality of fruits depends on sugar and acid balance and special aroma. One of the important targets of apricot breeding is introduce and develop of cultivars that can be cultivated in extensive areas. Target of recent study is primary evaluating of morphological and pomological traits of some cultivar and genotypes of apricot grown in Zanjan province. In order to introduce the cultivars that produces fruit with high quality and complete scientific researches to selection of ideal cultivars in this region for future. Method and material: This research carried out on four cultivars (Badami, Daneshkadeh, Shekarpareh, Shahroodi) and two genotypes (C and D) and was conducted in a completely randomize design with three replications. Evaluating of tree, branch, leaf, flower and some fruit traits performed based on existing descriptor. For determining some important pomological traits, fruits harvested in commercial time and transferred to laboratory. For measuring total soluble solid (TSS), refractometer (model: ATAGO-N1) was used. To determinetitratableacidity (TA) titration with 0.1 N NaOH method and for measuring pH content, pH-meter (model: JENWAY 3020) was used. The weight of fruit and stone was measured with digital balance. Flesh fresh weight also was determined with digital balance and flesh dry weight was measured after 72 hours dried in oven. Finally flesh firmness was determined with presser meter (model: OSK 1618). For evaluating fruit set percent, flowers of some branches in every cultivar was numerated then primary and final fruit set percent was calculated after 10 and 30 days, respectively. Data analysis was done with SAS 9.1, SPSS 20 and Statistica 10 software. Results and discussion: The results of qualitative data that analysis with non- parametric (Kruskal-wallis) method showed significant differences among some genotypes and cultivars. In terms of corebitternes strait genotype D showed significant differences with other cultivar and genotypes. Due to this trait, genotype D is suitable for use as rootstockbecause the genotypes with kernel are suitable for cultivation in lime and semi dry soil and also are resistant nematode. In terms of blooming time, genotype D (late blooming)had significant differences with genotype C, Badami and Shahroodi cultivars. Because of this trait, genotype D is resistance to late spring chilling injury. Based on trees growth habit, genotype C (long growth habit) showed significant differences with Shekarpareh cultivar (widespread growth habit). In terms of flower bud distributions genotype C (blooming on annual branches) showed significant differences with genotype D and Daneshkadeh cultivar (blooming on spurs). According to these traits genotype C is suitable for dense cultivation orchards and need to prune every year like peach. Results of correlations among traits showed that TA has negative significant correlations with flesh dry weight, TSS/TA ratio and flesh weight/stone weight ratio. During fruit ripening TA rates was decreased and TSS rates were increased, so during of TSS increasing as one of the non-structural components of dry matter, flesh dry weight increasing simultaneously. Positive correlations between flesh dry weight and TSS/TA ratio indicate that cultivars with big fruits have high dry matter, so they are sweeter than other cultivars. Also aprincipal component analysis (PCA) was used to determine the number of important factors that influenced on morphological identification. The results of PCA showed that total variance (90.2%) is justified by two factors. The first factor (73.05%) included all fruit traits, leaf length and first and second fruit set percent. The second factor (17.21%) contained flower diameter, core length and juice percent. Consider to this analysis, Shahrodi, Daneshkadeh and Shekarpareh cultivars were settled near each other but Badami cultivar, Cand D genotypes were placed separately. Conclusion: According to the results, high diversity was observed among genotypes and cultivars. This diversity provides suitable genetic resources for breeding works. Results of this study showed that Daneshkadeh cultivar has the biggest fruits and Shahroodi cultivar has the most rates of TSS and flesh firmness, so this cultivar has long storage life. Finally, the Shekarpareh cultivar showed the most flesh dry weight and flesh weight/stone weight ratio, so this cultivar is suitable for processing.