Evaluation of Fruit and Oil Yield of Olive Cultivars in Southern and Western Regions of Iran

Low fruit and oil yield are the most important challenges of olive production in the southern and western regions of Iran. For identifying and selecting high-yielding olive cultivars adapted to the environmental conditions of these regions, this research was carried-out in Fars (Kazeroun), Khuzestan (Baghmalek), and Kermanshah (Reejab) provinces. For this purpose, in each province in 2013, an orchard was established with 10 olive cultivars, four trees of each cultivar, using randomized complete block design with three replications. The vegetative and reproductive traits were measured and estimated in 2022 and 2023. The 10 olive cultivars included: Mavi, Keup, Avan, Tokhm Kabki, Dosty, Shiraz, Dehghan, Dakal, Amygdalolia and Konservolia. The results showed that in Kazeroun cv. Keup had the highest fruit yield (22 kg tree^-1) and oil yield (3 kg tree^-1). In Baghmelek cv. Keup and cv. Konservolia had the highest fruit yield (30 and 25 kg tree^-1, respectively), and oil yield (2.9 kg tree^-1). In Reejab, cv. Shiraz, cv. Dakal, cv. Tokhm Kabki, cv. Keup and cv. Konservolia had the highest fruit yield, respectively. Also, oil content in fresh matter of the olive cultivars in Reejab was 1.5 to 2.2 percent higher than in Kazeroun and Baghmalek.
 
Keywords:  Olive, vegetative traits, oil content, oil content in fresh matter, oil content in dry matter.
 
Introduction
Low fruit and oil yields are the most important challenges for olive production in the southern and western regions of Iran. Warm weather, dry air and high evaporation in the southern regions of Iran including; Fars, Khuzestan and Kermanshah provinces, cause a decrease the quantity and quality of olive fruit and oil yileds. High temperature stress reduces flower formation and proportion of perfect flowers (Zeinanloo et al., 2015), photosynthesis and assimilation (Nissim et al., 2020), oil accumulation (Zeinanloo et al., 2015; Conde et al., 2008), and fruit and oil quality (Khaleghi et al., 2015). Cv. Koroneiki has high fruit yield and oil content in the north of Iran. Its oleic acid content is more than 70 percent, however, it has very low fruit yield and oil content (less than 6%) in the southern part of Iran, and its oleic acid content is reduced to less than 40 percent (Ajamgard and Zeinanloo, 2013). Therefore, it is very important to select adapted olive cultivars with high fruit yield and oil content for the establishment of new olive orchards in these regions. This research was carried-out to select adapted olive cultivars with high fruit yield and oil content for Fars, Khuzestan and Kermanshah provinces.
 
Materials and Methods
To identify and select adapted and high-yielding olive cultivars for the southern and western regions of Iran, this research was carried-out in the provinces of Fars (Kazeroun), Khuzestan (Baghmalek), and Kermanshah (Reejab) provinces. For this purpose, in each province in 2013, an orchard was established with 10 olive cultivars, four trees of each cultivar, using randomized complete block design with three replications. The vegetative and reproductive traits were evaluated in 2022 and 2023. The 10 olive cultivars included: Mavi, Keup, Avan, Tokhm Kabki, Dosty, Shiraz, Dehghan, Dakal, Amygdalolia and Konservolia. The distance between the trees was
6 × 6 meters. In Reejab, terracing was created due to the slope and rocky nature of the land, and agricultural soil was used to fill the holes during planting.
The soil texture in Baghmalek and Kazeroun was clay-loam with the depth of agricultural soil of more than one meter. The trees were irrigated using drip irrigation system with four drippers of four liters hour^-1. Olive trees were pruned in the second year after planting. Fertilizers applied based on soil test and trees requirements was carried out according to the results of the soil test. Vegetative and reproductive traits including; tree height, trunk-cross sectional area, annual growth of  branch, flower number in cluster, perfect flower percentage in cluster, fruit weight, fruit yield tree^-1, fruit flesh percentage, oil content of fruit, oil content in fresh matter, oil content in dry matter and oil yield trees^-1, were measured and estimated.
 
Results and Discussion
The results showed that in Kazeroun cv. Keup had the highest fruit yield (22 kg tree^-1) and oil yield (3 kg tree^-1). In Baghmelek cv. Keup and cv. Konservolia had the highest fruit yield (30 and 25 kg tree^-1, respectively), and oil yield (2.9 kg tree^-1). In Baghmalek, cv. Avan had the highest oil content in fresh and dry matter of fruit. In Reejab, the average size of the trees was 47% smaller than Baghmalek and 23% smaller than Kazeroun.  In Reejab, stones of fruit were smaller and the percentage of fruit flesh was higher than the other two regions. Also, in Reejab, cv. Shiraz, Dakal, Tokhm Kabki, cv. Keup and cv. Konservolia had higher fruit yield than other cultivars, respectively. The oil content in fresh matter of olive cultivars in Reejab was 1.5 to 2.2% higher than in Kazeroun and Baghmalek. Cv. Avan, in Reejab, reached a record of 29 percent of oil content in fresh matter. Zeinanloo et al. (2015) reported that cv. Koroneiki had high fruit yield and oil content in the north of Iran. However, this cultivar had very low fruit yield and oil content (less than 6%) in the southern part of Iran (Ajamgard and Zeinanloo, 2013). According to the results of this research, selection of adapted olive cultivars with high fruit yield and oil content for Fars, Khuzestan and Kermanshah provinces is very important.
 
References
Ajamgard, F. and Shafiei, Z. A. 2007. Collection and evaluation of olive
 (Olea europaea L.) germplasm of Khuzestan province. Iranian Journal of Horticultural Science and Technolog, 7(4), pp.229-242.
Conde, C., Delrot, S. and Gerós, H. 2008. Physiological, biochemical and molecular changes occurring during olive development and ripening. Journal of plant physiology, 165(15), pp.1545-1562. https://DOI.org/10.1016/j.jplph.2008.04.018
Nissim, Y., Shloberg, M., Biton, I., Many, Y., Doron-Faigenboim, A. and Zemach, M. 2020. High temperature environment reduces olive oil yield and quality. PLoS One, 15(4), pp.1-24. DOI: 10.1371/journal.pone.0231956
Zeinanloo, A. A., Arji, I., Taslimpour, M., Ramazani Malak Roodi, M. and Azimi, M. 2015. Effect of cultivar and climatic conditions on olive (Olea europaea L.) oil fatty acid composition. Iranian Journal of Horticultural Science, 46(2), pp.233-242. DOI: 10.22059/IJHS.2015. 54619