Search

The evergreen tree olive (Olea europaea L.) is the only species of the genus Olea that produces edible fruits with high ecological and economic value. This tree species has developed a series of physiochemical mechanisms to tolerate drought stress and grow under adverse climatic environments. One of these mechanisms is photosynthesis activities, so that as yet little information achieved about the relations between olive production and photosynthetic parameters under drought conditions. An experiment was carried out during two consecutive years (2015–2017) to study the response of 20 different olive tree cultivars (Olea europaea L.) to drought stress. Several parameters like net photosynthetic rate (PN), stomatal conductance (GS), transpiration rate (TE), photosynthetic pigments (total chlorophyll, chlorophyll a, b and carotenoid) and fruit yield were measured. The results of combined analysis of variance for fruit yield and other measured traits showed that year, drought treatment, cultivar main effects and their interactions were highly significant. The results indicated that drought stress reduced all traits, however GS (42.80%), PN (37.21%) and TE (37.17%) significantly affected by drought. Lower reduction in photosynthetic performance (PN, GS and TE) in the cultivar T7 compared to other olive cultivars allowed them to maintain better fruit yield. Principal component analysis (PCA) identified two PCs that accounted for 82.04 and 83.27% of the total variation in photosynthetic parameters under optimal and drought stress conditions, respectively. Taken together, mean comparison, relative changes due to drought and biplot analysis revealed that cultivars ‘T7’, ‘Roghani’, ‘Koroneiki’, ‘Korfolia’ and ‘Abou-satl’ displayed better response against drought stress. According to our results, one olive cultivar namely ‘T7’, could be used in olive breeding programs to improve new high yielding cultivars with drought tolerance for use in the drought-prone environments.

This research aimed to determine the most suitable time to harvest olive fruits (Olea euopeae cv. Zard) infected with olive fly larvae based on the quality and quantity of the extracted oil. The experiment factors included the fruit type at two levels (1: infected fruits, 2: healthy fruits) and the harvest time at six levels (0: the time of olive fly larvae exit, 1: one week after the fly larvae exit, 2: two weeks after the olive fly larvae exit, 3: three weeks after the olive fly larvae exit, 4: four weeks after the olive fly larvae exit and 5: five weeks after the fly larvae exit). The fresh oil of fruit was extracted and analyzed for measuring qualitative and quantitative characteristics. The results showed that the effect of fruit type was significant on the extinction coefficient at 232 and 270nm (K232 and K270). The effect of harvest times was significant on K320, oil percent (p≤0.05) and acidity (p≤0.05), but had no significant effect on K270 and peroxide (p≤0.05). The interaction effect of fruit type and harvest time was significant only on acidity (p≤0.05) and was not significant on other parameters. Based on the results, the healthy fruits had lower acidity and peroxide number and higher oil percentage than infected fruits and therefore had better quality. It can be concluded that the best time to harvest the fruit was two weeks after the larva leaves the fruit because, after that, the negative effects of olive fly larvae on the quantity and quality of fruit oil are high, while before that, quality indicators of the fruit are not affected by olive fly larvae.

Objective The olive is considered as one of the most important horticultural crops, with more abundant number of cultivars. Thus, the aim of this research was to study the genetic diversity in a set of olive cultivars in Taroum station of Tran. Materials and methods In this research, 25 CBDP markers were used to study the genetic diversity and relationships of 20 promising and commercial Iranian and foreign varieties of olive. Results The 25 used primers amplified a total of 755 polymorph alleles, and the mean of PIC and MI indices were 0.941 and 5.64, respectively, indicating the high efficiency and differentiation power of CBDP markers. The genetic parameters of Nei and Shannon indices were higher in foreign cultivars than those of Iranian cultivars. The high gene flow (4.46) was observed among olive cultivars, which confirmed the low values of the inter-population differentiation (Gst) and FsT indices. Analysis of molecular variance (AMOVA) differentiated the total genetic variation into inter-group (Iranian and foreign cultivars) (17%) and within-group (83%) diversity. The cluster analysis using Dice coefficient and UPGMA method divided the Iranian and foreign cultivars into five groups, which the promising cultivar T24 and Koroneiki with the maximum difference with others were placed in separate groups. The Principal Coordinate Analysis (PCoA) was able to distinguish promising Iranian cultivars from the other commercial cultivars. The population structure analysis confirmed the results of the cluster and PCoA analysis and clearly separated the two groups of Iranian and foreign cultivars. Conclusions In conclusion, it was observed that the promising cultivar T24 with having a genetic similarity to both groups of Iranian and foreign cultivars can be a suitable candidate for commercialization with complementary characteristics of both groups. Also, it is recommended to use this marker to study the genetic diversity of other olive varieties.