فهرست مطالب روح الله یاوری نژاد

In some olive trees despite suitable vegetative growth and reproductive to maturity stage, fruits do not set and development do not occur, due mainly to lack of the adaptability. This research was conducted to determine the optimal time for topworking in olive trees using scions from two common cultivars in each of the six provinces including Fars, Khuzestan, Kermanshah, Lorestan, Ilam and Qazvin in Iran during 2021-2022. Results showed that optimal time for topworking in olive trees in Khuzestan was in the mid-October with cv. Conservolia scion, in Ilam in the second half of October with cv. Conservolia and cv. Diereh scions, in Lorestan in the first half of October with cv. Amygdalia scion, in Fars in the first half of October with cv. Consevolia scion, in Kermanshah in September with cv. Conservolia scion, in Qazvin on May 20th with cv. Conservolia scion.

In some olive trees despite suitable vegetative growth and reaching to maturity stage, fruits does not set and development do not occur, due mainly to lack of the adaptability (Hartman et al., 2017). Topworking has been practiced, for long-time, in some fruit trees such as pecan (Yates and Sparks, 1992) and walnut (Rezaee and Vahdati, 2008). Sometime in a region, a fruit tree variety is planted without assessment of its adaptability and quality properties. Therefore, its performance is not satisfactory and economically profitable. Therefore, changing the variety is necessary. In such a case, topworking-using scions from adapted and high yielding with desirable fruit and oil quality is a strategy to save farmer’s investments. It has been demonstrated that topworking in different olive varieties resulted in better vegetative growth and fruit yield. However, it differed with rootstock variety (Lion et al., 2020). In recent decades olive orchards in Khuzestan and Fras provinces in Iran has been established using olive varieties that are not well adapted and produce low yield with low quality (Ajamgard and Zeinanloo, 2013; Taslimpour, et al., 2016). To change the variety of olive orchard, olive producers should bear high costs. Therefore, topworking can help to graft scions from adapted high yield varieties on the rootstock of existing orchards. The main objective of this research was to determine the optimal time for topworking in olive trees in different regions of Iran, and to recommend the optimal time and suitable scion cultivars for each region. 

The experiments were carried out, during 2021 and 2022, as split-plot arrangements in completely randomized design with three replications. Grafting dates at five levels from Auguest 29th to November 28th (in Qazvin from May) were assigned to main plots, and olive cultivar at two levels (cv. Conservolia was common + one adapted cultivar in each location) were randomized in sub-plots. The grafting success rate and the scion growth were evaluated and recorded. Analysis of variance for data was performed using SAS 9.4 software. Duncan’s Multiple Range Test was employed for means comparsion at the 5% and 1% probability levels. 

The results showed that in Khuzestan province the mid-October was the optimal date for topworking of olive trees. Also cv. Conservolia’s scions had significantly (P ≤ 0.01) greater growth than cv. Avan scions. In Ilam province, the results showed that the maximum grafting success rate achieved in the second half of October with cv. Conservolia nd cv. Diereh scions. In Lorestan province, the grafting success rate, using scions of cv. Conservolia and cv. Amygdalolia were 88% and 80%, respectively, in the first half of October. In Fars province, the success of topworking in the first half of October was 80%, while the vegetative growth of cv. Conservolia’s scion was greater than cv. Amygdalolia. In Kermanshah province, the results showed that the grafting success rate of olive trees was significantly (P≤ 0.05) higher in September with cv. Consevolia scion. In Qazvin province, the results showed that the optimal date for topworking of olive trees was May 20th with grafting success rate of 75% and 94% for cv. Conservolia and cv. Zard, respectively. Hussain et al. (2021) reported that topworking in olive trees in Pakistan was more successful in June-July. Yates and Sparks (1992) and Rezaee and Vahdati (2008) also reported that topworking improved yield and quality of pecan and walnut, respectively.The highlight of the results of this research was determination of optimal time (optimal window) and suitable cultivars (scions) for topworking in olive trees in the six target regions in Iran. 

To select the high yielding and adapted pecan genotypes for Dezful climatic conditions in Iran, 50 seedling trees were evaluated in 2019-2021 in Dezful in southwest of Iran. The results showed that P200-7 and P200-8 genotypes had the largest and smallest nuts with 14.3 and 4.2 grams, respectively. P220-2-1 genotype had the highest and P200-9, and P220-2-5 genotypes had the lowest percentage of blank nuts. Kernel removal was easy in P200-1 and P200-10 genotypes, while it was very difficult in P200-3 and P200-31 genotypes. Fruit ripening time was the earliest in P200-1 and P220-2-5 genotypes and the latest in P200-23. P200-23, P220-1-1 and P200-9 genotypes had the highest yield index with 65, 49 and 39 g cm-2 of tree trunk, respectively. The results of evaluation for heat stress tolerance in pecan genotypes showed that 40 to 70% of the branches of all genotypes were damaged by hot temperatures in the summer of 2021 with 430 hours of temperatures above 45 oC, while the branches of P200- 23 genotype were not damaged. In addition, the results indicated that heat stress damage had significant correlation with yield index (r = 0.311*) and kernel color (r = 0.323*). There was highly significant (r = -0.597**) correlation between shell thickness and kernel removal. The relationship between mean fruit weight and nut length (r = 0.386**) and nut width (r = 0.440**) were also highly significant. Factor analysis showed that nut length, shell thickness, blank nuts percentage, nut weight, yield index and heat stress damage accounted for 67% of the total variance. Finally, P200-23 genotype with high yield index, golden bright kernel color and very high heat stress tolerance, and P220-1-1 genotype with high yield and low percentage of blank nuts were identified as promising genotypes for future supplemental research.

Investigation on adaptability of various olive cultivars in the Khuzestan climate conditions showed that most of the commercial cultivars in these regions were affected by the warm weather so that their yield and oil were strongly reduced. To obtain adapted olive cultivars with high yield and oil percentage, several studies were implemented at Safiabad Agricultural Research Center since 1998. Among genetic resources, a genotype, Avan, that had different oil accumulation process from other genotypes was identified. Preliminary evaluations showed that oil accumulation curve in Avan was double sigmoid and its oil content exceeded 20%, while the oil content in other local cultivars, such as Dezful and Zard, can rarely exceed 10%. For further evaluations, Avan plants were cultivated in Baghmalek, located in the east of Khuzestan province, in 2007. The results of experiments in Baghmalek also showed that the oil accumulation process of Avan had double sigmoid curve. The average yield of 6-years-old trees of Avan was 17 kg with 21% oil content in the fresh fruits. In contrast, the amount of oil content in Mavi (local olive cultivar in Baghmalek) was 10.5% and in Conservolia foreign cultivar this amount was less than 10%. Results of these studies showed that Avan is an adapted olive cultivar for subtropical regions with the ability to produce 5 to 7 tons of fruit and 1000 to 1200 kg of oil per hectare. Using Avan in subtropical regions of Iran such as east of Khuzestan, south of Fars and Kermanshah provinces and similar regions, can increase the yield of oil in olive orchards about 300-400 kgha-1. Avan is tolerant to biotic and abiotic stresses so that no signs of damage by pests and diseases as well as sunburn and drying on its branches have been observed so far.