پکان

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.

Characteristics of forty pecan genotypes in Golestan province were evaluated for three years using pecan descriptor. Cluster analysis based on quantitative and qualitative traits of fruit, fruit shape and maturity time, divided genotypes into ten main groups. Factor analysis was employed for defining the determinant factors, and the characteristics constituting each factor. The effective traits were categorized within four factors which accounted 70% of total variance. Within each factor, characters with coefficient values of more than 0.5 were considered significant. Factor analysis revealed that the traits of fruit shape, nut and oil percentage, kernel fresh and dry weight, fruit dimension, length to width ratio and shell thickness were some of the characteristics that constituted the main factors. Based on the obtained results and observation through these three years, six trees (genotypes) G2, G3, G4, G19, G20 and G28 showed better performance than the other genotypes.

Considering the importance of grafted seedlings for the development of pecan orchards in subtropical regions of Iran, and in order to achieve a scientifically practical method of producing grafted pecan seedlings, this project was carried out in Safiabad Agricultural Research Center of Dezful during 2011-12. The project investigated three grafting methods including hot cable, hypocotyl and lateral. For each grafting method, scions of Gratex, Wichita, Choctaw, 10J and Graking pecan cultivars were grafted onto two-year old seedling rootstocks having a diameter of 1-1. 5 cm. Scions were grafted on seedling rootstocks using the hot cable grafting method in 5 times ranging from late October to mid-February and the hypocotyl and lateral grafting methods in five times ranging from early November to early March. The graft success was then investigated four weeks after grafting. The best grafting time was late-January to late-February using the hot cable grafting method and mid-February to late-March using the hypocotyl grafting method. Also, the highest percentage of grafted success was achieved by using Wichita scions (91. 7%), while «10J» had the lowest percentage. The Lateral grafting method was unsuccessful compared to the other two methods and percentages for different cultivars using this method were below 20%.