Introduction
The Juglandaceae family includes about 50 species of 11 genera of which Carya (hickory tree), Pterocarya (wingnut tree), and Juglans are the major members. The pecan, Carya illinoinensis is the most economically important member of the Carya genus and is the most valuable native North American nut crop. The Carya genus comprises 20 species.
Materials and Methods
Golestan province is located in the northern temperate region between 37.2898° N, 55.1376° E from the Greenwich meridian and in the northern part of the country. The amount of precipitation reaches 200 mm in the northernmost part of the province and more than 700 mm in the southern parts of Alborz foothills. Temperature varies across different parts of the province, generally increasing from west to east and from south to north. The genotypes used in this project are G4, G3, G43, G63, which were selected and propagated from the elite trees available in the province after quantitative and qualitative evaluation, and the cultivars are Mahan and Comanche, which were propagated from grafted trees of the Dezful Research Center collection. Grafted seedlings were produced using thethermal cable technique and planted in the specified locations in the above 2 regions. Grafted trees from 4 elite genotypes of Golestan (G4,G3,G43,G63) plus Comanch and Mahan 2 commercial cultivars have been studied in randomized completely block design (RCBD) for 3 years in two regions. In the second phase of experiment, the fruit characters and yield evaluated based on pecan descriptor. The results were analyzed by SAS statistical software and the reactions of genotypes were evaluated in different places and during different years.
Results and Discussion
This evaluation was conducted during the years 2021 to 2024 at Chalki research station of the Golestan Agricultural and Natural Resources Research and Education Center in Gorgan and on the farmer's land located in Igder village, located 30 km from Gonbad city. Measurements were conducted on fruits harvested in 2022 and 2023. During both years, the Mahan cultivar did not produce a sufficient number of fruits in either region and was therefore excluded from the comparison. A significant effect of location and year was observed only for the fruit weight trait. Among the genotypes, G43 exhibited the highest fruit weight (11.75 g) and demonstrated vigorous growth with a broad canopy in both locations. However, fruit yield over the two years of evaluation showed no significant differences among the studied cultivars and genotypes across the two regions.Due to the results of the first phase, the maximum tree height was in Mahan (242.5 cm) and the lowest height in G63 (118.66 cm). The maximum canopy spread was in comanch (138.72 cm) and the lowest was in G63 (90.11 cm).There were significantly differences between two regions. The length of the growing season among cultivars was 257 days in Gonbad and 237 to 247 days in Gorgan. Study of dichogamy during the years 2021-2022 in the cultivars and genotypes showed two cultivars Comanche and Mahan were protandry in Gorgan, while both cultivars showed protogyny in Gonbad. Also, 4 genotypes of the province (G3, G4, G43, G63) showed protogyny.
Conclusions
This project, conducted over both vegetative and reproductive phases, evaluated elite pecan germplasm within the province. The objective was to utilize the region’s existing genetic potential and to compare it with commercially available cultivars in the country, with the goal of identifying and promoting superior genotypes for the establishment and expansion of new orchards in Golestan Province. The results of the two phases of this research showed that some of the introduced genotypes have the ability to compete with the existing commercial cultivars, which will require further investigation in the years of peak fruiting and maturity of the tree. The length of the growing season among cultivars was 257 days in Gonbad area and 237 to 247 days in Gorgan. Also, the effects of drought conditions in Golestan province during 2021-2022 should be included in the relative determination of the results. As a summary, based on the evaluation of these two phases and considering the growth and fruiting conditions, two genotypes G4, G43 and G63 can be considered as promising genotypes for development.
Acknowledgement
The authors consider it necessary to appreciate the support of Horticultural Sciences Research Institute (HSRI) and Golestan Agriculture and Natural Resources Research and Education Center in the implementation of this project. |
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