Document Type : Original Article
Authors
1
Ph.D. Graduate, Department of Horticulture, Faculty of Agriculture, University of Zanjan, Zanjan, Iran.
2
Associate Professor, Department of Horticulture, Faculty of Agriculture, University of Zanjan, Zanjan, Iran.
3
Associate Professor, Agricultural and Natural Resources Research Center of Zanjan Province, Zanjan, Iran.
4
Assistant Professor, Agricultural Engineering Research Group, Guilan Agricultural and Natural Resources Research and Education Center (AREEO), Rasht, Iran.
5
Agricultural and Natural Resources Research Center of Zanjan Province, Iran.
10.30466/rip.2021.53736.1194
Abstract
Alternate bearing is a common phenomenon in fruit trees that affects orchard management practices, tree growth physiology, and the economy of the olive industry. The Tarom region of Zanjan Province is one of the most important olive-producing areas in Iran; however, no systematic report has yet been published on the severity of this phenomenon among olive cultivars in this region. This study was conducted at the Tarom Research Station to determine the intensity of alternate bearing in 12 promising olive cultivars by evaluating growth, reproductive, and pomological traits over four consecutive years. The results showed that annual vegetative growth, percentage of perfect flowers, and final fruit set were generally higher in OFF-years than in ON-years. In contrast, fruit yield efficiency in all studied cultivars was significantly greater in ON-years. The findings revealed considerable variation among cultivars in alternate bearing intensity, despite being grown under identical climatic and orchard management conditions, confirming the genetic basis of biennial bearing in olive. Cluster analysis based on biennial bearing indices (BBI) classified the cultivars into four groups: severe, relatively severe, relatively low, and low alternate bearing. Overall, cultivars with low or relatively low BBI, including ‘Grossane’, ‘Zard’, ‘Marie’, ‘Koroneiki’, ‘Arbequina’, and ‘Abou-Satl’, are recommended for cultivation in the Tarom region.
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