Document Type : Research Paper
Authors
1 M.Sc. Graduate of Horticultural Science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran
2 Assistant Professor, Department of Horticultural Science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran
3 Associate Professor، Department of Horticulture Science، Faculty of Agriculture، Shahid Chamran University of Ahvaz، Ahvaz، Iran
Abstract
Background and Objectives
Olive is one of the most important fruit trees. It has special importance in the fruit production industry of Iran and the world. During the past decades, in Khuzestan province, like some regions of the country, many olive orchard have been stablished without considering the selection of suitable cultivars; so that after several years, olive trees have the problems in terms of flower production, such as lack of flowering, poor flowering, poor fruit set and a decrease in oil percentage. Different methods can be used to solve these problems. Girdling is one of the most important methods of bark prunning, which causes early flowering, fruiting, and increasing the tree's productivity time. Considering the role of girdling, this research was designed to investigate the effects of girdling at different times on the flowering and biochemical characteristics of three olive cultivars (Conservalia, Roghani, and Mission) with poor flower production.
Materials and Methods
This experiment was conducted in the olive research orchard of the Faculty of Agriculture of Shahid Chamran University of Ahvaz, on 20-year-old olive trees in 2022-2023. In this experiment, the effects of girdling on the quantitative and qualitative characteristics of flowers and some biochemical indicators were investigated.The statistical design was the split plots with a basic design of randomized complete blocks Cultivars (Conservalia, Roghani, Mission) as the main plot and girdling time (control without girdling, girdling in January, February and March) was considered as a sub-plot with 4 replications.
Results and Discussion
The results showed that girdling at all times increased the number of flowers in the inflorescence compared to the control treatment. In january girdling, the highest number of flower in the inflorescence was recorded (18.17), which was more than the number of flowers in the control (9.1). The highest number of flower in the inflorescence occurred in the Roghani cultivar (14.87). The highest percentage of complete flowers was recorded in january girdling (49.92%) and the Mission showed the highest percentage of complete flowers (45.31%). The relative water content in january girdling showed the highest value (84.49%), which was significantly higher than the relative water content in the control, february and march. The highest relative water content was recorded in Mission (72.33%). Girdling significantly increased the fresh weight of leaves in the ringed branches, but this effect was reduced from January to March. Roghani had the highest leaf dry weight (14.94 g), which was not significantly different from Mission's leaf dry weight (13.69 g), but it was significantly higher than Conservalia's dry weight. The highest amount of leaf dry weight was recorded in January girdling (17 g), which was higher than the dry weight of leaves in the control, February and March girdling.The highest amount of total soluble carbohydrates in the Roghani cultivar was obtained in June (22.23 mg/g). Girdling increased the amount of total soluble carbohydrate, but it decreased from January to March. The results showed that the number of flowers in the inflorescence, fresh and dry weight of flowers and inflorescences, the percentage of complete flowers in the branches treated with girdling, increased and the beginning of flowering was improved. Roghani and Mission cultivars showed better results regarding flowering characteristics, carbohydrates, leaf relative water content and leaf dry weight.
Conclusion
The immediate effect of girdling is to limit the transfer of sap flow from the leaves to the root tissue and the bottom of the plant, which accumulates sugar and plant hormones in the upper part of the wound. These accumulated materials are transferred to the growing buds and inflorescences and affect them. In general, in the present experiment, girdling improved the flowering traits and the best time of girdling is in January that recommended for olive cultivars.
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