The Effect of Volck Mineral Oil Spraying on Flowering and Biochemical Characteristics of Two Olive Cultivars under Ahvaz Condition

Olive (Olea europaea L.) is an evergreen tree and one of the most important products of the horticultural section in Iran due to high nutritional value of its oil and fruits. Adaptation of olive cultivars to the climatic conditions of different regions are not the same. The results of studies showed that special cultivars are recommended for each region. In tropical and subtropical climates with mild winter such as Ahvaz, the chilling requirement of olive trees is not completed. This condition has led to poor and insufficient flowering in some olive cultivars. Mineral oils, including volck oil are one of the most beneficial treatments to complete chilling requirement and bud break in fruit trees. The aim of this study was to investigate the response of two olive cultivars (Manzanilla and khaziri) to the application of volck mineral oil and studying their flowering and biochemical characteristics in Ahvaz condition.

In this experiment, the effect of volck mineral oil spraying [control (water spray), 1, 3, 5 %] on two olive cultivars were investigated. The experimental design was split plot arranged in complete block design with four replications. Measured traits included flowering characteristics such as the number of inflorescences in the branch, flowers in inflorescence, complete flowers, flowering days after treatments, percentage of flower fall, fresh and dry weight of flower and inflorescence. Biochemical properties such as bud carbohydrates and ABA, leaf proline and chlorophyll were measured.

The results showed that foliar application of 3 and 5 % volck oil caused flowering (31.8 and 28.7 days after treatment, respectively) in Manzanilla cultivar. Bud carbohydrate content increased significantly after tree spraying with volck oil in all of three concentrations. The highest content of bud carbohydrates (78.68 mg/g) was obtained in khaziri when treated with 3% volck oil. The use of volck oil was effective in increasing the ABA concentration in Manzanilla cultivar and its effect was as 3 and 5% volck oil (83.1 and 105.4 µg/g, respectively). The amount of proline in both cultivars increased until 60 days after applying three concentrations of volck oil. The levels of chlorophyll a, chlorophyll b and total chlorophyll increased until 30 days after treatment and then were decreased. Volck oil (3%) can be used for flowering of Manzanilla cultivar in climatic conditions of Ahvaz.

Based on the obtained results, it seems that the effect of volck oil on flowering and biochemical traits depends on the type and concentration of mineral oil and type of the cultivar. In the present study, flowering occurred when Manzanilla cultivar treated with mineral volck oil (3 and 5%) and the flowering traits were improved at 3% oil more than other treatments.