Potential Application of Different Amounts of Volck Oil to Provide Chilling Requirement of Pistachio Trees (Pistacia vera L.) under Field Conditions

A lack of adequate annual chilling in fruit growing trees of temperate regions especially pistachio is a principal problem observed in many areas with partially warm winters. Usually, this phenomenon results in disorders in vegetative and reproductive structures, decrease in production of pollen, falling of flower buds and decrease in or loss of fruit set. Presently the use of some substitute chemical compounds, which somehow compensate for the lack of chilling requirement, has been confirmed by some scientific reports. The field study was carried out to probably obviate the chilling requirement of pistachio trees (cv. Akbari) using different percentages of Volck oil including 2, 3, 4% and control and determine the most proper concentration of this oil in 2013–2014 at a research farm in Anar, Iran. These trees were irrigated with water having different electrical conductivity (EC) (9 and 15 dS m-1) as well. This study was performed as factorial test in a completely accidental block design with three replications and effect of different treatments on pistachio plant growth indices was measured and recorded. The results showed the trees treated with Volck oil (4%) together with irrigation with less salinity (EC of 9 dS m-1) had more positive effects on increased yield as compared to lower percentages (2 and 3%) of this oil, and control and irrigation with more salinity (EC of 15 dS m-1) under field conditions.