Evaluation of Incompatibility and Traits of some Plant Growth Regulators on the Quality and Quantity of Red Hawthorn (Crataegus monogyna Jacq.)

One of the cultivable fruit trees that can be cultivated in Iran, It is a typical Hawthorn with the scientific name Crataegus monogyna Jacq. Generally, hawthorn species are scattered in temperate regions of the northern hemisphere. The genus of hawthorn is also distributed in most parts of Iran. Its largest distribution is in the north, northeast, northwest and west. This genus in Iran has 27 species and hybrids. Hawthorn as a plant resistant to air pollution, it is compatible with a variety of soils and ornamental plants. In Europe this plant are widely used in fence building. The fruit of this plant has medicinal and edible value and is used in various forms such as refreshment, juice, jams, jelly and as a flavoring of food. Small size and lack of uniformity of hawthorn fruits set limits on the production and processing of the product. One reason of these restrictions is producing abundant flowers and converting a high percentage of them to fruit. This experiment was conducted to determine the level of compatibility or incompatibility of the hawthorn tree, as well as the effect of different growth regulators on the fruit content and fruit quality.

In this study, the possible incompatibility and effect of some plant growth regulators on the physical and chemical properties of hawthorn fruit were investigated. This study is a randomized factorial design with two levels of pollination (self-pollinated and open-pollinated) and growth regulators gibberellic acid (75 and 150 ppm), NAA (10 and 20 ppm) and ethephon (75, 150 ppm) in three replications. Indices of fruit set percent (3, 7, 10 and 17 weeks after full bloom), seed weight, flesh and fruit, flesh to seed ratio, dry weight and fruit juice percent, TSS, TA, TSS / TA and the number of cells per microscopic field of vision were investigated.

Effect of pollination (self and open pollination) and foliar application of plant growth regulators on the percentage of hawthorn fruit set, fruit weight, seed weight and pulp to seed ratio was significant while treatments do not significantly affect the weight of the meat and juice percent. According to the results, qualitative specifications of hawthorn fruit (soluble solids, total acid and ratio of total soluble solids to total acid) were affected by plant growth regulators used in this experiment (GA, NAA and ETHE). So that the number of cells were affected by treatment such that ethephon has greatest impact on the number of cells in open-pollinated and self-pollinated trees in concentrations of 75 and 150 ppm.

The results showed that the hawthorn used in this experiment was incompatible and for better fruit set requirement to free pollination (use of pollinators). Also, use of plant growth regulators on the percentage of fruit set and fruit size was effective. The highest percentage of fruit set was obtained by Gibberellin spray and the largest fruits were obtained by spraying with ethephon.