Effect of pollen grain type on some quantity and quality characteristics of fruit in three female cultivars of kiwifruit

Kiwi (Actinidia deliciosa) is a dioecious plant species, requiring cross pollination for fruit production. Because of its high resistance to the lower temperature (up to –18ºC), kiwifruit is a good alternative to Citrus orchards in north part of country encountering chilling stress. This research was done to study the effects of two male cultivars on quantitative and qualitative characteristics of three female cultivars to determine of the best cross for each female cultivar.

This study was carried out as factorial experiment; female cultivars in three levels (Hayward, Bruno, Monty) and male cultivars in two levels (Tomori and Matua) based on completely randomized design with 6 treatments, 4 replicates, 24 plots and 10 flowers in each plot. Different fertilization was done between male and female cultivars. After harvest of fruits, the effect of treatments on fruit fresh weight, fruit length, fruit diameter, fruit acidity, total solid solution and fructose content in fruits were measured.

Results showed that the type of cultivar alone had a significant effect on fruit weight, length and diameter, fruit acidity, soluble solids content and fruit sugar content at 1% level. Male cultivar showed significant differences in fruit weight, fruit length, acidity and soluble solids content at 1% and fruit sugar content at 5% level but no significant effect on fruit diameter. Also, interaction effect of male and female cultivars was significant on weight, length and total solution solid of fruit in 1% level and on fruit diameter in 5% level, but it has not effect on fruit acidity and sugar. The highest fruit weight (85.24 g), fruit length (70.82 mm) and total soluble solid (13.50°Brix) were obtained from cross of Bruno and Matua cultivars. The maximum fruit diameter (46.43 mm) and fruit fructose sugar (6.08 g L-1) was observed from cross of Hayward and Matua and Monty and Tomori cultivars, respectively. The lowest fruit acidity (pH) (3.53) was obtained in cross of Monty and Matua cultivars.

Artificial pollination is a suitable approach to overcome all kinds of problems caused by pollination and fertility and increases the quality and marketability of kiwifruit. Pollination at the right time and with the right method and the right choice of male and female cultivars will improve most quantitative and qualitative traits of kiwifruit. Increasing fruit size is important to increase marketability and increase fruit sugar to enhance fruit flavor, and the main focus of such studies should be on these issues.