Xenia and Metaxenia in Persian Walnut (Juglans regia L.)

In 2007 and 2008, the influence of pollen source on the shell and kernel traits of resulting seeds and on fruit set was examined to evaluate the potential for Xenia or Metaxenia in Persian walnut. Pistillate flowers of ‘Jamal’, ‘Chandler’, ‘Hartley’ and ‘Pedro’ were crossed with the pollen of ‘Serr’, ‘Z60’ and ‘Damavand’. The pistillate flowers on each female parent were covered about one week before starting the reception period of the flowers, and the bags remained 7-10 days after pollination. The catkins of the male parents were collected just prior to pollen shedding, and they were kept in room temperature for 24- 48 hours. Collected pollen was refrigerated until use. Pollination was done when the stigmas were expanded and were pinkish in color. Data recording were started after removing the bags and measuring the percent of fruit set and recording the fruit growth and time of ripening. The fruits, nut and kernel weight, length, diameter, length to diameter, shell thickness, shell weight and kernel percentage were evaluated after harvest. The result showed that nut and kernel diameter, kernel weight, length to diameter, shell-thickness and shell weight were affected by pollen source. There were also significant differences in the fruit set of the different pollen parents. Pollens of ‘Damavand’ and ‘Z60’ significantly decreased the nut diameter and weight in some female parents. Total fat and protein content of kernels were significantly affected by the type of pollen parent.