Investigations of Metaxenia in Northern Highbush Blueberry ( Vaccinium CorymbosumL.) Cultivars

Abstract

Metaxenia is a change in the tissue of a mother plant as effected by pollen source. A group of 10 cultivars with early to late ripening times were used as females and were cross-pollinated, in a greenhouse, with 10 cultivars (9 matching the female group) to examine the potential for ripening time and fruit-size metaxenia in northern highbush blueberries. Significant differences due to pollen sources were found both across and within cultivars as females; however, no single pollen source had a completely consistent effect on ripening (either accelerating or delaying). Within females, however, the use of 'Duke', 'Bluejay', 'Rube', and 'Elliott' as males, accelerated ripening in 8 of 9 possible combinations. The largest relative effects were delays of ripening, suggesting that poor pollination, poor fertilization, or inbreeding effects may have been factors contributing to the observed variation in ripening times. No correlation was observed between ripening interval of pollen source parents and the effect on the ripening interval of the cultivars as females (i.e. early-ripening males did not induce the fruit on females to ripen earlier). Similarly, for fruit weight, no correlation was found between the ripening interval of cultivars used as pollen sources and fruit weight on females pollinated by those sources. The ability of a pollen source to accelerate ripening was very highly correlated with ability to enhance fruit weight. In general, pollen that enhanced ripening and fruit weight on other cultivars came from cultivars that are regarded as self-fruitful.