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Submitted to: HortScience
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/7/2002 Publication Date: N/A Citation: N/A Interpretive Summary: Metaxenia is a change in the tissue of a mother plant due to pollen source, especially for characters such as fruit weight and ripening time. For example, an earlier study in southern blueberry cultivars suggested pollen from early-ripening cultivars induced larger, earlier ripening fruit on the recipient cultivar. To evaluate if this was true for northern highbush blueberry cultivars, 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. Significant differences due to pollen sources were found; however, no single pollen source had a completely consistent effect on ripening (either accelerating or delaying). As "males", 'Duke', 'Bluejay', 'Rubel', and 'Elliott' accelerated ripening in 8 of 9 possible combinations. The most common general effects across all lcombinations were delays of ripening, suggesting that poor pollination, poor fertilization, or inbreeding effects may have been factors contributing to the observed variating in ripening times. No directed metaxenia (i.e. pollen from early-ripening cultivars inducing larger, earlier ripening fruit) was observed in these cultivars; however the ability of a pollen source to accelerate ripening was strongly correlated with ability to enhance fruit weight. In general, the pollen sources which enhanced ripening and fruit weight on other cultivars the most are those also regarded as self-fruitful. Technical 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, 'Duke', 'Bluejay', 'Rubel', and 'Elliot' accelerated ripening in 8 of 9 possible combinations. The largest relative effects were seen in delays of ripening, suggesting that poor pollination, poor fertilization, or inbreeding effects may have been factors contributing to the observed variation in ripening times. A non-significant 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 size, a non-significant correlation existed between the ripening interval of cultivars used as pollen sources and fruit size 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 sources which enhanced ripening and fruit weight on other cultivars are those also regarded as self- fruitful. |
