Impact of Cross- and Self-pollination on Fruit Set, Fruit Size, Seed Number, and Harvest Timing Among 13 Southern Highbush Blueberry Cultivars

Abstract

<jats:p>Cross-pollination has been associated with improved fruit set, weight, and shortened time to ripening in southern highbush blueberry [SHB (<jats:italic>Vaccinium corymbosum</jats:italic> interspecific hybrids)]. Because of this, growers commonly plant two or more cultivars in small blocks to facilitate cross-pollination. However, many SHB cultivars may vary in the degree of improvement in each parameter after cross-pollination. Understanding the impacts of cross-pollination on a particular cultivar is crucial to forming planting recommendations, particularly as growers begin to transition to fields designed for machine harvest where large solid blocks would increase the harvest efficiency. The objective of this study was to examine the effects of cross- and self-pollination among 13 commonly planted or newly released SHB cultivars. Cross-pollination typically improved fruit set, fruit weight, and seed number while decreasing the average days to harvest. Cross-pollinated fruit always weighed more than self-pollinated fruit from the same cultivar, which was highly correlated to seed number per fruit. Although there was variation for each trait, interplanting with another unrelated cultivar sharing a similar bloom time remains the best recommendation to ensure early, high yield among these SHB cultivars.</jats:p>

Cross-compatibility of five highbush blueberry varieties and ideal crossing combinations

“…1.2) suggests that it is prudent to interplant whenever possible. Other studies have also shown that fruit mass can be increased when varieties are pollinated with pollen from other varieties (Bell et al, 2012;Harrison et al, 1993;Müller et al, 2013;Taber and Olmstead, 2016). In this study, the degree of benefit from inter-varietal pollen appeared to differ between varieties and while absolute positive effects were always detected, these were often not statistically significant.…”

“…For Suziblue and Twilight, intervarietal pollination also led to significant reductions in developmental time. Inter-varietal pollination has also been shown to decrease developmental time in other blueberry varieties such as Bluecrop, Bluegold, Legacy, Sierra, Toro and Patriot (Dogterom et al, 2000;Ehlenfeldt, 2001;Gupton and Spiers, 1994;Mackenzie, 1997;Müller et al, 2013;Taber and Olmstead, 2016). Choosing the correct pollen source appears to be especially important for varieties such as Eureka, Suziblue and Twilight as pollen quality is likely to have large consequences for yields and interplanting varieties to promote outcrossing therefore seems to be the best strategy for increased fruit mass and decreased developmental times.…”

“…Blueberry fruit quality is directly affected by pollen source, where inter-varietal pollination often positively affects fruit size, weight, and developmental time when compared to pollination within varieties (Bell et al, 2012;Dogterom et al, 2000;Ehlenfeldt, 2001;Gupton and Spiers, 1994;Harrison et al, 1993;Huang et al, 1997;Müller et al, 2013;Taber and Olmstead, 2016;Usui et al, 2005). In response to this constraint, growers often plant different varieties in adjacent rows in an orchard in attempt to increase yield through inter-varietal pollination.…”

Highbush Blueberry Cultivars Differ in the Relationship between Seed Number and Berry Weight during the Harvest Season

“…Cultivars differ in percent fruit set or seed set because of differing bloom periods and associated differences in weather (Arrington and DeVetter, 2017), differences in attractiveness of the flowers to pollinators (Courcelles et al, 2013), and genetic differences in self-or cross-compatibility and pollen quantity or quality (e.g., Brewer and Dobson, 1969;Chavez and Lyrene, 2009;Ehlenfeldt and Kramer, 2012;MacKenzie, 1997;Rabaey and Luby, 1988;Vander Kloet, 1983). As a result, cultivars have been found to differ in the seeds/berry and, often as a result, berry size (Arrington and DeVetter, 2018;Brewer and Dobson, 1969;DeVetter et al, 2016;Eaton, 1967;Ehlenfeldt, 2001;Ehlenfeldt and Martin, 2010;Gupton, 1984;Gupton and Spiers, 1994;Jackson et al, 1972;Lang and Danka, 1991;Lyrene, 1989;Meader, 1936;Meader andDarrow, 1944, 1947;Moore et al, 1972;Morrow, 1943;Payne et al, 1989;Taber and Olmstead, 2016).…”

“…Cultivars differ in the berry weight per seed (Bailey, 1938;Brewer and Dobson, 1969;Eaton, 1967;Gupton, 1984;Knight and Scott, 1964;Lyrene and Goldy, 1983;Meader and Darrow, 1944;Rabaey and Luby, 1988;Taber and Olmstead, 2016). It is possible that cultivars vary in growth hormones produced by the fertilized ovules or developing seeds (Mainland and Eck, 1968;Meader andDarrow, 1944, 1947;Moore et al, 1972).…”