Flower Bud Density Affects Vegetative and Fruit Development in Field-grown Southern Highbush Blueberry

Abstract

<jats:p>Floral budbreak and fruit set in many southern highbush blueberry (SHB) cultivars (hybrids of <jats:italic>Vaccinium corymbosum</jats:italic> L. with other species of <jats:italic>Vaccinium</jats:italic>) begin prior to vegetative budbreak. Experiments were conducted with two SHB cultivars, `Misty' and `Sharpblue', to test the hypothesis that initial flower bud density (flower buds/m cane length) affects vegetative budbreak and shoot development, which in turn affect fruit development. Flower bud density of field-grown plants was adjusted in two nonconsecutive years by removing none, one-third, or two-thirds of the flower buds during dormancy. Vegetative budbreak, new shoot dry weight, leaf area, and leaf area: fruit ratios decreased with increasing flower bud density in both cultivars. Average fruit fresh weight and fruit soluble solids decreased in both cultivars, and fruit ripening was delayed in `Misty' as leaf area: fruit ratios decreased. This study indicates that because of the inverse relationship between flower bud density and canopy establishment, decreasing the density of flower buds in SHB will increase fruit size and quality and hasten ripening.</jats:p>

Southern Highbush Blueberry Production in High Tunnels: Temperatures, Development, Yield, and Fruit Quality During the Establishment Years

“…Most cultivars require more chilling for vegetative than for reproductive bud break (Gough, 1994). Thus, floral bud break normally precedes vegetative bud break (Maust et al, 1999). If the reproductive chilling requirement is met, but the vegetative requirement Fig.…”

Flower power: Floral and resource manipulations reveal how and why reproductive trade‐offs occur for lowbush blueberry (Vaccinium angustifolium)

“…The sixth trait, ripe fruit production per node, did not increase in response to standard flower removal in this study but did increase in response to biased flower removal (Table ). Increases in vegetative mass (Hartemink et al., ; Maust et al., ), leaf area (Karlsson, Andersson, & Svensson, ; Maust et al., , ), fruit ripening rate (Maust et al., , ; Valantin‐Morison, Vaissière, Gary, & Robin, ), and fruit dry mass (Vallius, ) have all been reported in previous flower removal studies. However, we have found no studies besides ours that have reported significant removal effects on proportion node success or fruit titratable acidity.…”

“…Putting these trade‐offs in context, a concave‐up form is thought to be evidence that a taxon is evolving to minimize the negative effects of (or to “opt out” of) a trade‐off (Sletvold & Ågren, ). Lowbush blueberry reproductive structures may ultimately depend on vegetative structures for carbon (Birkhold, Koch, & Darnell, ; Maust et al., ), so it is logical that lowbush blueberry would evolve to opt out of a vegetative‐effort‐versus‐reproductive‐effort trade‐off to the extent possible, even when these two functions necessarily compete for carbon initially (Sletvold & Ågren, ). Similarly, lowbush blueberry fruit may rot quickly because of their high sugar content (Glass, Percival, & Proctor, ) and may compete for limited dispersal opportunities (Bell et al., ), so it also logical that lowbush blueberry would opt out of a fruit‐longevity‐and‐attractiveness‐versus‐reproductive‐effort trade‐off as well.…”

“…If a plant can produce many fruit, selection may favor prioritizing the highest‐quality of these instead of equal investment across all of them (Brown & McNeil, ). It may also be physiologically impractical for all fruit to ripen quickly and simultaneously (Maust et al., ) or for each fruit to be equally and highly rewarding (Stapanian, ), necessitating steep trade‐offs between reproductive effort and traits like those identified above. If our results are supported by future work, we may have documented some of the selection pressures that underpin reproductive phenotypes in lowbush blueberry.…”

“…When β 1 < 0 and β 2 > 0, the curve will be concave down, and when β 1 > 0 and β 2 < 0, the curve will be concave up. Additionally, in contrast to the quadratic‐family functions ( e.g ., Y = β 0 + β 1 X + β 2 X 2 ) used in the past to model trade‐off nonlinearity ( e.g ., Maust, Williamson, & Darnell, , ; Sletvold & Ågren, ), this exponential function is assured to be monotonic ( i.e ., continuously decreasing) as reproductive effort increases.…”