Mechanical Harvesting and Postharvest Storage of Two Southern Highbush Blueberry Cultivars Grafted onto Vaccinium arboreum Rootstocks

Abstract

<jats:p>The profitability of the fresh market blueberry industry in many areas is constrained by the extensive use and cost of soil amendments, high labor requirements for hand harvesting, and the inefficiencies of mechanical harvesters. <jats:italic>Vaccinium arboreum</jats:italic> Marsh is a wild species that has wide soil adaptation and monopodial growth habit. It has the potential to be used as a blueberry rootstock, expanding blueberry production to marginal soil and improving the mechanical harvesting efficiency of cultivated blueberry. The objectives of this research were to compare yield, berry quality, and postharvest fruit storage of own-rooted vs. grafted southern highbush blueberry (SHB) cultivars (Farthing and Meadowlark) grown on amended vs. nonamended soil and either hand or mechanical harvested. Yields of hand-harvested SHB during the first two fruiting years were generally greater in own-rooted plants grown on amended soil compared with own-rooted plants on nonamended soil or grafted plants on either soil treatment. However, by the second fruiting year, hand-harvest yields of grafted SHB were ≈80% greater than own-rooted plants when grown in nonamended soil. Yields of mechanical-harvested SHB grafted on <jats:italic>V. arboreum</jats:italic> and grown in either soil treatment were similar to yields of mechanical-harvested own-rooted plants in amended soil the second fruiting year, and greater than yields of own-rooted plants in non-amended soil. In general, mechanical harvesting reduced marketable yield ≈40% compared with hand harvesting. However, grafted plants reduced ground losses during harvest by ≈35% compared with own-rooted plants for both cultivars. Mechanical-harvested berries had a greater total soluble solids:total titratable acidity ratio (TSS:TTA) than hand-harvested berries, and berries harvested toward the end of the harvest season had a greater TSS:TTA than those from early-season harvests. As postharvest storage time increased, berry appearance ratings decreased and berry softness and shriveling increased, particularly in mechanical-harvested compared with hand-harvested berries. Firmness of mechanical-harvested berries decreased during storage, whereas firmness of hand-harvested berries remained relatively stable. However, fruit quality at harvest and during postharvest storage was unaffected by <jats:italic>V. arboreum</jats:italic> rootstocks or lack of pine bark amendment. This study suggests that using <jats:italic>V. arboreum</jats:italic> as a rootstock in an alternative blueberry production system has the potential to decrease the use of soil amendments and increase mechanical harvesting efficiency.</jats:p>

Applying New Technologies to Transform Blueberry Harvesting

“…As an alternative to hand harvesting, portable hand-held shaking devices (e.g., H model, BEI Inc., South Haven, MI, USA [24] and pneumatic limb shaker (Campagnola SRL, Bologna, Italy) have been used to harvest fresh market quality fruit onto a small, manually positioned catch frame [15][16][17]. However, the hand-held shaker such as the H1 berry stripper which weighs~2.4 kg has two major problems that limit its adoption: low harvest capacity and potential worker fatigue and injury.…”

“…Attempts have been made to harvest blueberries with semi-mechanical harvesting systems [15][16][17][18]. In these studies, hand-held, vibrating shakers (e.g., Model H1, BEI Inc., South Haven, MI, USA) and Hook Shaker (Campagnola SRL, Zola Predosa-Bologna, Italy) were used to detach blueberries from the plant and two portable fruit catching frames placed around two plants were used to collect the fruit (Figure 2).…”

“…However, the BEI's H1 vibrator weighs 2.4 kg and has a pistol grip attached to the shaker head. Holding the shaker by one hand made it difficult for a worker to use it continuously for a long period [15]. The hook shaker used in Chile [17] engaged one cane at a time limited harvest efficiency not much greater than the level achieved by hand harvesting.…”

Harvest of Southern Highbush Blueberry with a Modified, Over-The-Row Mechanical Harvester: Use of Handheld Shakers and Soft Catch Surfaces

“…Although pruning increased the number of marketable fruit, the selective removal of blue fruit remained a challenge. Studies with 'Meadowlark' and 'Farthing', two SHB cultivars from the University of Florida blueberry breeding program, have shown the potential for repeated harvests by commercial harvesters instead of hand harvest [5,7,8].The use of harvest aids such as handheld shakers is a low-cost option compared to more costly OTR harvesters, and handheld shakers were shown to reduce labor costs by increasing blueberry harvest efficiency [9,10]. Takeda et al [11] found that harvesting blueberries with handheld shakers in conjunction with a portable, soft catch surface frame resulted in less bruise damage than commercial OTR harvesters.…”

“…The use of harvest aids such as handheld shakers is a low-cost option compared to more costly OTR harvesters, and handheld shakers were shown to reduce labor costs by increasing blueberry harvest efficiency [9,10]. Takeda et al [11] found that harvesting blueberries with handheld shakers in conjunction with a portable, soft catch surface frame resulted in less bruise damage than commercial OTR harvesters.…”