Location: Fruit and Tree Nut ResearchTitle: Peach fruit set and buttoning after spring frost
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2016
Publication Date: 7/30/2016
Citation: Chen, C., Okie, W.R., Beckman, T.G. 2016. Peach fruit set and buttoning after spring frost. HortScience. 51(7):816-821.
Interpretive Summary: Spring frost, a frequent concern in many peach growing areas, may freeze buds, blooming flowers, and fertilized fruitlets causing them to brown and abscise, and can dramatically affect peach fruit set. Peach growers need cultivars that crop reliably. In frost years, some cultivars will produce fruit with dead seeds that hang on the tree and are impossible to distinguish when it comes time to thin the small fruit. At harvest these fruit are puny and unmarketable. Although frost damage to crops is often mentioned in media reports, studies on peach tolerance to natural frost remain very limited largely because natural frost, along with its potential damage, occurs unpredictably. A spring frost occurred on 29 Mar. 2015 at the USDA-ARS Byron station after three weeks of blooming when most fruitlets were forming, which provided a valuable research opportunity to assess fruit and button set among peach cultivars, selections, and seedlings. Our research identified some apparent genetic differences in buttoning tendency, a preliminary step in breeding better cropping peaches.
Technical Abstract: A spring frost occurred on 29 Mar. 2015 at the USDA-ARS Byron station after three weeks of blooming when most fruitlets were forming. Due to severe fruitlet drop, the overall fruit set on a scale of 0-9 was substantially reduced, from 5.61 averaged in 2014 to 2.61 in 2015. In addition, buttons (abnormally small fruit with dead embryos) and skin-damaged fruits were common on some peach (Prunus persica) genotypes. Comparison of fruit and button set rating shown there was no difference between cultivars and selections, but some significant differences in fruit set for four ripening months, between the two years, and among nine chilling clauses, respectively. Fruit set levels shown a positive correlation with chill requirement hours and ripening months; cultivars with lower chill requirement and earlier ripening month tended to have lower fruit set levels, suggesting those cultivars appeared more vulnerable to spring frost damage because they usually bloomed earlier. Among the cultivars, the most common button set rating was one while a few others were rated zero or more than one. For example, ‘Sunprince’, ‘Loring’, and ‘Carored’ trees were high in the button set rating, whereas ‘Flameprince’, ‘Julyprince’, and ‘Contender’ trees were low. As for peach selections, BY04P1690n was among those with the highest button set rating. In the population derived from a cross of button-prone BY04P1690n and button-free BY99P3866w, fruit and button counts from ten long fruiting shoots ranged from 4 to 53 fruits (21.63 on average) and 2 to 27 buttons (10.39 on average). The peach button ranged from 5.36% to 87.10% (30.70% on average). The range, distribution, and percentage of the button counts suggested that, if buttoning was genetically controlled, it appeared quantitative. Further assessment is needed.