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Figure 1. 

Images of the wild blueberry fields and the open-top warming chamber used in this study. (a) UAV image showing the mixture of different clones in a wild blueberry field; (b) a close-up image showing different colors of different clones; (c) an image showing the open-top warming chamber with the active heating system used in the present study. Photo credit: Xiaoxue Mo.

Figure 2. 

Physical properties of wild blueberries. (a) Berry diameter (mm), (b) berry weight (g), and (c) berry water content (%), under different climate warming and mitigation treatments. The treatments include warming without amendment (AH), warming with mulching (AH_M), and warming with biochar-compost mix (AH_BCM), compared with control plots without (CON) and with biochar-compost mix (CON_BCM). The bar within each violin plot represents the average value across 20 berries. Letters above the boxes indicate significant differences based on Tukey's HSD post hoc test following two-way ANOVA (p < 0.05).

Figure 3. 

Fruit chemistry of wild blueberries. (a) pH, (b) titratable acidity (TA), (c) total soluble solids (TSS), and (d) ripening index (TSS/TA) under various warming and mitigation treatments. Treatments include control without amendment (CON), control with biochar-compost mix (CON_BCM), active heating without amendment (AH), active heating with mulching (AH_M), and active heating with biochar-compost mix (AH_BCM). Bars represent the means and standard errors of six replicated clones. Clones and locations were treated as random effects and treatments as fixed effects. Bars with different letters indicate significant differences.

Figure 4. 

Wild blueberry sugars. (a) Fructose, (b) glucose, and (c) total soluble sugars under different warming and mitigation treatments. Treatments include control without amendment (CON), control with biochar-compost mix (CON_BCM), active heating without amendment (AH), active heating with mulching (AH_M), and active heating with biochar-compost mix (AH_BCM). Bars represent the means and standard errors of six replicated clones. Clones and locations were treated as random effects and treatments as fixed effects. Bars with different letters indicate significant differences (p < 0.05).

Figure 5. 

(a) Total soluble protein (TSP), (b) total anthocyanins, (c) total phenolic concentration, (d) and ferric-reducing antioxidant power (FRAP) in wild blueberries under different warming and mitigation treatments. Treatments include control without amendment (CON), control with biochar-compost mix (CON_BCM), active heating without amendment (AH), active heating with mulching (AH_M), and active heating with biochar-compost mix (AH_BCM). Bars represent means and standard errors of six replicated clones. Clones and locations were treated as random effects, and treatments as fixed effects. Bars with different letters indicate significant differences (p < 0.05).

Figure 6. 

Correlation analysis of nutritional quality traits, metabolites, and antioxidant activities in wild blueberries. Light-yellow boxes indicate traits with no correlations. Traits with cyan to blue colors represent positive correlations, while yellow to red indicate negative correlations. Groupings are as follows: berry pH and ripeness index (TSS/TA ratio); berry water content, size, and weight; anthocyanins and TAC/TPC; total soluble solids, fructose, glucose, and sugar-related compounds; and phenolic acids, antioxidant activities (FRAP), soluble proteins, titratable acidity, total organic acids, citric acids, and quinic acids.