Southern highbush blueberry responses to humic acid application in soilless substrates

Summary

This study evaluated humic acid as a biostimulant for southern highbush blueberry grown in soilless substrates across two greenhouse experiments: one on transplant establishment and one on fruit development. Although humic acid application elevated substrate respiration, pH, and electrical conductivity, it failed to improve root growth, transplant success, or fruit yield, and occasionally reduced fruit quality; responses were genotype-dependent. The authors conclude that humic acid applications offer limited benefit during these critical growth stages in substrate-grown blueberry.

Regional applicability

The study was conducted under greenhouse conditions, which may not fully reflect outdoor UK horticultural conditions or open-field cultivation. However, the soilless substrate system is directly relevant to UK glasshouse blueberry and soft fruit production; the findings suggesting limited benefit of humic acid in these systems could inform UK grower practice, though cultivar choice and local substrate formulations would require validation.

Key measures

Humic acid concentration (0, 7, 13, 24 mL⋅L−1); substrate respiration rates; substrate pH; electrical conductivity; root growth; transplant success; fruit yield; fruit quality; genotype-specific responses in three cultivars

Outcomes reported

The study measured root growth, transplant success, substrate respiration, pH, electrical conductivity, fruit yield, and fruit quality in southern highbush blueberry plants treated with varying concentrations of humic acid. Humic acid application altered substrate chemistry but did not improve transplant success, yield, or consistently enhance fruit quality.

Topic tags